Genetic diversity of Thaumetopoea pityocampa in Greece: the role of Quaternary changes in Aegean Sea

Abstract

Thaumetopoea pityocampa, the winter pine processionary moth, is one of the most important pests of pine trees in the Mediterranean region. To learn more about the refugial areas within the greater refugium of Greece, samples from 15 local populations were collected. Analysis of the Cytochrome Oxidase I region identified 15 haplotypes. One strongly supported clade was found, separating the Aegean island of Lesvos from the mainland populations. Mdiv analysis showed that this clade diverged from the general clade 155,000 y.a., suggesting the sea level changes during the Quaternary Period as a possible reason for its seclusion. Additionally, comparisons with similar studies in this region revealed a possible colonization of the eastern Aegean islands from the Turkish mainland rather than from Greece. However, no strong isolation-by-distance events were detected among the mainland populations, which could be attributed to the joint effect of regular gene flow and the lack of insurmountable geographic barriers. Finally, regarding population structure, Bayesian analysis as well as neutrality tests pointed towards an ongoing population expansion which verifies the potential invasiveness of this pest species, something that will have to be dealt with under the influence of climate change.

From refugia to contact: Pine processionary moth hybrid zone in a complex biogeographic setting

“…Our results confirm the low genetic diversity found elsewhere in Europe, and no new stable glacial refugium was identified in the easternmost part of its distribution. Nonetheless, we found some closely related but private haplotypes in south of the Dardanelles and in Lesvos island (as some already mentioned by Korsch et al, ), suggesting that T. pityocampa survived the last glacial period locally in this region. This scenario suggests that T. pityocampa is a recent invader in Anatolia sensu Poulakakis et al ().…”

“…This suggests that northeastern Aegean region would not be a long-lasting refugium for T. pityocampa but the edge of its expanded range. The main haplotype found here (haplotype-1, see Figure 2) is also the major one found all along from eastern France to Greece (Korsch et al, 2015;Rousselet et al, 2010). This confirms the extensive eastward postglacial range expansion of T. pityocampa throughout Europe.…”

“…Europe after the last glacial maximum, but its history in the eastern part of its range remains poorly documented, except in Greece (Korsch et al, 2015). Previous studies revealed four differentiated mitochondrial lineages within T. wilkinsoni: Crete, Cyprus, western Turkey, and eastern Turkey-Israel (Kerdelhué et al, 2009;Simonato et al, 2007) (the population in Crete might be a separate species, see Petsopoulos et al, 2018).…”

“…Several glacial refugia were identified for T. pityocampa , mostly in the south of the Mediterranean Basin and southern Europe (Kerdelhué et al, ; Rousselet et al, ). A major postglacial demographic expansion occurred throughout Europe after the last glacial maximum, but its history in the eastern part of its range remains poorly documented, except in Greece (Korsch et al, ). Previous studies revealed four differentiated mitochondrial lineages within T. wilkinsoni : Crete, Cyprus, western Turkey, and eastern Turkey–Israel (Kerdelhué et al, ; Simonato et al, ) (the population in Crete might be a separate species, see Petsopoulos et al, ).…”