Next-generation species delimitation and taxonomy: Implications for biogeography

Abstract

An accurate species-level taxonomy is paramount for biogeographical research, and conversely, biogeographical data are of importance for species delimitation. We here review recent developments and future perspectives of taxonomy of direct relevance for biogeographers. The understanding that species are independently evolving segments of population-level lineages, the rise of integrative approaches to delimit such lineages, and the advent of high-throughput sequencing have considerably renewed the discipline of taxonomy. Using genome-scale molecular datasets, the extent of admixture across hybrid zones can now be effectively assessed and the evolutionary independence of lineages inferred, leading to more reliable and comparable species delimitation criteria. Substantially divergent but admixing phylogeographical lineages can conveniently be named as subspecies, thus avoiding taxonomic oversplitting and taxonomic inflation. At the same time, comprehensive DNA barcoding and DNA metabarcoding efforts are uncovering an enormous proportion of undiscovered biotic diversity, and we encourage the development of bioinformatic pipelines that combine high-throughput species discovery and delimitation with diagnosis and scientific naming, to approach a biotic inventory of the globe without abandoning the established Linnaean system.