title: Genetic bottlenecks driven by population disconnection.
abstract: Connectivity among populations plays a crucial role in maintaining genetic variation at a local scale, especially in small populations affected strongly by genetic drift. The negative consequences of population disconnection on allelic richness and gene diversity (heterozygosity) are well recognized and empirically established. It is not well recognized, however, that a sudden drop in local effective population size induced by such disconnection produces a temporary disequilibrium in allelic frequency distributions that is akin to the genetic signature of a demographic bottleneck. To document this effect, we used individual-based simulations and empirical data on allelic richness and gene diversity in six pairs of isolated versus well-connected (core) populations of European tree frogs. In our simulations, population disconnection depressed allelic richness more than heterozygosity and thus resulted in a temporary excess in gene diversity relative to mutation drift equilibrium (i.e., signature of a genetic bottleneck). We observed a similar excess in gene diversity in isolated populations of tree frogs. Our results show that population disconnection can create a genetic bottleneck in the absence of demographic collapse.
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland. thomas.broquet@sb-roscoff.fr
authors.forename: Thomas
authors.initials: T
authors.lastname: Broquet
authors.forename: Sonia
authors.initials: S
authors.lastname: Angelone
authors.forename: Julie
authors.initials: J
authors.lastname: Jaquiery
authors.forename: Pierre
authors.initials: P
authors.lastname: Joly
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Lena
authors.forename: Thierry
authors.initials: T
authors.lastname: Lengagne
authors.forename: Sandrine
authors.initials: S
authors.lastname: Plenet
authors.forename: Emilien
authors.initials: E
authors.lastname: Luquet
authors.forename: Nicolas
authors.initials: N
authors.lastname: Perrin
mesh_terms: D000818:Animals; D001001:Anura / Q000235:genetics* / Q000502:physiology; D003198:Computer Simulation; D005787:Gene Frequency; D040961:Genetic Drift; D014644:Genetic Variation; D011156:Population Density; D011157:Population Dynamics