DISSERTATION RESEARCH: Genetic basis of parallel flower color shifts in Penstemon

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When a particular evolutionary change, such as a color, has evolved independently in related organisms, the change could be due to a mutation in the same stage of a developmental pathway in all the groups, or it could be due to different mutations. The PIs will examine this problem by using the wildflower genus Penstemon, which is made up of nearly 300 species, most of which have blue or purple flowers. However, bright red flowers are found in about 15-20 subgroups, and these changes evolved independently at least 10 times. The red flowers are probably an adaptation to attract hummingbirds as pollinators. The biochemical pathway that produces the types of flower pigments found in Penstemon is well-understood. The PIs intend to test whether these repeated or parallel episodes of adaptive evolution are due to similar genetic changes across subgroups of plants or different genetic changes in different subgroups. This study is one of a very few that addresses the genetic basis of parallel evolution, and whether certain types of genetic changes are more often observed to underlie adaptive evolution than others. Furthermore, it will address the broader question of whether the genetic basis of adaptive evolution is predictable or unpredictable.The PIs are integrating mentorship of local high school and Duke University undergraduate students into this project. This study system provides a clear and easily described example of parallel adaptive evolution; the PIs will work towards developing it as a potential textbook example for understanding the genetic basis of parallel evolution.