The farther, the closer: geographic proximity and niche overlap versus genetic divergence in Caucasian rock lizards.

This article investigates how evolutionary divergence time influences the geographic distribution, niche overlap, and spatial contact among 11 sexually reproducing species of Caucasian rock lizards (genus Darevskia) from the Caucasus Mountains. Using extensive field data and habitat modeling, the study finds that closely related species with recent divergence tend to have more spatially separated ranges and less niche overlap, often segregated by altitude, while more distantly related species exhibit greater range overlap and coexistence in the same habitats. The authors suggest that as divergence time increases, spatial isolation decreases, likely compensated by behavioral or phenotypic reproductive isolation mechanisms that reduce deleterious interspecific interactions such as hybridization. These findings support classical models of allopatric speciation followed by secondary contact and highlight the complex interplay between evolutionary history, ecological niches, and species coexistence in a speciose lizard group.