Pathogens, polymorphism, and the evolution of sex.
نویسنده
چکیده
For short-lived pathogens, adaptation to one host genotype is negatively correlated with adaptation to others when host genotypes are sufficiently differentiated. This may provide an adaptive basis for sexual recombina-tion, which lowers cross-genotypic correlations among offspring and other kin, and thereby interferes with pathogenic transmission, multiplication, and adaptation. Such pathogen-host interactions lead to generalized frequency-dependent selection for allozymic diversity. The ecological and life-historical correlates of parthenogenesis, inbreeding, chromosome number, and polymorphism are consistent with this hypothesis. Introduction The increasing theoretical precision, over the last two decades, of the conceptual revolution in evolutionary biology has isolated the question of the function of sexual reproduction as the one surviving issue which has resisted definitive assimilation into the individual selection paradigm (Maynard Smith, 1971). The disadvantages of sexual reproduction, including the costs of meiosis, recombination, and mating are large, ?~hile the advantages remain obscure (Maynard Smith, 1978). The most effective advocate of the individual selection viewpoint, G. C. Williams, has advanced a set of models showing sufficient advantage to sexual reproduction only under certain combinations of ecological and life historical conditions (Williams, 1975). The relevance of some of these models to natural circumstances has been disputed (Maynard Smith, 1978), but regardless of their validity, the models are not sufficiently universal to account for the present distribution of sexually reproducing species. This forced Williams to conclude that the costs of sex heavily outweighed the benefits among low fecundity taxa, such as birds, mammals, reptiles, and many insects. At approximately the same time that sexual reproduction was emerging as a major evolutionary anomaly, electrophoresis and the selective assay of enzymes was applied to population genetics, uncovering a surprising and theoretically unexpected degree of protein polymorphism (Lewontin & Hubby, 1966). The nature and significance of this genetic variation is still a matter of varied interpretation
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عنوان ژورنال:
- Journal of theoretical biology
دوره 97 4 شماره
صفحات -
تاریخ انتشار 1982