Dispersal versus vicariance in the Aegean: combining molecular and morphological phylogenies of eastern Mediterranean Dendarus (Coleoptera: Tenebrionidae) sheds new light on the phylogeography of the Aegean area

Abstract

Abstract The Aegean archipelago, as an ‘evolutionary laboratory of nature’, is an ideal model for research in phylogeography. In this area, the darkling beetles of the genus Dendarus (distributed from Morocco to the Caucasus) exhibit a high level of diversity with 36 species, 27 of which are island endemics. However, their taxonomy is complex and unstable, having undergone continuous revision to address extensive morphological and ecological plasticity. Here, we examine the phylogenetic relationships of 23 species from Greece and Turkey, using mitochondrial and nuclear DNA sequences and 61 morphological characters, to unveil their phylogeny in the Aegean. This helps to clarify phylogeographic scenarios and historical processes that shaped the observed patterns. The analyses reveal 13 distinct lineages with several para- and polyphyletic cases that correspond to three major phylogroups [south/south-east Aegean (D. foraminosus complex, D. rhodius, D. sporadicus, D. wettsteini); central to north Aegean, Turkey and mainland Greece (D. crenulatus, D. moesiacus group, D. sinuatus complex, D. stygius) and mainland Greece (D. messenius, D. paganettii)], indicating the need for further taxonomic re-evaluation. Lineage topology and phylogeography suggest a spatial and temporal sequence of geographic isolation, following either a vicariant or a dispersal model coincident with major palaeogeographic separations in the Aegean.