Integrative methods reveal multiple drivers of diversification in rice paddy snakes

Area of Science:

• Systematics and evolutionary biology
• Herpetology
• Biogeography

Background:

• Divergence dating is crucial for testing biogeographic hypotheses.
• Genomic data challenges limit sample sizes for fine-scale biogeographic studies.
• The diversification of Southeast Asian rice paddy snakes (Homalopsidae: Hypsiscopus) lacks clear dating.

Purpose of the Study:

• To investigate the diversification of Hypsiscopus using coalescent demographic models.
• To test the hypothesis that Hypsiscopus diversification was triggered by the Khorat Plateau uplift ~2.5 million years ago.
• To analyze niche differentiation between Hypsiscopus species in past and present environments.

Main Methods:

• Coalescent demographic modeling was employed to estimate divergence times.
• Ecological niche modeling was used to assess niche overlap and differentiation.
• Phylogenetic analysis of Homalopsidae snakes.

Main Results:

• Hypsiscopus diversification is estimated at approximately 2.4 million years ago.
• The Khorat Plateau uplift is supported as a potential driver for Hypsiscopus diversification.
• Significant niche differentiation and shifts were observed between Hypsiscopus species.

Conclusions:

• The Khorat Plateau uplift likely initiated the diversification of rice paddy snakes.
• Environmental heterogeneity played a role in sustaining species differentiation post-uplift.
• Multilocus datasets remain valuable for biogeographic hypothesis testing alongside genomic data.