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Lecture 12

BIO318 Lecture 12 (Oct 21).docx

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Sanja Hinic- Frlog

BIO318 Lecture 12 - Damselfly: a battle for paternity o Sperm competition - Last lecture o Rapid senescence in male marsupial mice: not group selection (brief review of levels of selection) but further support for antagonistic pleiotropy model of “aging” o Sexual conflict  Intraspecies conflict over mating rates in females o Secondary sexual characters in males can thus evolve via 1) female choice, 2) male-male competition, 3) sexually antagonistic coevolution - Bateman curves: sexual conflict o Shows the concept of sexual conflict o Graphical representation of different matings of different mates for both sexes and how much offspring o For males, additional females means more offsprings o For typical females (with no gift or benefits), one ejaculate from a male is enough to fertilize all her eggs, but the more mates the female have, she has a fitness decrease because she could be injured, get diseases from males or get eaten by predators during mating; therefore one mating is sufficient for typical females usually o By 3 mates, there’s a huge difference between females and males and their sexual conflict of mating rate - Assessing fitness based on number of offsprings o Easy to assess for females because how many offsprings are in her nest, but for males, it was harder to determine who were his offsprings o Thanks to recent molecular technology, we can assess male offsprings and then also can assess sexual conflict between males and females - Evolutionary fitness o Define o “survival of the fittest” (Herbert Spencer); picked up by Darwin in his 5 edition of The Origin  Crude; you could survive, but it’s also about the survival from those who survived, so if you live long, and don’t pass on genes, then that’s zero fitness o Population genetic –e.g. predominancy of certain Y haplotypes in humans  Genghis Khan fertilized a lot of women, perhaps related? o Behavioural: survival success and mating success - Episodes of sexual selection that Darwin overlooked o Cryptic female choice and sperm battles - Mating position in dragonflies o Grab female by the neck; fly in tandem for some time o Finds a spot and then transfer the testes o The male penis has two main function: remove previous sperm from other male competitors and then insert his own sperm o Females could control things as well, they can also control which male sires her offsprings o Females have complex sperm storage organ - Stiletto fly spermathecae o Spermathecal sac and has different pouches for different sperms from different males; the females can use certain muscles to control which sperm from which pouch will fertilize her eggs - Moth spermatheca o More simple way of storing sperm o Just a single blind pouch, but they can still control who fertilizes her eggs? - Directional cryptic choice o Last in, first out o the last male the
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