Varying rates of diversification in the genus Melitaea (Lepidoptera: Nymphalidae) during the past 20 million years

The influence of Quarternary glacial cycles on the extant diversity of Holarctic species has been intensively studied.
It has been hypothesized that palaeoclimatic changes are responsible for divergence events in lineages. A constant
improvement in DNA sequencing and modeling methods, as well as palaeoclimatic reconstruction, permit a deeper
exploration of general causes of speciation in geological time. In the present study, we sampled, as exhaustively as
possible, the butterflies belonging to the genus Melitaea (Lepidoptera: Nymphalidae), which are widely spread in
the Palaearctic region. We conducted analyses to assess the phylogeny of the genus and estimated the timing of
divergence and the most likely distribution of ancestral populations. The results obtained indicate that the
systematics of the genus is in need of revision and that the diversity of the genus has been profoundly shaped by
palaeoenvironmental changes during its evolutionary history. The present study also emphasizes that, when
employed with caveats, major palaeoenvironmental events could represent very powerful tools for the calibration
of the dating of divergences using molecular data.