Alpine lakes and ponds – a promising source of high genetic diversity in metapopulations of aquatic insects

Alpine lakes and ponds are unique and vulnerable aquatic habitats inhabited by specific species assemblages. In contrast to alpine streams, the genetic diversity and population structure of the organisms found in alpine standing waters are almost completely unknown. Here we present a population genetic study of a macroinvertebrate species from alpine lakes, the diving beetle <i>Agabus bipustulatus</i> (Linnaeus, 1767). We used partial cytochrome b (<i>Cyt b</i>) mtDNA gene of 560 specimens from 43 lakes and ponds distributed across 20 mountain valleys of the Tatra Mountains (Western Carpathians) and their foothills. The aims of this study were to provide detailed genetic metapopulation analysis of <i>A. bipustulatus</i> within a geographically small mountain system, to explore the role of ridges in isolating lake populations, and to test for the applicability of <i>Cyt b</i> in insect population genetic studies. We detected high genetic variability (42 haplotypes), comparable to many large spatial scale studies. There was a star-shaped genetic structure with few dominant haplotypes, which confirmed recent origin, rapid expansion of metapopulation, and multiple colonization of the Tatra Mountain region by <i>A. bipustulatus</i>. The populations within the mountain system differed from each other, suggesting that the Tatra Mountain lakes and ponds were colonized through multiple colonization events, and also that colonization of the region and evolution of metapopulations are to a certain extent influenced by ridge barriers.