Post-glacial partitioning of mitochondrial genetic variation in the field vole

Abstract

Genetic markers are often used to examine population history. There is considerable debate about the behaviour of molecular clock rates around the population-species transition. Nevertheless, appropriate calibration is critical to any inference regarding the absolute timing and scale of demographic changes. Here, we use a mitochondrial cytochrome b gene genealogy, based entirely on modern sequences and calibrated from recent geophysical events, to date the post-glacial expansion of the Eurasian field vole (Microtus agrestis), a widespread temperate mammal species. The phylogeographic structure reflects the subsequent expansion of populations that went through bottlenecks at the time of the Younger Dryas (ca 12 000 years BP) rather than the Last Glacial Maximum (LGM, ca 24 000 years BP), which is usually seen as the time when present-day patterns were determined. The nucleotide substitution rate that was estimated here, ca 4 Â 10 27 substitutions/site/year, remains extremely high throughout the relevant time frame. Calibration with similarly high population-based substitution rates, rather than long-term rates derived from species divergence times, will show that post-LGM climatic events generated current phylogeographic structure in many other organisms from temperate latitudes.

Fossorial morphotype does not make a species in water voles

“…Phylogeographic studies of widespread Palaearctic arvicolines repeatedly retrieved high genetic diversity in Western and Central Europe, which contrasts the genetic uniformity in Eastern Europe and Asia. Although each species has its own geographic pattern of genetic architecture, a west-to-east decay in distribution of genetic diversity is clearly evident in various arvicolines, e.g., Clethrionomys glareolus (Wójcik et al 2010), Microtus oeconomus (Brunhoff et al 2003), Microtus agrestis Searle 2002, Herman andSearle 2012), and Microtus arvalis (Haynes et al 2003, Tougard et al 2008). …”

Contrasting and congruent patterns of genetic structuring in two Microtus vole species using museum specimens

“…For the field vole, three main evolutionary units (which may represent cryptic species) have been described-Portuguese, Southern and Northern (Paupério et al 2012). For the Northern evolutionary unit in the field vole, six main mtDNA lineages have been identified: Eastern, Scandinavian, Central European, French, North British and Western (Herman and Searle 2011;Herman et al 2014). The differences in the distribution and origin of the mtDNA lineages between the common and field vole are evident in Poland (Herman et al 2014;Stojak et al 2015).…”

“…For the field vole, the two lineages that occur in Poland (Central European and Western; Fig. 1) are thought to represent expansion following the Younger Dryas cold period (12.9-11.7 ka BP; Herman and Searle 2011;Herman et al 2014). There appears to have been a single LGM refugium for the Northern evolutionary unit of the field vole (Herman and Searle 2011), but the location of this is uncertain.…”

“…1) are thought to represent expansion following the Younger Dryas cold period (12.9-11.7 ka BP; Herman and Searle 2011;Herman et al 2014). There appears to have been a single LGM refugium for the Northern evolutionary unit of the field vole (Herman and Searle 2011), but the location of this is uncertain. The Carpathians is a possibility, following the suggestion of Jaarola and Searle (2002); however, a later fossil assessment (Pazonyi 2004) suggested that field voles were not part of the LGM community in the Carpathians.…”

After the Ice Age: The Impact of Post-Glacial Dispersal on the Phylogeography of a Small Mammal, Muscardinus avellanarius

“…As such there is consensus that species dispersed into Northern regions and the UK from 23 kya onwards as glacial ice caps retreated and tundra steppes were no longer frozen. The Early Migration Hypothesis (hereafter, EMH) posits dispersal prior to the Younger Dryas period (12.6-11.7 kya; Herman and Searle, 2011). Species migrating at this time must have been more cold tolerant and able to survive the colder conditions of the Younger Dryas period (Stewart et al, 2010;Montgomery et al, 2014).…”