Oskar Heinroth

Influenced by rapid changes in climate and landscape features since the Miocene, widely distributed species provide suitable models to study the environmental impact on their evolution and current genetic diversity. The dice snake Natrix tessellata, widely distributed in the western Palearctic is one such species. We aimed to resolve a detailed phylogeography of N. tessellata with a focus on the Central Asian clade with four and Anatolia clade with three mitochondrial lineages, trace their origin, and correlate the environmental changes that affected their distribution through time. The expected time of divergence of both clades began at 3.7 Mya in the Pliocene, reaching lineage differentiation approximately one million years later. The genetic diversity in both clades is rich, suggesting different ancestral areas, glacial refugia, demographic changes, and colonization routes. The Caspian lineage is the most widespread lineage in Central Asia, distributed around the Caspian Sea and reaching the foothills of the Hindu Kush mountains in Afghanistan, and eastern European lowlands in the west. Its distribution is limited by deserts, mountains, and cold steppe environments. Similarly, Kazakhstan and Uzbekistan lineages followed the Amu Darya and the Syr Darya river systems in Central Asia, with ranges delimited by the large Kyzylkum and Karakum deserts. On the western side, there are several lineages within the Anatolia clade that converged in the central part of the peninsula with two being endemic to western Asia. The distribution of both main clades was affected by expansion from their Pleistocene glacial refugia around the Caspian Sea and in the valleys of Central Asia and by environmental changes, mostly through aridification.

Aim: Estimating the strength of niche conservatism is key for predictions of invasion risk. Most studies consider only the climatic niche, but other factors, such as human disturbance, also shape niches. Whether occupation of human habitats in the alien range depends on the native tolerances of spec…