topic 2 habitat and lifestyle - cochrane high school

A poplar tree:

absorbs light for photosynthesis

removes carbon dioxide from the air andreleases oxygen into the air

removes water and nutrients from the soil

stabilizes the soil from erosion (wearing away)

provides food and shelter for a wide variety of organisms

covers the ground with leaves in the fall, whichreturns nutrients back into the soil

These various activities are what thepoplar tree "does" and they make upits role in the ecosystem.

Habitat and LifestyleEveryone has special talents that make that personunique. What do you do better than anyone elsein the class? Like people, some organisms dosome things better than others. Variation inpeople and other organisms is more thanjust physical appearance. It can also bewhat an organism does well. For example,dandelions grow well in bright sunlight,while ferns grow well in the shade.

The Niche: What Makes anOrganism Special?As you have seen, adaptations allow an organism to play a specific rolein its environment. Adaptations also help organisms to compete witheach other for the needs of life. You may remember from earlier studiesthat an organism’s niche includes two parts: where an organism lives(its habitat) and what it does. Look at the poplar treein Figure 1.9. This poplar’s habitat is a mountain

forest just outside of Banff. But whatdoes the poplar tree do? What is its role?

16 MHR • Biological Diversity

T O P I C 2

Figure 1.9 This poplar tree performsmany functions, which, together withits habitat, make up its niche.

Describe the niches ofthree other organismsfound in Alberta.Describe at least oneplant and one animal.Write your answers inyour Science Log.

Variation and CompetitionWhen resources such as food, water, or sunlight are plentiful, manyspecies can share them. However, when any one of these resourcesbecomes scarce, the organisms that depend on the resource must compete for it. Competition can occur between members of the samespecies or between different species.

Whenever two individuals compete, variations between the individualsmay give one of them an advantage. Again, this is true of members ofthe same or different species. For example, if two species, such as muledeer and white-tailed deer, are competing for the same resource, one mayhave more favourable adaptations. Mule deer are able to tolerate coldwinters much better than white-tailed deer. However, white-tailed deerthrive near agricultural lands. Depending on the surroundings, themembers of one species may be faster or better able to avoid predators.This would allow the better-adapted deer species to reproduce andeventually “take over.” In order for future generations to survive, theless successful species may have to change to a less desirable foodsource or move to another habitat.

Figure 1.10 These deer must compete with each other and with other species for food and space.

Some species avoid competition with more dominant species by using adifferent food source or keeping different habits or behaviours. Cougarhunt large herbivores like deer, elk, or bighorn sheep, and are usuallyfound in thick pine forests. Lynx can inhabit the same area as cougars,but tend to feed on snowshoe hare. Many owls avoid competing withhawks by hunting at night. As organisms change to avoid or reducecompetition, they alter their niches. These subtle changes eventuallyincrease the variation within or between species.

Habitat and Lifestyle • MHR 17

Hawaiian plants do nothave thorns or toxins.Although pigs, goats, anddeer have been intro-duced to the islands,there are no browsingmammals native toHawaii. As a result, nativeplants did not evolveadaptations for protectionfrom browsing mammals.

Think about what youwould need to knowabout various speciesof trees and otherplants in order to dis-cuss the issue onpages 82–83. Is therean advantage toremoving old trees?What effect might thisaction have on com-petition among otherkinds of organisms on the area?

Lo

oking

Ah e a

d

yellow- rumpedwarbler

bay- breastedwarbler

Cape Maywarbler

black- throatedgreenwarbler

Blackburnianwarbler

Warblers are small, active birds with sharp beaks adapted for capturinginsects. Numerous species of warblers can be found in Alberta duringthe summer. They winter in the southern United States and in Centraland South America. In the spruce forests of Canada five warbler speciescan co-exist in the same tree:• Cape May warbler feeds on insects

at the top and tips of the tree.• Yellow-rumped warbler feeds on

insects near the trunk’s lowerbranches and on the ground.

• Black-throated green warbler feedsnear the middle of the tree.

• Blackburnian warbler feeds fromthe outer tips from the middle tothe top.

• Bay-breasted warbler feeds fromthe lower half of the tree awayfrom the tips.All of these birds live in the

same tree, but do they share the same niche?

Animals are not the only organ-isms that have very specific niches.Did you know that countless numbers of micro-organisms inhabit thehuman body? You could say that each part of your body is its ownecosystem. Most of these micro-organisms are not harmful and the different species that inhabit the skin, the mouth, and the digestivetract are your constant companions.


Figure 1.11 Which characteristics do all ofthe warblers share? How are these birdsable to avoid competing with one another?

In your Science Log, create a scenario thatwould explain how thefeeding habits of the different warblers developed.

Explain why the diagramof the spruce tree doesnot show a completelyaccurate picture of thewarblers’ feeding pat-terns. How could youdesign an experiment toget a more accurate pic-ture of what is happening?Write your thoughts inyour Science Log.

Figure 1.12 The bacterium Streptococcus mutans is amajor component of dental plaque. Regularbrushing is required to prevent plaque frombuilding up and causing cavities.

The Broad NicheIf you have had the chance to travel around northern Canadaand observe the wildlife, you may have noticed two things.First, there are not as many different species of plants andanimals as there are in other regions. Second, there are verylarge populations of the species that you do find. There arevast herds of caribou and millions of arctic hare. Even largecarnivores like wolves and polar bears are found not only innorthern Canada but also all around the northern regions ofthe globe. These same species of wolf (Canis lupus) and polarbear (Ursus maritimus) are found in Russia and northernEurope. In contrast, if you travel through the rainforests ofCentral and South America, you may see hundreds or thou-sands of different species, but each population is very small. It is quitepossible that you could walk through the jungle and not see the samekind of bird twice in one day.

Why do Canadian ecosystems lack diversity but support high numbersof the species that live here? The animals that live here year-roundmust be able to withstand daily and seasonal changes in temperature.


Find OutBird WatchingAlberta is home to many birds, such as therobin, sparrow, magpie, chickadee, and duck,which are common in neighbourhood backyardsor parks.

Materials

binoculars (optional)tape recorder (optional)notebookpensProcedure

1. With a group, choose two or three birds in your neighbourhood to observe. Devise a procedure for making and recordingobservations.

2. Make your observations of the birds, keepingthe following questions in mind:(a) In what location do the birds live? (For

example, one bird may live next to apond in the local park.)

(b) Where do the birdsmake their nests?

(c) What do thebirds eat?

(d) Do other birdsor animals live in the same areaas the birds youare studying?Which ones?

What Did You Find Out?

1. How were your answers similar to or different from your classmates’ answers?

2. Based on your observations, describe theniches of your study birds. Compare andcontrast their niches.

3. How would your observations be different ifyou had done this activity at another timeof year?

Performing and Recording

Communication and TeamworkInitiating and Planning

Figure 1.13 Wolves needlarge areas of land to live.Wolves currently travelbetween Canada and theUnited States along awildlife corridor, a naturalroute used by animals, inthe Rocky Mountain region.

Analyzing and Interpreting

They also must be able to eat a variety of plants or other animals asseasons and conditions change. There are exceptions, but in general,organisms that survive here must have a broad niche. They must haveadaptations that allow them to survive in the heat of the summer andthe freezing cold of the winter. These Canadian species are generaliststhat are able to spread over large areas.

Diversity in the Tropics: The Dangers of aNarrow NicheIn the tropics, temperatures and food supplies are relatively stable. Inthese regions, most organisms are specialists, which means they haveadaptations that make them very efficient at surviving in their own envi-ronments. Plants and animals tend to have very narrow niches withadaptations directed toward competing for one dependable food source,one type of soil, or one level of light. This specialization allows manydifferent species to inhabit a single area, but it prevents any one speciesfrom spreading over a large area. The result is that the tropics have anincredible diversity of species, but their populations tend to remain low.

A specialist is well suited to one particular environment. This hasbeen described as “the trap of specialization.” As the species competeswith others, the more useful adaptations it acquires and the more suc-cessful it becomes. However, many of the adaptations that make aspecies successful in one environment may prevent it from being ableto inhabit other environments. For example, the lion-tailed macaque ofIndia is specialized for life in the forest canopy. This monkey is not suitedfor life on the ground. As the forests are cut down the lion-tailedmacaque has nowhere else to live.


Figure 1.14 Like thecaribou, polar bear, andwolf, the arctic hare is ageneralist, and is adaptedto living in cold winters andmild summers.

Plants and animals thathave specialized niches inwetlands are put at riskwhen wetlands aredrained. Research Albertawetlands to learn aboutsome of the species thatlive there. You can usethe library or the Internetfor your research, or youcan contact an expertwith a wildlife conserva-tion group. How wouldyou advise the local government about anyplans to build housesover a wetland area?Record your findings inyour Science Log.

Figure 1.15 The tropical rain forestsof the world are areas of richbiological diversity. Many parts ofthese forests have never beenexplored by scientists and likelycontain many undiscovered species.

Figure 1.16 Not all specialists live in the tropics. Theprairie white-fringed orchid is an endangered specialist. Ifpopulations of the hawkmoths that pollinate this flowerdecrease, what will happen to the orchid?

www.mcgrawhill.ca/links/sciencefocus9

What happens if a new species is introduced into a food web?To begin your research for this activity, go to the web site above,

and click on Web Links to find out where to go next. Presentyour findings in a short talk to your class.

Dependencies Between SpeciesLiving things have struggled to survive for millions of years. Few, if any,have done so alone. You may think that an elk needs only water to drinkand plants to eat. In fact, the elk would not be able to digest its foodwithout the help of communities of micro-organisms that live in theelk’s rumen, a specialized stomach. In turn, the elk providesthe micro-organisms with a place to live. This kind ofclose partnership is common in natural communities.

Many plants depend on mycorrhizae, specialized fungi,to help absorb water and minerals from the soil. Thefungi attach to the roots of the plants, which increasesthe surface area of the roots. The mycorrhizae also pro-tect the plants from some diseases. The fungus benefitsby being able to draw nutrients from the plants. Youmay recognize that this is a symbiotic relationship inwhich two organisms live in direct contact. It is also anexample of mutualism, because the relationship benefitsboth species.


Figure 1.17 The ability of plants and mycorrhizaeto live in symbiosis is an adaptation — but with adifference. In each case the adaptation was madein close harmony with the other species. Bothpartners in the relationship developed compatibleadaptations at the same time. Here, the fungus isshown as it infects a plant root.

plant cell

mycorrhizae

www.mcgrawhill.ca/links/sciencefocus9

Many micro-organisms play important roles in the environment.To find out more about them, go to the web site above, and click on

Web Links to find out where to go next. Record the names of three ormore beneficial micro-organisms. Write a short paragraph

explaining the importance of each.

Find OutIntroducing . . .Generalists can live almost anywhere. Theiradaptations allow them to survive in a varietyof environments and live on a variety of differ-ent food sources. When introduced into a newarea where there are too few predators or com-peting organisms, generalists spread rapidly. Asyou may recall, an introduced generalist cansometimes take over, forcing out species thatare specialized for life in local ecosystems.

Procedure

Research an example of an introduced species,find out if it was introduced intentionally oraccidentally, and detail its effect on local speciesand ecosystems.

What Did You Find Out?

1. How have populations of local specieschanged since the arrival of the introducedspecies?

2. What niche does the introduced speciesnow occupy?

3. Should we limit the spread of the introducedspecies? If so, what steps are being takento control the further spread of this species?

4. Make a list of all of the species introducedto Canada that you and your classmateshave researched. Enter the names of thesespecies into a data base that other peoplecan search.



Clover and Soil BacteriaClover, peas, beans, and other plants called legumes have symbiotic relationships with certain soil bacteria. These bacteria, known as rhizobia, are able to live in the plant roots, where they remove nitrogen from theair and change it into nitrogen compounds the plant can use.

HypothesisFormulate a hypothesis about the importance of rhizobia to clover plantsand their role in soil communities.

Safety Precautions

• Be careful when cutting nodulesfrom roots.

Apparatussmall shovel microscopescissors slideeye dropper cover slip

Materialsmethylene blue dye

ProcedureClover is found in mostlawns and fields. Find patchesof clover in your schoolyardor local park.

Dig up two or three cloverplants, taking care to keepthe roots intact.

In the lab, gently rinse theroots to remove any soil.

Examine the roots to findany bumps or nodules (seefigure at top right).

Cut out one or two of thenodules and place them on amicroscope slide. Add oneor two drops of methyleneblue dye. Put on a cover slipand press gently on the cov-er slip to crush the nodules.

Observe the nodules on the highest magnificationavailable.

1-C1-C


Analyze1. Where did you find the

clover?

2. Could you see the bacteriafrom the crushed nodule?

3. Why is it difficult to seethe bacteria?

Conclude and Apply4. What evidence did you

observe in the field thatindicates the bacteria areadding nitrogen to the soil?

5. Why do farmers some-times alternate clover with other crops?

6. Can legume plants grow without living in symbiosis with rhizobia? Explain your answer.

Extend YourKnowledge

7. Repeat the experimentwith pea plants or bean plants. Chooseplants from fertilized and unfertilized soils.Which plants have nodules? Explain your findings.

S K I L L C H E C K

Initiating and Planning



Communication and Teamwork

Life in the ExtremeWould you expect to find life at 110 °C? In a salt lake? In the desertsand? In fact, there are organisms adapted to living in all of theseextreme environments. The Antarctic springtail, for example, is adapt-ed to the extreme cold. This tiny arthropod produces a type ofantifreeze in its tissues, which allows it to survive temperatures as lowas -35 °C. Snow algae, which can be found on snowfields around theglobe, have cell membranes that are adapted to cold temperatures.Being photosynthetic, the snow algae make their food using the energyof sunlight. However, high in the mountains, sunlight can be veryintense. Some snow algae produce reddish pigments that protectagainst the Sun’s damaging rays.

Many organisms have adaptations that defy our current understandingof life. Scientists who are curious about the possibility of life on other,less hospitable planets hope to learn from these strange, earthly species.


Without special stains, many microscopic structures would be almostimpossible to see, even using a microscope. As mycorrhizal fungi surround and enter roots, the roots themselves change shape. Shownhere are the roots of an orchid seedling colonized by a mycorrhizal fungus. In order to see mycorrhizae, biologists used a fluorescent stain. Ablue light was then shone on the stained specimen. When seen througha microscope, the mycorrhizal fungi showed up in fluorescent colours.

Figure 1.18 Have you ever seen pink snow? Snowalga is a red alga that is well adapted to living in coldclimates. It can be found living on the surfaces ofsnowfields and glaciers.

Figure 1.19 The desertspadefoot frog has itsniche in the harshconditions of theAustralian desert. Thisfrog can remaininactive for years whileburied in the desertsand awaiting rain.

Specialized bacteriacalled archaebacteriamake their home in theboiling waters of geysersin Yellowstone NationalPark, in the United States.The study of heat-lovingbacteria led to thediscovery of an importantheat-stable product usedin scientific research.

No one knows for sure how they got there, but the brightgreen parrots of New York City aren’t leaving anytimesoon. Flocks of the birds make New York their home,

where they build nests on high-voltage power poles. The parrots are also called feralparakeets because they are probably descended from pet birds that escaped. It ishard to say if these parrots are generalists or just very lucky specialists!

1. What two things make up an organism’s niche?

2. (a) Both red squirrels and grey squirrels live in Alberta, although the greysquirrel was introduced from eastern Canada. Both feed on seeds,nuts, flowers, fruit, insects, and birds’ eggs. Do these squirrels have tocompete for resources? What are some ways they could avoid compet-ing for resources?

(b) Would you classify red squirrels and grey squirrels as specialists orgeneralists? Explain.

3. Describe two examples of symbiotic relationships found in nature. In eachexample, how do the adaptations of one organism depend on the other’s?


Lemmings do not intentionally jump off cliffs to drown in thesea, as some people may think. Mass movements of thesenear-sighted little rodents may result in their accidentaldrowning, however. University of British Columbia ecologistDr. Deborah Wilson went to Nunavut in Canada’s Far Northto study lemmings. As part of her study, she looked at theirpopulation peaks and crashes, which have led to the cliff-jumping myth.

“Lemming numbers fluctuate quite regularly,” Deborahexplains, “with peaks in the population every three years. Weplace small radio transmitters on individual lemmings and follow their movements. This helps us learn whether theybecome food for predators or whether some other factor isresponsible for the steep declines in numbers. Predators (suchas arctic foxes and ermine) are responsible for most lemmingdeaths, but that’s not the whole story. Lemmings reproduce ata lower rate when they are very abundant. Whether their lowerreproduction is a response to the population density or to ashortage of food or space to live in is not known.”

One great thing aboutworking in the North,Deborah reports, “wasgetting to know theInuit who lived near ourremote field station.Some helped with ourfield study, and we wereable to learn about theirculture and the difficultiesthey face living in anarctic environment.”

Deborah started her working life as a computer programmer,but later realized that she would rather be an ecologist. Thismeant more years of study, but it was worthwhile. “Keepstriving to do what you love,” she advises students. “It tookme a long time to be able to work in the field of ecology,where my real interest lies. It is much less lucrative thanworking in business, but that doesn’t matter to me at all.”

AcrossCanada

T O P I C 2 Review

If you need to check an item, Topic numbers are provided in brackets below.

Key Terms

Reviewing Key Terms1. In your notebook, match the description in

column A with the correct term in column B.

A B

• a struggle for resources • diversity index (1)between organisms of the same or different species

• a species with a very • generalists (2)narrow niche

• the word that describes • behavioural adaptations (1)both the role and the habitat of an organism

• the many differences • competition (2)between individuals of the same or different species

• a mathematical expression • symbiotic (2)of the different kinds of organisms in an area

• a direct or close association • variation (1)between two different species

• the habits of a species that • niche (2)have been developed over time

• populations of these • specialist (2)organisms tend to be high, although there is not usually very much diversity in the kinds of these organisms

Understanding Key Concepts2. Examine the photograph of the eagle. What

structural and behavioural adaptations does ithave that enable it to obtain food?

3. How could you go about measuring the biological diversity in a tropical area? Whatwould you expect to find? (1) What hashappened over time to produce this level of diversity? (2)

4. What are the advantages of a broad niche?When can these advantages turn out to be disadvantages for different species? (2)

5. Define the term “species” using your ownwords. Are all organisms that look alike thesame species? Are all organisms that look different from separate species? Explain your answer. (1)

6. If an area of tropical rainforest were clearedto make room for a farm, how might the localwildlife be affected? Would the consequencesbe worse for specialists or generalists?Explain. (2)

Wrap-up Topics 1–2 • MHR 25

T O P I C S 1 – 2Wrap-up

variation

biological diversity

species

speciation

structural adaptation

behavioural adaptation

diversity index

environment

competition

broad niche

generalist

specialist

narrow niche

specialization

symbiotic association

topic 2 habitat and lifestyle - cochrane high school

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