PSYC 3100 Lecture Notes - Lecture 22: Drosophila Melanogaster, Parental Investment, Homicide

• School: University of Guelph
• Department: Psychology
• Course: PSYC 3100
• Professor: Pat Barclay

Document Summary

Competition for mates does not end at mating. Only one male"s sperm will fertilize each egg. Sperm condition: increasing the likelihood that one"s sperm will fertilize the eggs. Across species: rates of polyandry (risk of sperm competition) correlate with testes size (relative to body size: cost of producing and storing. All else equal, natural selection will favor against that cost if its not needed. If sperm production is needed that natural selection will be for. Sperm plug: blocks up female"s reproductive track so that next male cannot get into female"s eggs. Some sperm for offence, some for reproduction, some for defense. Sperm competition tactics: mate more often, release more sperm per mating ( overwhelming ), remove competitors sperm. Differential parental investment: reduced investment in presence of cues of non- paternity. Rat will ejaculate more sperm if he has just seen female mating with another male.