Trivers argument is illustrated by the following

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Trivers argument is illustrated by the following graph: B. Trivers and Willard argued that if animal is in good condition, produce males; if in poor condition produce females C. Evidence mixed: 1. Yes: rodents; no: deer 2. Precise experiment that of McClure on wild Wood Rat. When she restricted food, females rejected their male offspring. SR went from 50:50 = 1.0 to 0.51. D. The key for this argument is that it applies to species in which male achieves differential reproductive success by being in good condition/large size (e.g. polygynous). Next have the opposite:
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V. Charnov theory of deviations from 50:50. A. Parasitic wasp Lariophagus . Lays single egg in weevil (beetle) larva. Larva lives in wheat grain and it hollows the grain out while feeding. Larva becomes pupa, adult wasp emerges from pupa, and we can sex it. 2 slides, adult weevil blurred on slide (see no weevil) B. If larva is large, a female hatches out. If larva is small, a male hatches out. Investigator can tell size of larva from tunnel in grain. The opposite of the polygynous species. Why class?
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VI. Female control of sex ratio. A. Haplodiploidy in wasps. So is egg fertilized or not? Imagine that would be relatively easy to control, and haplodiploid insects can do it in some cases at least. B. Study by Sheldon et al again on Blue Tit (discussion) . Both sexes are colorful slide , but sexes differ in the ultraviolet (you can’t see this, it is especially on crown). Males that have a higher UV survive better. The stronger the UV reflectance of the male mate, the more the offspring are skewed to males. If you diminish UV on the male how would you do this class? ( find out in lecture or discussion section ), the female will produce more females. Unexpected amount of control of sex ratio, mechanism unknown.
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Topic 9B. Age I. Age distribution: Def – The fraction of individuals belonging to different age groups. It is how we describe age structure.
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