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Abstract

Explaining variation in life history strategies has been a central challenge of ecology and organismal biology for at least 250 years. To test classic theory of drought as a driver of adaptive plant life history strategies, we have been integrating diverse data and approaches including satellite imagery, herbarium specimens, whole genome sequencing, and transgenic experiments. In this seminar, I present recent research on the ecology and functional genomics of drought adaptive life history evolution. First, we tested classic life history theory by integrating satellite¤based drought detection with herbaria occurrence records to study life history evolution at phylogenetic scales. By comparing historical drought regimens, we observed that annuals occur in environments where droughts are significantly more frequent. We also found evidence that annual plants adapt to predictable drought regimens by escaping drought¤prone seasons as seeds. In addition to macroevolutionary patterns of life history evolution, we were also interested to understand drought as a driver of intraspecific variation. Thus, we developed novel approaches to study natural loss-of-function alleles associated with drought histories. The genes we identified exhibit population genetic signatures of adaptive evolution and shared associations with flowering time phenotypes in directions consistent with longstanding adaptive hypotheses seven times more often than expected by chance. We then confirmed predicted phenotypes experimentally in transgenic knockout lines. This research has yielded valuable insight into the evolution of life history strategies; validating long standing theoretical predictions about drought as important agent of selection and also providing surprising results about the functional genomics of this evolution.