Gene Flow and Isolation in the Arid Nearctic Revealed by Genomic Analyses of Desert Spiny Lizards.

This article focuses on the genetic diversification and biogeographic structuring of the Desert Spiny Lizards (Sceloporus magister complex) across arid western North America, examining the roles of geographic barriers, gene flow, and environmental factors. Using genomic-scale data, mitochondrial sequences, and climatic information, the study finds that the Western Continental Divide (WCD) acts as a strong barrier to gene flow, while the Colorado River is a more permeable barrier, allowing some admixture between populations. The hypothesized Mid-Peninsular Seaway in Baja California shows ambiguous effects, with climate rather than a physical barrier better explaining genetic differentiation in Baja populations. The research highlights that both physical barriers and isolation by environment contribute to lineage divergence, and some populations within the complex may represent distinct species warranting taxonomic revision.