Abstract
PREMISE: Comparative surveys allow us to characterize the influence of specific factors on population genetic diversity and structure. We conducted a comparative phylogeographic study for three Mexican oak species to identify how their climatic niche preferences and breadth may have influenced historical demography and range shifts during Pleistocene climatic oscillations. METHODS: We estimated genetic diversity and structure for Quercus deserticola, Q. glaucoides, and Q. peduncularis. We inferred historical demographic changes using approximate Bayesian computation and used ecological niche models to determine present potential distribution of the species and used past climatic scenarios to estimate range and altitudinal shifts. We also measured the niche breadth of each species and evaluated niche similarity among species. RESULTS: We identified differences in population history, which we related to the climatic niche of individual species. For Q. deserticola, we inferred a historical bottleneck consistent with the interglacial refugia hypothesis. Quercus glaucoides, which is characterized by a narrow niche breadth, had high levels of genetic structure based on plastid DNA. Quercus peduncularis had high genetic diversity and low structure. We found correlations between niche breadth and values of genetic structure and diversity. Interglacial contraction and glacial expansion in the three species differed in magnitude, with Q. deserticola exhibiting the most drastic contraction during the interglacial. CONCLUSIONS: Mexican oak species responded differently to historical climatic changes since they have distinct distributions in geographic and climatic space. Levels and patterns of genetic variation agreed with the population history of each species inferred using niche modeling.