The Whitlock lab
  Geographic histories of western mountain meadows
         
 

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Wet meadows in the mountains of California and Nevada form islands of habitat created by specific conditions in elevation, temperature, and hydrology. These meadows may be particularly vulnerable to climate change. However, fossil evidence suggests that the distribution of plants in the west has shifted in the past. Understanding the history of migration of wet mountain meadows may help us to predict and manage their fate as climate changes in the future. In this project, we are comparing the biogeography of seven co-distributed species of wildflowers in the gentian family to inform our understanding of the history of montane-alpine wet meadow communities. We are conducting fieldwork in 25 biogeographically significant meadows in western North America to sample individuals from seven targeted species and are using DNA sequences from three chloroplast regions to infer relationships among individuals and populations of each species. The resulting evolutionary trees are compared to identify common patterns of historical relationships among the meadows. Specific hypotheses include: (1) Populations within species exhibit geographic structuring of genetic diversity. (2) Different species with overlapping ranges show similar geographic structuring of their population. (3a) Major lineages within species correspond to river drainage systems, or alternatively (3b) are linked along geographically contiguous areas of high elevation. So far, we have retrieved substantial geographic structure for populations of each of the seven targeted species. Additional sampling is allowing us to test for common patterns across species that may illuminate the geographic history of the community as a whole.

This project has been funded by the National Geographic Society Committee for Research and Exploration.

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