Interglacials are driving speciation and intraspecific differentiation in the cold‐adapted butterfly species group Boloria pales / napaea (Nymphalidae)

• Published in: Journal of Biogeography
• Main Authors: Ehl, Stefan, Ehl, Sarah, Kramp, Katja, Schmitt, Thomas
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2020
• Subjects: Arctic; The Splits
• Online Access: http://dx.doi.org/10.1111/jbi.13988; https://onlinelibrary.wiley.com/doi/pdf/10.1111/jbi.13988; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jbi.13988

Abstract Aim Cold‐adapted species had their largest distribution areas during glacial periods, whereas the subsequent interglacials led to retreats of these taxa into mountain ranges and more northern regions, but existing data are not sufficient for generalizing these range dynamics. To improve our knowledge of the different phylogeographical patterns existing for cold‐adapted species, we examined two closely related butterfly species of the genus Boloria with alpine disjunct and arctic–alpine distribution respectively. Location Europe: High mountain areas and Scandinavia. Taxa Boloria pales and B. napaea . Methods We sequenced two mitochondrial (COI, ND1/trRNA/16S region) and two nuclear genes (wingless and EF‐1α) for 182 B. pales specimens from 37 localities and 60 B. napaea specimens from 12 localities representing the whole distribution area of both species in Europe. We used existing and known calibration points to date the age of the relevant splits. Results While nuclear DNA showed no genetic structures, the mitochondrial loci revealed 91 haplotypes belonging to three well‐differenced genetic lineages: (a) all samples of B. napaea from the Alps and Scandinavia, (b) the samples of B. pales from the Alps, Carpathians, High Tatra, Pirin Mountains, Dinaric Alps in Montenegro and the Apennines and (c) all samples of B. pales from the Pyrenees. The time estimates for the splits between these three groups range from 1.3 to 0.84 million years ago (mya). The further within‐groups differentiations are not older than 0.32 mya, but reveal a subtle pattern among and within mountain ranges. Main conclusions Allopatry during the mid‐Pleistocene has led to differentiation into three major genetic groups, each of which possibly representing a separate species today. Especially within the today widespread mountain group (i.e. the pales sensu stricto group), repeated expansion out of their Alpine centre and a number of different peri‐Alpine glacial distribution areas have produced the subtle genetic structure observed over ...