Genetic structure of Proclossiana eunomia populations at the regional scale (Lepidoptera, Nymphalidae)

Populations of Proclossiana eunomia (Lepidoptera, Nymphalidae) occur in mid dle Europe in patchy habitats of hay meadows along valleys or peat bogs. Sa mples of P. eunomia populations from the Ardennes region (northern France a nd southern Belgium) were analysed by allozyme electrophoresis. Patches iso lated by more than 2 km of mature forests proved genetically distinct from their neighbouring populations. Mantel tests and regression analysis showed that the degree of genetic differentiation between the 26 studied populati ons is related to the geographical distances between them. Autocorrelation analysis (Moran's I) showed that allele frequencies are positively correlat ed for populations up to 13 km apart and that the genetic neighbourhood of individuals is in the range of 0.9 km, which is in accordance with movement studies in this species conducted in the same area. Analysis using Wright' s F-statistics revealed that the highest differentiation occurs between pop ulations of the same subregion, whereas the whole Ardennes region is not ge netically partitioned into subregions. This is probably because the connect ivity of the network of suitable habitats has significantly weakened only s ince the 1950s, and thus subregional differentiation has not yet occurred.