Understanding speciation is one of the cornerstones of biological diversity research. Currently, speciation is often understood as a continuous process of divergence that continues until genetic or other incompatibilities minimize or prevent interbreeding. The Palearctic snake genus Natrix is an ideal group to study speciation, as it comprises taxa representing distinct stages of the speciation process, ranging from widely interbreeding parapatric taxa through parapatric species with very limited gene flow in narrow hybrid zones to widely sympatric species. To understand the evolution of reproductive isolation through time, we have sequenced the genomes of all five species within this genus and two additional subspecies. We used both long-read and short-read methods to sequence and de-novo-assemble two high-quality genomes (Natrix h. helvetica, Natrix n. natrix) to their 1.7 Gb length with a contig N50 of 4.6 Mbp and 1.5 Mbp, respectively, and used these as references to assemble the remaining short-read-based genomes. Our phylogenomic analyses yielded a well-supported dated phylogeny and evidence for a surprisingly complex history of interspecific gene flow, including between widely sympatric species. Furthermore, evidence for gene flow was also found for currently allopatric species pairs. Genetic exchange among these well-defined, distinct, and several million-year-old reptile species emphasizes that speciation and maintenance of species distinctness can occur despite continued genetic exchange.

Department of Ecology Faculty of Science Charles University Viničná 7 12844 Praha 2 Czech Republic

IES Castilla Junta de Castilla Castilla y León 42003 Soria Spain

IRCCS San Raffaele Hospital Unit of Dermatology Via Olgettina 60 20132 Milan Italy

Molecular Ecology and Evolution at Bangor School of Natural Sciences Bangor University Environment Centre Wales Bangor LL57 2UW Wales UK

Senckenberg Biodiversity and Climate Research Centre Senckenberg Nature Research Society Senckenberganlage 25 60325 Frankfurt am Main Germany

Senckenberg Biodiversity and Climate Research Centre Senckenberganlage 25 60325 Frankfurt am Main Germany; Institute for Ecology Evolution and Diversity Goethe University Max von Laue Straße 9 60325 Frankfurt am Main Germany

Senckenberg Biodiversity and Climate Research Centre Senckenberganlage 25 60325 Frankfurt am Main Germany; Research Institute of Wildlife Ecology University of Veterinary Medicine Vienna Savoyenstraße 1 1160 Vienna Austria

Senckenberg Dresden Museum of Zoology A B Meyer Building 01109 Dresden Germany

Citace poskytuje Crossref.org

Widespread Adaptive Introgression of Major Histocompatibility Complex Genes across Vertebrate Hybrid Zones

Protecting isolated reptile populations outside their main area of distribution: a predictive model of the Dice snake, Natrixtessellata, distribution in the Czech Republic