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Behavioral ecology study guide 3

Behavioral ecology study guide 3 - Behavioral ecology study...

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Behavioral ecology study guide 3 Chapter 8: Sexual Conflict and Sexual Selection *reproduction includes conflict of interest between the sexes Males and Females: *in all animals the basic difference between the sexes is the size of their gametes -females produce large, immobile, food-rich gametes called eggs -males produce tiny, mobile, consistent of little more than a piece of self-propelled DNA(sperm) *females put more resources than do males in each offspring *male courtship and mating behavior is too large extent directed towards competing for and exploiting female investment Females as a scarce resource: *parasitism of a large egg by a small sperm *males can potentially fertilize eggs at a faster rate then they are produced *Male reproductive success is often limited by access to females, while females are limited by resources *Robert Trivers: relationship between the investment of resources in gametes and other forms of care and sexual competition. “Where one sex invests considerably more than the other, members of the latter will compete among themselves to mate with members of the former” *Parental investment: potential rate of reproduction and sexual competition *females generally put more effort into parental effort while males put more effort into mating effort *males are under strong selection to be good at seeking out and competing for females The Sex ratio: *the sex ratio is usually 50:50 *more precisely, the ratio of investment in males and females is equalized
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*when sons and daughters cost different amounts of make, the stable strategy in evolution is for the parent to invest equally in the two sexes and not to produce equal numbers. Local mate competition: *if brothers compete for mates, the sex ratio should be female-biased *when two sons compete for mates, their value to their mother is reduced *the mother should then bias her ratio of investment towards daughters *extreme competition is to be expected in species with limited powers of dispersal (because brothers will stay in the same place) and therefore is tends to be associated with inbreeding *the best sex ratio is to produce just enough sons to fertilize her daughters since any other males will just be wasted * Parasitoid wasps: lays eggs inside pupae of flies; if one female parasitizes a pupae, her daughters are all fertilized by her sons and the sex ratio of eggs is biased towards females Local resource competition or enhancement: * South American prosimian: have a male-biased investment among offspring. Females disperse far less than males, and often end up competiting both with their mother and with each other for rich sources of food in the mothers home range. This reduces their value as offspring *the sex that does not compete with parents may be more valuable *if one sex helps its parents, the sex ratio may be biased in favor of that sex Maternal condition: *there is a direct link between a mother’s competitive ability while lactating and her son’s expected reproductive success * red deer:
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Behavioral ecology study guide 3 - Behavioral ecology study...

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