Phylogeography of the montane caddisfly Drusus discolor: evidence for multiple refugia and periglacial survival

Abstract

We studied the genetic population structure and phylogeography of the montane caddisfly Drusus discolor across its entire range in central and southern Europe. The species is restricted to mountain regions and exhibits an insular distribution across the major mountain ranges. Mitochondrial sequence data (COI) of 254 individuals from the entire species range is analysed to reveal population genetic structure. The data show little molecular variation within populations and regions, but distinct genetic differentiation between mountain ranges. Most populations are significantly differentiated based on F(ST) and exact tests of population differentiation and most haplotypes are unique to a single mountain range. Phylogenetic analyses reveal deep divergence between geographically isolated lineages. Combined, these results suggest that past fragmentation is the prominent process structuring the populations across Europe. We use tests of selective neutrality and mismatch distributions, to study the demographic population history of regions with haplotype overlap. The high level of genetic differentiation between mountain ranges and estimates of demographic history provide evidence for the existence of multiple glacial refugia, including several in central Europe. The study shows that these aquatic organisms reacted differently to Pleistocene cooling than many terrestrial species. They persisted in numerous refugia over multiple glacial cycles, allowing many local endemic clades to form.

The phylogeography of an alpine leaf beetle: Divergence within Oreina elongata spans several ice ages

“…The contemporary distributions of alpine populations correspond to the four refugia proposed for alpine plants along the southwestern, southern and eastern edges of the Alps (Schönswetter et al, 2005;Margraf et al, 2007). Peripheral refugia in the southwestern and southern Alps have also been suggested for the mountain ringlet, Erebia epiphron (Schmitt et al, 2006), and the caddisfly, Drusus discolor (Pauls et al, 2006). O. elongata therefore joins the list of high altitude plant and animal species that appear to have survived glacial periods close to their current distribution (Schmitt, 2009).…”

“…Whilst these patterns have been well documented for many lowland species, much less is known about the influence of ice ages on high altitude animals (Pauls et al, 2006;Schmitt et al, 2006;Haubrich and Schmitt, 2007;Schmitt, 2009). They provide a contrast with the lowland taxa, since the current warm climate represents a period in which their range has probably contracted.…”

Genetic diversity in the Alpine flatworm <i>Crenobia alpina</i>

“…In the central parts of the Alps, we found no clear geographical structuring of C. alpina. The detected spatial structuring fits with previous findings for plants (Schönswet-ter et al, 2005) and animals (e.g., Pauls et al, 2006) and thus might be a promising hint for future studies with more samples per site and additional markers. With such approaches it would be possible to retrieve a more complete and convincing picture of the inter-and intraspecific divergence and to test whether closely related cryptic species show vicariant patterns as documented between flatworm genera (Wright, 1974;Snook and Milner, 2001;Roca et al, 2006).…”

Population genetic structure of Simulium degrangei (Diptera: Simuliidae) from Western Carpathians

“…It cannot be excluded that such re-colonisation occurred independently, and simultaneously or gradually, from two refugia and directions during periods of more favourable conditions for the species. Subsequently, in the Atlantic, or even later, this formerly continuous population may have become fragmented, since similar processes have been recognized in many European mountain species and especially those in dinodal mountain species (Malicky 1983(Malicky , 2000Pauls et al 2006;Schmitt et al 2010).…”