On the Way to Speciation: Shedding Light on the Karstic Phylogeography of the Microendemic Cave Beetle Aphaenops cerberus in the Pyrenees.

The highly modified morphology and ecological features of cave-dwelling organisms are a strong obstacle to dispersion. Hence, they represent ideal models for the study of historical biogeography at both large and fine timescales. Here, we study the phylogeography of Aphaenops cerberus, an endemic hypogean ground beetle with a fragmented distribution in the French Northern Pyrenees. We extracted 75 exemplars of 17 populations of A. cerberus and sequenced one mitochondrial and one nuclear marker to assess the geographic structuration as well as the recent biogeographic history of this species. We used Bayesian Inference and Maximum Likelihood to reconstruct the relationships among most of the extant populations of this species across its distributional range. We inferred divergence time estimates using carabid substitution rates and reconstructed haplotype networks to investigate the recent biogeographic history of this lineage. We recover a strong geographic structuration of the populations across the mountain range. The strong impact of geology on the structure of the populations is evidenced although geological continuity does not systematically lead to continual gene flow. The origin of the species is dated from the Early Pleistocene and the dispersal predates the main Last Glacial Maximum. Our results indicate broad similitudes between islands and karsts, which make cave organisms an excellent model for the study of evolution mechanisms. © The American Genetic Association. 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.