sexual selection and mate choice Flashcards
sexual selection hypothesis
DARWIN:
traits might evolve if they are sexually selected, that is if they increase the individual’s reproductive success, even at the expense of their survival
what does sexual selection depend on
struggle between male + female
types of sexyal selection competition
intersexual
intrasexual
intrasexual competition
competition between members of the same sex (usually males) for access to mates
intersexual competition
where members of one sex (usually females) choose members of the opposite sex.
Bateman-Trivers Theory
female reproduction is primarily limited by their access to resources to nourish and produce these large gametes, whereas male reproduction is mainly limited by access to females
—> members that invest more into babies; are themselves a limited resource= so females are picky and males want females
mechanisms of sexual selection
- sperm competition
2. cryptic female choice
types of male competition
endurance scramble competition contest competition reproductive suprression sperm competition alternative mate tactics
stages of mate choice
- behvaviour
- cryptic choice of sperm
- game selection
when are males choosy?
lots of females available (and varying quality)
long term residency
resource allocation
monogamous system
what is the cluton brock and vincent idea
difference in POTENTIAL reproductive roles of MM and FF= predict variation in STRENGTH of sexual selection
fertilization-insurance hypothesis
females copulate iwth multipel males to be mores uccesful
why is it weird that females would want to have sex with a lot of guys
- because it would not increase the NUMBER of offspring
2. its COSTLY to mate with a lot of guys= hence are choosy
why WOULD females want to have sex
fertliization insurance hypothesis
‘girls just wanna have fun’ hypothesis
theories of mate choice
explain why females are choosy
what are the direct benefits of mate choice
choosy sex gets resources
I.e. ferliziation, sex for food/proteection and parental investment
what are indirect benefits of mate choice
choosy sex gets only GENES
theoris of indirect benefits of choosy mate choice
- fisherian runaway
- genetic indicators of good genes (handicape principle and host parasite coevulition)
- heterozygozity hypothesis
- genetic compatibility hypothesis
what is the non adaptive hypothesis (and the 2 theories)
choosy sex gets NOTHING
- either sensory bias (trait selected due to pre-existing bias in species)
- chase away hypothesis (exaggerated traits chosen to OVERCOME female bias/increase variation)
fisherian runaway selection
sexual selection mechanism to account for the evolution of exaggerated male ornamentation (such as a peacock’s plumage) by persistent, directional female choice
good genes hypothesis
traits females choose when selecting a mate are honest indicators of the male’s ability to pass on genes that will increase the survival or reproductive success of her offspring. (AVOID INFERIOR GENES)
hence
- handicap principle ( costly traits= male strong quality)
- host parsite; traits selected for parasite resistance)
heterozygoity hypothesis
dissailimar traits are selected for to avoid inbreeding and increase variation
genetic compability hypothesisi
avoid ‘bad sperm’ to assert genetic advatange
non adaptive hypothesis?
no ‘evolutionary sense’; just random
(i.e. just for aesthethic reasons or biases)
- sensory bias hypothesisis
- chase-away hypothesis
PROSTITUTE HYPOTHESIS
females have sex for food
just wanna have fun theory
sexual pleasure= motivates fertilization
