PopulationEcology

Hands-On Labs, Inc.

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Lab Report Assistant

Thisdocumentisnotmeanttobeasubstitute foraformallaboratoryreport.TheLabReport Assistantissimplyasummaryoftheexperiment’squestions,diagramsifneeded,anddatatables thatshouldbeaddressedinaformallabreport.Theintentistofacilitatestudents’writingoflab reports by providing this informationin an editable filewhich can be sent to an instructor.

Exercise 1: Modeling ExponentialPopulationGrowth

Data Table 1: ExponentialPopulationGrowth
Generation / Initial population (N) / Number of births (B) / Number of deaths (D) / Final population N+B-D / Rate of natural increase (B-D)/N / Net population change (final- initial)
0
1 / 4 / 2 / 0 / 9 / (2-0)/4= 0.5 / 4-9=5
2 / 5 / 2 / 0 / 7 / (2-0)/5=0.4 / 5-7= 2
3 / 7 / 3 / 0 / 10 / (3-0)/7= 0.43 / 7-10= 3
4 / 8 / 2 / 3 / 7 / (2-3)/8= 0.125 / 8-7= 1
5 / 9 / 2 / 2 / 9 / (2-2)/9= 0 / 9-9= 0
6 / 10 / 4 / 1 / 13 / (4-1)/10= 0.3 / 10-13= 3
7 / 11 / 4 / 1 / 14 / (4-1)/11= 0.27 / 11-14= 3
8 / 12 / 3 / 4 / 11 / (3-4)/12=0.83 0.830.8312- / 12-11= 1
9 / 13 / 6 / 2 / 17 / (6-2)/13=0.31 0.000.300.30 / 13-17= 4
10 / 14 / 3 / 1 / 16 / (3-1)/16=0.13 0.125 / 14-16= 2
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30

Exercise 2: Estimatingpopulationsize: mark-recapture

Data Table 2: Mark-recapture
Marked
(M) / Total captured (n) / Recaptured marked (m) / N
estimate / Standard error / Confidence Interval (low, high)
Capture / 61
1st
Recapture / 61 / 43 / 22
2nd
Recapture / (43-22)+61= 82
3rd
Recapture
4th
Recapture
True population size

Questions

Exercise 1: Modeling ExponentialPopulationGrowth

A. Didyouhaveanypopulationsthatinitiallywentextinct?Whatdoesthissayaboutminimum populationsize? I did not find any population that went extinct, but I was getting closer to losing more due to deaths and dice that had no value. Being that the minimum population is very small, 113, with that number of inhabitants the population will need to continue to grow so that they will not go extinct.

B. Graphthefinalpopulationonthey-axisandthegenerationsonthex-axis.Whatdoesthis graph look like? Explain what is happening to the population.

C. Graphthe rateofnaturalincreaseonthe y-axisandthegenerationsonthex-axis.Whatisthe shape of the graph?

D. Explainthedifferencebetweendensity-dependentfactorsanddensity-independentfactors and give an example of each.

E. Inthisexercise,youmodeledexponentialgrowth.Inarealpopulation,canthisoccurforever? Why or why not?

F.Whydoconservationbiologistswanttomakeprojectionsaboutpopulationgrowth?Howdo you think such informationcan be used?

G. What is the average rate of natural increase for your population?

Exercise 2: Estimatingpopulationsize: mark-recapture

A. What happened to the estimateas you performed subsequent recaptures?

B. What happened to the standard error for each recapture phase?

C. What happened to the 95% confidenceinterval for each recapture phase?

D. How close was your finalestimateto the true number of individuals?

E. Inanactualresearchstudy,howmightthetimebetweenrecaptureeventsinfluencethe accuracy of your estimate?

F.Whymightnon-invasivetechniques,suchasfecalsamplingandhairtraps,bepreferableto capturing and marking individuals?

G. Besidespopulationsize,whatareotherimportantthingstoknowaboutapopulationinorder to project its growth?

H. Youhavecapturedandmarked51individualsinapopulation ofdusky-footedwoodrats (Neotoma fuscipes).Inasubsequentrecapturephase,youcaptured65individualsofwhich34 hadbeenpreviouslymarked.Estimate thepopulationsize,thestandarderrorofyourestimate, and the 95% confidenceinterval.