Between the Balkans and the Baltic: Phylogeography of a Common Vole Mitochondrial DNA Lineage Limited to Central Europe

Abstract

The common vole (Microtus arvalis) has been a model species of small mammal for studying end-glacial colonization history. In the present study we expanded the sampling from central and eastern Europe, analyzing contemporary genetic structure to identify the role of a potential ‘northern glacial refugium’, i.e. a refugium at a higher latitude than the traditional Mediterranean refugia. Altogether we analyzed 786 cytochrome b (cytb) sequences (representing mitochondrial DNA; mtDNA) from the whole of Europe, adding 177 new sequences from central and eastern Europe, and we conducted analyses on eight microsatellite loci for 499 individuals (representing nuclear DNA) from central and eastern Europe, adding data on 311 new specimens. Our new data fill gaps in the vicinity of the Carpathian Mountains, the potential northern refugium, such that there is now dense sampling from the Balkans to the Baltic Sea. Here we present evidence that the Eastern mtDNA lineage of the common vole was present in the vicinity of this Carpathian refugium during the Last Glacial Maximum and the Younger Dryas. The Eastern lineage expanded from this refugium to the Baltic and shows low cytb nucleotide diversity in those most northerly parts of the distribution. Analyses of microsatellites revealed a similar pattern but also showed little differentiation between all of the populations sampled in central and eastern Europe.

A complex scenario of glacial survival in Mediterranean and continental refugia of a temperate continental vole species ( Microtus arvalis ) in Europe

“…Our model‐based phylogeographic analysis inferred the location of the most recent common ancestor of all haplotypes in a region between the Alps and southern Germany around 51,000 ybp (95% HPD: 62,400 –39,500 ybp). This location is consistent with the oldest fossil remains of M. arvalis found in SW Germany (Kowalski, ) and relates closely to what (Tougard et al, ) proposed as the common cradle of M. arvalis in “western Central Europe.” Moreover, our date estimates for the root of the tree and of major lineages coincided with recent research (Stojak, McDevitt, et al, ). This scenario is clearly not consistent with the fossil evidence (oldest fossil remains of M. arvalis in Central Europe from the Late Cromerian, 465,000 ybp; (Kowalski, )) although accurate species identification in fossil remains appear to be problematic and should always be considered cautiously for this and related species (Navarro et al, ; Tougard, ).…”

“…Overall, the distribution of M. a. asturianus in Iberia is limited to the north and south by the Ebro and Tajo rivers, respectively. The range of the Italian lineage is also limited to the south by the Po, and the Central lineage is roughly delimited by the transitional zone between Oder and Vistula to the west and by the Danube to the south (Stojak, McDevitt, et al, ; Stojak, Wójcik, et al, ). Furthermore, the part of the Danube basin in the eastern Balkan region seems to represent a geographic boundary between the Balkan and Eastern lineages.…”

“…We used the HKY model of sequence evolution and a strict molecular clock with an average substitution rate across the tree of µ = 3.27 × 10 –7 substitutions/site/year (assuming a generation time of 1 year) (Martínková et al, ). We obtained this value from the most recently published—and likely most accurate—rate for cytochrome b of M. arvalis (Martínková et al, ; Stojak, McDevitt, et al, ; Stojak et al, ; Stojak, Wójcik, et al, ), estimated using ancient DNA sequences from radiocarbon‐dated specimens. We ran four independent MCMC chains for 3 × 10 7 generations sampling every 3,000 generations.…”

“…Some of these studies, therefore, contrast with the classical view in considering southern refugia as areas driving high endemism, where mountain ranges may have precluded north–south postglacial dispersal and gene flow. Instead, recolonization would have originated from cryptic—continental—glacial refugia and rapidly expanded along a rough east–west axis (Stojak, McDevitt, et al, ; Stojak et al, ; Stojak, Wójcik, Ruczyńska, Searle, & McDevitt, ). However, whether one or more extra‐Mediterranean refugia existed, their location, or whether they coincided with classical Mediterranean refugia are topics that remain largely unknown.…”

Genetic structure and diversity of a rare woodland bat, Myotis bechsteinii: comparison of continental Europe and Britain

“…The cytochrome b gene is known as a good indicator of mitochondrial diversity for mammals (Combe et al 2016;Stojak et al 2016) and other vertebrates (Zhu et al 2014). However, several European bat species show very little mitochondrial divergence throughout their range as observed with M. bechsteinii (Çoraman et al 2013;Ibáñez et al 2006;Rebelo et al 2012;Salgueiro et al 2007).…”