Evolutionary explanations for partner preferences Flashcards
what is sexual selection?
Darwin’s concept of sexual selection concerns the selection of those characteristics that aid successful reproduction. Attributes or behaviours that increase reproductive success are passed on and may become exaggerated over succeeding generation of offspring.
e.g. Aggression in animals
what is anisogamy?
refers to the differences between male and female sex cells, sperm is small mobile and created continuously from puberty to old age. eggs are large and produced at intervals.
a consequence of anisogamy is that there is no shortage of fertile males but fertile females are a much rarer source
anisogamy important partner preference as it gives rise to two types of sexual selection
what are the two types of sexual selection?
inter-sexual selection
intra-sexual selection
what is inter-sexual selection?
The strategies that males use to select females or females use to select males. Inter-sexual selection is the preferred strategy of the female, quality over quantity as ova are rarer than sperm
what did Trivers (1972) suggest in terms of inter-sexual selection?
The females make a greater investment of time, commitment before during and after birth. Consequences for wrong partner choice are more serious for the female so they tend to select a genetically fit partner who is able to provide resources. This female preference determines what traits are passed onto offspring
what is the sexy sons hypothesis in terms of inter-sexual selection?
developed by Fisher (1930)
the genes we see today are those that enhanced reproductive success, a female who mates with a male who has a certain characteristic will then have sons who inherit this “sexy” trait. her sons are then more likely to be selected for reproduction by successive generations and this ‘sexy trait’ is perpetuated.
what is intra-sexual selection?
Preferred strategies of the males to be the one selected, quantity over quality as there is plentiful supply of sperm.
there’s competition between males to be selected to mate with a female. Strategy has given rise to dimorphism where males and females end up looking very different due to intra-sexual selection. size matter in males but not in females as they aren’t competition so no evolutionary drive towards favouring larger females. (however, men favour women with large hip to waist ration as seen as fertile). It has behavioural consequences like intelligence and aggression in order to acquire fertile females.
