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Unformatted text preview: Darren Rothberg Biol 105 Evolution 11.28.07 I) The Evolution of Life Histories 1) A life history consists of the overall set of traits an organism possesses that directly affect the number of successful offspring it produces a These are sometimes referred to as decisions, but they are decisions in the evolutionary sense, not decisions in the conscious sense. b Like any other trait, a life history can evolve, and it does so via selection acting upon the various individual traits that combine to make up the overall life history. 2) Life History Traits a Age/size at first reproduction b Reproductive effort c Clutch size d Egg size e Growth rate? f Allometric considerations g Higher-level traits : (i) Mode of reproduction Egg-laying Live-bearing (ii) Aspects of development 3) Approaches to the study of life-history evolution a Optimization - Maximization of some fitness measure (i) Some measure of fitness (for the parent) is optimized (ii) Ultimate fitness measures: r R (iii) Proximate fitness measures: (Offspring fitness) x (offspring number) = (reproductive output) Return on parental investment (iv) Given limited energy, time, space, etc., what is the best combination of traits (produced the most successful offspring) b Game theory (i) (E)volutionary (S)table (S)trategies In game theory, the optimal value for some trait depends upon what other individuals in the population are doing....
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- Fall '08