title: Population genetics reveals origin and number of founders in a biological invasion.
abstract: Propagule pressure is considered the main determinant of success of biological invasions: when a large number of individuals are introduced into an area, the species is more likely to establish and become invasive. Nevertheless, precise data on propagule pressure exist only for a small sample of invasive species, usually voluntarily introduced. We studied the invasion of the American bullfrog, Rana catesbeiana, into Europe, a species that is considered a major cause of decline for native amphibians. For this major invader with scarce historical data, we used population genetics data (a partial sequence of the mitochondrial cytochrome b gene) to infer the invasion history and to estimate the number of founders of non-native populations. Based on differences between populations, at least six independent introductions from the native range occurred in Europe, followed by secondary translocations. Genetic diversity was strongly reduced in non-native populations, indicating a very strong bottleneck during colonization. We used simulations to estimate the precise number of founders and found that most non-native populations derive from less than six females. This capability of invasion from a very small number of propagules challenges usual management strategies; species with such ability should be identified at an early stage of introduction.
authors.affiliation: Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université de Savoie, 73376 Le Bourget du Lac cedex, France. francesco.ficetola@unimi.it
authors.forename: Gentile Francesco
authors.initials: GF
authors.lastname: Ficetola
authors.forename: Aurelie
authors.initials: A
authors.lastname: Bonin
authors.forename: Claude
authors.initials: C
authors.lastname: Miaud
mesh_terms: D025041:Animal Migration; D000818:Animals; D003198:Computer Simulation; D045303:Cytochromes b / Q000737:chemistry / Q000235:genetics; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics; D005060:Europe; D005260:Female; D018703:Founder Effect; D014644:Genetic Variation; D006239:Haplotypes; D008957:Models, Genetic; D016133:Polymerase Chain Reaction; D011157:Population Dynamics; D011892:Rana catesbeiana / Q000235:genetics* / Q000254:growth & development*
chemical_list: D004272:DNA, Mitochondrial; D045303:Cytochromes b