The Genetical Evolution of Patterns of Sexuality: Darwinian Fitness

R. A. Fisher (1930) was perhaps the first to realize that the key to sex ratio evolution lay in the almost trivial fact that (under diploidy) everyone has one mother and one father; that in terms of autosomal genes males and females contribute equally to any zygote formed. This paper shows that his observations proves a useful key to a host of other sex related problems. It is for this intuitive reason that fitness measures for the alteration of sex function are often of the general form W = m̂/m + f̂/f. In such a measure male and female function are assigned equal weight. It is somewhat surprising that this notion continues to hold under haplodiploidy (at least from the mother's viewpoint). There is much that this paper has ignored--inbreeding, fluctuating or stochastic environments, etc. A treatment of many of these is much beyond me. It will be quite interesting to know how well the m̂/m + f̂/f notion holds up to alterations in the basic models proposed here.