Rates of Range Expansion in Eastern Trees Based on Molecular and Fossil Records

Duke University, Durham NC

Investigators

Abstract

Anticipated rapid climatic change over the next decades to centuries raises the concern that plant populations will be unable to migrate fast enough to track changing environmental conditions. Migration rates depend on dispersal of seed and on barriers to population spread, such as mountain ranges, large water bodies, and patterns of urban and agricultural land use. Range expansions at the end of the last ice age provide evidence that populations tracked global change in the past, but current evidence does not indicate the speed of these migrations. The proposed research will determine the pathways of past population spread and provide insights into rates of corresponding migrations. We will construct and analyze maps of chloroplast DNA variation across the ranges of common eastern North American tree species. Such maps reveal the "genetic fingerprint " of late-glacial refugia and post-glacial migration routes, and complement existing data for fossil pollen. The maps of post-glacial migration we will provide a framework for analysis of population expansion. Results will be used to test hypotheses concerning how growth of trees and dispersal of seeds affect the potential of plants to track rapid environmental change.