Mating preferences

Abstract: The joint evolution of female mating preferences and secondary sexual characters of males is modeled for polygamous species in which males provide only genetic material to the next generation and females have many potential mates to choose among. Despite stabilizing natural selection on males, various types of mating preferences may create a runaway process in which the outcome of phenotypic evolution depends critically on the genetic variation parameters and initial conditions of a population. Even in the absence of genetic instability, rapid evolution can result from an interaction of natural and sexual selection with random genetic drift along lines of equilibria. The models elucidate genetic mechanisms that can initiate or contribute to rapid speciation by sexual isolation and divergence of secondary sexual characters.

Abstract: Why do females prefer elaborate male mating displays in species where they receive little more from males than their sperm? Here we review three hypotheses for the evolution of mating preferences: direct selection, the runaway process and the parasite mechanism. There is growing support for direct selection, in which preferences evolve because of their direct effects on female fitness rather than the genetic effects on offspring resulting from mate choice.

Abstract: The past two decades have seen extensive growth of sexual selection research. Theoretical and empirical work has clarified many components of pre- and postcopulatory sexual selection, such as aggressive competition, mate choice, sperm utilization and sexual conflict. Genetic mechanisms of mate choice evolution have been less amenable to empirical testing, but molecular genetic analyses can now be used for incisive experimentation. Here, we highlight some of the currently debated areas in pre- and postcopulatory sexual selection. We identify where new techniques can help estimate the relative roles of the various selection mechanisms that might work together in the evolution of mating preferences and attractive traits, and in sperm‐egg interactions.

Abstract: A paradox for evolutionists has been the development in one sex, usually females, of preferences for mates possessing characters that impair survival. Darwin (187 1) extensively documented cases of sexual selection in animals and showed that many of the most dramatic examples are attributable to female mating preferences operating in polygynous populations. But while he was untroubled to explain the evolution of adaptations for male-male sexual competition, Darwin did not provide a hypothesis for the origin or maintenance of female mating preferences. Fisher (1958, p. 150-153) provided a subtle solution to this puzzle. He reasoned that the initial evolution of a female mating preference would require "bionomic conditions in which such preference shall confer a reproductive advantage. " He showed that evolution of the preferred male trait could then "proceed, by reason of the advantage gained in sexual selection, even after it has passed the point in development at which its advantage in Natural Selection has ceased." Because females with stronger preferences mate with males bearing more exaggerated traits, a genetic correlation between the preference and trait is maintained by sexual selection. If the -more extreme males are increasing in frequency, the genetic correlation results in the evolution of stronger preferences and so causes further selection for the extreme males. Fisher dubbed this a "runaway process." O'Donald (1967, 1980) used simulations to verify several essential features of Fisher's argument. He differed with Fisher, though, in his belief that females must respond to supernormal mating stimuli for a male trait to evolve to a point where it decreases viability. O'Donald (1977, 1980) pointed out that a small increase in the male trait might result in a small additional viability loss but a large gain in mating advantage by this mechanism. The primary conclusion of the present paper is that the initial selective advantages for the female preference assumed by Fisher, O'Donald, and many later authors are not necessary for either the origin or subsequent elaboration of mating preferences for traits associated with reduced survivorship. Using a two-locus analytic model that follows evolution of both the preference and the trait in a polygynous population, I will show that such mating preferences are neither selected for nor against. A sufficiently strong mating preference can, however, maintain in the population a male trait that causes greatly reduced viability. The result can be a dramatic deterioration of the average survivorship, as Fisher and O'Donald concluded, but no particular assumptions about behavioral mechanisms (e.g., response to supernormal mating stimuli) are