Ecology And Evolution
Ecology And Evolution BIOL 221
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This 15 page Class Notes was uploaded by Favian Swaniawski on Saturday September 12, 2015. The Class Notes belongs to BIOL 221 at West Virginia University taught by Staff in Fall. Since its upload, it has received 12 views. For similar materials see /class/202743/biol-221-west-virginia-university in Biology at West Virginia University.
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Date Created: 09/12/15
Previous lecture Interspeci c competition LemIIeE I Lecture 8 H Complete interspeci c competition H Evolutionary predictions of Lotka7Volterra H Begin predatoriprey population dynamics 5amp5 Chap otation Warning Variable names in 5amp5 are nonstandard so ours will be different Lecture 2 Graphical analysis Case 1 Species 1 Wins Conditions Lecture 2 Case 2 Species 2 Wins Case 3 Try Another One Yourself Case 4 Conditional Competitive Exclusion Lecture 8 QInterspeci c Competition Review We solved the competition equations with a graphical analysis Four outcomes possible HCase 1 Species 1 wins HCase 2 Species 2 wins HCase 3 Coexistence HCase 4 Conditional competitive exclusion Lecture 2 STOP FOR CLICKER QUESTIONS LemIIeE Boundary Condition for Stable Coexistence Lecture I Coexistence and species similarity Premise Morphologicallyphysiologically similar species Will compete strongly with each other Lecture 2 Coexistence and species similarity The greaer the morphological or physiological difference compaition coef cient will be Lecture 2 Limiting Similarity mit rig similarity is the degree ofdifference d which ust exist between two specieguixrlz order for them to coexist Evolutionary Prediction of Limiting Similarity MCharacter displacement Lecture 8 Graphlc deplctlon of character dlsplacement Geographic distribution Species 1 Species Z Trait values n I diverge 1n portion X X of distribution where the two I Regions of allopatry species overlap I Region of sympathy his reduces competition such Species l f Species 2 product of natural selection Lecture 8 Real World Example L inner Darwin s Finches on Human uni Galapagos mun mmquot Islands ween miquot 1i i l I 5 Hi wit Lm HHvuum 1 ii ii m i r Pm hum Ll Two Similar Local WOOdPGCkers mgtHairy and downy woodpeckers are morphologically similar however Hairys are almost 2X the weight of Downys What would be predicted about these woodpeckers by the theory of character displacement Lecture 8 Predation arasitism Commensah39snl Mutualism Control of N Role of Consumers Predator captures kills eats prey Lecture 8 Consumers 139 Dim ana camne eartworms 3 ts postmortem LectureS 39 I More Consumers mgtParasitoid Wasps ies Whose larvae consume tissues of host 39vwquot Consumers mgtHerbivore grazers browsers of plants Lecture 8 397 3 Consumers Detritivore consumers of waste material of other species eg leaf litter feces carcasses Predator Prey Population Dynamics Predator prey relationships are ubiquitous in nature it i Term1nology cautlon wrt book Let Prey Population N1 SampS use Nprey Let Predator Population N2 8amp8 use Npred We will develop 2 population growth equations 1 for prey l for predator Lecture 8 9 Predator Prey Dynamics Starting Point Exponential Population Growth prey population I Lecture 2 I Functional response of predator Functional response 7 the number of prey caught per predator per unit time p is the me C for WM this variable 9 Prey Population Growth Substituting le for the functional response Where N1 is the prey population size r1 is the prey intrinsic rate of increase p is the proportion of prey caught per predator per 39t time and N2 is the predator population size We I More realistic functional responses An asymptotic function may be more realistic and indicative of predator satiation eg l77yr cicada strategy We 9 MORE realistic functional responses Predator satiation PLUS frequencyidependent predation Lecture 2 9 Predator Population Dynamics Start from exponential growth equation Assume prey population size mainly affects predator birth rate Q The manner in which prey N affects predator births is the numerical response of the predator Lecture 2 Numerical response of the predator mgtHovv many ground squirrels are required to make one baby fox lecture 8 Predator numerical response mgtWhat fraction of a gyrfalcon chick is formed from each ground squirrel caught 39 3 Numerical response 3 Birth rate of the predator ef ciency with which caught prey are converted to baby predators X the number of prey caught per predator per unit time Note we use the Variable a for the ef ciency of conversion 8amp8 use b Iwill st ck with a because 1 has a different meaning Lecture 8 11 9 Predator Population Growth Integrating the numerical response into the predator population growth equation we have E Lecture 2 Predator Prey Equations B 0th equations contain N1 and N2 B 0th equations contain p Lecture 2 9 Graphical analysis Find zeroigrowth isolines for species 1 Lecture 2 9 Graphical analysis sp 1 Lecture 2 I Graphical analysis sp 2 Find zeroegrowth isolines for species 2 predator Lecture 2 9 Graphical analysis predator The predalor N large but es when prey populalion size is smal Lecture 2 9 Predator Prey Dynamics The predatopprey equatiors predict a neutrally stable cyc1e I Stable limit cycle 9 Summary Predatoreprey theory developed from exponential growth equations based on two premises Hprey population growth rates are reduced by predation Via dea Hpredator births are positively in uenced by prey population size Predicts neutrallyestable oscillations of both predator and prey population sizes Lecture 2 Next lecture Implications of predatoriprey theory Correspondence with the real world MS ample problems Lecture 2
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