Discordances between phylogenetic and morphological patterns in alpine leaf beetles attest to an intricate biogeographic history of lineages in postglacial Europe

Abstract

Pleistocene glacial and interglacial periods have moulded the evolutionary history of European cold-adapted organisms. The role of the different mountain massifs has, however, not been accurately investigated in the case of high-altitude insect species. Here, we focus on three closely related species of non-flying leaf beetles of the genus Oreina (Coleoptera, Chrysomelidae), which are often found in sympatry within the mountain ranges of Europe. After showing that the species concept as currently applied does not match barcoding results, we show, based on more than 700 sequences from one nuclear and three mitochondrial genes, the role of biogeography in shaping the phylogenetic hypothesis. Dating the phylogeny using an insect molecular clock, we show that the earliest lineages diverged more than 1 Mya and that the main shift in diversification rate occurred between 0.36 and 0.18 Mya. By using a probabilistic approach on the parsimony-based dispersal ⁄ vicariance framework (MP-DIVA) as well as a direct likelihood method of state change optimization, we show that the Alps acted as a cross-roads with multiple events of dispersal to and reinvasion from neighbouring mountains. However, the relative importance of vicariance vs. dispersal events on the process of rapid diversification remains difficult to evaluate because of a bias towards overestimation of vicariance in the DIVA algorithm. Parallels are drawn with recent studies of cold-adapted species, although our study reveals novel patterns in diversity and genetic links between European mountains, and highlights the importance of neglected regions, such as the Jura and the Balkanic range.

Molecular Biogeography of the High Mountain Systems of Europe: An Overview

“…Quite similar phenomena, with similar biogeographic explanations, are known between the north-eastern Alps and the Tatra mountains (e.g. Kropf et al 2003;Muster and Berendonk 2006;Schönswetter et al 2006;Suda et al 2007;Paun et al 2008;Triponez et al 2011;Schmitt et al 2014) as well as the south-eastern Alps and the north-western Balkan mountains (Triponez et al 2011; examples for boreo-montane species: Ronikier et al 2008b;Kramp et al 2009). Although genetic data from the western Balkan mountains are generally scarce, it is worth noting that the south-eastern Alps-western Balkan mountains link is frequently supported by the existence of taxa that only occur in these two regions (e.g.…”

“…This mountain range sometimes even possesses its own endemic genetic lineages, supporting the idea of independent glacial refugia in its geographic proximity without recent genetic exchange, neither with the western Alps nor with the Pyrenees (e.g. Pauls et al Triponez et al 2011;Kropf et al 2012). Genetic links are known with the Pyrenees (e.g.…”

“…A particularly interesting case involves representatives of the beetle species complex Oreina alpestris/speciosa. In this example, the populations of the northern Apennines show much higher similarity with ones from the south-western Alps than with those of the central Apennines (Triponez et al 2011), thus indicating several colonisation waves from the south-western Alps to the Apennines, with the older ones preserved in the more southern mountains, the younger ones more to the North.…”

“…Genetic links are known with the Pyrenees (e.g. Descimon 1995;Ronikier et al 2008b (however, these two species are not typical alpine elements); Schmitt et al 2014) and the western Alps (Kramp et al 2009 (but referring to a boreo-montane species); Triponez et al 2011). However, the latter link seems to be less frequent than the former, thus supporting the idea that the isolating power of the Rhone valley was stronger than that of the hilly regions between the Massif Central and the Pyrenees.…”

Molecular barcoding for central-eastern European Crioceris leaf-beetles (Coleoptera: Chrysomelidae)

“…Similar research on the application of DNA barcoding for testing taxonomic and phylogenetic species concepts of closely related species of leafbeetles were performed e.g. on Oreina genus [57,58] and Bruchidius genus [59]. As opposed to Oreina leafbeetles, which some morphological species were not valid species and others were species complexes [57,58] and similarly to Bruchidius beetles [59], Crioceris species turned out to be monophyletic and clearly distinct from each other in respect to their mtDNA.…”