title: Spatial structuring of the population genetics of a European subterranean termite species.
abstract: In population genetics studies, detecting and quantifying the distribution of genetic variation can help elucidate ecological and evolutionary processes. In social insects, the distribution of population-level genetic variability is generally linked to colony-level genetic structure. It is thus especially crucial to conduct complementary analyses on such organisms to examine how spatial and social constraints interact to shape patterns of intraspecific diversity. In this study, we sequenced the mitochondrial COII gene for 52 colonies of the subterranean termite Reticulitermes grassei (Isoptera: Rhinotermitidae), sampled from a population in southwestern France. Three haplotypes were detected, one of which was found exclusively in the southern part of the study area (near the Pyrenees). After genotyping 6 microsatellite loci for 512 individual termites, we detected a significant degree of isolation by distance among individuals over the entire range; however, the cline of genetic differentiation was not continuous, suggesting the existence of differentiated populations. A spatial principal component analysis based on allele frequency data revealed significant spatial autocorrelation among genotypes: the northern and southern groups were strongly differentiated. This finding was corroborated by clustering analyses; depending on the randomized data set, two or three clusters, exhibiting significant degrees of differentiation, were identified. An examination of colony breeding systems showed that colonies containing related neotenic reproductives were prevalent, suggesting that inbreeding may contribute to the high level of homozygosity observed and thus enhance genetic contrasts among colonies. We discuss the effect of evolutionary and environmental factors as well as reproductive and dispersal modes on population genetic structure.
authors.affiliation: Laboratoire de Biologie des Ligneux et des Grandes Cultures, EA 1207, Université d'Orléans 45067, Orléans, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Bankhead-Dronnet
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS - Université François Rabelais. UFR Sci. & Tech. Tours, 37200, France.
authors.forename: Elfie
authors.initials: E
authors.lastname: Perdereau
authors.affiliation: FCBA - Institut technologique, Dpt Biologie et Préservation du Bois Allée de Boutaut BP227, 33028, Bordeaux, France.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kutnik
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS - Université François Rabelais. UFR Sci. & Tech. Tours, 37200, France.
authors.forename: Simon
authors.initials: S
authors.lastname: Dupont
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS - Université François Rabelais. UFR Sci. & Tech. Tours, 37200, France.
authors.forename: Anne-Geneviève
authors.initials: AG
authors.lastname: Bagnères
keywords: Bayesian clustering; Reticulitermes grassei; breeding system; population structure; spatial genetics; spatial principal component analysis