Quaternary Glaciation Accelerates Speciation in Aquatic Snakes Through Recent Bottlenecks

Area of Science:

• Evolutionary Biology
• Genomics
• Zoology

Background:

• Climatic fluctuations during glacial periods significantly influence species' demographic history and gene flow.
• Mountain stream snakes in Central China (Opisthotropis latouchii species complex) provide a model for studying these effects.

Purpose of the Study:

• Investigate biogeographic patterns, genetic divergence, and demographic history of the Opisthotropis latouchii species complex.
• Determine the impact of Quaternary climatic oscillations on this species complex.

Main Methods:

• High-throughput sequencing of 67 individuals.
• Comprehensive genomic analyses to assess genetic divergence and demographic trajectories.

Main Results:

• Identified four distinct genetic lineages within the Opisthotropis latouchii species complex, each associated with a major mountain range in Central China.
• Discovered one previously unrecognized species.
• Observed population bottlenecks during Quaternary glaciations, with initial isolation in southern glacial refugia followed by northward postglacial expansions.
• Detected divergence along latitudinal gradients and gene flow facilitated by mountain ranges acting as refugia and dispersal corridors.

Conclusions:

• Central China's mountain ranges served as crucial refugia during glacial periods, driving speciation.
• These ranges also acted as dispersal corridors during interglacial periods, promoting range expansion and gene flow.
• Quaternary climatic oscillations profoundly shaped the genetic structure, demographic history, and gene flow of these endemic snakes.