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define intrasexual selection?

competition within sex for mating access


intersexual selection?

selection by one sex for traits in the other


2 fold disadvantage to sex?

-if asexual and sexual produce the same amount of offspring the asexual will have twice as many daughters
-asexual should replace sexual due to rapid increase


advantages of sex?

-combines beneficial mutations (from 2 individuals)
-generation of novel genotypes through recombination
-faster evolution due to increased genetic variance in offspring (red queen)
-clearance of deleterious mutations


red queen hypothesis?

evolutionary arms race between parasite and sexually reproducing organism
-novel genotypes and quick evolution helps to evolve resistance


evidence for red queen hyp?

in a study of new zealand freshwater snails in lakes with more parasites there were more males present in lakes with more parasites


why should sex lead to sexual selection?

this is because of anisogamous gametes (different sizes/strategies). so different costs to each sex. leads to sexual conflict and selection


for the organism what are the preferential strategies for M and F?

-males reproduction increases with the number of mates
-females increases with the best possible male to increase fitness of offspring


example of species where sexual conflict informs differing strategies?

-Dunnocks and their mating systems
-main mating system is polyandry


models to explain preferences for certain traits- direct benefit model?

the non limiting sex provides direct benefit to the limiting sex such as parental care, protection from predation,resources, territory


(indirect) runaway sexual selection 'sexy son'?

son has improved success because he inherited traits that made father appealing to the mother
-this is an arbitrary mechanism


(indirect) good genes/ indicators, handicap model?

the trait the males possesses indicates high viability (the trait correlates with high genetic quality)


hamilton zuk hypothesis?

that sexual ornaments are indicators of parasite/ disease resistance (good genes model)


sensory bias hypothesis?

this is a preexisting bias model. the preference is an artefact of how they are wired.
-feed on red berries- mate choice red


types on intrasexual selection?

-precopulatory- fighting, singing

-post copulatory- spermicides