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9:16 Biological Evolution

2 need to divide work of parental provisioning among

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Unformatted text preview: sation- Sexual selection: Individuals of one gender are in competition with others of the same gender Effect of sexual reproduction: 1. How to divide work of postnatal care? - Females, by definition, start out with increased parental provisioning. (Provision of female gamete; nutrients) - The question - What is the best way to maximize reproductive success? Provide care, do not provide and search for other mates or survive to next breeding season) - Which gender will abandon first (internal vs external fertilization), which has less to lose (less investment to date), which has more reproductive options if it leaves (based on biological parts), which has more confidence that the offspring are theirs? *It all depends on the biology on how to divide the work. There isn't one particular strategy* 2. With whom should one mate? Note: While mating preferences can occur in bother genders, females tend to be pickier or choosier. We will focus on female preferences. Prefer males that best help produce offspring: - Good providers: can take good care of offspring (where they stick around) - Good genes: you have good systems and are healthy and can pass those traits onto the children, and attractiveness. (where they don't stick around) But sometimes females preference seems strange, they prefer to mate with the flashiest males. Runaway selection: 1. 2. Composition of the starting population: longer tail—better flier (better genes?) Two types of MALES: ancestral type even longer tail—worse fliers (worse genes??) modified type (common) (rare) ancestral type modified type (common) Wow! longer tail!! Oh whatever! Two types of FEMALES: no mating preference ancestral type prefers to mate with longer-tailed males (common) Benefits: better flier modified type (rare) Wow! longer tail!! Composition after many generations: Wow! longer tail!! Benefits: greater mating success (so better at negotiating all aspects of the reproductive obstacle course entailing flight). Costs: less mating success (due to the relative nature of the female mating preference). Both modified types are exp...
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