Phylogeography of the Volcano Rabbit (Romerolagus diazi): the Evolutionary History of a Mountain Specialist Molded by the Climatic-Volcanism Interaction in the Central Mexican Highlands

Abstract

Processes such as climate fluctuations together with recent volcanism have driven the diversification and local persistence of biodiversity within the Mexican highlands. We reconstruct the phylogeographic pattern and historical demography of the volcano rabbit, Romerolagus diazi, an endemic lagomorph in central Mexico, to elucidate the effect of the climate-volcanism interaction on its evolutionary history. We sequenced two mtDNA regions for 152 individuals from 45 sample sites located at the volcanic fields Sierra Chichinautzin and Sierra Nevada. We surveyed the genetic diversity, and reconstructed and dated an intraspecific phylogeny. The effective population size trough time was estimated, and an Ecological Niche Model was projected onto the past. Results showed a well-supported phylogeny with five monophyletic lineages with a north to south geographic pattern at Sierra Nevada, and east to west at Sierra Chichinautzin. Dating estimates indicated that those lineages might have started their diversification ca. 1.4 Ma, which agrees with the geological dating reported for the volcanic fields rising. We detected changes in demographic history and potential distribution, with a global population expansion during the Last Glacial Maximum and a retraction during the Last Interglacial period. The molecular evidence showed that the volcano rabbit had a dynamic evolutionary history molded by geological and climatic events during the Pleistocene. The volcanic events that shaped Sierra Chichinautzin and Sierra Nevada generated regions that allowed the colonization, isolation and posterior in-situ diversification of their populations. Additionally, the climatic fluctuations of the latest glacial-interglacial cycles promoted altitudinal populations shifts, with a sky-island dynamic that allowed their persistence.