Consequence of past anthropogenic forest fragmentation on the genetic structure of European mammals: the example of the edible dormouse (Glis glis)

The genetic structure of forest animal species may allow the spatial dynamics of the forests themselves to be tracked.
Two scales of change are commonly discussed: changes in forest distribution during the Quaternary, due to glacial/
interglacial cycles, and current fragmentation related to habitat destruction. However, anthropogenic changes in
forest distribution may have started well before the Quaternary, causing fragmentation at an intermediate time
scale that is seldom considered. To explore the relative role of these processes, the genetic structure of a forest
species with narrow ecological preferences, the edible dormouse (Glis glis), was investigated in a set of samples
covering a large part of its Palaearctic distribution. Strong and complex geographical structure was revealed from
the use of microsatellite markers. This structure suggests that fragmentation occurred in several steps, progressively
splitting the ancestral population into peripheral isolated ones. The fact that this structure postdates post-glacial
recolonization, together with dating based on microsatellite data, supports the hypothesis that the differentiation
was recent, starting around 9000 years ago, and took place stepwise, possibly up to Medieval times. This complements
a classic phylogeographical interpretation based on the effect of past climate change, and supports the role of
anthropogenic deforestation as a trigger of recent intraspecific differentiation.