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Lecture 7

BIO318 Lecture 7 (Sept 30).docx

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University of Toronto Mississauga
Sanja Hinic- Frlog

BIO318 Lecture 7 - Banks of credit river picture o Swarms of flies (heather proctor) o Dance swarm under tree gaps o In ornamentations, it’s usually males, but in these fly swarms, they’re actually females o Female has permanent set of ornaments; fringe legs; two red pouches where she breathes air and forces it into the abdomens o The male doesn’t have the elaborate abdominal pouches but they catch insects and they feed them to the females o Reversal in sex roles o More females than males in spider webs o Large ornamental females are selective o The larger females with larger abdominals will most likely survive the spider web - Also behaviour and other life history traits o Mate choice is typically by females o Sexual competitiveness is typically males o Risky mating behaviour and mating mistakes is usually by males  Ex. Picture of moose trying to mount a statue bison o Female biased longevity (independent of risks) - Last lecture o Strength of selection is really high because we get rapid evolutionary change in species lineages o 2 potential mechanisms of sexual selection  Prof will add a third mechanism  Raw sense  Sexual selection in context of sexual competition o Examining adaptation  Reverse engineering • Ex. Taking apart a heart and then observing it to understand its functions - Finding alternatives in getting mates; last time was horn size which was determined by genetic; now we are looking at getting mates through variation in sex differences that is “plastic” - Sexual selection histogram o Higher number of males means less off springs produced per - Why are females feminine, males masculine and occasionally vice versa? - Theories o Darwin: sexual selection is greater on males than females o Parental investment theory - What are males competing for? o Access to females/gametes o Inseminating females o Operational sex ratio o Time-out from mating  Why are females taking time out of mating?  What is it about females?  There are less of them for mating o Female life history is producing offsprings o Male main duty is to look for mates o Females have other activities; the whole essence of femaleness is to produce offsprings and to take care of them o Organs that are geared to provide maternal care; even if there are no maternal care, the female still provide the lion share of producing the offspring - We do know that some males will also provide for their offs
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