Sexual selection Flashcards
what is sexual selection
a mode of natural selection which acts on an organisms ability to obtain or successfully copulate with a mate which functions to maximise an individuals reproductive success
what is needed for sexual reproduction
two sexes
- male and female may be found in the same individual
- sexes may be separate
- individuals may change sex during their lifetime
what is meant by asymmetry in investment in regards to sexual reproduction
males and females do not share interests over reproduction, one sex always invests more usually the female
why do females tend to invest more in sexual relationships than males
they produce larger, non-motile and few produced eggs compared to males which produce small, motile and many gametes which requires less energy
what are the four different types of mating systems
1) monogamous- one male and one female
2) polygynous - one male with multiple females
3) polyandry - one female with multiple males
4) polygynandry- multiple males and females
what are the characteristics of a monogamous mating system
low competition but both sexes may compete for mates
sexes are similar in size and appearance
both sexes often care for the young
what are the characteristics of polygynous mating systems
high level of competition for mates between males
high levels of dimorphism
females tend to care for young
what are the characteristics of polyandry mating systems
females tend to compete more intra-sexually for mates
sexes are similar in size and appearance but females may be larger if comp is high
both sexes or males only care for young
what is intrasexual selection
secondary male characteristics are used pre-mating to get a mate such as fighting etc
male- male choice
what is intersexual selection
the mates choice
males show coloration or ornaments to attract a mate
what are the direct benefits of intersexual selection (mate choice)
- increased fitness of choosy sex through direct material advantages
e.g. territory quality, increased parental care, protection from predators
what are the indirect benefits of intersexual selection (mate choice)
increase genetic fitness of the offspring e.g. better genetic quality and more attractive offspring
what are the intersexual selection mechanisms
1) indicator traits
2) sensory bias
3) runaway selection
4) genetic compatibility
what are indicator traits
an intersexual selection mechanism where females use a single to see which males are in better condition or quality such as being more red
what is sensory bias
an intersexual selection mechanism where females show a preference for a trait in a non-mating context and is the exploited in order for one sex to obtain mating opportunities
