RELATIONSHIPS- sexual selection Flashcards
who thought of sexual selection?
darwin
what did darwin say about sexual selection?
species do not just evolve through natural selection but also through sexual selection
what is sexual selection-darwin?
a view that competition for mates between individuals the same sex affects the evolution of certain traits
what is s.s?
any physical trait that enhances reproductive success will gradualy be passed down and enhanced over evolutionary time
what did darwin propose?
animals possess features that make them attractive to opposite sex and allow them to compete better with members of same sex
example of darwins proposal? & who said it ?
pagel et al
relative hairlessness of human beings being compared by great apes feature allowed not only to keep cool but to advertise good hygiene.
what does this example explain?
trait is desirable in sexual selection. greater loss of body hair in women would been through greater pressures on women from s.s. in comparison to men
what about the peacocks tail?
peacocks tail goes against as offers no advantage. it is heavier more noticable by predators and dont help fly better
what did zahavi propose?
proposed “handicap principle” in support of s.s
what did handicap principle state?
if any indicator too costly to produce and still displayed=sign of good genes and health as peacocks able to portray bright feathers and still survive= more attractive to females and such rules apply to humans
what also happens between male and female for s.s.?
different s.s pressures occurs between genders due to differences in gametes (eggs+sperm)
what about females for the different pressures?
limited no. eggs each representing huge investment during and after preg but certain of paternity. due to this must be choosy finding strong healthy males with resurces
what about males for the different pressures?
natural selection favours them maximising paternity opportunities. have millions of sperm h.w can never be certain of paternity and suffer little cost to reproduction
what are the 2 types of s.s that take place in human reproductive behaviour?
intrasexual & intersexual
what does intrasexual occur in?
males who compete with each other 4 access to females
what is intrasexual as a consequence of this?
as consequence men have evolved indicators to show strenghth and testosterone that women seek