The phylogeography of an alpine leaf beetle: Divergence within Oreina elongata spans several ice ages

Abstract

a b s t r a c tThe genetic landscape of the European flora and fauna was shaped by the ebb and flow of populations with the shifting ice during Quaternary climate cycles. While this has been well demonstrated for lowland species, less is known about high altitude taxa. Here we analyze the phylogeography of the leaf beetle Oreina elongata from 20 populations across the Alps and Apennines. Three mitochondrial and one nuclear region were sequenced in 64 individuals. Within an mtDNA phylogeny, three of seven subspecies are monophyletic. The species is chemically defended and aposematic, with green and blue forms showing geographic variation and unexpected within-population polymorphism. These warning colors show pronounced east-west geographical structure in distribution, but the phylogeography suggests repeated origin and loss. Basal clades come from the central Alps. Ancestors of other clades probably survived across northern Italy and the northern Adriatic, before separation of eastern, southern and western populations and rapid spread through the western Alps. After reviewing calibrated gene-specific substitution rates in the literature, we use partitioned Bayesian coalescent analysis to date our phylogeography. The major clades diverged long before the last glacial maximum, suggesting that O. elongata persisted many glacial cycles within or at the edges of the Alps and Apennines. When analyzing additional barcoding pairwise distances, we find strong evidence to consider O. elongata as a species complex rather than a single species.

Phylogeographic Insights into a Peripheral Refugium: The Importance of Cumulative Effect of Glaciation on the Genetic Structure of Two Endemic Plants

“…Although the differentiation between main lineages is most likely to have begun in the Middle Pleistocene, haplotype divergence within main lineages probably occurred successively (Fig 4). This is congruent with the observation that in some Alpine animal species the separation of the major clades occurred long before the LGM and the following repeated glacial and interglacial periods may have been the motor for marked differentiation that is currently observed [69, 70]. A similar time frame was detected in another endemic species in the calcareous cliffs of the Maritime and Ligurian Alps, P .…”

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.…”

Recent Speciation in Three Closely Related Sympatric Specialists: Inferences Using Multi-Locus Sequence, Post-Mating Isolation and Endosymbiont Data

“…*BEAST can do bayesian estimation of species trees from multilocus data under the coalescent model, an extension of the coalescent prior designed to handle multiple species, and also can handle different numbers of gene copies for each taxon. Furthermore, *BEAST infers species trees from multilocus data and shows advantages in computational speed and accuracy over other similar methods [40], [41]. All of the five partitions were employed for the species-tree analysis.…”

“…Instead, branch lengths and node ages in the BEAST analysis were estimated by applying a gene-specific substitution rate. In present analysis, only mtDNA sequence data were used with average pairwise divergence rates as 1.73% My −1 for COI and 1.38% My −1 for COII [41]. A relaxed clock with log-normal branch length distribution was used and a Yule speciation model was applied to model population size through time, other prior parameters were set as default.…”