Date of this Version
American Naturalist (June 1985) 125(6).
A substantial body of theory is devoted to understanding the relative advantages of sexual and asexual reproduction. It is generally understood that asexual forms potentially have a higher rate of reproduction because they save the cost of producing males. The micro-evolutionary consequences of sexual and asexual reproduction are less clear. Sexual reproduction generates abundant genotypic diversity which may be adaptively advantageous (Williams 1975; Maynard Smith 1978). Asexual reproduction may perpetuate combinations of genes that are co-adapted (Templeton 1979), heterotic (Suomalainen et al. 1976; White 1979), or specialized (Vrijenhoek 1979, 1984). Thus, it is possible that the fitness of a sexual population may be lower than an asexual, in part, because recombination tends to break up especially favorable genotypes (Williams 1975; Hebert 1978). If it is generally observed that asexual reproduction has an immediate adaptive as well as a reproductive advantage, then it is difficult to see how sexual reproduction can be maintained by short-term advantages (Williams 1975).
A comparison of closely related sexual and asexual forms is a promising avenue of research to evaluate experimentally the consequences of both modes of reproduction (Maynard Smith 1978). In this study, geometrid moth larvae (Alsophila pometaria) derived from both kinds of reproduction were reared on different host plants. The goal was to assess larval viability and growth in an ecologically relevant context and thus partially characterize the fitness of sexual and asexual reproduction.