Journal Article

Analysis of population genetic structure and gene flow in an annual plant before and after a rapid evolutionary response to drought

Rachel S. Welt, Amy Litt and Steven J. Franks

in AoB PLANTS

Published on behalf of Annals of Botany Company

Volume 7, issue
Published online April 2015 | e-ISSN: 2041-2851 | DOI: https://dx.doi.org/10.1093/aobpla/plv026

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  • Biodiversity and Conservation Biology
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  • Plant Evolution
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The impact of environmental change on population structure is not well understood. This study aimed to examine the effect of a climate change event on gene flow over space and time in two populations of Brassica rapa that evolved more synchronous flowering times over 5 years of drought in southern California. Using plants grown from seeds collected before and after the drought, we estimated genetic parameters within and between populations and across generations. We expected that with greater temporal opportunity to cross-pollinate, due to reduced phenological isolation, these populations would exhibit an increase in gene flow following the drought. We found low but significant FST, but no change in FST or Nm across the drought, in contrast to predictions. Bayesian analysis of these data indicates minor differentiation between the two populations but no noticeable change in structure before and after the shift in flowering times. However, we found high and significant levels of FIS, indicating that inbreeding likely occurred in these populations despite self-incompatibility in B. rapa. In this system, we did not find an impact of climate change on gene flow or population structuring. The contribution of gene flow to adaptive evolution may vary by system, however, and is thus an important parameter to consider in further studies of natural responses to environmental change.

Keywords: Brassica rapa; climate change; drought; gene flow; phenological isolation; population structure; resurrection study

Journal Article.  6900 words.  Illustrated.

Subjects: Biodiversity and Conservation Biology ; Ecology and Conservation ; Plant Evolution ; Genetics and Genomics ; Plant Sciences and Forestry ; Biological Sciences

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