21-Intrasexual Selection starting at male-male compet, alt mate tactics

the plainfin midshipman alt mating tactics

males come in two diff varities, these fish

the males set up a nest, spend all time calling and making a humming sound, the males put nest under rocks, making humming sound trying to attract females, type 2 males don’t do humming sound, instead they mimic females by sneaking fertilizations of eggs just while hanging out with females

___ ___s sneak in and try to mate and fertalize eggs when females arn’’t watcthing

why can’t territoral male recognize that the type 2 is a male when the female can? who knows

type 2

male male competition

sperm competiion

when fertilization happens inside tract,

sperm compete with one another to ferlize egg

sperm competting

can get evulution of largic ejaculate size (bats), alteration of ejaculate size (fruit flies); mate guarding by males

snakes and rats use copulatory plugs

"cooperative” sperm (deer mice) giant sperm (fruit flies)

damselfly=

male grabbs onto female, penis full of hormones and spimes, scrubs out femal’s sperm storage organ before passing his own sperm to her

Sperm competition=

cooperation among deer mice sperm- when you look at these groups, sperm aggregate more often with sperm from closely related individuals, makes them more likely to fertalize young= form of kin selection

male male competition

mate guarding

when female is fertile, male hangs around next to her, to prevent her from mating with other males

female’s fertile period, number of intrusions, socially manogammas , period when she’s fertil, gray bar here, male guards female so no other males get close to her

other males go into territory before she is fertile, then he blocks her

exoeriiment=

they put eggs in nest, females mate was experimentally induced to leave her unguarded by the placement of a false egg in the nest

male male competition

infanticide=

in some species males will kill offspring that are not theirs in order to mate with females sooner, seen in lions and some primates