Phylogenetic relationships in the genus Lethrus (Coleoptera: Geotrupidae) reveal contrasting evolutionary history in Europe

Abstract

In this study we analysed for the first time the phylogenetic relationships among the European Lethrus species based on mitochondrial (COI, 16S) and nuclear (H3, wingless) markers. The phylogenetic inference based on these genes indicated that the European Lethrus species form a monophyletic group with two main lineages. One of them is distributed in the central part of the Balkan Peninsula (North Macedonia, northwestern Greece and southwestern Bulgaria) and includes five species (L. perun, L. raymondi, L. strymonensis, L. halkidikiensis and L. elephas). Three species of the other clade (L. schaumii, L. ares and L. schneideri) occur in the eastern part of the Balkan Peninsula (southeastern Bulgaria and northeastern Greece) while its fourth member, L. apterus, could colonize much larger areas in central and eastern Europe. Despite its large geographic distribution, L. apterus proved to be a single species. By contrast, we found strong intraspecific differentiation in both L. schaumii and L. halkidikiensis in spite of their restricted distribution. Surprisingly, two highly divergent mitogroups were also detected within a single L. schneideri population. As the microsatellite markers did not show any differentiation between them, this finding is likely to be accounted for by a unidirectional hybridization event. These findings highlight that phylogenetic studies or species descriptions should not be based on mitochondrial markers alone. Our study clearly demonstrates that allopatric speciation is the most important speciation mechanism in the European species of the genus Lethrus, although we also hypothesize that other well‐known factors, such as hybridization or the glacial‐interglacial dynamics, could significantly affect the speciation patterns of certain lineages.

Multi-Locus Genetic Identification of a Newly Discovered Population Reveals a Deep Genetic Divergence in European Blind Mole Rats (Rodentia: Spalacidae: Nannospalax)

“…Geographic barriers, especially large rivers are known to be effective barriers for animal species with a reduced mobility and can have an isolating effect on populations (e.g., Trizio et al 2005, Kennis et al 2011 and species (e.g. Tóth et al 2019). For example, the effective isolation of European ground-squirrel (Spermophilus citellus) populations was observed by Ćosić et al (2013) in the southern part of the Danube-Tisza Interfluve.…”

Range-wide phylogeography of the flightless steppe beetle Lethrus apterus (Geotrupidae) reveals recent arrival to the Pontic Steppes from the west

“…4 ). Two haplotypes of Lethrus schaumii were used as outgroup from our forerunning phylogeny (GenBank accession numbers: MK558533–MK558540) 26 . The maximum clade credibility tree divided the ingroup haplotypes into four monophyletic lineages.…”

“…Whereas we do not have further evidence to support the presence of an ancestral area here, we cannot rule out the primary role of this territory in the colonisation of Lethrus apterus . As the sister species, L. schaumii 26 , lives in North-Eastern Greece, formal logic would imply that the Bulgarian Plain was colonised first. From here, the species might have colonised towards the north-west and reached the Pannonian Region.…”

“…This raises the possibility that the western part of this distribution might have a more important role in shaping the current area than previously thought. The historical formation of this peculiar Pontic-Pannonian distribution range of Lethrus apterus is also interesting from a speciation point of view as it represents the most wide-spread species of a lineage that most probably originated on the Eastern Balkans 26 . Additionally, Lethrus apterus is also an emerging model species of parental care in behavioural ecology 27 – 29 .…”

“…We address the question of how the current distribution range (Fig. 1 ) of this species has developed since the separation from its Eastern Balkan sister-species, Lethrus schaumii Reitter, 1890 26 The understanding of the phylogeography of L. apterus may help us to deepen our understanding of the biogeographic history of this part of the ESSZ.…”