INSTABILITY OF THE SEXUAL CONTINUUM

Maynard Smith & Szathmary (1995) have posed the problem of demonstrati ng the conjectured instability of a continuum of sexual types with fin ite interbreeding. Here, I propose a model in which one can analyse ex actly when and how the existence of the instability can depend on an A llee effect, and how the growthrate and typical scale of the unstable perturbations depend on the strength and range of competition, mating preference, fecundity and offspring variance due to Mendelian segregat ion and mutation. Instabilities of various kinds are shown to occur in the majority of parameter regimes. In short: the continuum often brea ks up into incipient species.