title: Evolutionary dynamics of a quantitative trait in a finite asexual population.
abstract: In finite populations, mutation limitation and genetic drift can hinder evolutionary diversification. We consider the evolution of a quantitative trait in an asexual population whose size can vary and depends explicitly on the trait. Previous work showed that evolutionary branching is certain ("deterministic branching") above a threshold population size, but uncertain ("stochastic branching") below it. Using the stationary distribution of the population's trait variance, we identify three qualitatively different sub-domains of "stochastic branching" and illustrate our results using a model of social evolution. We find that in very small populations, branching will almost never be observed; in intermediate populations, branching is intermittent, arising and disappearing over time; in larger populations, finally, branching is expected to occur and persist for substantial periods of time. Our study provides a clearer picture of the ecological conditions that facilitate the appearance and persistence of novel evolutionary lineages in the face of genetic drift.
authors.affiliation: Department of Zoology and Biodiversity Research Centre, University of British Columbia, 6270 University Boulevard, Vancouver, B.C., V6T 1Z4, Canada; Centre Interdisciplinaire de Recherche en Biologie (CIRB), Collège de France, CNRS UMR 7241 - Inserm U1050, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France. Electronic address: florence.debarre@normalesup.org.
authors.forename: Florence
authors.initials: F
authors.lastname: Débarre
authors.affiliation: Department of Zoology and Biodiversity Research Centre, University of British Columbia, 6270 University Boulevard, Vancouver, B.C., V6T 1Z4, Canada. Electronic address: otto@zoology.ubc.ca.
authors.forename: Sarah P
authors.initials: SP
authors.lastname: Otto
mesh_terms: D005075:Biological Evolution; D040961:Genetic Drift; D005828:Genetics, Population; D006801:Humans; D008957:Models, Genetic; D011156:Population Density
keywords: Branching; Diversification; Drift; Finite population; Quantitative trait