Exam Review WFS 446
Popular in Population Dynamics
One Day of Notes
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Popular in Wildlife Studies
This 6 page Study Guide was uploaded by Dani on Sunday February 1, 2015. The Study Guide belongs to WFS 446 at Pennsylvania State University taught by David Miller in Spring2015. Since its upload, it has received 97 views. For similar materials see Population Dynamics in Wildlife Studies at Pennsylvania State University.
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Date Created: 02/01/15
Population Dynamics 11215 Population Dynamics 0 Concerned with understanding and quantifying how populations change in number and composition and the factors that influence these changes Why study population dynamics OOO Often we want to manage population abundance for a species Understanding individual populations first step towards community management Tools to make smart decisions about wildlife populations Types of applications I Harvestexploitation I Pestinvasive species management I Species conservation I Management of rareendangered species Population models 0 O O O A representation of reality that we can learn from Mathematical models I Equations to describe how population abundance and structure change across time and space Step beyond conceptual models I Quantify predictions Why do we use models I Explain how things became the way they are retrospective o What was the effect of road construction on the abundance of interior forest birds past I Predict the future and the effect of potential actions prospective o What will be the effect of increasing fishing access on the number of trout in a stream future Predicting effects of harvest 0 O O 0 How does harvest effect survival How does survival effect abundance What other factors affect abundance How does abundance effect reproduction of new individuals Harvest management model 000 N Nlt SAt SJt Pt SAt harvest rate and environment SM harvest rate and environment Pt environment 11415 I Decision making 0 Objective maintain and increase populations of arroyo toads 0 Actions protect habitat change waterflow regimes remove nonnatives I Nonnative examples fish crayfish bullfrogs I Why a population model 0 Determine the impact of nonnatives on toads 0 Determine how water affects interactions nonnatives are reliant on water I Basic steps to build a population model 0 Determine the problem 0 Determine the decision context I Objectives I Actions I Potential models 0 Collect and analyze data 0 Build a mathematical model 0 Make predictions I This class will focus on the tools to complete these five steps I Basics of population dynamics 0 Models for populations I Unstructured simplest way to describe a population 0 Description of how abundance total of individuals changes across time 0 Ex time series on lynx and hare populations changes shows lynx populations will increase at a slight lag with hare population increase I Structured add more complexityrealism 0 Age or size classes 0 Males vs females FEMALES ARE MOST IMPORTANT FOR PREDICTIONS 0 Demographic parameters included 0 Spatial distribution of populations 0 Basics of unstructured models I Exponentialgeometricgrowth o The rate of change stays constant 0 A 10 annual increase is bigger when we have 10000 individuals than when we have only 10 o No effect of density no density dependence 0 Reproduction and survival not affected by the current abundance I Density dependent growth 0 Negative effect of density 0 Logistic types growth curve Scurve o Difficult to determine carrying capacity 0 BIDE Model I Management focused on changing B D E rates depending on needs of population I Births and immigration 0 Introducing new animals into population I Deaths and emigration 0 Number of animals leaving the population I Nt1NtBID E 0 Open population 0 Increasing abundance o BI gt DE o Decreasing abundance o BI lt DE o If movement does not occur in a population or if negligible I Nt1NtB D 0 Closed population 0 Structured models I Not all individuals are equal I Age and size dependent demography 0 Survival 0 Age of first reproduction o Fecundity I Sex specific models 0 Males often ignored I Continuous versus discrete 0 Continuous population abundance measured on a continual basis 0 Insects and invertebrates with short lifespans o Longlife span species with lots of generational overlap 0 Discrete abundance measured at intervals 0 Often annual 0 Seasonal reproduction or little overlap in generations I Stochastic versus deterministic o Deterministic variables stay constant across time o Often sufficient to ignore variation 0 Stochastic variability across time 0 Lots of sources I Environment I Small populations I Sampling error 12115 0 Measuring change in abundance o Arithmetic change y mx b I Absolute change is constant 0 Eg abundance increases by 10 individuals per year I Does not make sense for populations 0 Geometric growth discrete I Rate change is constant 0 Eg 10 increase in population size per year I Abundance measured at discrete intervals 0 Exponential growth continuous I Instantaneous rate of change continuous measurement I New individual immediately contribute to growth 0 Compound interest 0 Basic exponentialgeometric growth model 0 Density dependent I Growth rate is constant I Longterm unrealistic I Shortterm may be a good predictor o Unstructuredexponential I All individuals are the same I Age size and other characters not considered 0 Per capita growth rate I Lambda 1 population stable I Lambda gt 1 population increasing I Lambda lt 1 population decreasing o Geometric growth 0 If population continues to grow for quotTquot years 0 NT No1 A2 A3 AT NT No N I A NTNo1T 0 Exponential growth 0 Instantaneous rate of change given by r I r 0 stable I r gt 0 increasing I r lt 0 decreasing o Shrink interval between observations until it approaches 0 o rN dNdt rate of change in N with respect to change int I depends on r growth rate and N abundance 0 growth period over time period T given by NT NoerT I A er I lnA r Average rate of increase 0 LnNTNo1 r Ex NT 500 N0 100 T 34 o r 0473 O Tdouble ExponentialGeometric Equations 0 Other applications I Banks and finance interest calculated using exponential equation I Physics halflife of a radioactive isotope Plotting abundance O Exponential curves on a natural scale I Linear on a log scale 0 Stable flat line 0 Decline negative slope 0 Increase positive slope I LnNT lnNo rT 0 r constant 0 lnNo intercept Plotting GeometricExponential Growth 0 O O O Abundance versus time Lnabundance versus time Change in abundance versus abundance Per capita growth rate versus abundance BIDE and Geometric growth 0 O O 0 Delta N BD For geometric or exponential growth B and D are proportional to N Bt bNt and Dt dNt I b and d are constants per capita birth and death rates Nt1 N bNt dNt 9 1bdNt I R bd 39 Nt NtR Nt1 I A 1bd 1R I deltaN NtR Nt1 If birth rate greater than death rate increasing population Negative Density Dependence 12615 12815 0 Population growth rate decreases as abundance increases 0 Carrying capacity abundance where we expect population growth to be stable 0 Denoted using K o K is I Abundance where birth rate equals death rate I Abundance where A1 or r0 o Equilibrium value population abundance will tend to move towards the carrying capacity I If NgtK the population will decrease I If NltK the population will increase 0 Logistic equations continuous o dNdt roN 1 NK o NT K1IltNo No e T 0 When does population size increase fastest 0 Max population change when NK2 LAB NOTES 0 N Abundance o N Population at Time years 0 N1938 in year 1938 0 NM Next year 2 Nt1Nt 0 per capita growth rate AN Nt139Nt o absolute change in population size
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