title: Rapid selection against inbreeding in a wild population of a rare frog.
abstract: Populations that are small and isolated can be threatened through loss of fitness due to inbreeding. Nevertheless, an increased frequency of recessive homozygotes could increase the efficiency of selection against deleterious mutants, thus reducing inbreeding depression. In wild populations, observations of evolutionary changes determined by selection against inbreeding are few. We used microsatellite DNA markers to compare the genetic features of tadpoles immediately after hatch with those of metamorphosing froglets belonging to the same cohort in a small, isolated population of the threatened frog Rana latastei. Within a generation, the inbreeding coefficient (F IS) decreased: at hatch, F IS was significantly >0, whereas F IS was <0 after metamorphosis. Furthermore, heterozygosity increased and allelic frequencies changed over time, resulting in the loss of genotypes at metamorphosis that were present in hatchlings. One microsatellite locus exhibited atypically large F ST values, suggesting it might be linked to a locus under selection. These results support the hypothesis that strong selection against the most inbred genotypes occurred among early life-history stages in our population. Selective forces can promote changes that can affect population dynamics and should be considered in conservation planning.
authors.affiliation: Dipartimento di Biologia, Università degli Studi di Milano Milano, Italy ; Dipartimento di Scienze dell'Ambiente e del Territorio, Università degli Studi di Milano-Bicocca Milano, Italy.
authors.forename: Gentile Francesco
authors.initials: GF
authors.lastname: Ficetola
authors.affiliation: Institute of Zoology, Zoological Society of London London, UK.
authors.forename: Trenton W J
authors.initials: TW
authors.lastname: Garner
authors.affiliation: Institute of Zoology, Zoological Society of London London, UK.
authors.forename: Jinliang
authors.initials: J
authors.lastname: Wang
authors.affiliation: Dipartimento di Biologia, Università degli Studi di Milano Milano, Italy.
authors.forename: Fiorenza
authors.initials: F
authors.lastname: De Bernardi
keywords: Rana latastei; genetic purging; heterozygosity; microsatellites; temporal variation