Phylogeny and evolution of the genus Abax, a genetic and biosystematic approach (Carabidae, Pterostichini).

Abstract

Abstract A study of mitochondrial and nuclear markers of the genus Abax (Carabidae, Pterostichini) has been carried out to test hypotheses about its evolutionary history and to get an integrative taxonomical framework. Sequences of all putative species always made-up monophyletic clades. The subgenera Pterostichoabax (four species) and Abacopercus (monotypic) are likely natural taxa supported by all data. However, Pterostichoabax was found to be interspersed among the species of the nominal subgenus Abax, making it a polyphyletic taxon. Despite this problem, several clades of this subgenus that include two or more taxa seem to correspond to monophyletic lineages. Haplotype variation is seemingly related to the geographic origin of individuals of Abax parallelepipedus and Abax pyrenaeus and may correspond to current subspecies of both taxa. It has been corroborated hypotheses about a close relationship of species of the POBE group (A. pilleri, A. oblongus, A. baeninngeri, A. exaratus); between A. carinatus, A. pyrenaeus, and A. parallelus, the basal position of A. schueppeli and the monophyly of Pterostichoabax. Hypotheses about a close relationship between the species pairs schueppeli-carinatus, parallelepipedus-fiorii, and ovalis-parallelus (among others) are not supported by molecular results. The evolutionary history of the genus Abax has been traced back at least before Middle Tortonian (10.3 MYA). Successive lineage splits during the second half of the Miocene gave rise to main lineages with a rapid radiation during the Pleistocene. Lineage diversification included moderate ecological, behavioral and molecular changes accompanied with morphological conservatism and diversified geographic patterns.