Bio 3400 1nd Edition Lecture 26 Outline of Last Lecture I Models of Population Growth and Regulation II Limits to Growth III R and K Selection Outline of Current Lecture I Resource allocation II R and K selection III Demographic models IV Guppy life histories V Unit 10 Interactions Current Lecture I II III Why do life histories vary among organisms i Coconut seeds versus orchid seeds b Resource allocation i Reproduction maintenance storage growth Organisms are constrained by limited resources a Example if an organism produces many offspring offspring are small compared to if an organism produces few offspring which results in larger offspring Early idea r and K selection a MacArthur and Wilson 1967 i R selection low population size density independent mortality favors high rate of growth produce as many offspring as you can ii K selection stable population size density dependent mortality favors high competitive ability b How do you maximize r i R ln R0 T 1 Develop fast reproduce early produce a lot of offspring c What problems are there with Pianka s r and k selected life history trait predictions i Only focused on density other factors could be at play ii Not all predictions are justified especially K selected traits and not all predictions match up in similar experiments iii Applied without establishing cause and effect i e density dependence or independence These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute IV V VI VII iv Ignored all other factors except density Demographic models a Age specific extrinsic not because of density mortality i High adult mortality Early reproduction higher reproductive effortproportion allocated to reproduction doesn t need to maintain as much since going to die soon anyway ii High juvenile mortality Delayed reproduction lower reproductive effortproportion allocated to reproduction allows to focus more on growth and maintenance Guppy Life Histories a Low predation Killifish Rivulus only eat juveniles i Prediction later maturity lower reproductive effort b High predation Cichlids eat adults i Prediction early maturity higher reproductive effort Additional Complexity a What factor influenced the evolution of life history traits in guppies i Density resources environmental fluctuations age specific extrinsic mortality b Is r and K selection a useful paradigm c What are the advantages of more complex models of life history evolution Are there any disadvantages i More realistic more accurate predictions but harder to execute and harder to understand Unit 10 Interactions a The environment contains limited resources i Competition affects both parties negatively ii Exploitative competition indirect interaction stemming from utilizing the same resources iii Interference competition direct aggressive interaction between individuals or access to resources iv Intraspecific competition competition between the individuals of the same species v Interspecific competition competition between individuals of a different species b The log growth model assumes intraspecific competition limits population size i Carrying capacity results from competition between individuals in the population ii Performance declines with increasing density
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