L12 - Intrasexual selection Flashcards
(10 cards)
define what intrasexual selection is
differences in attractiveness to the opposite sex, usually non random mate choice by females
explain what anisogamy is and how it impacts males vs females
anisogamy is the fusion of 2 gametes, in which one is costly (female egg) while the other is cheap (male sperm) thus the initial disparity in the costs of sexual reproduction will impact parental investment and care, and also who gets to “choose”
what is Batemans principle
male gametes not as limiting, so male reproductive success increases linearly with number of mates, which makes the sexual selection hgiher on males
what happens when the roles are reversed (eg in a pipefish or male giant water bug)
increase in male parental investment means females will experience stronger sexual selection (eg “pregnant” males)
why do males compete
because there is a variation of ccśuccess in reproduction,, therefore males will evolve so they get to mates faster and are able to defend/win them
how do males avoid damage when competing for resources/mates
asses the relative RHP, large males will have an advantage, however large size means longer development, therefore even smaller males get a chance as they develop sooner
what are the 2 different types of plasticity males may have in reproductive behaviour
behavioural plasticity and developmental plasticity
what are some different ways behavioural plasticity may be demonstrated
pure strategy - always play a certain tactic, genetically polymporphic population with frequency dependent selection) or conditional strategy (genetically monomorphic, tactic played depending on threshold status)
what are some examples of animals that experience behavioural plasticity
male ruff morphs (independent, satellite and feeder - born with different strategies), marine isopods where strategies sneak mimic or fight build (alpha beta gama strategies), side blotched lizards where different coloured throats mean different territory defense Strat, all strategies (alpha beta gama) have average same fitness and frequencies oscillate as rarest type an advantage (enemy encounter less common, so exploited less)
what is an example of a genetically monomorphic population with single genotype in which individuals may play alternative tactitcs
dung beetle - the environment during development (nutrition and resources available) dictate whether it is of benefit to develop big horns (guard) or to have no horns (sneak), ESS swithcpoint, not a frequency, optimizing own fitness based on conditions
