Adaptive dynamics: Neither F nor G

Most recent models of phenotypic evolution make similar assumptions about the dynamics of traits and of populations. Traits in these models change at a rate proportional to the slope of the individual’s fitness function. However, several different assumptions have been made about other aspects of the evolutionary process, including ecological stability and sympatric speciation. This article argues that a method (the ‘G-function approach ’ of Cohen et al., 1999) that assumes ecological stability and unlimited invasion or sympatric speciation may often not apply to biological communities. For sexual populations, evolutionarily stable trait values that minimize fitness are often a potential result of adaptive evolution