The central Alps comprise a major dispersal barrier between western and eastern populations of two butterfly species

Abstract

AbstractAimGenetic connectivity and diversity are key components of species' resilience to environmental change. However, the specific factors shaping species' resilience are poorly understood. We here aim to strengthen our understanding of resilience in two butterfly species, by identifying regions of high genetic diversity and barriers to dispersal.LocationEuropean Alps.TaxonCopper butterflies (Lycaena spp.).MethodsWe sampled 21 Lycaena hippothoe and 14 L. virgaureae populations with 18 individuals each in the European Alps. Using 14 and 9 microsatellite markers, respectively, we analysed genetic diversity and population structure (using arlequin, genalex, structure and snmf). We analysed spatial patterns of gene flow and genetic diversity (using an estimated effective migration surface), population demographic history and effective population size (diyabc), habitat suitability (maxent), and isolation by distance, and with resistance (genalex, circuitscape).ResultsWe found higher genetic diversity and a more pronounced genetic structure in L. hippothoe than in L. virgaureae. Both species displayed a major genetic barrier in the central Alps. Western and eastern populations showed the highest genetic diversity in L. hippothoe, but central ones in L. virgaureae. Populations of both species were structured by geodetic distance, and minimum and maximum altitude.Main ConclusionsThe population genetic structure of both Copper butterflies seemed to be strongly affected by population history, demography and geographic features. Valleys and high mountain ridges seem to comprise major dispersal barriers. The high genetic diversity and pronounced population structure found in L. hippothoe seems to be related to a low dispersal ability and closed populations with high local abundances as opposed to L. virgaureae. We suggest that different conservation strategies are needed for these closely related species, focussing on connecting suitable habitats in L. hippothoe and increasing local population sizes in L. virgaureae.