Sexy son hypothesis

Several key moments are important in the game for the laziest parent, which takes place between males and females in a great many species. The female attempts to delay the actual act of copulation for as long as possible, so that the male has already invested as much as possible at the beginning of reproduction. Simultaneously, she cannot postpone copulation disproportionately long, because the male could lose patience and could try to obtain a more compliant (and more permissive) female. Simultaneously, intrasexual competition takes place amongst the males in the population – the evolutionary game of “who’s dumbest”, i.e. a competition for the most patient suitor, “if not this one, then another one”, i.e. a competition for the most successful searcher for a permissive female, “for the dude”, i.e. a competition in willingness to risk invested precopulation efforts and, after achieving copulation, go on to the next house, and a great many more, at least as interesting games.

            A number of evolutionary games also take place within the population of females; I will leave their designation to the fantasy of the reader. Simultaneously, choice of suitable strategy is frequently even more complicated for females in that the choice of a suitable sexual partner must be subject to other criteria to a far greater degree than only the probability of immediate gain from the game as to who is the laziest. While the optimal (although not always evolutionarily stable) strategy of males lies in maximum quantity, i.e. in lack of selectivity in reproduction, females must rather favor the qualitative aspect. They can influence their probable reproductive success primarily through selection of the best sexual partner, i.e. the male with the greatest fitness. Thus, for a female it is not a simple matter to determine the criteria according to which she should chose a suitable male. The fitness of a male need not be in any way correlated with his willingness to contribute to care for his progeny. In most cases, we can probably expect negative correlation, following from the existence of evolutionarily advantageous conditional strategy. If you are beautiful  and strong, then play the game of “if not this one then another one”; if you are low on sex appeal, than you still have a chance in the game of “who’s dumbest” {11547}. Observations of swallows has shown that females prefer to copulate with individuals with long tail feathers, while these individuals provide the least paternal care for their offspring (Reynolds 1996).

             The sexy-son hypothesis refers to the situation where it is more advantageous for females to choose a sexual partner that does not care much for his offspring, but which is most attractive for other females on the basis of different criteria. The disadvantage that choice of such a male represents for bringing up one’s own young is compensated here by the fact that the sons inherit attractiveness from their fathers and have a greater chance of reproducing in the next generation.

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more