Meeting Abstract
The evolutionary “success” of a genus is considered nearly synonymous with its species richness. Many animal taxa that contain rapid evolutionary radiations– cichlid fishes in African Great lakes, Anolis lizards on Caribbean islands, cone snails– have been the focus of theory-driven work in evolutionary biology. On the other hand, the preponderance of genera contain one or very few species. Many studies have noticed this, and suggested that there was some selective bias favouring lineages that have already survived the extinction that wiped out their nearest relatives. There are therefore seemingly contradictory hypotheses about general mechanisms in evolution: the potential selective bias for some heritable traits that either lead to adaptive radiations, or lead to the success of isolated monotypic lineages. An alternative hypothesis is that diversification, at global scales, is a dispassionate stochastic process. In terms of species richness, there are a large number of very small genera, and a small number of large genera, worldwide, in all animal groups. This size-frequency of genera in the real-world, agrees with predictions from very straightforward models of species-level evolution. The fact that there are predictable patterns in taxonomy that can be deduced from the mathematics of phylogeny, provides an important step forward to understand the mechanisms of selection and diversification.
