2007

Abstract:

Evolutionary biologists, including Darwin, have long puzzled over the adaptive significance of the sex ratio (i.e. the ratio, #females: #males). When a parent has only a limited amount of some breeding resource at its disposal, investment in a son necessarily comes at the expense of investment in a daughter. Parental investment strategies (or what I call, "sex allocation strategies") can be intimately connected to the population sex ratio. Identifying the "best" parental investment strategy, then, is often the key to developing an adaptive explanation for the sex ratio. In this talk, I will introduce some classical models for the evolution of sex allocation strategies. As we will see, applying sex-ratio theory to species of vertebrates is often problematic. Nevertheless, I will argue that many of the "inconsistent results" from vertebrate sex ratio studies can be understood using a single, albeit complicated, model of sex-ratio evolution. The new ideas I will discuss are the result of joint work with Stuart West, Institute of Evolutionary Biology, Edinburgh.