Low genetic diversity and future challenges for the Caspian bent-toed gecko (Tenuidactylus caspius) in a changing climate

Abstract

Climate change significantly impacts species distributions and adaptability. This study investigates the evolutionary history, genetic variation, and potential distribution shifts of the Caspian bent-toed gecko (Tenuidactylus caspius) in Iran under past, present, and future climate conditions. Phylogenetic analysis revealed two distinct subclades within T. caspius, which diverged approximately 1.14 million years ago. Despite this divergence, distinct subclades were not observed in terms of notable differentiation, as the species showed low genetic diversity, with only nine haplotypes and limited nucleotide variation. Population size remained relatively constant over time, with a slight recent decline. Biogeographic analysis indicated a complex history of dispersal and vicariance events. Species distribution modeling suggests a historically wider range, with a northward expansion during the Last Glacial Maximum. The current range is reduced, and future projections (2061–2080) indicate a further decline, especially in marginal areas, with the eastern range becoming the core habitat. The low genetic diversity raises concerns about the species' adaptability to climate change. Conservation efforts should focus on protecting existing populations, particularly in the eastern range, and maintaining habitat connectivity to support gene flow. This study highlights the importance of integrating genetic and historical data for effective conservation planning in the context of climate change.