The “integrated evolutionary speed hypothesis” proposes that the rate of genetic evolution influences all major biogeographical patterns of diversity including those associated with temperature, water availability, productivity, spatial heterogeneity and area. Consistent with this theory, rates of genetic evolution correspond with patterns of diversity and diversification. Here we review the mechanisms that have been proposed to explain these biogeographic patterns in rates of genetic evolution. Tests of several proposed mechanisms have produced equivocal results, whereas others such as those invoking annual metabolic activity, or a “Red Queen” effect, remain unexplored. However, rates of genetic evolution have been associated with both productivity mediated rates of germ cell division and active metabolic rates and these explanations therefore justify further empirical investigation.