Integration of conflict into integrative taxonomy: fitting hybridization in species delimitation of Mesocarabus (Coleoptera: Carabidae)

In species differentiation, characters do not usually diverge synchronously and there are also processes that effectively shuffle character states present in lineages descendant from a common ancestor. Species are thus expected to show some degree of incongruence among characters, and we argue that taxonomic delimitation actually benefits from integrative approaches and objective strategies dealing with character conflict. We illustrate the potential of exploiting conflict for species delimitation in a study-case of ground beetles of the subgenus Carabus (Mesocarabus), where traditional taxonomy fails to accurately delimit species. The molecular phylogenies of four mitochondrial and three nuclear genes, cladistic analysis of the aedeagus, ecological niche divergence, and morphometry of pronotal shape in altogether more than 500 specimens of Mesocarabus, show that none of these character sets are fully congruent with each other. For these data, a three-steps operational strategy is propo...