Sexual Selection Flashcards
what was Darwin worried about?
the problem of perfection
about traits which seemed detrimental to the possessor and how in some cases these traits could have evolved by natural selection
why do we know elaborate bird traits evolved before flight?
Epidexipteryx was a bird-like dino with four ribbon like tail feathers used in display but had no sign of flight feathers
what did Darwin suggest that people weren’t happy with?
females had a sense of aesthetics
males were pretty to seduce females
Wallace thought this idea weakened ‘darwinism’
do females choose mates on basis of sexually dimorphic traits?
peacocks - higher mating success based on the higher number of eye spots (Petries)
widow birds - manipulation of tail feathers - females reallocated away from short tail feathers (Anderson)
why do females choose?
unequal sexual investment starts with anisogamy (egg vs sperm)
if one sex invests heavily in offspring - the other has greater reproductive potential as can fertilize more individuals - typical sex roles
whats a spermatophore?
a nupital gift
when can the roles switch?
under bad conditions - males reject more, females fight for access
when no pollen male bushcrickets invest less in mating and would reject females - females would never turn down mating - sex role reversal
why do sex role reversals happen?
due to different levels of investment in reproduction
what is courtship cannibalism?
when nupital gifts are parts of body
or when after copulation usually the male gets eaten (or part eaten e.g banana slugs)
whats special about black widows?
males have evolved a mechanism to survive long enough for two copulations
females have paired sperm storage organs
