Reevaluation of a classic phylogeographic barrier: new techniques reveal the influence of microgeographic climate variation on population divergence
Article first published online: 25 APR 2013
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Ecology and Evolution
Volume 3, Issue 6, pages 1603–1613, June 2013
How to Cite
Ecology and Evolution 2013; 3(6): 1603–1613
- Issue published online: 12 JUN 2013
- Article first published online: 25 APR 2013
- Manuscript Accepted: 27 MAR 2013
- Manuscript Revised: 16 MAR 2013
- Manuscript Received: 13 DEC 2012
- University of Florida
- Howard Hughes Medical Institute Science
- Apalachicola river;
- geographic barrier;
- Geomys pinetis ;
We evaluated the mtDNA divergence and relationships within Geomys pinetis to assess the status of formerly recognized Geomys taxa. Additionally, we integrated new hypothesis-based tests in ecological niche models (ENM) to provide greater insight into causes for divergence and potential barriers to gene flow in Southeastern United States (Alabama, Florida, and Georgia). Our DNA sequence dataset confirmed and strongly supported two distinct lineages within G. pinetis occurring east and west of the ARD. Divergence date estimates showed that eastern and western lineages diverged about 1.37 Ma (1.9 Ma–830 ka). Predicted distributions from ENMs were consistent with molecular data and defined each population east and west of the ARD with little overlap. Niche identity and background similarity tests were statistically significant suggesting that ENMs from eastern and western lineages are not identical or more similar than expected based on random localities drawn from the environmental background. ENMs also support the hypothesis that the ARD represents a ribbon of unsuitable climate between more suitable areas where these populations are distributed. The estimated age of divergence between eastern and western lineages of G. pinetis suggests that the divergence was driven by climatic conditions during Pleistocene glacial–interglacial cycles. The ARD at the contact zone of eastern and western lineages of G. pinetis forms a significant barrier promoting microgeographic isolation that helps maintain ecological and genetic divergence.