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Lecture 18

Lecture 18.docx

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Western University
Biology 1001A

Lecture 18  Some traits valued more highly by one sex than the other  o females: rank potential mates (value) o  athletic ability  kindness to children  resource holding potential o males rank potential mates (value) o  circulating estrogen (fertility)  waist to hip ratio o males are more sensitive to being cheated on sexually (unknowningly raising someone else's children) o females are more sensitive to being cheated on emotionally  Sexual selection (gold)  o why does it happen? o  relative parental investment o Which sex competes, which chooses? o  low parental investment compete for high parental investment sex o can it operate on both sexes at the same time? o  yes, both sex can compete and choose  Selection is fundamentally competitive  o struggle for existence  But group living and cooperation are common  o cooperation is wide spread o group living is even more wide spread  Types of social interaction  o o Actor benefits Actor is harmed Recipient benefits Cooperation Altruism Recipient is harmed Selfishness Spite o Altruism is "a special difficulty, which at first appeared to me insuperable (unsolvable), and actually fatal to my whole theory"  Altruism?  o parents invest heavily to their children o parents defend their child against predators o by providing care for their own offspring but still increasing their fitness because genes went to the next generation o parental care shouldn't count as altruism because it helps fitness of parents but altruism is when organism of unrelated or not indirectly related organism help one with the risk of their own life  Altruism?  o ground squirrel makes a high pitched sound to alert the whole group of predators, but this puts the signaling squirrel in greater risk because predator is more likely to find them o some organism's offspring does not find their own territory but just stay with their parents and help out with raising their parent's offspring o How can traits reduce fitness (offspring production) be selectively favoured? o  Sacrificing individual fitness for the good of the group?  More to "fitness" than simply producing direct descendants  o Personal reproduction -> direct fitness o more tha
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