BIOL 121 Lecture Notes - Lecture 31: Sperm Competition, Anisogamy, Handicap Principle
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Difference in form or traits between the sexes of the same species. Different investments produce different gametes (anisogamy- different size between sperm and egg) Female reproductive success is limited by her ability to gain resources needed to: intrasexual selection (within 1 single sex): same sex. Male contests e. g. elephant seals, elk, fiddler crabs. Variation in reproductive success e. g. male stalk-eyed flies. Endurance rivalry- reproductive success of a male will be correlated with the amount of time that he spends copulating or at the mating site e. g. stick insects. Sperm competition- reproductive success of a male will be correlated with some feature of his sperm e. g. salmon, fruit flies, damselflies: intersexual selection (between different sexes) females choosing males e. g. mandrill baboon, fiddler crabs (fight each other) Not always females that invests more e. g. phalaropes (bird species), and seahorses. Female is more attractive / impressive: female choice. Male"s guard, shelter and protect young in birds, fish, ammals and insects.
