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
Self-Check
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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