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CHAPTER

3W H AT I S E C O L O G Y ?

Diversity of life forms

Generally, red foxes live in sheltered temperate forests. They eat on the borders of these forests. Red foxes mostly eat small mammals like mice and hares, but they also eat insects, fish and fruits. They can adapt to very different environments and change their diets depending on the time of year. Fox pups are sometimes eaten by predators like wolves or lynxes.

Like red foxes, living organisms depend on other living organisms in their environment, as well as the environment itself. Ecologists examine these relationships between living organisms and their environment. They are interested in the ways in which living organisms adapt to their environment over a certain period of time. Ecology is therefore strongly linked to other branches of biology, including evolutionary science.

Ecology is the science that studies the relationships between living organisms and their interactions with their environment.

In this chapter, you will learn about species and the categories we use to classify living organisms.Then, you will learn about populations, habitats and ecological niches.Finally, you will discover how species adapt to their environment and how that can influence their evolution over a long period of time.

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SpeciesYou probably already know that there are millions of species on Earth. Some species are endangered. Some are invasive and take the place of other species. But do you really know what a species is?

What is a species?What do living organisms like Angora cats and Siamese cats, which are part of the same species, have in common? Are very similar animals like dogs and wolves the same species? What about plants, like the sugar maple and the red maple?

3.1

3.1.1

A species is a group of living organisms (plants, animals, etc.) that share common criteria. Three criteria allow us to determine whether two living organisms are of the same species.

Generally, they look similar (in colour, length, mass, shape, etc.).

Criterion 1

They can reproduce together—in other words, they can produce viable (able to survive) offspring that look similar to them.

Criterion 2

They give birth to fertile offspring (offspring that can also reproduce).

Criterion 3

D E F I N I T I O N

Species as a conceptJohn Ray, an English naturalist, was the first to use the word “species” in a scientific sense. To him, a species was a group of living organisms whose characteristics carried from one generation to the next. To come up with this definition, he studied 18 600 species of plants.

John Ray (1627–1705)

1 6 8 6 E N G L A N D

Chapter 3 73 Diversity of life forms


Are today’s domestic cats of the same species as the cats worshipped in ancient Egypt?

Cats were sacred in ancient Egypt. For a long time, they represented an incarnation of the goddess Bastet, who was a symbol of maternity and fertility. Millions of mummified cats have been found in Egyptian tombs. DNA analyses have shown that these cats were closely related to modern domestic cats, but different from the species of wild cats in the Egyptian region.

Two squirrels of the same species Take the example of the black squirrel and the grey squirrel, which are two animals of the same species. Let’s look at the characteristics of these two animals that live in Québec.

Because they have common characteristics, can reproduce together and can produce viable and fertile offspring, the black squirrel and the grey squirrel are of the same species.

Black squirrel Grey squirrel

TYPE OF SQUIRREL

CHARACTERISTIC

Fur colour Black Grey

Size (as an adult)

43 cm to 54 cm 43 cm to 54 cm

Mass (as an adult)

340 g to 680 g 340 g to 680 g

Lifespan (in a natural environment)

6 years to 10 years

6 years to 10 years

Reproduction

Can mate with the grey squirrel and have offspring that can also reproduce.

Can mate with the black squirrel and have offspring that can also reproduce.

The black squirrel and the grey squirrel have a similar appearance, except for their fur colour.

As adults, the black squirrel and the grey squirrel are the same size and have the same mass.

The black squirrel and the grey squirrel both live 6 years to 10 years.

The black squirrel and the grey squirrel can both give birth to viable and fertile offspring.

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Squirrels of a different species The red squirrel is another type of squirrel that lives in Québec. Let’s compare it to the black squirrel and the grey squirrel to show that it doesn’t belong to the same species.

What happens in a sheepdog’s head when it’s guarding sheep?

If a sheepdog is raised with sheep, it learns to live with them as if they were dogs. It becomes part of the herd. Researchers believe that sheepdogs treat sheep as if they were members of its own species.

The red squirrel has different characteristics than the black squirrel and the grey squirrel. Also, it cannot reproduce with them. We can therefore conclude that the red squirrel is of a different species.

Red squirrelBlack or grey squirrel

TYPE OF SQUIRREL

CHARACTERISTIC

Fur colour Black or greyReddish brown (white stomach)

Size (as an adult)

43 cm to 54 cm 28 cm to 35 cm

Mass (as an adult)

340 g to 680 g 140 g to 250 g

Lifespan (in a natural environment)

6 years to 10 years

3 years to 4 years

ReproductionCan mate together, but not with the red squirrel.

Cannot mate with the black squirrel or the grey squirrel.

As an adult, the red squirrel is not the same size and does not have the same mass as black and grey squirrels. It doesn’t have the same lifespan, either.

The red squirrel cannot reproduce with the other two types of squirrels.



What is binomial nomenclature?The names “black squirrel,” “grey squirrel” and “red squirrel” are used in everyday language. To properly distinguish species across all languages, scientists use binomial nomenclature.

3.1.2

D E F I N I T I O N

Taxonomy, p. 82

Binomial nomenclature is used to designate a species. It involves two Latin words, written in italics. It is an international naming system.

It indicates the genus to which the living organism belongs. This word starts with a capital letter.

A genus is a group of closely related species. For example, dogs and wolves are very closely related. They are part of the same genus (Canis).

First word of the nomenclature

It qualifies the first word and specifies the species. To name a species, we need to combine the genus name with this second word.

For example, in Latin, Lupus means “wolf” and familiaris means “familiar.” The wolf’s scientific name is Canis lupus and the dog’s scientific name is Canis familiaris.

Second word of the nomenclature

Binomial nomenclaturePassionate about plants, Carl Linnaeus was nicknamed “little botanist” by his classmates at 8 years old. It’s thanks to this Swedish naturalist that we use binomial nomenclature today. Linnaeus decided to use Latin to name species, because it was the language scholars of 18th century understood. He was the one who named the human species Homo sapiens, meaning “wise man.”

Carl Linnaeus (1707–1778)

1 7 5 8 S W E D E N

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Scientific names for the three squirrelsLet’s take another look at those squirrels from Québec and see how scientists have named them.

The above table shows that the red squirrel is not of the same genus or species as grey and black squirrels. Binomial nomenclature is therefore a good tool to help determine whether living organisms are part of the same species.

Can a zebra and a mare reproduce together?

A zebra (Equus burchelli) and a mare (Equus caballus) can mate and produce offspring, because they are closely related. They belong to the same genus. However, because their parents are not of the same species, the offspring (called “zorses”) are sterile; they cannot produce offspring of their own. Currently, all attempts to pair a female zebra with a male horse appear to have failed.

TYPE OF SQUIRREL COMMON NAME SCIENTIFIC NAME

Grey squirrel Sciurus carolinensis

Black squirrel Sciurus carolinensis

Red squirrel Tamiasciurus hudsonicus

As you just saw, the black squirrel and the grey squirrel are of the same species. That’s why they have the same scientific name.

The two species of squirrels in the table are from different genera (Sciurus and Tamiasciurus).

The red squirrel is of a different species than the other two squirrels. It has a different scientific name.



Binomial nomenclature in plantsUntil now, we have only looked at examples of animal species. However, the concepts of species and binomial nomenclature apply to all living organisms, including plants. Let’s take a look at an example of plant species.

The five types of trees in the table have different characteristics and have different scientific names. That means there are five species in the table: three species of maple and two species of oak. To name the trees, scientists had to start by observing their different characteristics.

MAPLES AND OAKS IN QUÉBEC

TREE LEAF HEIGHT FRUITFRUIT

PRODUCTION

Maples

Sugar maple (Acer saccharum)

25 m to 28 m

Fall

Red maple (Acer rubrum)

22 m to 28 m

Spring

Mountain maple (Acer spicatum)

Less than 8 m

Fall

Oaks

White oak (Quercus alba)

20 m to 30 m

Fall

Red oak (Quercus rubra)

19 m to 25 m

Fall

The types of maples in this table have different scientific names. Therefore, they are different species.

The types of oaks in this table have different scientific names. Therefore, they are different species.

The oaks in this table are from the genus Quercus.The maples in this table are from the genus Acer (see above).

The shape of the leaves and the appearance of the fruits differ between these trees.

The red maple is the only tree that produces fruit in the spring.

The mountain maple is the only tree that is less than 8 m tall.

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THE LIMITS OF SPECIES DEFINITIONThe biological concept of “species” has certain limits. For instance, how can we tell whether fossil species, bacteria or plants “can reproduce together?” For that reason, scientists also rely on other definitions of “species.” For example, they can use distinctive physical characteristics, DNA analysis or the study of ecological niches (a living organism’s role in its environment) to define a species.

THE NUMBER OF KNOWN SPECIES ON EARTHAccording to researchers, there are several million species on Earth. However, as the following diagram shows, only a few of these species are known.

SOME DATA ON SPECIES IN QUÉBEC• In total, there are approximately 9000 known species of plants, algae

and mushrooms in Québec.

• There are approximately 650 species of vertebrates (mammals, birds, fish, amphibians and reptiles).

• There are thousands of species of invertebrates, including around 30 000 insects.

• Some species are vulnerable, meaning that they’re at risk because of disruptions to their environment.

• Other species are endangered—they’re even more likely to disappear.

The number of species on Earth

Nematodes

Crustaceans

Protozoans

Algae

Vertebrates

Mollusks

Fungi

Arachnids

Plants

Insects

0 0.4 0.8 1.2 1.6 20.2 0.6 1 1.4 1.8

Known speciesUnknown species(estimation)

Millionsof species

8 million

Source: WCMC, Global Biodiversity Assessment, Chapman & Hall, 1992.



A C T I V I T I E S 1. In order to increase the number of beavers in Forillon National Park in Gaspésie, a researcher suggested introducing beavers from Norway. How can he make sure that the Norwegian beavers belong to the same species as those in the park?The two types of beavers must have physical characteristics in common. He

also must make sure that they can reproduce together and produce viable and

fertile offspring.

2. A horse (Equus caballus) and a donkey (Equus asinus) can reproduce and give birth to a mule or a hinny: an animal that has characteristics of both a donkey and a horse.

Alexandro would like to breed mules. He wants to start with three mules and a hinny (female mule). Will his business be successful? Explain your answer. No. Alexandro will not obtain any offspring, because donkeys and horses do not

belong to the same species. The mules and the hinny that he wants to use are

therefore sterile.

3. Here are some different evergreens.

a) How many species are listed above? Five.

b) Name the evergreens of the same species.All of the evergreens are of different species.

c) How many different genera are there? Name them.Two. Pinus and Picea.

White pine (Pinus strobus)

Jack pine (Pinus banksiana)

Red pine (Pinus resinosa)

White spruce (Picea glauca)

Black spruce (Picea mariana)

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4. Here are some frogs from Québec, along with their scientific names.

a) Which of these frogs belong to the same species? Explain your answer. Frogs B and D belong to the same species. They have the same scientific

name: Rana pipiens.

b) Which ones belong to the same genus? Explain your answer.Frogs B, C, D and E belong to the same genus. Their scientific names begin

with Rana.

c) Would you be able to tell which frogs are a part of the same species just by looking at them? Explain your answer. Sample answer: Yes. By looking closely, you can see that frogs B and D are

exactly the same colour. The others are different.

5. There are millions of varieties of roses. Rose growers are always looking to create new ones. They want the prettiest, best-smelling, hardiest roses. However, most of the roses they create cannot reproduce. Explain why.

Growers obtain roses that cannot reproduce because they are crosses between

different species.

Pseudacris crucifer

A

D

Rana pipiens

Rana pipiens

Rana clamitans

Rana sylvaticus

Hyla versicolor

B

E

C

F


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TaxonomyA friend is trying to impress you and tells you she ate a salmonid last night for supper. You reply, “Salmo salar or Oncorhynchus mykiss?” (Translation: “Atlantic salmon or rainbow trout?”) As you might have guessed, both species are salmonids, a family of fish. All living organisms are classified into categories based on their similarities.

What is taxonomy?Scientists have had to find a way to arrange the many, many species on Earth into groups so they can be studied. We call it the “taxonomy” of living organisms.

3.2

3.2.1

The Flore laurentienneAfter founding the Montréal Botanical Garden, this professor started creating a list of flora in Québec. In 1935, he published the results of his work in a book called Flore laurentienne, which described 1568 plants and had 2800 illustrations. The book was re-edited in 1964 and 1995, and is still used today. Brother Marie-Victorin, born

Conrad Kirouac (1885–1944)

1 9 3 5 C A N A D A

D E F I N I T I O N

Taxonomy is the science of classifying living organisms into different categories. Scientists classify species based on common characteristics that are shared between living organisms and their ancestors (fossils).

(Scientists may also differentiate individuals by their DNA [genetic code], for example when they want to categorize very similar bacteria.)

This system groups living organisms into five kingdoms.

• Kingdoms have many phyla.• Classes are divided into orders,

orders are divided into families, families are divided into genera and genera are divided into species.

• One phylum has several classes.• Species are the base unit of this

classification system.

Most common classification system

Species, p. 73

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The five kingdomsHere is a diagram of the five kingdoms into which all living organisms are classified. We have given you some character-istics of these kingdoms so you can see how scientists define them. These characteristics might seem complex. You will look at them in more depth in chapter 4.

Each of the five biological kingdoms is composed of millions of living organisms that share certain characteristics.

Plant and animal cells, p. 117

Legend:Unicellular organisms only visible under a microscope

Monerans. 5 000 known species.Monerans, like the bacteria shown here, are the only organisms without a cell nucleus.

Plants. 300 000 known species.Plant cells almost always contain chlorophyll, which gives leaves their green colour and allows them to transform energy from the sun into food.

Fungi. 150 000 known species.Some fungi, like yeast and mould, are unicellular (left photo). Others are made up of many cells. They are multicellular (right photo).The cells in fungi do not contain chlorophyll. Fungi feed by decomposing living or non-living matter (like mineral elements).

Monerans and protists are made up of only one cell. They are unicellular.

Animals. 1 200 000 known species.

Protists. 31 000 known species.

Plants and animals are multicellular.



There are so many species on Earth that they need to be classified into many different groups according to their shared traits.

Other levels of classificationAs you have just seen, living organisms are classified into five kingdoms. Each kingdom contains many species, so biologists created more and more precise categories to classify them. For example, let’s look at the grey wolf (Canis lupus).

Multicellular organisms that eat other living organisms to obtain energy.

Group that contains dogs, coyotes and wolves.

Carnivores that don’t have retractable claws (unlike cats).

Mammals that eat meat.

Chordates that have hair and nurse their young.

Animals that have a dorsal neural tube (like your spinal cord).

Kingdom Animals 1 200 000 species

Species Canis lupus 1 species

Genus Canis 9 species

Family Canids 35 species

Order Carnivores 231 species

Class Mammals 5 400 species

Phylum Chordates 52 000 species

In the animal kingdom, there are around 20 phyla, including mollusks, worms (like earthworms), and chordates (like wolves and humans).

Each level of classification corresponds to a criterion.

As you go from the kingdom to the species, there are fewer and fewer animals in each category.Fish (non-fused scales),

amphibians (smooth, moist skin), reptiles (fused scales) and birds (feathers) form other classes in the chordate phylum.The “mammal” class contains 26 orders: bats, primates, rodents, etc.

When you’re researching a species, don’t be surprised if you find subdivisions in the classification system. For example, the grey wolf is part of the sub-order of caniforms.

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What is a taxonomic key?How do you navigate all of these levels of classification? To solve that problem, biologists use a tool called a “taxonomic key.”

3.2.2

A taxonomic key is a tool that allows the user to distinguish one species from another.

D E F I N I T I O N

Leaves shaped like needles

Needles grouped into bundles

Flattened needles

Leaves shaped like scales

Isolated needles

Squared needles

Evergreens (Leaves shaped like needles or scales. Fruits: cones)

LEAVES SHAPED LIKE NEEDLES

NEEDLES IN BUNDLES

Bundles of more than 5 needles (that fall from the tree in the fall)............................................. Tamarack Larix laricina

Bundles of 5 or fewer needles • 5 needles ........................................................................ White pine Pinus strobus • 3 needles ............................................................................ Pitch pine Pinus rigida • 2 bent needles that measure between 2 cm and 4 cm ..... Grey pine Pinus banksiana • 2 needles that are between 10 cm and 15 cm long ............. Red pine Pinus resinosa

NEEDLES ATTACHED INDIVIDUALLY TO THE BOUGHS

Flattened needles (don’t roll between your fingers) ............... Balsam fir Abies basalmea

Squared needles (roll between your fingers) ......................... White spruce Picea glauca

LEAVES SHAPED LIKE SCALES

(Fruits: small cones made up of 8 to 17 scales) ........ Eastern White Cedar Thuja occidentalis

The taxonomic key for some evergreens in QuébecHere’s how to use a taxonomic key. Suppose you want to know the name of the tree that you got this branch from. Follow the key, using the information on the left.

A taxonomic key is a tool that helps identify the group that a species belongs to. It looks like a series of choices between two or more descriptions that lead to an answer for the category we need (class, order, species, etc.).

The tree you’re looking for belongs to the evergreen phylum.

Its leaves look like needles, not scales.

The needles are in bundles of 3.

Therefore, the branch comes from a pitch pine (Pinus rigida).



A C T I V I T I E S 1. Fill in the table by checking the characteristics that apply to each kingdom.

2. What is the main difference between fungi and plants?Sample answer: Plants use energy from the sun to feed themselves, while

fungi decompose matter. OR Plants contain chlorophyll (which gives them their

green colour), while fungi do not.

3. What kingdom do these living organisms belong to?

a) Cats. Animals. b) Turtles. Animals.

c) Roses. Plants. d) Yeast. Fungi.

e) Earthworms. Animals. f) Firs. Plants.

4. Write the levels of classification in increasing order (according to the number of species each contain).

Species, genus, family, order, class, phylum and kingdom.

5. Use the taxonomic key on the previous page to identify the tree that this branch belongs to. Explain your process.It’s a balsam fir. Its leaves are shaped like needles (not scales), they are

isolated (not in bundles), and they are flattened (not squared).

KINGDOMCHLOROPHYLL CELL NUMBER OF CELLS

Presence Absence Has a nucleus Does not have a nucleus Unicellular Multicellular

Animals

Plants

Fungi

Protists

Monerans

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6. Name three characteristics that could help you determine which species of trees these leaves belong to. For example, you could note whether the leaf is made up of one single leaf or several smaller leaflets.

Sample answer: shape, colour, size, whether it has jagged, smooth or rounded

edges, whether or not it has leaflets, etc.

7. True or false? If a statement is false, correct it.

a) The phylum is the largest taxonomic group.False. The kingdom is the largest taxonomic group.

b) You need a microscope to see a protist.True.

c) There are many different systems for classifying living things.True.

8. Fill in the table using the words in the margin.

CLASSIFICATION OF THE BLUE WHALE

Kingdom Animals.

Phylum Chordates.

Class Mammals.

Order Cetaceans.

Family Balaenopterids.

Genus Balaenoptera.

Species Balaenoptera musculus.

Animals

Balaenoptera

Balaenoptera musculus

Balaenopterids

Cetaceans

Chordates

Mammals



PopulationWhen you hear people talk about the “population” of a city, a village or a neighbourhood, they’re talking about all of the people that live there. You can do the same thing for other species. For example, you might want to describe the population of the cats in a village, the cacti in a desert or the protists in a lake.

What is a population?Let’s look more closely at what the word “population” means in biology.

3.3

3.3.1

African animal populationsThe African savannah is a good way to show what a population is. Many groups of animals live close together: elephants, antelopes, zebras, wildebeests, etc.

A population doesn’t include all the individuals of a species, but all that live in a particular place

D E F I N I T I O N

A population includes all the individuals of the same species that live in a given territory.

Species, p. 73

Among these animals, there are two species: zebras and wildebeests. All of the zebras that occupy the savannah form one population and all of the wildebeests form another.

Zebras don’t all live in the same place in Africa. That’s why it’s important to specify where a population lives. For example, here we’re looking at the population of zebras in the Serengeti National Park, in Tanzania.

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Population sizeLike in the savannah, different species live side by side in a sugar bush. Each of these species has many individuals.

The number of individuals in a population can change from one place to another or from one time of year to another.

The study of chimpanzeesMore than 50 years ago, British primatologist Jane Goodall studied the population of chimpanzees in Gombe National Park in Tanzania, Africa. One day, she made a major discovery: she saw a chimpanzee remove the leaves from a branch to catch termites in their nest. Before this discovery, scientists believed that only humans were able to make tools.

Jane Goodall (1934– )

1 9 6 0 T A N Z A N I A

600 sugar maples

10 white-tailed deer

In a sugar bush, some species, like the sugar maple, are very common. Others, like the white-tailed deer, are more rare. For example, a maple syrup producer could say that there are a population of 600 sugar maples and a population of 10 white-tailed deer in his sugar bush.

In a different sugar bush or another place, the populations of sugar maples and white-tailed deer would be different. Populations are generally larger in places where the conditions favour their survival.

Why would you measure the size of a population?• To figure out which habitat is best for a species.• To compare the size of one population at different times

of the year and from one year to the next. By measuring a population’s size, you can also understand how fragile a species is within a habitat.

How do you measure the size of a population?• By counting the number of individuals, if possible.• By using samples or clues. For example, you could count

the approximate number of ants in a colony and the number of colonies in a sugar bush.



A C T I V I T I E S 1. What is the difference between a population and a species?A “species” describes all individuals that look similar, can reproduce together

and can produce viable and fertile offspring. A “population,” on the other hand,

applies to a geographic region. A population includes all of the individuals that

live in a given territory.

2. When describing a population, you need to specify two things. What are they? Give an example.You need to specify the name of the species and the region where it lives.

For example, the population of white-tailed deer on Anticosti Island.

3. Check the statements that describe a population.

a) The broad beech ferns in Mont Saint-Bruno.

b) The study of great apes allows us to understand the ancestry of different species of hominids.

c) The Homo sapiens (humans) in Montréal.

d) All Felis domestica (cats).

e) Researchers counted fewer polar bears on the Arctic ice floes this summer.

4. Blue Lake is a huge, beautiful pond. To profit from it, residents of the city of White Mountain built a footbridge and observation deck.

Before the footbridge After the footbridge

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a) Create a profile of the populations in Blue Lake before and after the footbridge by filling in the following table. Use the legend to count the plants and the animals.

b) Which population do you think was the most affected by the footbridge ? Explain your answer.Sample answer: The frogs were the most affected. The frog population is

only one third of what it was.

c) What do you think would happen if the population you described in b) disappeared completely from the area?Sample answer: The other populations would change. For example, the pike

would have less food and might disappear from the lake as well.

d) What can the residents of White Mountain do to reduce the effects of the footbridge on the flora and fauna?Sample answer: They can limit visiting hours and ban activities that could

harm the plants and animals. OR They don’t need to do anything. In time,

the populations will recover on their own.

LEGEND BEFORE FOOTBRIDGE AFTER FOOTBRIDGE POPULATION VARIATIONS

= 20 frogs

3 × 20 = 60

60 frogs

1 × 20 = 20

20 frogs

60 – 20 = 40

40 fewer frogs

= 30 trout

6 × 30 = 180

180 trout

4 × 30 = 120

120 trout

180 – 120 = 60

60 fewer trout

= 5 pike

2 × 5 = 10

10 pike

1 × 5 = 5

5 pike

10 – 5 = 5

5 fewer pike

= 40 water lilies

4 × 40 = 160

160 water lilies

3 × 40 = 120

120 water lilies

160 – 120 = 40

40 fewer water lilies

= 25 cattails

6 × 25 = 150

150 cattails

4 × 25 = 100

100 cattails

150 – 100 = 50

50 fewer cattails



HabitatHave you ever heard the expression “happy as a fish in the water?” It gives you an idea of what is meant by habitat. A fish can’t live in the desert or in the snow. However, depending on its species, it can live in warm or cold water, in fresh or salt water, etc.

What is a habitat? Each species lives in a specific environment that meets its needs. Let’s look a bit more closely at what characterizes a habitat.

3.4

3.4.1

Varied habitatsThe habitats of the plants and animals below are very different. Let’s take a quick look at a few of them.

As you can see, we can describe the habitat of a living organism by geographic location, climate, relief, flora or fauna, etc.

D E F I N I T I O NA habitat is a specific place where a species is normally found, and that provides the conditions necessary for a species’ survival.

Some characteristics of a habitat are: geographic location, climate, relief (mountains, valleys, etc.), fauna (animals), flora (plants), presence of water, closeness to human structures, etc.

The blue peacock is common in hot and humid regions of India and Sri Lanka. It lives in forests, alongside rivers and on the edges of big clearings.

The wallaby, a cousin of the kangaroo, lives in coastal forests in the temperate climate of eastern Australia.

The polar bear lives on ice floes on the edge of the Arctic Ocean, where the climate is polar.

This cactus is originally from the Sonora Desert, in northern Mexico and the southern United States. It is the largest desert area in North America.

The yellow water lily grows in swamps and calmer areas of lakes and rivers. Its habitat reaches from Central America up to southern Canada.

Species, p. 73

What is relief?, p. 158

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A C T I V I T I E S 1. Fill in the table to describe the Northern gannet’s habitat. Use the information contained in the following text.

The Northern gannet (Morus bassanus) can be found on the coast of the northern Atlantic. The largest colony of Northern gannets is on Bonaventure Island, in Gaspésie. They can be seen from March to November. These seabirds nest on the sides of cliffs. They feed on small fish like mackerel, herring, capelin and sand eel. Many tourists visit the region each year in the hope of seeing them plunge into the water to catch their prey.

2. Describe the habitat of a raccoon that lives near your house.

ELEMENT NORTHERN GANNET’S HABITAT

Geographic location Coast of the northern Atlantic.

Climate Maritime climate of Gaspésie.

Relief Cliffs.

Fauna Mackerel, herring, capelin, sand eel.

Human presence Tourists and residents of the coast.

Presence of water Atlantic Ocean.

ELEMENT RACCOON’S HABITAT

Geographic locationOn the northern bank of the Saint Lawrence River, halfway between Montréal

and Québec.

Climate Continental climate (Saint Lawrence lowlands).

Relief Generally flat.

FaunaUrban fauna: dogs, cats, turtledoves, squirrels, marmots, etc.

FloraUrban flora: flower beds, cedar hedges, flower and vegetable gardens, etc.

Human presence The city has 130 000 inhabitants.

Presence of water The Saint Lawrence and Saint-Maurice rivers.

Sample answer for the city of Trois-Rivières:



4. In Québec, the road to Saguenay–Lac-Saint-Jean crosses the Laurentides Wildlife Reserve. This region is the habitat of many species, including the caribou, the moose and the black bear. What effect do you think the road has on the species in the reserve?Sample answer: The road divides the reserve into two parts. If the road is

fenced, animals can no longer cross from one side to the other. Even if they

are able to cross, doing so is dangerous for them. The road can also make

reproduction and hunting prey (for predators) more difficult.

3. Link each species (on the left) with its habitat (on the right).

a) Polar bear • • Tropical forest

b) Clownfish • • Temperate forest

c) Koala • • Savannah

d) Great white shark • • Ice floes

e) Beaver • • Coral reef

f) Giraffe • • Ocean

The living 94 world


Ecological nicheAll living organisms don’t play the same role in their environment.

What is an ecological niche? Each species occupies a different ecological niche.

3.5

3.5.1

Ecological niche of the beaverHere is a brief description of the beaver’s ecological niche.

D E F I N I T I O NAn ecological niche describes the role that a species plays in its environment. It includes all interactions with the living and non-living elements of its environment.

More specifically, an ecological niche is described in terms of an animal’s diet, its sleeping patterns (whether it is diurnal or nocturnal), its habitat, etc.

An ecological niche is the place occupied by a species in its environment. Each species has its own niche. Each niche is different from that of other species.

Species, p. 73

Habitat, p. 92

Relationships with other species. The beaver limits the populations of the trees it eats because it cuts those trees down.

Diet. The beaver feeds on the bark, wood and leaves of the trees it cuts down. During the summer, it also eats aquatic plants.

Relationships with other species. Fish benefit from ponds created by beaver dams.

Relationships with predators. A few predators, including black bears, eat beavers.

Dwelling. The beaver lives in a lodge made of branches. It constructs a dam so that the entrance to its lodge is underwater and hard for predators to reach. The dam also creates new ponds.

Sleeping patterns. The beaver is diurnal: it is awake during the day and sleeps at night.



ABIOTIC AND BIOTIC FACTORSEcological factors—factors in the environment that have an impact on living organisms—can be classified into two categories: abiotic factors and biotic factors.

Abiotic factors are all of the non-living elements in an environment. For example:• amount of light; • relief;• temperature; • soil type;• precipitation; • amount of oxygen in the water;• wind; • salinity (amount of salt in the water).

Biotic factors involve all of the interactions between living organisms in an environment. For example:• plants that serve as food or shelter;• animals that act as predators or prey;• fungi and bacteria that decompose matter from living organisms;• bacteria that provide nutrients to plants;• protists that act as decomposers or predators.

PRODUCERS, CONSUMERS AND DECOMPOSERS• A producer is a living organism that produces living matter by absorbing

and reorganizing non-living matter. Plants are considered producers because they get energy through photosynthesis.

• A consumer is a living organism that consumes other living organisms. Herbivores (which feed on plants), carnivores (which feed on animals) and omnivores (which feed on both plants and animals) are all consumers.

• A decomposer is a living organism that feeds on dead organisms or on waste products of other organisms (plants or animals).

Producer (plant)

First-order consumer (herbivore)

Decomposer

Second-order consumer (carnivore)

The living 96 world


A C T I V I T I E S 1. Explain why two different species cannot occupy the same ecological niche.Two species that are active at the same time, eat the same species and occupy

the same territory will be forced into competition. Eventually, one of the species

will leave the territory or disappear.

2. Since the beginning of the year, Juliette has been watching two species of birds in her yard: black-capped chickadees and American goldfinches. Here is what she has learned about the two species:

a) Name three things these birds have in common.

• They can eat the same food, but their primary diet is different.

• Their territories overlap.

• They are both diurnal.

b) Do these birds occupy the same ecological niche? Explain your answer.No. They don’t have exactly the same diet and mostly occupy different

territories. Their nesting habits are different.

Black-capped chickadee (Poecile atricapillus)

American goldfinch (Carduelis tristis)

SPECIES DIET TERRITORY PLACE IT REPRODUCES SLEEPING PATTERNS

Feeds mostly on insects, but also eats buds, berries and seeds.

Found in Alaska, Canada and the northern United States. Lives in forests, parks and gardens.

Nests in birdhouses or holes that it carves in dead trees.

Active during the day. Sleeps at night.

Mostly eats seeds, but sometimes eats insects.

Found mostly in fields and prairies in North America. Also found in orchards, gardens and along roadsides.

Nests in the branches of shrubs and small trees.

Mostly feeds during the day.



3. Read the text below, then answer the questions.

a) What is the polar bears’ diet? They eat seals, fish, seabirds and caribou.

During the summer, they also eat

berries and other plants.

b) What is their habitat? Arctic regions, around the North Pole.

They can also be found in Greenland and in

a few regions south of the Arctic Circle.

c) What are their predators? Human beings. Male walruses and other polar

bears sometimes attack cubs.

d) What are their relations with other species?Other than humans, polar bears are the biggest

predators in the Arctic.

e) How do they reproduce? The female has a gestation period of nine

months. She gives birth to between one and four

cubs, which she raises for two or three years.

During pregnancy, the female retreats into a den.

f) What are their sleeping habits? Polar bears are diurnal. They are the only bears

that don’t hibernate.

Polar bears’ ecological niche

The polar bear (Ursus maritimus) lives mainly in Arctic region, around the North Pole. It can also be found in Greenland and in a few regions south of the Arctic Circle in North America and Asia.

Polar bears are diurnal mammals. Their thick fur, short tail and rounded ears help reduce heat loss. They have a thick layer of fat that protects them from the cold. Their black skin helps them retain heat effectively.

Polar bears are primarily carnivores. They eat seals, fish, seabirds and caribou. During the summer, when the ice melts, they also eat berries and other plants. Other than humans, polar bears are the biggest predators in the Arctic. Their white fur acts as camouflage. They are excellent swimmers: they can chase prey easily in the icy water as well as on ice floes.

Polar bears live between 15 years and 30 years. They are the only bears that don’t hibernate. However, when females are pregnant they retreat into a den to make sure that their cubs are born in a safe place. After a nine-month gestation period, female polar bears give birth to between one and four cubs. Females raise cubs for two or three years. During that time, the female protects her cubs from predators, like male walruses and other polar bears.

The polar bear’s survival is threatened by global warming, especially the melting ice floes. Researchers have already observed a decrease in population in some regions, like Hudson Bay.

The living 98 world


Present era (Asian elephant)

2 million years ago (Deinotherium)

20 million years ago (Gomphotherium)

35 million years ago (Phiomia)

50 million years ago (Moeritherium)

Evolution in elephantsLiving organisms change over time, as the evolution of these five species shows.

Evolution is a slow process that leads to modifications in living organisms. These modifications allow them to adapt to changes in their environment. The theory of evolution explains why there are so many different life forms on Earth.

Evolution is based on natural selection, which causes a species to adapt to its environment over generations. Individuals that have characteristics which give them an advantage are more likely to survive and reproduce.

D E F I N I T I O N

As this example shows, evolution happens stage by stage and occurs over millions of years.

Moeritherium, a predecessor to the modern elephant, lived 50 million years ago. It was smaller and had a shorter trunk than today’s elephant.

Scientists have been able to trace the evolution of the elephant by studying fossils.Over generations, the elephant’s ancestors grew larger and their trunks and tusks lengthened.

EvolutionLiving organisms have not always looked the way they do today. There were no horses, dogs or humans 100 million years ago. And a number of species that existed are no longer here today. Dinosaurs, for example, disappeared approximately 65 million years ago. Mammoths went extinct around 10 000 years ago.

What is evolution? How and why do living things evolve from one form to another? You’ll learn why in this section.

3.6

3.6.1

Physical and behavioural adaptations, p. 103



3 4

Stages of evolutionLet’s look at the giraffe as an example of the stages of evolution. The giraffe’s predecessors did not have long necks or long legs.

Imagine a place in Africa, millions of years ago, where there was a population of “little giraffes.” In this region, the “little giraffes” grazed on grass.

Natural selection explains how and why species change over millennia.

5

1 2

Giraffes have adapted to their new environment. Over time, “small giraffes” are replaced by “big giraffes.” The giraffe population has changed. It adapted to its new environment. “Big giraffes” became a new species.

5

The selected characteristics are hereditary. A hereditary characteristic is passed down from parents to their young. For example, hair and eye colour are hereditary characteristics. In giraffes, parents that are bigger and have longer necks give birth to babies that are more likely to be bigger and have longer necks. In fact, they might even end up being bigger than their parents.From one generation to the next, the biggest giraffes have had better chances of survival. Smaller giraffes gradually disappeared. And bit by bit, from generation to generation, giraffes’ necks and legs lengthened.

4

There is a change in the environment. The climate changes, the grass becomes more rare. Animals that eat grass are now in competition. Some “small giraffes” start eating the leaves on trees instead of grass.

1

Individuals in the “small giraffe” population are not all identical. Some “small giraffes” are slightly bigger and have a slightly longer neck than others.

2

Natural selection occurs. Over time, natural selection favours larger giraffes. Giraffes that are a little bit bigger have a slight advantage over others. They can eat leaves that are higher up on trees. That means they eat better, are in better shape and are better equipped to care for their young. They can also escape predators more easily, so they’re more likely to reproduce.

3

The living 100 world


1. Here are a series of statements about evolution. For each evolutionary stage, two statements are given. One is true, the other is false. Underline the statements that are true.

A C T I V I T I E S

Millions of years ago, a population of a certain species lived in a given region. This species no longer exists today. It was replaced by another species. Fossils show that the species that disappeared is an ancestor of the species that lives in that region today. How can you explain that evolution?

STAGE 1

A. The environment where this species lived has changed.

B. The environment where this species lived has not changed.

STAGE 2

A. All of the individuals of that species were identical and had the same chances of adapting to changes in their environment.

B. The individuals of that species were slightly different from each other.

STAGE 3

A. The individuals of that species struggled to adapt to the changes. In doing so, they managed to change some of their characteristics.

B. Some individuals of the species already had a characteristic that allowed them to adapt to the changes, giving them a better chance of surviving and reproducing.

STAGE 4

A. The individuals that inherited the characteristic that allowed them to adapt to the changes passed that characteristic on to their offspring.

B. The individuals that struggled to adapt to the changes in their environment passed the characteristics they managed to change down to their young.

STAGE 5

A. Over time, natural selection occurred, favouring individuals that had the hereditary characteristic that allowed them to adapt to the changed environment. This population became a new species.

B. Over time, the individuals that struggled to adapt to the changed environment adapted effectively. These individuals always belonged to the same species.



2. Explain natural selection in your own words. It’s a stage in the evolutionary process where the individuals that have adapted

best to changes in their environment survive and reproduce.

3. True or false? If a statement is false, correct it.

a) Species do not change.False. If the environment changes, species evolve and end up adapting to

those changes.

b) Modern species have adapted to their environment and will therefore survive in the future.False. They will only survive if their environment doesn’t change. Otherwise,

they will either die off or be forced to adapt.

c) All of the individuals in a species are identical.False. There are differences between members of the same species.

d) Fossils can provide hints about the evolution of a species.True.

4. Put the stages in the correct order.

A. The selected characteristics are hereditary.

B. Individuals in a population are not all identical.

C. The environment changes.

D. Individuals are adapted to their new environment.

E. Natural selection occurs.

C, B, E, A and D.

5. Explain hereditary characteristics in your own words.A hereditary characteristic is passed down from parents to their young. Hair

and eye colour, the shape of certain body parts, and some illnesses are all

hereditary.



Why are there so many different life forms? It’s because living organisms have had to adapt over the course of their evolution.

What is a physical adaptation? Adapting is sort of like transforming so that a species can continue living in the same place.

3.7

3.7.1

Physical and behavioural adaptations

Bird feetHere is a good example of physical adaptation: bird feet are different shapes depending on what they’re used for.

A physical adaptation is a physical characteristic that improves a species’ chance of survival in its environment.

D E F I N I T I O N

These examples show that the shape of bird feet are adapted to their lifestyles.

Swimming birds, like ducks, have webbed feet. The webs help them swim in ponds and other bodies of water.

Climbing birds, like woodpeckers, have two toes pointing forward and two toes pointing backward. These toes help them hold on to tree bark.

Walking birds, like chickens and ruffed grouses, have toes that lay flat on the ground. This allows them to walk and run.

Perching birds, like Eastern bluebirds, have three toes pointing forward and one toe pointing backward. That way, they can grip branches and stay perched.

Evolution, p. 99



As these examples show, mammal teeth are different depending on the animal’s diet.

Insectivores, like moles, have many sharp teeth that allow them to pierce bug shells.

Grazers, like cows, only have incisors on their lower jaws. Those incisors are used to pull grass. Then they chew it with their flattened molars.

Rodents, like beavers, have sharp incisors and strong molars that help them cut branches and grind bark.

Mammal teethHere is a second example of physical adaptation. Over time, mammal teeth have changed. They have adapted to different diets and lifestyles.

Natural selectionCharles Darwin, an English naturalist, is famous for publishing a book that was revolutionary at the time: On the Origin of Species by Means of Natural Selection. In this work, Darwin revealed the theory of evolution that he developed by observing adaptations in many plant and animal specimens during a trip around the world. His theory provided the foundations for modern theories of evolution.

1 8 5 9 E N G L A N D

Canines

Molars Molars

MolarsCanines

Molars

Incisors Incisors

Incisors

Incisors

Carnivores, like wolves, have pointed canines that allow them to maul their prey. Their molars are sharp.

Charles Darwin (1809–1882)



Arctic hare in the summer Arctic hare in the winter

Monarch

The examples on pages 103 to 105 have shown you some of the many physical adaptations in the world. In fact, all living things have physical adaptations.

Monarchs feed on a plant that makes them taste bad. Therefore, birds avoid eating them.

Viceroy butterflies have similar colours to the monarch butterfly. Birds avoid eating them because they believe they are monarchs.

In summer, the Arctic hare has a grey-brown coat. In winter, it turns white, which camouflages it in the snow.

Mimicry and camouflageMimicry and camouflage are two other types of physical adaptation.

Why do palm trees and cacti have such different leaves?

Plants also develop physical adaptations. Palm trees grow in areas where hurricanes are common. The slits in their leaves allow them to resist the wind. Cacti, on the other hand, grow in the desert. Their leaves have turned into spikes in order to limit water evaporation. The spikes also protect them from herbivores.

With mimicry, one species imitates another. They might do this to protect themselves from predators.

Camouflage serves to make an animal almost invisible in its environment.

Viceroy

Camouflage

Mimicry



Why do insects make life harder for themselves by flying in zigzags?

If an insect always flew in a straight line, it would be easy prey for birds. It would not be difficult to predict their position. Furthermore, when an insect is seeking food, it flies in many short bursts, making its path look random. But if you’ve ever angered a bee, you’ll know that it is perfectly capable of flying in a straight line!

What is a behavioural adaptation?Why do some Québec birds migrate south in the fall, while others stay here all winter? It’s due to behavioural adaptations that vary depending on the climate and the bird’s diet. For example, insectivores leave the cold climate in Québec because their food becomes too rare in winter.

3.7.2

A behavioural adaptation is a behaviour that improves a species’ chance of survival in its environment.

D E F I N I T I O N

Plants grow in the direction that allows them to best meet their needs (water, sun, minerals, etc.). Their behaviour changes to adapt to their environment.

Behavioural adaptation in plants Here are two examples of behavioural adaptations in plants.

Phototropism is an adaptation that plants have made in response to light. Their stems and leaves grow towards light sources.

Geotropism is an adaptation that plants have made in response to gravity. Their roots grow downwards, while their stems grow upwards.



1. In the following text, highlight the physical adaptations in yellow and the behavioural adaptations in blue.

The crested gecko (Rhacodactylus ciliatus) has tiny,

sticky hairs on each of its toes that allow it to grip most

surfaces. It lives in the treetops in tropical forests. Like

most geckos, if a predator grabs it by the tail, the

crested gecko lets it fall off. The gecko’s brown colour

allows it to camouflage itself against tree bark. It

doesn’t have eyelids, so it licks its eyeballs to keep

them moist. Its strong rear legs allow it to jump and

catch flying insects.

2. Fill in tables a) and b) by putting the adaptations in the right place.

a) Animal adaptations.

A C T I V I T I E S

Building a nest of twigs.

Having a stinger for attacking enemies.

Hunting in packs.

Making a noise to alert other animals of danger.

Producing milk to feed young.

Singing to attract females.

ELEMENT PHYSICAL ADAPTATIONS BEHAVIOURAL ADAPTATIONS

Food

Producing milk to feed young.

Hunting in packs.

Protection against predators

Having a stinger for attacking enemies.

Making a noise to alert other animals

of danger.

Reproduction

Singing to attract females.

Building a nest of twigs.

Legend: = yellow = blue



b) Plant adaptations.

3. Indicate whether the following adaptations are physical (P) or behavioural (B).

a) A fish’s caudal fin (the fin that forms its tail) allows it to swim and change direction. P

b) Worker bees forage in flowers to bring nectar back to the hive. B

c) Horses have hooves to run on very hard ground. P

d) Some carnivorous plants have a digestive organ that looks like a flower, which attracts insects. P

4. A long time ago, polar bears adapted to survive in Arctic regions. Using the text that describes their ecological niche (see page 98), list four physical adaptations polar bears have undergone to adapt to their environment.

• Their thick fur, short tail and rounded ears help reduce heat loss.

• They have a thick layer of fat that protects them from the cold.

• Their black skin helps them retain heat effectively.

• Their white fur acts as camouflage.

Flowers are colourful to attract insects and pollinating birds.

Rose bushes have thorns to protect themselves from herbivores.

Seeds are covered in a shell that’s difficult to digest.

The more light there is, the bigger the leaves are.

ELEMENT ADAPTATIONS

FoodThe more light there is, the bigger the leaves are.

Protection against predators

Rose bushes have thorns to protect themselves from herbivores.

ReproductionFlowers are colourful to attract insects and pollinating birds.

Seeds are covered in a shell that’s difficult to digest.



5. What is the difference between mimicry and camouflage?• Mimicry involves imitating the look or behaviour of another species.

• Camouflage involves being almost invisible in its environment.

6. In each case, indicate whether the species protects itself using mimicry or camouflage.

a) Soles are flat fish that slide beneath the sand to escape predators.Camouflage.

b) Katydids imitate the leaves on trees so that they can’t be detected by predators.Camouflage.

c) The coral snake (on the left) is one of the most venomous snakes in the world. The milk snake (on the right) imitates the coral snake so that predators won’t attack it.Mimicry.



Chapter 3 Review1. Here is the classification of the giant panda and the black bear.

What does the taxonomy of these two animals tell us about their ancestry and differences?They both belong to the same family (Ursids). They are from different genera

and species.

2. Read the text below, then answer the questions.

Biologists classify giant pandas as carnivores, like other ursids. However, 95% of the panda’s diet is plant-based, comprised mostly of bamboo leaves. The leaves are not very nutritious and the panda’s digestive system is not well-adapted to a vegetarian diet, so pandas spend almost 23 hours a day eating. In China, bamboo forests are slowly disappearing. They are being replaced by houses and agriculture. The female panda gives birth to one or two cubs, but she can only care for one.

a) What do you think is happening to populations of giant pandas? They are endangered.

b) Describe three adaptations that giant pandas should develop to survive.

• They should eat food that is more

nutritious than bamboo.

• They should develop a digestive system that

can better digest bamboo.

• They should adapt to a different environment,

because bamboo forests are slowly

disappearing.

LEVEL GIANT PANDA BLACK BEAR

Kingdom Animals Animals

Phylum Chordates Chordates

Class Mammals Mammals

Order Carnivores Carnivores

Family Ursids Ursids

Genus Ailuropoda Ursus

Species Ailuropoda melanoleuca Ursus americanus

Sample answer:



3. Describe the human being’s ecological niche by filling in the table below.

4. The following statements are partially true. Explain how they could become completely true.

a) All species that are alive today are adapted to their environment.If they are there, it’s because they have adapted to previous changes to

their environment. However, regions continue to change. Not all current

species are adapted to these ongoing changes.

b) Among other reasons, evolution can be caused by changes to a species’ environment.Evolution is always caused by changes to a species’ environment.

c) All of the ancestors of modern species have disappeared.Species whose environment has changed have evolved and transformed

into new species. Their ancestors have therefore disappeared. However,

if their environment did not change, the species that lived there will have

stayed the same.

ELEMENT ECOLOGICAL NICHE

Sleeping patternsActive all year (doesn’t hibernate), generally diurnal.

HabitatAll continents on Earth.

DietHuman beings are generally omnivores.

PredatorsNo real predators.

Reproduction and shelter for young

Build houses to reproduce and care for children.



chapter diversity of life forms - contact · similar animals like dogs and wolves the same species?...

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