Polytomies, signal and noise: revisiting the mitochondrial phylogeny and phylogeography of the Eurasian blindsnake species complex (Typhlopidae, Squamata)

Polytomies are multifurcating nodes on a phylogenetic tree that represent unresolved relationships. Contrary to ‘hard’ polytomies that hide simultaneous splitting events, ‘soft’ polytomies can theoretically be resolved with the addition of phylogenetic signal. This is not always successful, especially when a radiation is old and rapid, because adding more signal will inevitably increase the noise. The Xerotyphlops vermicularis species complex is an example of a largely unresolved old and rapid radiation. This mt DNA phylogeny is revisited by analysing samples representative of all lineages and generating a 3700‐bp final data set, after preliminary tests found two of the analysed markers responsible for long‐branch attraction. The new enhanced data set increased phylogenetic resolution, resulting in a robust time‐calibrated phylogeny and phylogeographic conclusions. Jordan/south Syria populations separated during the Middle Miocene, and the Messinian salinity crisis ( MSC ) appears responsible for the second diversification wave. A third radiation occurred during the Early Pliocene, resulting in four mt DNA groups west, east and south of the Amanos mountains in east Turkey/north Syria. Finally, three hypotheses regarding the number of potential ‘species’ within the complex are made, with the most moderate ‘four species’ hypothesis fitting very well with the diversity patterns and established systematics of east Mediterranean reptiles.