The evolutionary maintenance of sexual reproduction: The solutions proposed for a longstanding problem

Abstract

The evolutionary maintenance of mixis is one of the major unsolved problems in modern biology. This paper reviews the phenoraenon of sex, the hypotheses for its maintenance, and recent evidence bearing on the hypotheses. One elegant experiment supports the idea that bacterial transformation, an analogue and possible forerunner of eukaryolic mixis, functions as a repair mechanism. All mechanisms that produce a short-term advantage for sex in eukaryotes and that are supported by experimental results rely on strong genotype by environment interactions for fitness. While many environmental factors are involved, most prominently parasites, disease, and coarse-grained environmental heterogeneity of other sorts, each is effective only insofar as it is involved in a genotype by environment interaction for fitness. © 1990 Indian Academy of Sciences.