lec 22- sexual selection Flashcards
what is the extreme extended phenotypes the bowerbird makes?
bowers, an extremely ornamented nest which increases their fitness if constructed well
what is the direct benefit of females choosing mates?
benefit the female during the breeding season because selected males may provide better food, nest sites, and protection
why is it important for females to choose a good male?
because they have a larger investment then males, being choosy helps maximize limited resources for their limited fitness
what do peahens focus on a peacock?
the number of ornamental eyes, average # is 150, more is better for mating while less don’t mate at all
is female choice more common than male-male competition?
yes
do direct benefits (gifts) increase the biological fitness of the female?
yes, more eggs laid
how does cannibalism benefit the female?
eating the male provides proteins and other nutrients that help the female give birth to healthy offspring that may increase number or size
what is an example of cannabalism during mating?
mantis, redback spiders
what characteristics of ornaments increased mating by showing they have good genes?
ability to handle handicaps like long tails, bright colours increase success
can a females choice be arbitrary rather then based on genetic quality?
yes, females may simply find them attractive, so selection goes to extremes in males (eg. stalk eyed flies, having longer stalks means more mating)
what increases human mating success?
behaviours rather than genetic traits, like ornaments (clothes) and nuptial gifts (diamond rings)
what is the sexy son hypothesis?
females select males with attractive traits expecting that those traits will be passed on to offspring
what are the 3 types of mating systems?
-monogamy: one male pairs with one female (sexual: partners mate exclusively, social: partner pair but may cheat)
-polygyny: males mate with multiple females
-polyandry: females mate with multiple males (rare) and breeding adaptation reversed (males care for nest and young)
what type of bird is polyandrous?
red-necked phalarope
do differences in sexes indicate stronger sexual selection than of those with similar sexes?
yes
why do some female birds cheat with males they form a strong bond with?
to maximize genetic quality of offspring
male ducks are rapists, why are they unsuccessful at mating?
females have side punches with dead ends for unwanted sperm, allowing female to select for wanted sperm
what type of duck has a penis?
Ruddy Duck
what is sperm competition?
-when males compete for fertilization of a females egg, occurs during or after mating
-sperm is usually in higher numbers for advantage
-sperm has brush like structures to remove sperm from previous mating
