The African-Iberian connection in Odonata: mtDNA and ncDNA based phylogeography of Aeshna cyanea (Muller, 1764) (Odonata: Aeshnidae) in Western Palaearctic

We explore the phylogeography and inter-population relationships of the Southern Hawker dragonfly, Aeshna cyanea (Muller) in the Western Palaearctic region based on 603 bp Cytochrome Oxidase Subunit 1 (COI) mtDNA and 732 bp Internal Transcribed Spacer region (Internal Transcribed Spacer 1, 5.8S ribosomal RNA gene and Internal Transcribed Spacer 2, ITS region) ncDNA with an increased sampling from Europe compared to a previous study. Both DNA fragments recover a remarkable and compatible pattern: the recently described Aeshna vercanica Schneider et al. is the sister group of A. cyanea, which in turn comprises three distinct populations. These populations are: a population in the Caucasus region; a North African population; and a European population. When analysed alone, the ITS fragment recovered A. vercanica and the Caucasus A. cyanea population as separate units, but the North African and European A. cyanea populations were recovered as intermixed. FST population genetic analyses of COI data revealed high degrees of isolation between all populations as all inter-population values were between 0.818 (North Africa - Europe) and 0.944 (Europe - A. vercanica). Average pairwise distance in COI (uncorrected p) between populations followed this pattern and was lowest between Europe and North Africa and highest between North Africa and A. vercanica, and between Europe and A. vercanica. Within population pairwise distance values were approximately an order of magnitude lower. Pairwise distance values between populations for the ITS region were much lower than for COI, but followed the same pattern. Our results therefore support the full species status for A. vercanica, and clearly indicate that the current Western European A. cyanea population originated from a North African galcial refugium and dispersed to Europe (the Iberian Peninsula) prior to the Holsteinian interglacial period. While the North African and European populations likely remained in contact initially, the European population was probably isolated in the Iberian Peninsula during the Holsteinian interglacial period, and subsequently spread throughout Europe in late Pleistocene - early Holocene.