common ancestor

red panda

raccoon

giant panda

other bears

SECTION

1.2Determining How Species Are Related

Key Terms

ancestor

anatomy

physiology

phylogenetic tree

h e goal of modern classii cation is to assign species to taxa so that the classii cation

rel ects both morphological similarities among organisms as well as hypotheses about

their phylogeny (evolutionary history). To do this, biologists use the concept of shared

evolutionary history. If two species share much of the same evolutionary history, it means

they have a fairly recent common ancestor. In other words, the more a species shares

its evolutionary history with another, the more closely related they are thought to be.

Consider the example of the animals in the family Canidae, which includes wolves,

coyotes, jackals, foxes, and domestic dogs. Members of this family have morphological

characteristics in common, including having i ve toes on the front feet and four toes on

the back feet. h ey are not able to retract, or pull closer to the body, their claws, unlike

other carnivores such as cats. h ey also have elongated snouts. Aside from morphology,

what other types of evidence do scientists examine to determine relationships among

species? In terms of phylogeny, it is hypothesized that organisms in family Canidae

share a common ancestor. In particular, based on DNA evidence, scientists believe that

the grey wolf is the ancestor of the domestic dog.

Evidence of Relationships Among Species

Do you think that the giant panda in Figure 1.5 is more closely related to bears or

raccoons? Giant pandas have characteristics of both groups, and scientists debated the

puzzle of how to classify them for more than 100 years. How do scientists determine

how much of the evolutionary histories of two species is shared? In modern taxonomy,

three main types of evidence that are used include anatomical, physiological, and DNA.

h e information is then interpreted to make hypotheses about evolutionary history

and how closely related dif erent species are. In the case of the giant panda, both

physiological and DNA evidence placed this species closer to bears than raccoons.

ancestor an organism

(or organisms) from

which other groups

of organisms are

descended

Figure 1.5 This branching tree diagram shows the relationships among giant pandas, bears, and raccoons.

Chapter 1 Classifying Life’s Diversity • MHR 17

A C

Whale Bat Horse Human

B

Anatomical Evidence of Relationships

Recall that morphology refers to the body size, shape, and other physical features of

organisms. Studying morphology helps scientists learn more about how an organism

develops and functions structurally. Studying morphology also helps scientists

determine evolutionary relationships among species. Anatomy, which is the study of

the structure of organisms, is a branch of morphology. Study the oviraptor and the

New Guinean cassowary shown in Figure 1.6.

At i rst glance, it may not seem that these two organisms—one a dinosaur, the other

a bird—are closely related. In fact, biologists used to think that modern reptiles shared a

much closer evolutionary relationship with dinosaurs than birds did. However, detailed

studies over the past several decades provide convincing evidence that dinosaurs and

birds share a surprising number of anatomical features. For example, both have bones

with large hollow spaces, whereas living reptiles have dense bones. Also, the arrangement

of dinosaur bones in the hip, leg, wrist, and shoulder structures show stronger similarities

to birds than to living reptiles. Some small dinosaur fossils, calculated to be about

150 million years old, have feathers, as you can see in Figure 1.6 (C). h ese are some

of the kinds of anatomical evidence that biologists have used to hypothesize a close

evolutionary relationship between modern birds and dinosaurs.

anatomy the branch

of biology that deals

with structure and

form, including internal

systems

Another example of using anatomical evidence to determine relationships among

organisms comes not from fossils, but from living species. Compare the bones in

Figure 1.7 from a whale l ipper, a bat wing, a horse leg, and a human arm. Even though

these species look dif erent on the outside, they have similar bone structures on the

inside. Over millions of years, the size and the proportions of the bones have been

modii ed for dif erent purposes (swimming, l ying, running, and grasping). However,

the overall arrangement and similarities indicate a shared evolutionary history.

Figure 1.6 (A) This artist’s conception of Oviraptor philoceratops might not appear to be related

to the cassowary (B), a bird from New Guinea, but these animals have many similar characteristics

that indicate a shared evolutionary history. (C) This fossil shows the remains of Archaeopteryx,

an animal from about 150 million years ago that had many dinosaur features as well as feathers.

Infer Which similarities might prompt you to think that the oviraptor and the cassowary are

more closely related than was commonly thought?

Figure 1.7 The same

bones are found in the

forelimbs of these four

mammals. The matching

sets of bones are colour-

coded in this illustration.

18 MHR • Unit 1 Diversity of Living Things

A B

Physiological Evidence of Relationships

Physiology is the study of the functioning of organisms—how they work. Physiology

includes studying the biochemistry of organisms, including the proteins they make.

Whether as enzymes or as parts of cells and tissues, an organism’s proteins are

determined by the organism’s genes, since genes are coded instructions for making

proteins. By comparing proteins among dif erent species, the degree of genetic

similarity or dif erence can be determined. Modern technology has provided new tools

for comparing species at this level, which has led to some organisms being reclassii ed.

physiology the branch

of biology dealing

with the physical and

chemical functions of

organisms, including

internal processes

For example, do you think the guinea pig and the mouse in Figure 1.8 are closely

related? In the past, both mammals were classii ed in the order Rodentia, the rodents.

However, an analysis of several proteins, including insulin, caused scientists to rethink

this classii cation. Guinea pig insulin is so dif erent from that of typical rodents that

guinea pigs were reclassii ed into a taxon of their own. What about the horseshoe crab

in Figure 1.9? Although it has the word crab in its common name, studies of blood

proteins in the horseshoe crab have shown that this animal is more closely related to

modern spiders than to crabs.

Figure 1.8 Guinea pigs (Cavia porcellus) (A) were once considered to be in the rodent order,

like mice (B). Studies of protein structure suggest that guinea pigs are sufficiently different from

other rodents that they should be placed in a separate order.

7. What is the main goal of modern classii cation?

8. Use a graphic organizer, such as a l owchart or a

main idea web, to show clearly how the following

words are related: morphology, anatomy,

and physiology.

9. Scientists ot en reclassify organisms as new

information is discovered. Why is it important

for scientists to continue to classify and

reclassify organisms?

10. Sharks and dolphins have similar morphological

characteristics. h ey both have i ns and bodies

shaped for swimming. How could examining their

anatomy and physiology help to further classify

these two organisms?

11. Refer to Figure 1.5. Which pair of organisms in

the diagram do you think is more closely related—

Pair A: a giant panda and a red panda or Pair B: a

red panda and a raccoon? Explain your reasoning.

12. Many animal species have red blood cells that

contain the oxygen-carrying protein hemoglobin.

Chickens (45), dogs (15), gorillas (1), frogs (57),

and humans are included in this list. h e numbers

in brackets represent the number of amino acid

dif erences between human hemoglobin and the

hemoglobin of the other species. Based on this

information, rank these animals from most closely

to least closely related to humans.

Learning Check

Figure 1.9 Horseshoe

crabs have pincher-like

appendages and lack jaws.

Chapter 1 Classifying Life’s Diversity • MHR 19

A

Animals PlantsFungi

Common Ancestor

Tim

e

B

DNA Evidence of Relationships

Study the diagram in Figure 1.10. Are you surprised that it shows that fungi are more

closely related to animals than to plants? Genetic analysis suggests that this is the

case. Genes are sections of DNA made of long chains of molecules called nucleotides.

(You will learn more about genes, their composition, and their function in Unit 3.)

Technological advances over the past few decades have made it increasingly possible

to determine the sequence of the nucleotides of specii c genes. Just as anatomical

and physiological evidence can be compared among species, so too can these DNA

sequences. h is research has been a great benei t to our understanding of evolutionary

history and its application to classii cation.

In some cases, new DNA evidence has meant that prior classii cations based on

morphological, physiological, or other evidence have to be dramatically restructured.

Sometimes DNA evidence indicates unexpected relationships. For example, fungi

and plants are superi cially similar in that they do not move and they grow out of the

ground. However, DNA evidence suggests that fungi are more closely related to animals

than to plants. h e diagram in Figure 1.10 rel ects this evidence. Similarly, Canada’s

only vulture, the turkey vulture shown in Figure 1.11, appears similar to vultures from

Asia and Africa. However, DNA indicates the turkey vultures may be more closely

related to the storks, which are large wading birds.

Phylogenetic Trees

Once scientists have studied the features of organisms and learned more about their

evolutionary histories, they ot en use a tool called a phylogenetic tree to represent a

hypothesis about the evolutionary relationships among groups of organisms. You saw

an example of a phylogenetic tree in Figure 1.5, when you considered the relationships

among giant pandas, bears, and raccoons.

phylogenetic tree

a branching diagram

used to show the

evolutionary relationships

among species

Figure 1.10 Based on

analysis of DNA, scientists

hypothesize that animals

and fungi are more closely

related to each other than

plants and fungi.

Figure 1.11 DNA evidence

suggests that the turkey

vulture (A) is really more

closely related to the

wading stork (B) than it is

to the vultures of Asia and

Africa. Both turkey vultures

and storks are the only

birds known to urinate on

their legs, which they do to

help keep their bodies cool

during hot weather as well

as to kill bacteria and other

pathogens that cling to

their legs.

20 MHR • Unit 1 Diversity of Living Things

Aepyceros melampus(impala)

Oryx gazella(oryx)

Cervus elaphus(red deer)

Rangifer tarandus(reindeer)

Aepyceros Oryx Cervus Rangifer

Bovidae Cervidae

Artiodactyla

Species

Order

Family

Genus

Order Artiodactyla

Figure 1.12 shows another example of a phylogenetic tree—this time, one that

illustrates the phylogeny of hooved mammals. Like a family tree, the roots or the base

of the phylogenetic tree represents the oldest ancestral species. h e upper ends of the

branches represent present-day species that are related to the ancestral species. Forks

in each branch represent the points in the past at which an ancestral species split—

evolved, or changed over time—to become two new species.

In Figure 1.12, these four species have a common ancestor, and this common

ancestor has general characteristics that it shares with all the species that evolved from

it. Members of the order Artiodactyla typically have an even number of hooved toes on

each foot and have specialized teeth and digestive systems adapted to eat plants. h ere

are about 150 members of this order worldwide, including goats, deer, cattle, antelopes,

and pigs.

Family Bovidae

New species that evolve from a common ancestor have some characteristics in common

with the common ancestor, as well as new features. Biologists use these new features to

dei ne each family level of classii cation on this tree. For example, members of the family

Bovidae (cows and antelopes) are artiodactyls that have the anatomical feature of horns.

Members of the family Cervidae (deer) are artiodactyls that have the anatomical features

of antlers. h ere are about 110 species of Bovidae and 40 species of Cervidae.

With continuing evolution, further new characteristics develop. On the time

scale of the tree, members of dif erent genera have split apart from one another more

recently than members of dif erent families. Smaller dif erences help distinguish one

genus from another. For example, the family Cervidae includes 16 genera. h e genus

Cervus includes deer with highly branched antlers, while animals in the genus Rangifer

are deer with broad, palmate antlers (having the shape of a hand).

Figure 1.12 This phylogenetic tree shows the evolutionary relationships among various species

of plant-eating hooved mammals.

Interpret To which other organism shown in the phylogenetic tree is Cervus elaphus most

closely related?

Chapter 1 Classifying Life’s Diversity • MHR 21

A B

The Importance of Classification to Technology,

Society, and the Environment

Understanding the evolutionary relationships among species and groups of organisms

can have important consequences in the medical i eld, as well as in agriculture and in

the conservation of biodiversity. Consider the following examples:

• When scientists are looking for sources of pharmaceutical drugs, hormones, and

other important medical products, they can narrow their search to species closely

related to organisms already known to produce valuable proteins or chemicals.

• Understanding phylogeny can help scientists trace the transmission of disease and

develop and test possible treatments. Diseases can spread more rapidly between

species that share certain genetic characteristics. For example, Creutzfeldt-Jakob

disease, a disease that af ects the nervous system, may be transmitted from cows

to people.

• In agriculture, ways to increase crop yields and disease resistance have already been

developed by cross-breeding closely related species. Biological control through the

use of natural predators, parasites, and diseases also depends on a knowledge of

dif erent taxa and their particular characteristics.

• Sometimes, i nding a new species or reclassifying an organism as a separate species

has implications for environmental conservation. For example, in 2001, based

on morphological and DNA analysis, scientists reclassii ed the forest-dwelling

elephants in Africa as a new species, Loxodonta cyclotis. h ese elephants, shown in

Figure 1.13, had previously been considered the same species as the African bush

elephant, Loxodonta africana. Conservationists worried about the status of the new

species. Loxodonta africana is classii ed as threatened and protected by anti-poaching

and anti-trading laws. Now that Loxodonta cyclotis was a separate species, it was

potentially no longer protected. However, an international agreement that helps

protect species from illegal trading gives Loxodonta cyclotis the highest category

of protection.

Figure 1.13 The forest-dwelling elephant (Loxodonta cyclotis) (A) have smaller bodies, smaller ears,

and longer tusks than the African bush elephant (Loxodonta africana) (B).

22 MHR • Unit 1 Diversity of Living Things

Section 1.2 R E V I E W

Review Questions

1. C Construct a chart that dif erentiates the three

main types of evidence scientists use to determine

relationships among species. Include an example of

each type of evidence.

2. K/U Explain why knowing the shared evolutionary

history of organisms is useful to each of the following:

a. a biologist

b. a biology student

c. a pharmaceutical laboratory assistant

d. a conservation ecologist

3. K/U List three anatomical features scientists have

used to hypothesize the relationship between modern

birds and dinosaurs.

4. K/U What do the nucleotide sequences in the genes

of turkey vultures suggest about their relatedness to

vultures of Asia and Africa?

5. A You are comparing three species (A, B, and C)

and you face a dilemma. Morphologically, species A

and B are very similar, but they are both dif erent from

species C. However, you have sequenced some genes in

all three and the gene sequences indicate a high degree

of similarity between species B and C. How would you

resolve this situation?

6. T/I Use the phylogenetic tree below to justify the

conclusion that the leopard is more closely related to

the domestic cat than it is to the wolf.

Wolf Leopard Domestic Cat

Common Ancestor

7. A Refer to Figure 1.12. Explain why a reindeer

(Rangifer tarandus) is more closely related to a red deer

(Cervus elaphus) than it is to an oryx (Oryx gazella).

8. A Invasive species can out-compete native

species when they are introduced outside of their

natural environment. h is can threaten a region’s

ecosystems, economy, and society. Recently, Canadian

researchers helped identify 15 new bird species

through genetic analysis. Scientists were able to

identify so many new species by analyzing and

comparing the DNA of over 600 North American bird

species. Explain how you think the use of genetic

analysis could help prevent the introduction of new

invasive species into Canada.

9. C h ere is growing concern worldwide about the

number of species that are going extinct. Conservation

organizations work to protect endangered species, but

there may be a disagreement about exactly what a

species is.

a. How can classifying an organism inl uence our

attitudes about that organism? For example, is a i sh

more likely to be protected if it is known to be an

endangered species, or if it is newly discovered and

dif erent from all known species of i sh?

b. Suppose you had been working for a conservation

group when the forest-dwelling elephants

(Loxodonta cyclotis) were reclassii ed as a separate

species. Write a letter urging the Convention on

International Trade of Endangered Species to

consider the new species as endangered.

10. C Construct a graphic organizer of your choice to

show the importance of classii cation to technology,

society, and the environment.

Section Summary

• Modern classii cation organizes diversity according to

evolutionary relationships.

• Taxonomists rely on morphological, physiological, and

DNA evidence to identify and classify species.

• Anatomical evidence includes comparing the structure

and form of organisms, including bones.

• Physiological evidence includes comparing the

biochemistry of organisms, including proteins. DNA

evidence includes comparing organisms’ DNA sequences.

• Understanding phylogeny can help scientists trace the

transmission of disease and develop and test possible

treatments.

Chapter 1 Classifying Life’s Diversity • MHR 23

SECTION

1.3Kingdoms and Domains

All of the millions of species on Earth share certain fundamental similarities, such

as being made of cells and having DNA. Despite these similarities, however, the

structural diversity of Earth’s species—diversity that is based on variety of both

external and internal structural forms in living things—is so great that it is almost

impossible to imagine. Examining all of life’s structural diversity at the species level

would be impractical, so biologists look for similarities and dif erences at a much

higher taxonomic rank, such as kingdoms and even domains.

The Six Kingdoms

Until the 1800s, the highest category for classifying organisms was the kingdom and

there were only two: Plants and Animals. Table 1.3 summarizes how the number of

kingdoms has changed since that time. In the 1800s, single-celled organisms were

added to the classii cation system through the creation of the kingdom Protista,

bringing the total to three. In the i rst half of the 1900s, some single-celled organisms

were found to be extremely small and without a cell nucleus, so a new kingdom,

Bacteria, was created for them, bringing the total to four. By the 1960s, it was known

that fungi were so dif erent that they also needed their own kingdom, bringing the total

to i ve. During the 1990s, with new genetic information, the bacterial kingdom was

divided in two, giving the current six-kingdom system.

In Chapters 2 and 3, you will examine each of the six kingdoms in more detail.

As you study the remainder of this chapter, keep the following three important ideas

in mind:

• h ere are two main cell types that are signii cant for classii cation at the upper

ranks, such as kingdom.

• h e study of cell types and genes has led scientists to add a rank higher than

kingdom—the domain.

• It is important to understand how biologists think the domains and kingdoms

are connected in their evolutionary history.

Table 1.3 Changes in Classification Systems for Life’s Kingdoms

Original 1860s 1930s 1960s 1990s

Animals Animals Animals Animals Animals

Plants

Plants Plants Plants Fungi

Plants Fungi Protists

Protists Protists Protists Bacteria

Bacteria Bacteria Archaea

structural diversity

a type of biological

diversity that is

exhibited in the variety

of structural forms

in living things, from

internal cell structure to

body morphology

Key Terms

structural diversity

prokaryotic

eukaryotic

dichotomous key

autotroph

heterotroph

24 MHR • Unit 1 Diversity of Living Things

Prokaryotic cell

Eukaryotic cell

A

B

cell wallcell membraneDNA

capsule

flagellum

nucleus

cell membrane

chromosomes

ribosomes

Figure 1.14 Species are made of one of two kinds of cells. Compared to eukaryotic cells,

prokaryotic cells are small, less complicated, and without a membrane-bound nucleus.

Describe one other difference between the prokaryotic cell and eukaryotic cell shown above.

Two Major Cell Types

If an organism is made up of one cell only, it is described as being single-celled or

unicellular. If an organism is made up of more than one cell, it is multicellular. h ere

is substantial variation among the cells of unicellular and multicelluar organisms.

However, at er centuries of study, biologists agree that there are two major types of

cells: prokaryotic cells and eukaryotic cells.

Prokaryotic cells, such as the bacterial cell shown in Figure 1.14, are the most

ancient cell type, though they remain abundant today. h ey do not have a membrane-

bound nucleus. h e name prokaryotic rel ects this important distinction in the two

cell types, because it means “before the nucleus.” Eukaryotic, on the other hand,

means “true nucleus.” Eukaryotic cells do have a membrane-bound nucleus. h ere

are other dif erences as well. Eukaryotic cells, also shown in Figure 1.14, have a much

more complex internal structure, and on average they are about 1000 times larger than

prokaryotic cells. h us, the two cell types represent a major division in the structural

diversity of life. You will read more about dif erences between prokaryotes and

eukaryotes in Chapter 2.

prokaryotic a smaller,

simple type of cell

that does not have

a membrane-bound

nucleus

eukaryotic a larger,

complex type of cell that

does have a membrane-

bound nucleus

Chapter 1 Classifying Life’s Diversity • MHR 25

Domains

Traditional eukaryotic kingdoms

Bacteria Archaea Eukarya

Protista Fungi Plantae Animalia

Dichotomous Keys

Even when taxonomists have put together logical classii cations, biologists still face a

practical challenge. Imagine having a specimen whose identity is completely unknown.

How could sorting through all the names and ranks in various classii cations assist

in determining what it is? h e short answer is: it cannot. As a result, taxonomists use

another tool to identify individuals or species: the dichotomous key.

A dichotomous key [dih-KAW-ta-mus kee] is a system for narrowing down the

identii cation of a specimen, one step at a time. h e word key is used as a solution, and

a dichotomy is a two-pronged fork, where there are two choices. So, a dichotomous

key is an identii cation solution that uses many two-part choices to narrow down the

solution. An example of a two-part choice could be something as simple as red and

not red.

dichotomous key an

identification tool

consisting of a series of

two-part choices that

lead the user to a correct

identification

Figure 1.15 There are

six major categories in

the classification system

for living and extinct

organisms.

The Three Domains

As scientists continued to analyze organisms in the kingdoms Bacteria and Archaea,

the category of domain was added to the classii cation system. Scientists found that the

dif erences between these two groups at the genetic and cellular levels were so great

that each group was elevated to a rank higher than kingdom—domain. So Bacteria and

Archaea are two of the three domains.

As a result of reclassifying these kingdoms as domains, biologists reclassii ed the

remaining kingdoms in a domain of their own, Eukarya. h is makes sense, since the

other four kingdoms represent all the organisms with eukaryotic cells. Organisms in

the two prokaryotic domains are unicellular, whereas both unicellular and multicellular

organisms occur in the Eukarya. Figure 1.15 shows the current classii cation at the level

of domain and kingdom.

13. Explain how scientists overcome the impractical

task of studying the structural diversity of life at the

species level.

14. What led scientists to add the category called

domain to modern classii cation systems?

15. Make a table to compare and contrast prokaryotic

cells and eukaryotic cells. Include the following

categories in your table: Meaning of Name, Presence

of Nucleus, Size, and Internal Structure.

16. Draw a l owchart or other graphic organizer

illustrating the relationship between the domains

and the kingdoms found in each domain.

17. h e following is the i rst step in a tool used by

taxonomists to classify vertebrate animals. Identify

this tool and describe how it works.

1a. Hair present . . . . . . . . . . . . . . . . . . . . . . . . . Class Mammalia

1b. Hair absent . . . . . . . . . . . . . . . . . . . . . . . . . . go to Step 2

Learning Check

26 MHR • Unit 1 Diversity of Living Things

Using a Dichotomous Key

h e ultimate goal of many taxonomists is to make an identii cation at the species level.

Table 1.4 shows a small key that could be used to distinguish among just eight species:

the frogs and toads in central Ontario.

Table 1.4 Dichotomous Key—Frogs and Toads of Algonquin Park

1a. Skin dry and warty .. . . . . . . . . . . American toad 1b. Skin not dry and warty .. . . . . . . . . . . . . . . . go to 2

2a. Toes with “sticky pads” .. . . . . . . . . . . . . . . . go to 3 2b. Toes without sticky pads .. . . . . . . . . . . . . . go to 4

3a. Brown, < 2 cm, a darker X-shaped mark on

the back .. . . . . . . . . . . . . . . . . . . . spring peeper

3b. Grey or green, yellow under the legs . . . . . . . . . .

eastern grey treefrog

4a. Back without a pair of ridges . . . . . . . . . . go to 5 4b. Back with a pair of ridges . . . . . . . . . . . . . . go to 6

5a. Mottled pattern, with a mammal-like odour

.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mink frog

5b. Unmottled green pattern; to 15 cm ... . . . . . . . . .

bullfrog

6a. Back with large round or squarish spots

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . go to 7

6b. Back unspotted (or with a few small spots)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . go to 8

7a. Spots round .. . . . . . . . . . . . . . . . . . . . . . . . leopard frog 7b. Spots squarish .. . . . . . . . . . . . . . . . . . pickerel frog

8a. Predominantly green colour .. . . . . . . . . . . . . . . . . . . .

green frog

8b. Brown, with a dark mask through the eye

.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . wood frog

Assume you are trying to identify the species in Figure 1.16. Before you begin, since

you do not actually have the specimen in your hand, be aware that it has smooth, moist

skin and it does not have “sticky pads” on its toes. To use a dichotomous key, always

begin by choosing from the i rst pair of descriptions (1a and 1b). In this case, because

the skin is not dry and warty, you proceed to the next description within the i rst

pair of choices, 1b. If the skin had been dry and warty, you would have concluded the

animal is an American toad, and your use of the key would be complete.

At the second set of choices (2a and 2b), since the toes are not sticky, you are

directed to the fourth pair of choices (4a and 4b). Here, because you can see from

Figure1.16 that the back has a pair of ridges, you move on to the sixth pair of choices

(6a and 6b). Check Figure1.16 again to see if the back is spotted or unspotted. Because

it is unspotted, you then move to the eighth pair of choices (8a and 8b). Finally, here

you decide, based on its brown back and dark mask, that it is a wood frog (8b).

Figure 1.16 Use the dichotomous key in Table 1.4 to identify this species.

Chapter 1 Classifying Life’s Diversity • MHR 27

Dichotomous keys are very helpful to identify and classify

organisms. In this activity, you will develop a dichotomous

key as you group familiar objects based on their

characteristics.

Possible Materials

• several diff erent types of an object or material, such as

backpacks, shoes, pens, or notebooks

Procedure

1. Choose an object for which you will create a

dichotomous key.

2. Place a collection of the object in a pile. For example, you

may have your group members all place their backpacks

or their notebooks in a pile.

3. Examine the objects and write the fi rst question for

your dichotomous key. The question should focus on a

distinguishing characteristic among the objects. Divide

the objects into two groups based on that distinguishing

characteristic.

4. Examine the characteristics of the objects in each

subgroup. Write a second question that focuses on a

characteristic that distinguishes the objects in one of the

groups. Divide that group into two smaller groups based

on this distinguishing characteristic.

5. Continue adding questions to your key and dividing

the objects until there is only one object in each group.

Make a branching diagram to identify each object with a

distinct name.

6. Use your diagram to classify the same type of object

from a diff erent source.

Questions

1. Relate the groups you used to classify your object to taxa.

How do your groups relate to the groups of kingdom,

phyla, and the remaining six taxa in the modern

classifi cation system?

2. How did you use your dichotomous key to classify the

object from a diff erent source in step 6? For example, did

you have to revise your key? Explain.

3. How could you modify your dichotomous key so that the

user could more eff ectively identify an object of this type?

Activity 1.2 Create a Dichotomous Key

SuggestedInvestigation

Inquiry Investigation 1-C,

Creating a Dichotomous

Key to Identify Species

of Beetles

A Dichotomous Key for Kingdoms

To design a key to make identii cations at the species level, appropriate choices of

characteristics must be made. For instance, to identify the species of wildl owers

growing on a lawn, it would be logical to focus on things like the number and

arrangement of leaves, l ower colour, plant size, and branching pattern.

But keys are not always designed to identify species. If you are instead designing

a key to determine what kingdom an organism is in, the focus has to be dif erent. Here,

it is more useful to consider fundamental dif erences, such as the following: cell type

and cell structure; whether the organism is multicellular; and methods of reproduction

and obtaining nutrition.

28 MHR • Unit 1 Diversity of Living Things

Main Characteristics of Kingdoms

Table 1.5 summarizes some of the main characteristics of kingdoms and, below

it, Figure 1.17 shows some examples of organisms in each kingdom. A distinction

has already been made between prokaryotic and eukaryotic cells based on size,

the presence of a nucleus, and internal complexity. Another cell-level distinction

is the cell wall, a tough structure that surrounds most cells. Cell walls are absent

in animals, but in other organisms the composition of the cell wall varies. With

respect to nutrition, an autotroph is an organism that obtains energy by making

its own food, usually using sunlight. A heterotroph must consume other organisms

to obtain energy-yielding food. Finally, asexual reproduction can be found in all

kingdoms. However, sexual reproduction, in which genetic material from two

parents combines to form of spring with a unique combination of genes, is a trait

that only occurs in the Eukarya. h e data in Table 1.5 are all that is needed to make

a dichotomous key that can assign any species to its kingdom.

Table 1.5 Characteristics That Differentiate the Six Kingdoms

autotroph an organism

that captures energy

from sunlight (or

sometimes non-living

substances) to produce

its own energy-yielding

food

heterotroph an

organism that cannot

make its own food and

gets its nutrients and

energy from consuming

other organisms

Domain Bacteria Archaea Eukarya

Kingdom Bacteria Archaea Protista Plantae Fungi Animalia

Example Staphylococcus Sulfolobus archaea Amoeba Maple tree Mushroom Rabbit

Cell type Prokaryote Prokaryote Eukaryote Eukaryote Eukaryote Eukaryote

Number of cells Unicellular Unicellular Unicellular and

multicellular

Multicellular Mostly

multicellular

Multicellular

Cell wall material Peptidoglycan Not peptidoglycan;

occasionally no

cell wall

Cellulose in some;

occasionally no

cell wall

Cellulose Chitin No cell wall

Nutrition Autotrophs and

heterotrophs

Autotrophs and

heterotrophs

Autotrophs and

heterotrophs

Autotrophs Heterotrophs Heterotrophs

Primary means

of reproduction

Asexual Asexual Asexual and

sexual

Sexual Sexual Sexual

Figure 1.17 Organisms from each of the six kingdoms represent Earth’s biodiversity.

Staphylococcus 4800×

Maple tree

Sulfolobus archaea 5000×

Mushroom

Amoeba 160×

Rabbit

Chapter 1 Classifying Life’s Diversity • MHR 29

Section 1.3 R E V I E W

Review Questions

1. C Make a Venn diagram to compare and contrast

prokaryotic and eukaryotic cells.

2. K/U Identify the three domains and the kingdoms

within each domain.

3. K/U Refer to Figure 1.15. Explain, in your own words,

how scientists arrived at the three-domain system.

4. C Explain how a dichotomous key works.

5. K/U Distinguish between autotrophs and

heterotrophs.

6. A Refer to Table 1.5 to answer the following

questions.

a. What form or forms of nutrition do eukaryotes use?

b. What type of reproduction is used primarily by

prokaryotes?

c. Describe the cells of organisms in domain Archaea.

d. What is one characteristic that is unique to all

animals?

7. A Cyanobacteria, commonly called blue-green

algae, are classii ed in the kingdom Bacteria.

Cyanobacteria make their own food using carbon

dioxide, water, and energy from sunlight. h ey contain

the pigment chlorophyll and another pigment that is

blue. Explain why scientists in the early days of

taxonomy would likely have classii ed cyanobacteria in

the kingdom Plantae.

8. T/I Refer to Table 1.5. A student was looking at

some pond water under a microscope and noticed a

single-celled organism in the i eld of view. h is

organism had a nucleus as well as chloroplasts in its

cytoplasm. h e organism was enclosed by a cell wall.

At er looking through a dichotomous key, the student

determined this organism was a green alga. Predict the

domain and kingdom of this organism. Explain the

basis for your prediction.

9. A Use the dichotomous key in the table below to

identify the organism in the image.

Dichotomous Key—Salamanders of Algonquin Park

1a. Skin without spots

. . . . . . . . . . . . . . . . . . . . . go to 2

1b. Skin with spots

. . . . . . . . . . . . . . . . . . . . . go to 4

2a. Found under cover in or

beside streams .. . . . . . . . . . .

two-lined salamander

2b. Found in forests

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

go to 3

3a. Red stripe down back

.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

red-backed salamander

3b. Grey-black overall . . . . . . .

red-backed salamander

(black variant)

4a. Bright red small spots

. . . . . . . . . . . . . . . . . . . . . go to 5

4b. Blue or yellow spots

. . . . . . . . . . . . . . . . . . . . . go to 6

5a. Green overall, found

in aquatic ecosystems

.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

red-spotted newt

5b. Reddish overall, found

in terrestrial ecosystems

.. . . . . . . red-spotted newt

juvenile (“red et ”)

6a. Many irregular blue

spots . . . . . . . . . . . . . . . . . . . . . . . .

blue-spotted salamander

6b. Large yellow spots . . . . . . .

yellow-spotted

salamander

10. C Use a graphic organizer to compare the

characteristics of the kingdom Plantae to those of the

kingdom Animalia.

Section Summary

• h e variety of internal and external forms exhibited

by species represents structural diversity.

• h ere are two cell types: prokaryotic and eukaryotic.

Prokaryotic cells do not have a membrane-bound

nucleus. Eukaryotic cells are more complex and do

have a membrane-bound nucleus.

• Organisms in the domains Bacteria and Archaea

are unicellular and prokaryotic.

• Organisms in the domain Eukarya have eukaryotic

cells and are unicellular or multicellular. h ere are four

kingdoms in the domain Eukarya: Protista, Plantae,

Fungi, and Animalia.

• Taxonomists use dichotomous keys to make choices

between pairs of options to narrow down identii cations.

30 MHR • Unit 1 Diversity of Living Things

C

A B

SECTION

1.4Classifying Types of Biodiversity

Key Terms

species diversity

genetic diversity

ecosystem diversity

gene pool

population

resilience

When you hear or read the word biodiversity, you probably think i rst about species

diversity. Species diversity is the variety and abundance of species in a given area.

However, there are other ways of thinking about diversity other than species diversity,

and they are just as important. Genetic diversity is evident in the variety of inherited

traits within a species. h e patterns on the tails of humpback whales, such as the one

shown in Figure 1.18, are evidence of genetic diversity within this species. Ecosystem

diversity is the rich diversity of ecosystems found on Earth, each of which contains

many species. In this section, you will learn about the importance of all three of these

types of diversity.species diversity the

variety and abundance

of species in a given area

genetic diversity the

variety of heritable

characteristics (genes)

in a population

of interbreeding

individuals

ecosystem diversity

the variety of

ecosystems in the

biosphere

Figure 1.18 Biological diversity exists at different levels. (A) Within species there is genetic

diversity, as evident in the different tail patterns of humpback whales. (B) Within ecosystems,

like this alpine meadow, is species diversity. (C) Finally, a variety of ecosystems, such as this one

in Algonquin Park, make up ecosystem diversity.

Describe one example of genetic diversity and one example of ecosystem diversity.

Chapter 1 Classifying Life’s Diversity • MHR 31

Genetic Diversity

Since 1996, Tasmanian devils (Sarcophilis harrisii), shown in Figure 1.19, have been

suf ering from a contagious cancer that causes tumours on the face and mouth of

the animals. h e disease, spread from one individual to another by biting, eventually

results in death. h e population of Tasmanian devils has been reduced so extensively,

from about 150 000 in 1996 to between 20 000 and 50 000 by 2006, that the species

was classii ed as endangered. Research has shown that a lack of genetic diversity in the

Tasmanian devil population is a key factor in the impact of the disease.

Genes are the genetic material that controls the expression and inheritance of traits,

such as sugar content in blueberries, pattern arrangement in ladybeetles, and human

height. h e variation among individuals in a population is largely a result of the dif erences

in their genes. Genetic diversity within a population is known as the gene pool. In other

words, the gene pool is the sum of all the versions of all the genes in a population. h e

genetic diversity within a species is typically greater than that within a population, because

the gene pools of separate populations exposed to dif erent environmental conditions

usually contain dif erent types or combinations of the dif erent versions of genes.

Genetic Diversity Provides Resistance to Disease

Genetic diversity is especially important in disease resistance. As illustrated by the

Tasmanian devil example, populations that lack genetic diversity are more susceptible to

disease than those that have high diversity. If none of the individuals in a population have

the ability to survive the disease, the entire population could be eliminated. If populations

of the same species continue to be eliminated, it can lead to the extinction of the species.

Resistance to disease is just one example of why genetic diversity is important.

Genetic diversity also allows populations and species to survive changing

environmental conditions, such as a change in resource availability, climate change, a

change in a predator population, or the introduction of a non-native species.

Genetic Diversity Supports Conservation Biology

As scientists have learned more about the importance of genetic diversity and its

relationship to species survival, they have begun to use their knowledge to help struggling

populations. For example, in 1995 the population of Florida panthers, shown in

Figure 1.20, had been reduced to between 30 and 50 individuals, partially due to a lack

of genetic diversity. As part of the recovery plan for this endangered species, scientists

introduced eight female panthers taken from a population of panthers in Texas. h e ef ort

was considered a success, and in 2009 the population had risen to about 100 individuals.

gene pool all the genes

of all the individuals in a

population

population a group of

individuals of the same

species in a specific area

at a specific time

Figure 1.19 The Tasmanian

devil is native to Tasmania,

the island that is the

southernmost state of

Australia.

Figure 1.20 The Florida

panther (Felis concolor coryi)

population continues to be

threatened by habitat loss

and collisions with vehicles.

32 MHR • Unit 1 Diversity of Living Things

Ecosystem Diversity

If the smallest scale at which scientists consider biodiversity is genetic diversity, then the

largest scale is ecosystem diversity. Ecosystem diversity refers to the variety of ecosystems

in the biosphere. Recall that ecosystems are made up of two components—biotic factors

and abiotic factors. Biotic factors include interacting populations of species. Examples of

abiotic factors include altitude, latitude, geology, soil nutrients, climate, and light levels.

Because of the diversity of relationships among organisms and the variety of abiotic

factors, Earth’s surface is highly varied physically and chemically, making ecosystem

diversity very rich. Ecosystems can range in size from a small plant that grows on another

plant to an entire biome, such as a tropical rainforest or Canada’s vast boreal forest.

18. Describe the dif erence among the three types of

biodiversity.

19. Refer to Figure 1.18 (C). Identify three ecosystems

you might i nd in Algonquin Park.

20. What is a gene pool?

21. Explain why genetic diversity within a species is

always greater than the genetic diversity within

an individual population.

22. Explain why genetic diversity is important to the

survival of a species.

23. In the case of the Florida panther, humans

intervened to save the species. Do you agree or

disagree that humans should intervene to save

endangered species? Explain your answer.

Learning Check

Sustainable agriculture must balance the risks of technology

with the benefi ts. For example, atrazine is a herbicide used

in agriculture to prevent the growth of weeds. Crops that

have atrazine applied early in the growing season show a

25 percent increase in weed control, an 8 percent increase in

corn yield, and an increase in profi t of $20 per hectare.

On the other hand, the herbicide is applied to crops early

in the spring and can run off into nearby lakes and rivers.

Studies have shown that atrazine and other chemicals can

reduce reproductive success in many freshwater organisms.

The timing of atrazine contamination of water sources

directly coincides with amphibian breeding activities, since

many amphibians reproduce during early spring rains.

In several European nations, atrazine has been banned

because of environmental concerns. However, atrazine

is approved for use in Canada. Alternative forms of weed

control in corn crops are being investigated and include

the use of bacteria and low-growing plants that block

weeds from growing. Should the use of atrazine be banned

completely worldwide?

Procedure

1. Read the introductory text and make a T-chart to list the

benefi ts and risks of using atrazine on corn crops.

2. Examine the graph on the right and add information to

your chart.

3. Discuss the benefi ts and risks of using atrazine on corn

crops with classmates.

Questions

1. Why is the timing of atrazine application such an

important factor?

2. Draw an illustration that shows the steps involved in how

atrazine reaches aquatic ecosystems.

3. What is the direct impact of atrazine use on the leopard

frog? Why is this something to be concerned about?

4. Name fi ve other species that would be aff ected by

reduced frog reproduction. Sketch a food web to show the

eff ects of atrazine on the biodiversity in ponds.

5. Analyze your T-chart. Do the benefi ts of using atrazine

outweigh the risks? Explain your reasoning.

The graph shows the

results of an experiment

in which male northern

leopard frogs were

exposed to atrazine

during development.

The levels of

testosterone in the

atrazine-treated frogs

were then compared to

testosterone levels in

non-treated male and

female frogs.

Test

ost

ero

ne

(N

g/m

L)

Treatment Group

Testosterone Levels inNorthern Leopard Frogs

(Rana pipiens)

5

4

3

2

1

0

Atrazin

e-treate

d

Male

s

Non-treate

d

Male

s

Non-treate

d

Female

s

Activity 1.3 Sustainability and Diversity—Find a Balance?

Chapter 1 Classifying Life’s Diversity • MHR 33

Ecosystem Services

Ecosystem services are the benei ts experienced by organisms, including humans,

which are provided by sustainable ecosystems. Without ecosystem diversity, Earth

would lose most of the services that ecosystems provide, which are shown in

Table 1.6. Forests, for instance, take up carbon dioxide and maintain soil fertility.

Ecosystems also maintain populations of organisms that are necessary for pest control,

pollination, waste management, and other processes benei cial to people.

In particular, wetlands provide several important ecosystem services, including

storing water, which reduces the risk of l oods; i ltering water, which removes pollutants;

and providing habitat for commercially important species of i sh and shelli sh. Because

wetlands are so valuable, government agencies and non-governmental organizations

ot en work together to preserve and protect them. For example, between 2000 and

2005, acting under the Great Lakes Wetlands Conservation Action Plan, more than

12 000 hectares of wetlands around the Great Lakes region were preserved. During that

same time period government agencies worked with private organizations to restore

another 4400 hectares of wetlands that had been disrupted by human activities such as

agriculture and development.

Table 1.6 Examples of the World’s Ecosystem Services

Ecosystem Service Example

Atmospheric gas supply Regulation of carbon dioxide, ozone, and oxygen levels

Climate regulation Regulation of carbon dioxide, nitrogen dioxide, and methane levels

Water supply Irrigation, water for industry

Pollination Pollination of crops such as apples, blueberries, and clover

Ecological control Pest population regulation

Wilderness Habitat for wildlife

Food production Crops, livestock

Raw materials Fossil fuels, timber

Genetic resources Medicines, genes for disease resistance in plants

Recreation Ecotourism

Cultural benei ts Aesthetic and educational value

Waste treatment Sewage purii cation

Soil erosion control Retention of topsoil

Nutrient recycling Nitrogen, phosphorus, carbon, and sulfur cycles

Ecosystem Function and Species Diversity

Ecologists have long had the sense that ecosystems with greater species diversity

were more likely to provide important services reliably. As well, there has also been a

belief that such ecosystems exhibit resilience, the ability of an ecosystem to maintain

an equilibrium, or balance, even in the face of signii cant outside disturbances. Field

research conducted by scientists from the University of Minnesota in the 1980s and

1990s has provided convincing evidence that this is the case.

Experiments came from a long-term project using many growing plots, each with

a specii c number of native plant species, ranging from 1 to 24. In all cases, the more

species present in the plot, the more ei cient the ecosystem. h e plots with more native

species produced more biomass, which means they trapped more carbon dioxide. h ey

also consumed more nitrate, which can be toxic in high quantities. h e more diverse

plots were better able to resist the invasion of non-native species and exhibited reduced

disease. h e results of these experiments are shown in the graphs in Figure 1.21.

resilience the ability

of an ecosystem to

remain functional and

stable in the presence of

disturbances to its parts

SuggestedInvestigation

ThoughtLab Investigation

1-B, Resilience of a

Grassland Ecosystem

34 MHR • Unit 1 Diversity of Living Things

65

60

55

50

45

40

35

30

25

0 5 10 15 20 25

Tota

l Pla

nt

Co

ve

r (%

)

Plant Species Diversity

Plant Species Diversity andPercentage of Plant Coverage

Plant Species Diversity andNumber of Invasive Species

Plant Species Diversity andDisease Severity

4

3

2

1

0 4 8 12 16 20

Plant Species Diversity

8

6

4

2

0 5 10 15 20 25

Nu

mb

er

of

Inv

asi

ve

Sp

eci

es

(%)

Plant Species Diversity

Dis

ea

se S

ev

eri

ty I

nd

ex

Ecosystem Services and Human Actions

Sometimes humans make changes to an ecosystem to enhance the services of the

ecosystem. For example, wildlife oi cials may stock a lake with i sh to provide

recreation for i shing enthusiasts. But what ef ects could this action have on the natural

ecosystem of the lake? h e results of a four-year study conducted by wildlife biologists

in California showed that the introduction of non-native trout to mountain lakes in the

western United States led to reduced population numbers of several amphibian species

and changes in the number and variety of aquatic insect species. In particular, trout

consume aquatic insects in the larval stage. Other organisms, including amphibians

and other i sh, also rely on insect larvae as a food source. As well, birds and bats that

live near the lakes eat adult insects. All of these species must now compete with the

non-native trout for food. h e presence of trout has been linked with a decrease in the

number of birds and in the activity of some types of bats.

In Ontario, the most successfully stocked i sh is the smallmouth bass, shown

in Figure 1.22. Introductions to previously bass-free lakes have greatly increased its

Ontario range northward. h is has enhanced recreational i shing, but ecologists have

documented resulting changes to lake ecology. One consequence is the loss of some

native i sh species such as stickleback and dace. h is leads to a decline in species

diversity and af ects ecosystem diversity because the system loses complexity.

Where the bass are introduced into lakes with lake trout, the situation is worse.

Trout are commonly top predators, but the reduced numbers of small i sh caused by the

introduced bass af ect trout populations. With fewer small i sh, trout must then consume

less nourishing food, resulting in slower growth, smaller ultimate size, and decreased

population numbers. h is is a further impact on ecosystem diversity because of the food

web alteration. Research documenting the negative ef ects of bass introductions has

greatly reduced the practice. In Chapter 3, you will read more about how human actions

af ect biodiversity, particularly species diversity and ecosystem diversity.

Figure 1.21 In experiments conducted at the University of Minnesota from 1982 to 1993,

researchers concluded that greater biodiversity in an ecosystem results in at least three beneficial

patterns: increased plant cover, more resistance to invasive species, and more disease resistance.

Figure 1.22 Widespread

introductions of the

smallmouth bass in

thousands of Ontario lakes

have increased recreational

fishing opportunities, but

there have been negative

consequences for species

and ecosystem diversity.

Chapter 1 Classifying Life’s Diversity • MHR 35

BIOLOGY Connections

S T S E

DNA Bar Codes

Connect to the Environment

One benei t of DNA bar code technology might be that

farmers could identify pests and use species-specii c methods

for their removal. Do some research to i nd out what is

meant by “species-specii c methods” and assess whether

they are less harmful to the environment than other methods

of pest removal.

Most people would i nd it odd if their friend collected vials

containing muscles from 940 dif erent species of i sh—but

then again most people haven’t undertaken a project as

ambitious as this one.

DNA UPC Paul Hebert, a geneticist at the University of

Guelph, in Ontario, is trying to gather cell samples from all

of the world’s organisms. With small pieces of tissue no larger

than the head of a pin, Hebert and his colleagues are working

to assign DNA bar codes to every living species.

Hebert has shown that the segment of mitochondrial

DNA, called cytochrome c oxidase I, or COI, can be used as

a diagnostic tool to tell animal species apart. h e COI gene

is easy to isolate and allows for identii cation of an animal.

A dif erent gene would need to be used for plants. Just like

the Universal Product Codes (UPC) that appear on product

packaging, the DNA segment sequence could be stored in

a master database that would allow for easy access to the

material. A hand scanner, when supplied with a small piece

of tissue, such as a scale, a hair, or a feather, could identify

the species almost instantly.

POTENTIAL BENEFITS h is technology has several potential

benei ts. A doctor might use it to pinpoint disease-causing

organisms quickly to prevent epidemics or to determine what

antidote to give a victim of a snake bite. Health inspectors

could scan foods for plant and animal contaminants. People

who are curious about their surroundings could learn what

lives around them. Farmers would be able to identify pests

and use species-specii c methods for their removal.

A NEW WAY TO CLASSIFY Using bioinformatics—a i eld of

science in which biology, computer science, and information

technology merge—to create a database of DNA bar codes

allows taxonomists to classify more organisms quickly.

Currently, taxonomists have identii ed approximately two

million species. Scientists estimate that anywhere between

5 and 20 million species exist. Historically, species have been

classii ed using morphology, genetics, phylogeny, habitat,

and behaviour. While the bar codes would not replace classic

taxonomic methods, they could supplement them by giving

scientists another tool to use.

This representation of DNA bar codes shows that the more closely

related two species are, the more similar their bar codes are.

Honeybee American robin

Bumble bee Hermit thrush

36 MHR • Unit 1 Diversity of Living Things

Section 1.4 R E V I E W

Review Questions

1. C Use a graphic organizer to show the relationship

between the terms biodiversity, species diversity, genetic

diversity, and ecosystem diversity.

2. A A pitcher plant (Sarracenia

purpurea), shown on the right, is

an Ontario bog plant with leaves

that hold water in which various

organisms live. Is a pitcher plant a

species or an ecosystem? Explain

your answer.

3. K/U Identify which of the following are ecosystems

and explain what your answers tell you about

ecosystem diversity.

a. l ower basket

b. surface of your skin

c. schoolyard

d. Lake Ontario

e. the tundra

4. K/U Explain how the relationship between genetic

diversity and disease resistance is similar to the

relationship between species diversity within an

ecosystem and disease resistance.

5. K/U Using examples from Table 1.6, explain why it is

important to conserve ecosystem diversity.

6. K/U Why is it important to protect species diversity

within an ecosystem?

7. C Summarize the information shown in the

graphs in Figure 1.21.

8. T/I A microhabitat is an identii ably dif erent

portion of a larger discrete habitat such as a forest.

Microhabitats of er a variety of microclimates, food,

camoul age, and shelter. h e northern l icker is a

woodpecker that i nds shelter in a hole in a tree, while

a millipede i nds food and shelter in the leaf litter at

the base of the tree. Based on this information, predict

the relationship between structural diversity and

species diversity of an ecosystem.

9. A Attempts to calculate the cash value of diverse

ecosystems have been made. One 1997 estimate placed

Earth’s ecosystem services at more than 33 trillion

dollars per year. Use the table below to answer the

following questions.

a. Which ecosystem has the greatest global economic

value? Why do you think this is?

b. Which ecosystem has the least global economic

value? What is dif erent about this ecosystem

compared to the others?

c. In your opinion, which ecosystem provides the

most important ecosystem service? Why?

Value of the World’s Ecosystem Services

Ecosystem

Total Global Value (trillions

of dollars)Ecosystem

Service

Coastal shelf 4283 Nutrient cycling

Coral reef 375 Recreation

Cropland 128 Food production

Estuaries 4100 Nutrient cycling

Grasslands 906Waste treatment/

food production

Lakes and rivers 1700 Water regulation

Open ocean 8381 Nutrient cycling

Swamps 3231 Water supply

Temperate forest 894 Climate regulation/

timber

Tropical forest 3813 Nutrient cycling/

raw materials

10. K/U Explain the statement, “Maintaining the

diversity of Earth’s ecosystems is important for

species diversity.”

11. C Make a concept map that organizes the results

of the study by biologists in which non-native trout

were introduced to mountain lakes in the western

United States.

Section Summary

• Too little genetic diversity reduces a population’s ability

to resist disease or other changing environmental

conditions.

• Ecosystems are diverse due to variations in abiotic and

biotic factors.

• Ecosystems provide services, such as recycling nutrients

and regulating gases in the atmosphere.

• Ecosystems with greater species diversity have higher

resilience.

Chapter 1 Classifying Life’s Diversity • MHR 37

ThoughtLabI N V E S T I G AT I O N

S k i l l C h e c k

Initiating and Planning

✓ Performing and Recording

✓ Analyzing and Interpreting

✓ Communicating

Materials

• reference books

• computer with Internet access

Classifying Aquatic SpeciesIn the same way that marine organisms are mixed up in seafood stew, the names

of the taxa that identify i ve species are mixed up in the table below. In this lab,

you will place each organism in its proper taxon at each level of the hierarchy.

Organisms in Seafood Stew

Common name Market squid, American lobster, blue mussel,

Virginia oyster, European oyster

Phylum Arthropoda, Mollusca, Mollusca, Mollusca, Mollusca

Class Malacostraca, Bivalvia, Bivalvia, Bivalvia, Cephalopoda

Order Decapoda, Decapoda, Mytiloida, Pterioida, Pterioida

Family Ostreidae, Ostreidae, Nephropidae, Mytilidae, Loliginidae

Genus Homarus, Mytilus, Ostrea, Loligo, Crassostrea

Species americanus, virginica, edulis, edulis, opalescens

Pre-Lab Questions

1. What is the order of classii cation for organisms?

2. Why is it useful to have a classii cation system for organisms?

Question

Which organisms are closely related to each other? Which are not?

Organize the Data

1. Draw a table with six columns and seven rows. At the top of the i rst

column, write “Taxon.” At the top of each of the other columns, write the

common name of each organism. Label the rows Phylum, Class, Order,

Family, Genus, and Species.

2. Use reference books or the Internet to classify each organism at each

taxon level.

Analyze and Interpret

1. Which order name is found in both the Arthropoda and Mollusca phyla

(plural of phylum)? What does this name mean?

2. Which two genera (plural of genus) have species with names containing the

same word? What does this word mean?

Conclude and Communicate

3. Which two organisms are most closely related to each other? Explain why.

4. Which organism is least closely related to the other four? Explain why.

Extend Further

5. INQUIRY Place i ve organisms from your neighbourhood in the proper

taxon at each level of the hierarchy.

6. RESEARCH How are names for the levels in the hierarchy determined?

1-A

The American lobster and the blue

mussels shown here are both members

of the animal kingdom.

Go to Organizing Data in a Table in

Appendix A for help with making

your table.

38 MHR • Unit 1 Diversity of Living Things

S k i l l C h e c k

Initiating and Planning

✓ Performing and Recording

✓ Analyzing and Interpreting

✓ Communicating

Materials

• graph paper

• ruler

Resilience of a Grassland EcosystemResilience is the ability of an ecosystem to maintain an equilibrium, or

balance, despite signii cant outside disturbances. Results of studies conducted

using experimental plots of plants showed that increased biodiversity in the

experimental plots led to increased resistance to the invasion of non-native

species and decreased incidence of disease. h e scientists who reported these

results also recorded data about the ability of grassland plants to resist drought

conditions in relation to species diversity. h ey measured the change in biomass

of the plants from 1986, the year before the drought began, to 1988, the peak of

the drought. h e data collected are shown in the table below. Resistance values

closer to zero imply greater resistance to the drought.

Pre-Lab Questions

1. What is resilience?

2. How is resilience related to species diversity within an ecosystem?

3. Why is it important to maintain biodiversity in ecosystems?

Question

How does species diversity af ect the resilience of an ecosystem?

Organize the Data

1. Make a line graph of the data in the table. Note that the values on the

y-axis begin with zero and decrease to negative values.

2. Label the axes of your graph and give your graph a title.

Analyze and Interpret

1. Explain the relationship between resilience and species diversity in the

grassland plots used in this experiment.

2. Another factor that scientists analyze when determining the stability of an

ecosystem is the amount of time it takes for the ecosystem to return to the

conditions that existed before the disturbance. Predict which plots returned

to the pre-drought conditions more quickly—those with high species

diversity or those with low species diversity. Explain your reasoning.

Conclude and Communicate

3. How does species diversity af ect the resilience of an ecosystem?

Extend Further

4. INQUIRY Describe another experiment to gather more evidence about the

relationship between the resilience of an ecosystem and its biodiversity.

5. RESEARCH Find out more about how planting native species in a disturbed

area can help improve the ecosystem. Use the Internet or library to i nd an

example of how the resilience of a disturbed ecosystem was improved at er

native plants were planted.

ThoughtLabI N V E S T I G AT I O N

1-B

Resilience of a Plant Community

During a Drought

Number of Plant Species

Resistance to Drought (change

in biomass/yr)

0 0.00

2 -1.10

4 -0.80

6 -0.75

8 -0.65

10 -0.50

12 -0.42

14 -0.40

16 -0.40

18 -0.40

20 -0.38

22 -0.38

24 -0.38

Go to Constructing Graphs in Appendix A

for help with making your graph.

Chapter 1 Classifying Life’s Diversity • MHR 39

InquiryI N V E S T I G AT I O N

S k i l l C h e c k

Initiating and Planning

✓ Performing and Recording

✓ Analyzing and Interpreting

✓ Communicating

Materials

• illustration of 18 beetles

• sample dichotomous keys

Creating a Dichotomous Key To Identify Species of BeetlesIf you i nd an insect you have never seen before, how could you discover

its identity? Many i eld guides help you match up the characteristics of your

specimen with those of similar organisms using a dichotomous key. h is

identii cation key uses a series of paired comparisons to sort organisms into

smaller and smaller groups. In this investigation, you will learn how to make

your own keys to identii cation.

Pre-Lab Questions

1. What characteristics do all insects have in common?

2. Name two characteristics that scientists use to tell dif erent insects apart.

3. How can you use the characteristics of beetles to classify them?

Question

How do you make a dichotomous key?

Prediction

Predict which characteristics of insects will be most useful in creating an

identii cation key.

Procedure

1. Copy the diagram of a dichotomous tree shown here onto a separate

piece of paper.

group 7

group 8

group 3

group 4

group 9

group 10

group 1

group 2

group 11

group 12

group 5

group 6

group 13

group 14

All

beetles

2. Study the illustration of 18 beetles shown on the next page.

3. Select one characteristic and sort the beetles into two groups based on

whether they have the characteristic or not.

4. List each beetle’s number under either group 1 or group 2 on your diagram.

1-C

A dichotomous key can help you

identify beetles such as these.

40 MHR • Unit 1 Diversity of Living Things

1

Variegated

mud-loving beetle

2

Mycetaeid beetle

3

Apricot borer

4

Water tiger

5

Predaceous

diving beetle

6

Crawling

water beetle

7

Flathead apple borer

8

Red-necked

cane borer

9

Cucumber

snout beetle

10

Whirligig beetle

11

Ironclad beetle

12

Broad-horned

lour beetle

13

Red lour beetle

14

Blind

ant-beetle

15

False wireworm

beetle

16

White-marked

spider beetle

17

Monterey

cyprus beetle

18

Drug store

beetle

5. Record the characteristic that identii es each group.

6. Select another characteristic of each subgroup, and

repeat steps 4 and 5 for the next level down on your

diagram.

7. Continue to subdivide the groups until you have 18

groups with one beetle in each.

8. Using the characteristics shown on your diagram,

construct a dichotomous key that someone could use

to identify any beetle from the original large group.

a. To do this, create a series of numbered steps with

the i rst step showing the i rst characteristic you

used.

b. At each step, of er two choices for classifying the

beetle based on a single characteristic. For example,

you may have used the characteristic “antennae

longer than front legs” as your i rst dividing

characteristic. h e i rst numbered step in your key

would be (1a) antennae longer than front legs or

(1b) antennae not longer than front legs.

c. Use the sample keys provided by your teacher to

help you.

9. Exchange your key with a partner. Use your

partner’s key to classify a beetle, and record all the

characteristics of the species you chose.

Analyze and Interpret

1. Did your partner produce a dichotomous key identical

to yours? Explain why or why not.

2. Which beetle characteristics were not useful for

creating your key? Explain why.

Conclude and Communicate

3. Why does a key of er two choices at each step and not

more than two?

4. In your own words, dei ne dichotomous key.

Extend Further

5. INQUIRY Your teacher will provide you with several

dif erent “mystery” beetles. Use your dichotomous

key to see if you can identify what species they are.

You may be unable to completely identify your beetles

using your key. If this is the case, how far could you

go with your key?

6. RESEARCH Visit the library or the Internet and get a

i eld guide to beetles. Use this to identify the mystery

beetles. What characteristics would you have needed

in your key in order to fully identify them?

Chapter 1 Classifying Life’s Diversity • MHR 41

S T S E

Case Study

This large monoculture operation shows regularly spaced

eucalyptus trees in Brazil. The regular, unobstructed

spacing makes planting and harvesting easier than in a

natural eucalyptus forest, but monocultures are at risk

if a pest or disease attacks the crops.

Tree PlantationsThe root of the problem or the solution to deforestation?

You have joined the International Youth Delegation (IYD),

an international coalition of youth working on urgent

ecological issues, such as deforestation. The Food and

Agriculture Organization of the United Nations (FAO) reports

that approximately 13 million hectares of forests worldwide

are cut down every year. Much of that land, particularly in

the tropics, is cleared to increase arable land so people can

grow food. A possible solution is to encourage the planting

of fast-growing and economically important tree species,

such as eucalyptus, as crops to be harvested. These managed

tree plantations would provide income to local landowners

and, at the same time, discourage ongoing deforestation.

Your IYD group has been asked to assess the viability of

monoculture tree plantations as a solution to deforestation.

Many large organizations, including the United Nations

and the World Bank, support the practice of monoculture

tree plantations. Members of the IYD are divided on the

issue. The members who agree with the UN and the World

Bank have summarized their position on the issue. The key

points of this summary include the following:

• Tree plantations can be planted on cleared and deforested

land. These “re-created” forest areas provide habitats for

many plant and animal species, some of which are at risk

of extinction due to habitat loss.

• Forests reduce the potential for damage from drought

and fl oods. As well, forests reduce soil erosion, which

dramatically benefi ts local water quality in streams

and rivers.

• Tree plantations bring many social and economic

benefi ts to local farmers, including providing income

and opportunities for other agricultural activities in the

plantation, such as livestock grazing.

• Aside from providing the raw materials for the lumber

industry, tree plantations also provide the waste wood

that remains after harvesting. The waste wood can

be used to produce renewable energy in the

form of biofuels.

• The tree plantations act as a carbon

sink, storing carbon in the wood of the

trees and helping to keep it out of the

atmosphere. Forests are known to store

more carbon than they emit, so increasing

forest cover means reducing net emissions

of greenhouse gases.

Other members of the IYD have a diff erent

opinion. They do not agree that planting trees

as part of monoculture tree plantations is a

solution to the problem of deforestation. Rather,

they believe these plantations will increase

the problems associated with loss of forest

biodiversity, particularly in tropical countries.

IYD members who oppose monoculture tree

plantations have compiled a list of their concerns

about tree plantations in a memo to the FAO, shown

in the next page.

42 MHR • Unit 1 Diversity of Living Things42 MHR • Unit 1 Diversity of Living Things

Research and Analyze 1. There are tree plantations in

Canada, and one of the key

species planted is red pine.

The purpose of these tree

plantations varies from helping

the recovery of accidentally

destroyed forests, such as those

aff ected by forest fi re, to replacing

the stock of wood harvested by

pulp and paper companies. Research and

analyze the similarities and diff erences between

tree plantations in Canada and tree plantations in

tropical countries as described in the scenario.

2. Tree plantations are considered to be a key factor

in the fi ght against climate change because forests

capture carbon. The United Nations Framework

Convention on Climate Change (UNFCCC) is

promoting a program to subsidize tree plantations

in order to trap carbon and create “carbon credits”

for the plantation owners. These credits can then

be sold in international carbon markets, such as the

European Union Emission Trading Systems (EU ETS).

Research these programs and consider whether

you agree that tree plantations are an important

part of fi ghting climate change.

3. Make a Venn diagram to compare and contrast

monoculture tree plantations and natural

forests. What is your opinion of monoculture tree

plantations? What questions do you have regarding

tree plantations?

Take Action 1. Plan In a group, discuss the concerns related to

the issue of monoculture tree plantations. Based on

research and the information in the scenario, what

are the diff ering points of view in your group with

respect to the practice? What are the diff erences, if

any, between tree plantations in Canada and tree

plantations in other, less developed countries?

Share the results of the research and analysis you

conducted in questions 1 to 3 above.

2. Act Prepare a letter to be submitted to the FOA

outlining your recommendations about the

viability of monoculture tree plantations as a

solution to deforestation. Support your position

with information from credible sources.

From: International Youth Delegation

To: United Nations Food and Agriculture Organization

RE: Concerns About the Practice of Tree Plantations

We believe that encouraging landowners to plant desirable tree

species, such as eucalyptus and mahogany, for later harvesting is

counterproductive in the fi ght against deforestation. h e economic

benefi ts of tree plantations actually encourage local farmers to clear

existing stands of natural forests in order to plant large tracts of

monoculture trees.

h e practice of developing tree plantations in order to make up for

the loss of natural ecosystems does not recognize that tree plantations

have no relationship to natural forests—the only similarity between

them is that they both contain trees. Natural forests contain many

diff erent species of trees and other plants that form the basis

for supporting a huge diversity of other organisms, including

insects, reptiles, and mammals. Monocultures may support some

biodiversity, but they provide a limited number of habitats compared

to naturally occurring forests, which are able to support ecosystems

rich in biodiversity. For example, a natural forest ecosystem in

Nigeria has between 40 and 55 species of trees, and each provides

habitat and resources for other species, such as birds and mammals.

A tree plantation has only a single species of tree.

h e benefi ts of natural forests include providing many ecosystem

services, such as regulating water supply and reducing soil

erosion. h ese ecosystem services cannot be replaced by planting

monocultures of tree species destined for harvest.

Monocultures are highly vulnerable to pests, disease, and natural

disasters. If any of these threats occurs, entire crops will be wiped

out. Farmers will be devastated and have no other crop to support

them as they replant and wait for new crops to mature.

Chapter 1 Classifying Life’s Diversity • MHR 43

SUMMARYChapter 1

Classifying and Naming SpeciesSection 1.1

Taxonomists classify species by using two-part scientifi c

names and by using hierarchical classifi cation based on

eight ranks.

KEY TERMS

binomial nomenclature

classifi cation

genus

hierarchical classifi cation

morphology

phylogeny

rank

species

taxon

taxonomy

KEY CONCEPTS

• Biologists use the morphological species concept, the

biological species concept, and the phylogenetic species

concept to defi ne species.

• Species often have common names. However, they are

formally known by two-part scientifi c names.

• All species are classifi ed by being placed in eight nested

ranks. The broadest category is the domain, continuing to

narrow to kingdom, phylum, class, order, family, genus, and

fi nally species, which is the narrowest category.

• Each named rank is known as a taxon.

Determining How Species Are RelatedSection 1.2

Modern classifi cation uses a variety of types of evidence

to classify and determine relationships among species,

but genetic information is currently a strong infl uence

in our understanding of how to classify.

KEY TERMS

anatomy

ancestor

phylogenetic tree

physiology

KEY CONCEPTS

• Modern classifi cation organizes diversity according to

evolutionary relationships.

• Taxonomists rely on morphological, physiological, and DNA

evidence to identify and classify species.

• Anatomical evidence includes comparing the structure and

form of organisms, including bones.

• Physiological evidence includes comparing the

biochemistry of organisms, including proteins. DNA

evidence includes comparing organisms’ DNA sequences.

• Understanding phylogeny can help scientists trace the

transmission of disease and develop and test possible

treatments.

Kingdoms and DomainsSection 1.3

All species are placed in three domains that contain six

kingdoms, and taxonomists use dichotomous keys to

identify species.

KEY TERMS

autotroph

dichotomous key

eukaryotic

heterotroph

prokaryotic

structural diversity

KEY CONCEPTS

• The variety of internal and external forms exhibited by

species represents structural diversity.

• There are two cell types: prokaryotic and eukaryotic.

Prokaryotic cells do not have a membrane-bound

nucleus. Eukaryotic cells are more complex and do have a

membrane-bound nucleus.

• Organisms in the domains Bacteria and Archaea are

unicellular and prokaryotic.

• Organisms in the domain Eukarya have eukaryotic cells and

are unicellular or multicellular. There are four kingdoms in

the domain Eukarya: Protista, Plantae, Fungi, and Animalia.

• Taxonomists use dichotomous keys to make choices

between pairs of options to narrow down identifi cations.

Classifying Types of BiodiversitySection 1.4

Species diversity, genetic diversity, and ecosystem

diversity are three types of biodiversity. Each is

important to the health of a population, a species,

and an ecosystem.

KEY TERMS

ecosystem diversity

gene pool

genetic diversity

population

resilience

species diversity

KEY CONCEPTS

• Too little genetic diversity reduces a population’s ability to

resist disease or other changing environmental conditions.

• Ecosystems are diverse due to variations in abiotic and

biotic factors.

• Ecosystems provide services, such as recycling nutrients

and regulating gases in the atmosphere.

• Ecosystems with greater species diversity have higher

resilience.

44 MHR • Unit 1 Diversity of Living Things

REVIEWChapter 1

Knowledge and Understanding

Select the letter of the best answer below.

1. Which kingdom has species whose cells do not have

cell walls?

a. Animalia d. Plantae

b. Archaea e. Protista

c. Bacteria

Use this table to answer questions 2 and 3.

Classification of Selected Mammals

Kingdom Animalia Animalia Animalia Animalia

Phylum Chordata Chordata Chordata Chordata

Class Mammalia Mammalia Mammalia Mammalia

Order Carnivora Perissodactyla Perissodactyla Perissodactyla

Family Phocidae Rhinocerotidae Equidae Equidae

Genus Halichoerus Diceros Equus Equus

Species Halichoerus grypus

Diceros bicornis

Equus caballus

Equus grevyi

Common

Name

Grey seal Rhinoceros Horse Zebra

2. Which animal is the most distant relative to the others?

a. E. grevyi d. rhinoceros

b. grey seal e. zebra

c. horse

3. At which level does the rhinoceros split from the

zebra?

a. class d. order

b. genus e. species

c. family

4. Which term describes an identii cation tool that uses

a series of two-part choices?

a. binomial nomenclature

b. dichotomous key

c. phylogenetic tree

d. phylogenetic key

e. taxonomic key

5. Which type of diversity describes the variety

of heritable characteristics in a population of

interbreeding individuals?

a. biodiversity

b. ecosystem diversity

c. evolutionary diversity

d. genetic diversity

e. species diversity

6. Which species concept focuses on the evolutionary

relationships among organisms?

a. morphological species concept

b. biological species concept

c. phylogenetic species concept

d. taxonomic species concept

e. hierarchical species concept

7. In which kingdom would you place an organism that

is multicellular, has a cell wall made of cellulose, and is

autotrophic?

a. Bacteria

b. Archaea

c. Protista

d. Plantae

e. Fungi

8. Which structure that makes up genes is of most

interest to modern taxonomists?

a. glucose

b. chitin

c. cellulose

d. eukaryote

e. DNA

Answer the questions below.

9. What is the main benei t of scientists using the same

system to classify living things?

10. Explain the meaning of the term binomial

nomenclature.

11. What is a domain? Give an example of a domain.

12. Which organisms are more closely related, those in the

same genus or those in the same family?

13. In your notebook, state whether each of the following

statements is true or false. If the statement is false,

rewrite it so that it is true.

a. Some species of bacterium are eukaryotes.

b. Species in the same family are more closely related

to one another than species in the same class.

c. h e morphological species concept classii es

organisms based on their evolutionary histories.

14. h e little brown bat (Myotis lucifugus) is common

throughout northwestern Ontario. h e northern

long-eared bat (Myotis septentrionalis) is

also found in many regions of Canada. Explain the

taxonomic relationship between these two mammals.

15. Identify i ve ecosystem services that sustainable

ecosystems provide.

Chapter 1 Classifying Life’s Diversity • MHR 45

REVIEWChapter 1Chapter 1

16. Describe how anatomical evidence can be used to

indicate the shared evolutionary history of whales,

bats, horses, and humans.

Thinking and Investigation

17. You have discovered an unknown organism while on a

i eld trip. You think it is a new species of protist. How

could you test to identify this species as a protist? What

data would you need to classify it in kingdom Protista?

18. You have found a heterotrophic species with cell walls

made of chitin. What resources could you use from

this chapter to determine in which kingdom it belongs?

Identify the kingdom to which it belongs.

19. Many agricultural crops are known as monocultures,

in which a single species is cultivated in a large

i eld. Identify some problems that might occur in

monocultures, given experiments that show the

relationship between species diversity and ecosystem

ei ciency.

20. All living things can be classii ed according

to their anatomical and physiological

characteristics. Study the organisms shown below.

Create a dichotomous key to identify them. Give the

key to another person to use to identify the organisms.

Make revisions to your key as needed.

21. h e scientii c name of a Bengal tiger is Panthera

tigris tigris, and the Siberian tiger’s scientii c name is

Panthera tigris altaica. h e third term in each name

identii es the subspecies of these animals. Why do

you think taxonomists added the third term to the

scientii c names of these animals?

22. Infer the relatedness of the vertebrate animals shown in

this phylogenetic tree. Explain your reasoning.

Common

Ancestor

Snakes Lizards

Crocodiles Birds

Communication

23. Create a graphic organizer such as a main idea web to

show the dif erent domains and kingdoms.

For each grouping, include a list of the characteristics

that dei ne the grouping.

24. Create a handout to compare and contrast prokaryotic

and eukaryotic cells. If you were to teach this material

to students in a lower grade, what information

would be the most important to teach them the basic

dif erences between the two cell types?

25. Human activities af ect the diversity of

living things in ecosystems. h ere are many

examples of plants that are harvested for medicinal use,

such as the Pacii c yew, which is used to make

medication used in the treatment of certain cancers.

In some areas, native plants used for medicinal

purposes have been overharvested. h ink about the

possible ef ects that overharvesting of medicinal plants

could have on biodiversity within an ecosystem. Make

an argument for regulating the number of plants that

can be harvested from a particular ecosystem.

26. Over 100 billion Cavendish bananas are consumed

worldwide annually. As a result of agricultural

practices, each Cavendish is genetically identical to

all others. Write an e-mail to the owner of a banana

plantation outlining your concerns about the lack of

genetic diversity found in this important food source.

27. Biological diversity exists at dif erent levels. Draw a

pyramid diagram showing the relationship between the

three widely accepted levels of biodiversity.

28. Summarize your learning in this chapter using a

graphic organizer. To help you, the Chapter 1 Summary

lists the Key Terms and Key Concepts. Go to Using

Graphic Organizers in Appendix A to help you decide

which graphic organizer to use.

46 MHR • Unit 1 Diversity of Living Things

Application

29. Taxonomists rely on more than anatomical,

physiological, and DNA evidence to classify. With

animals, they also compare behaviour patterns

between dif erent species to determine the degree of

relatedness.

a. How valuable do you think this type of evidence is?

Explain.

b. Provide an example of a type of behaviour that

may be helpful to a taxonomist, and give reasons to

support your answer.

30. Use the information in the table below to answer the

following questions.

Ontario Reptiles

Common Name Scientifi c Name Family

Eastern garter snake h amnophis sirtalis Colubridae

Painted turtle Chrysemys picta Emydidae

Eastern massasauga

rattlesnake

Sistrurus catenatus Viperidae

Snapping turtle Chelydra serpentine Chelydridae

Spotted turtle Clemmys guttata Emydidae

Five-lined skink Eumeces fasciatus Scincidae

Smooth green snake Opheodrys vernalis Colubridae

Musk turtle Sternotherus

odoratus

Kinosternidae

Ringneck snake Diadophis

punctatus

Colubridae

Eastern ribbon

snake

h amnophis

sauritus

Colubridae

a. Which pair of species is the most closely related

pair? Explain.

b. How many families are represented by the four

turtle species? Explain.

c. How many families are represented by the i ve snake

species? Explain.

d. Is the spotted turtle more closely related to the

painted turtle or the musk turtle? Why?

31. Canadian researchers have helped uncover 15 new

bird species through a process of genetic testing that

they say will pave the way for cataloguing the world’s

organisms. h e discovery of so many new species was

made possible by analyzing and comparing the DNA

genetic bar codes of 643 North American bird species.

Predict what the use of DNA genetic bar codes will

have on the current taxonomic systems.

32. In 2005, a hunter shot what he thought was a polar

bear in the Canadian Arctic. h e bear was brownish

white and had some other features not typical of

polar bears. Genetic tests proved it was a hybrid, the

of spring of a grizzly bear and a polar bear mating.

Your friend says that this is evidence that polar bears

and grizzly bears are the same species. Do you agree?

What other information might you want to know

before you agree or disagree? Explain your reasoning.

33. Use the dichotomous key below to answer the

following questions.

A

B

1a. Front and hind wings similar in size and shape,

and folded parallel to the body when at rest

. . . . . . . . . . . . . . . . damselfly

1b. Hind wings wider than front wings near base,

and extend on either side of the body when

at rest. . . . . . . . . . . . . . . . dragonfly

a. Identify the organisms shown in the diagrams.

Explain how you came to your decision.

b. From the key and the diagrams above, explain why

you could conclude that dragonl ies and damsell ies

evolved from a common ancestor.

34. Use the Internet or the print resources in your school’s

library to research the common names of the animal

Puma concolor. Based on your research, explain why

scientists prefer to use binomial nomenclature rather

than the common names of organisms.

35. Scientists are racing to discover new species that live

just below the ice in the Arctic Ocean. However, the

sea ice is disappearing and many of these unique

organisms may become extinct. Use the Internet or

print resources to research the services provided by

this ecosystem. Based on this information, predict

how the loss of sea ice will af ect these services.

Chapter 1 Classifying Life’s Diversity • MHR 47

Chapter 1 SELF-ASSESSMENT

Select the letter of the best answer below.

1. K/U Which is the correct order of the categories of

classii cation, from most diverse to most specii c?

a. Kingdom, Domain, Phylum, Family, Class, Order,

Species, Genus

b. Species, Genus, Family, Order, Class, Phylum,

Kingdom, Domain

c. Kingdom, Family, Domain, Species, Genus, Phylum,

Class, Order

d. Domain, Kingdom, Phylum, Class, Order, Family,

Genus, Species

e. Domain, Kingdom, Phylum, Family, Class, Order,

Species, Genus

2. K/U Of the organisms listed below, which is the

closest relative of the snowy owl (Bubo scandiacus)?

a. barn owl (Tyto alba)

b. great horned owl (Bubo virginianus)

c. saw-whet owl (Aegolius acadicus)

d. eastern screech owl (Megascops asio)

e. burrowing owl (Athene cunicularia)

3. K/U Which two kingdoms are not classii ed in

Domain Eukarya?

a. Protista and Fungi

b. Plantae and Animalia

c. Bacteria and Fungi

d. Archaea and Protista

e. Bacteria and Archaea

4. K/U h e monarch butterl y (Danaus plexippus) and

viceroy butterl y (Limenitis archippus) look almost

identical. Which species concept might have led

taxonomists to classify them as the same species?

a. phylogenetic species concept

b. Linnaean species concept

c. biological species concept

d. morphological species concept

e. binomial species concept

5. K/U An autotrophic prokaryote with no cell wall

would be found in which kingdom?

a. Archaea d. Fungi

b. Bacteria e. Plantae

c. Protista

6. K/U Which species concept focuses on the ability of

organisms to interbreed in nature and produce viable,

fertile of spring?

a. morphological species concept

b. biological species concept

c. phylogenetic species concept

d. taxonomic species concept

e. hierarchical species concept

7. K/U Which statement about binomial nomenclature

is false?

a. An organism’s scientii c name is made up of two

words.

b. h e i rst word of an organism’s scientii c name is

its genus, and the second word is its species.

c. h e scientii c name is italicized if typed.

d. h e scientii c name is underlined if handwritten.

e. Both the genus and species names are capitalized.

8. K/U h e following is an example of a tool used by

taxonomists to divide Order Cetacea (whales,

dolphins, and porpoises) into two suborders.

1a. have baleen plates for i ltering food from water . . . . . .

Suborder Mysticeti: baleen whales

1b. have teeth .. . . . . . . . . . Suborder Odontoceti: toothed

whales

What is the name of this taxonomic tool?

a. scientii c name

b. binomial nomenclature

c. phylogenetic species concept

d. dichotomous key

e. hierarchical classii cation

9. K/U Identify the level of diversity that is evident in

the variety of inherited traits within a species.

a. species diversity

b. genetic diversity

c. ecosystem diversity

d. taxonomic diversity

e. phylogenetic diversity

10. K/U Which is not a benei t of understanding the

evolutionary relationships among species?

a. discovering the source of new medicines

b. discovering new proteins or chemicals

c. identifying biological controls through use of

natural predators

d. protecting and conserving existing species

e. determining the number of wolves in an area

48 MHR • Unit 1 Diversity of Living Things

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Use sentences and diagrams as appropriate to answer the

questions below.

11. K/U Identify the kingdom in which you would place

a single-celled, eukaryotic organism that makes it

own food.

Use the table below to answer questions 12 and 13.

Classification of a Coyote and a Dog

Rank Coyote Dog

Domain Eukarya Eukarya

Kingdom Animalia Animalia

Phylum Chordata Chordata

Class Mammalia Mammalia

Order Carnivora Carnivora

Family Canidae Canidae

Genus Canis Canis

Species Canis latrans Canis familiaris

12. A Use the scientii c name of the coyote to explain

binomial nomenclature.

13. T/I Predict the family into which the red wolf

(Canis rufus) would be classii ed. Explain, in terms of

the hierarchical classii cation system, your prediction.

14. C Construct a dichotomous key you could use to

classify the music of 10 performers on a personal

digital audio player.

15. C A group of concerned students is developing a

plan to increase the biodiversity of their school’s

grounds. Currently, the school ground is primarily a

large open grass i eld with a handful of trees planted

near the chain-link fence that surrounds the grounds.

Make a list of at least i ve actions the students could

include in their plan to increase the biodiversity of

their school’s grounds.

16. T/I Two scientists, working independently, produce

the phylogenetic trees shown below for the same group

of organisms. Explain why the two scientists could

come up with the two dif erent phylogenetic trees.

Common Ancestor

Phylogenetic Tree A

NML

Common Ancestor

Phylogenetic Tree B

MLN

17. A h e clouded leopard is a medium-sized wildcat

found in the forests of Asia. In a study comparing

dif erences in clouded leopard coat patterns and

coloration throughout the cat’s range, researchers

concluded that individuals found on the islands of

Borneo and Sumatra are markedly dif erent from

animals found on the Southeast Asian mainland.

h ese observations have been supported by genetic

testing. Based on this information, are the clouded

leopards of Borneo and Sumatra the same species as

those on the mainland, or are the two groups dif erent

species? Explain your reasoning.

18. A In the 1800s, Irish farmers planted a large

number of potatoes that were genetically identical to

one another. When a potato disease swept through the

country in the 1840s, the potatoes, and the people who

depended on them for food, were devastated. Explain

how the lack of genetic diversity of the potatoes grown

in Ireland could have contributed to a period of low or

no crop yield and widespread starvation.

19. T/I Rhizopus stolonifer can be found growing on an

old loaf of bread or a piece of fruit that has been sitting

on the counter for several days. Members of this

species cannot make their own food, and they have a

cell wall. Is there enough information provided above

to dei nitively place this species in one of the six

kingdoms? Explain why or why not.

20. K/U List the characteristics of eukaryotic cells and

prokaryotic cells.

21. K/U Dei ne the term ecosystem services and list i ve

examples of the world’s ecosystem services.

22. T/I While hiking in the Hudson Bay Lowlands, you

i nd a multicellular organism growing on the bark of

a dying black spruce tree. Under a microscope, you

observe that its cells are eukaryotic, have cells walls,

and do not contain chloroplasts. Into what kingdom

would you classify this organism? Explain why.

23. C Suppose you had to explain the phylogenetic

tree shown in Figure 1.5 to a class of Grade 6 students.

Write a short paragraph explaining what the diagram

shows and how scientists use other diagrams like it to

help classify organisms.

Chapter 1 Classifying Life’s Diversity • MHR 49