Résumé
Although the recent emergence of the field of landscape genetics has led
to several studies investigating the effects of habitat composition
between populations on genetic differentiation, much less is known on the
impact of within-habitat ecological characteristics on levels of gene flow
and genetic differentiation among populations. Using data on 840
individuals sampled in 8 sites in Corsica and 1 in southern France and
analyzed at 10 microsatellite loci, we assessed the spatial and temporal
population genetic structure of blue tits (Cyanistes caeruleus) in Corsica
and identified the ecological factors, both between- and within-sampling
sites, responsible for the observed genetic structure. We found temporally
stable fine-scale genetic structure within Corsica, with genetic
differentiation values among populations corresponding to ~25% of levels
observed between Corsica and the mainland. This structure was not
explained by the geographic distance among populations or by the presence
of physical barriers but was instead related to local habitat types
(deciduous or evergreen oaks). Our results are thus consistent with
previously documented phenotypic differences among habitats in
morphological and reproductive traits. These findings suggest that
although individuals have high dispersal ability, local adaptation might
reduce gene flow among populations located in different habitats.