NamePeriod

Chapter53:PopulationEcology

Thenextthreechaptersonpopulation,community,andecosystemecologyprovidetheacademic backboneforthisunitonecology.Eachchapterisadifferentorganizationallevelinecology,starting withpopulationecology.Beforebeginningyourstudyofeachchapter,besureyouhaveaclear understanding of the termsinthechaptertitle.

Concept53.1Dynamicbiologicalprocessesinfluencepopulationdensity,dispersion,and demographics

1.Whattwopiecesofdataareneeded to mathematically determinedensity?

2.Whatisthedifferencebetweendensityanddispersion?

3.WorkthroughFigure53.2,doingthemathtomakesureyougetthesameanswerasthetext.

Noteandunderstandwhatthelettersofthe formula mean. Next, try the following problem.

Apopulationecologistwishedtodeterminethesizeofapopulationofwhite-footeddeermice, Peromyscusleucopus,ina1-hectarefield.Herfirsttrappingyielded80mice,allofwhich weremarkedwithadabofpurplehairdyeonthebackoftheneck.Twoweekslater,the trappingwasrepeated.Thistime75miceweretrapped,outofwhich48ofthemicewere marked.UsingtheformulaN=sn/x,whatisthepopulationofmiceinthefield?(Answerisat the end of this reading guide.)

4.Explaintheimpactofimmigrationandemigrationonpopulationdensity.(Toavoidconfusion betweenthesetwoterms,itmighthelptousethismemorytrick:immigrationisthemovement into a population, whileemigration is theexitingof individuals froma population.)

5.Labelthedispersionpatternshownbyeachpopulationinthefigurebelow.Second,andmost important, what do the dispersion patterns tell us about the populationand its interactions (Explain)?

6.Survivorshipcurves showpatternsofsurvival.Ingeneralterms,survivorshipcurvescanbe classifiedintothreetypes.Usingthefigurebelow,labelandexplainthethreeidealized survivorship patterns.

7.In the natural world, many species show survivorship curvesthat are combinations of the standardcurves.Howwouldanopennestingsongbird’ssurvivorshipcurveappearifitwas Type III for the first year and then Type II for therestofitslifespan?Sketchthiscurveonthe survivorship curve graph in question 8.

8.What doesa reproductive tableshow?

Concept53.2Theexponentialmodeldescribes population growth in an idealized, unlimited environment

Donotletthemathinthissectionbeaproblem.Insteadoftryingtounderstandthecalculusinvolved, concentrateontheideaofexponentialgrowth,howitisgraphed,andwhatthistypeofgrowth indicates about a population.

9.Whatistheadvantagetousing percapitabirthanddeathratesratherthanjusttherawnumbers of births and deaths?

10.Whatwillthepercapitabirthanddeathratesbeifapopulationisdemonstratingzero population growth?

11.What does it mean for a population to be inexponential population growth?

12.Inthegraphbelow,explainwhythelinewiththevalueof1.0showsasteeperslopethat reaches exponential growth more quickly thandoesthelinewiththe value of 0.5. On this graph,addathirdlinethat approximates a population withan exponential value of 1.25.

13.What are two examples of conditions that might lead toexponential population growthin natural populations?

Concept 53.3Thelogisticmodeldescribeshowapopulationgrowsmoreslowlyasitnearsits carrying capacity

14.What is carrying capacity?

15.What are sixexamples of limiting resources that can influence carrying capacity?

16.In thelogistic population growth model, the per capita rate ofincreaseapproacheszeroasthe

is reached.

17.Ifthecarryingcapacity(or K) is 1,000 andNis 10, the term(K– N)/Kislarge.Explainwhya large value for (K– N)/Kpredictsgrowthclosetothemaximumrateofincreaseforthis population.

18.Inthegraphbelow,explainwhythelogisticmodel predicts a sigmoid (S-shaped) growth curve when the population density is plotted over time. Hint:Thecriticalpartofthisanswerconcerns why growth slows as Napproaches K.

Concept 53.4 Life history traits areproductsofnaturalselection

19.On what is thelife historyof an organismbased?

20.Whatthreevariablesformthe life history of a species?

21.Theendofthisconceptattemptstobringtogethertheideasoflifehistoriesandgrowthmodels.

Thisisdonewiththeintroductionoftwonewterms: K-selection and r-selection. Explain the ideas behindthe creationof these two terms.

Concept53.5Many factors that regulate population growth are density dependent

22.Compare and contrast these two terms:

density-independent regulation

density-dependent regulation

23.Explainhownegativefeedbackplaysanessentialroleintheunifyingthemeofregulationof populations.Doesnegativefeedbackplayarole in both density-independent and density- dependentregulation?

24.Completethefollowingchart.

Density-DependentPopulationRegulation

Negative Feedback Mechanism / Explanation / Example
Competion for resources
Territoriality
Disease
Predation
Toxic wastes
Intrinsicfactors

25.Givebothbioticandabioticreasonsforpopulationfluctuations overthelast50yearsinthe moose population on Isle Royale, based onpopulation dynamics.

26.Explain the importance of immigrationandemigrationin metapopulations.

Concept53.6Thehumanpopulationisnolongergrowingexponentiallybutisstillincreasing rapidly

27.Summarize human population growthsince1650.(Ofallthereportedstatistics, which one surprises you the most?)

28.What is demographic transition? Use the figure below to explain the process in Sweden and Mexico.

29.Youshouldbeabletolookatage-structure graphs andmakepredictionsaboutthefuture growth of the population. Using Figure 53.24, describethekeyfeaturesforthethreeage- structure graphs and predict how thepopulationofeachcountrywillgrow.

Country / Key Features / Predicted Future Growth
Afghanistan
United States
Italy

30.Why doinfant mortalityand life expectancyvary so greatly between certain countries?

31.Cantheworld’spopulationsustainanecological footprint thatiscurrentlytheaverage American footprint?Explain.

TestingYourKnowledge:Self-QuizAnswers

Now you should be ready to test yourknowledge.Placeyouranswershere:

1.2.3.4.5.6.7.8.9.10.

Answer to Question 3:125P.leucopus