NSF Postdoctoral Fellowship in Biology FY 2021: Investigating the Genetic Basis of Local Adaptation in Yellow Starthistle (Centaurea solstitialis)

This action funds an NSF Plant Genome Postdoctoral Research Fellowship in Biology for FY 2021. The fellowship supports a research and training plan in a host laboratory for the Fellow who also presents a plan to broaden participation in biology. The title of the research and training plan for this fellowship to Dr.

Bryan Reatini is "Investigating the genetic basis of local adaptation in yellow starthistle (Centaurea solstitialis)". The host institution for the fellowship is the University of Arizona and the sponsoring scientist is Dr. Katrina Dlugosch.

Yellow starthistle is a major agricultural pest and is among the most ecologically and economically damaging invasive plant species in the western United States. Consequently, there is considerable interest in understanding what allows yellow starthistle – and other agricultural pests like it – to spread so aggressively. Previous research has shown that yellow starthistle has evolved to become better suited to the local environmental conditions of California, which likely contributed to its rapid spread.

Yet the specific genes that have played a role in this process, and the source of the genetic variation involved, remain unknown. This project will determine the source and type of genetic variation that has contributed to the evolution of yellow starthistle to become better suited to the local environmental conditions of California. In doing so, this research will inform how evolution can contribute to the aggressive spread of agricultural pests such as yellow starthistle, and provide information that may be used to mitigate the future spread of agricultural pests.

Another objective of this project is to train university students with the tools and skillset required to generate maps that can be used to predict areas at risk of invasion by species like yellow starthistle. Throughout this training process, a collection of maps will be created and provided to the United States Department of Agriculture to help inform management decisions regarding the spread of invasive species.

Understanding how local adaptation is maintained despite gene flow remains an ongoing area of research in evolutionary biology. Range expansions offer exceptional opportunities to study local adaptation with gene flow in real time, but theoretical predictions have quickly outpaced empirical tests of those predictions. Yellow starthistle (Centaurea solstitialis) offers unique opportunities to close that knowledge gap, because adaptive trait evolution to local environmental conditions has occurred rapidly despite gene flow between nearby populations in its invaded range.

To determine how connections between genotype, phenotype and environment have been achieved under gene flow in this system, this project will determine: 1) the genetic basis of an important adaptive trait in this invasion – increased plant size – using associations between genetic variation and phenotypic variation; 2) associations between genetic variation and environmental variation for environmental conditions that appear to be driving the evolution of this adaptive trait; and 3) the source of genetic variation contributing to adaptive evolution, using computational methods in order to evaluate the potential contribution of admixture to adaptation. All data generated by this research will be made publicly available via the searchable public databases of the National Center for Biotechnology Information and Dryad.

Ultimately, this project will contribute to fundamental understanding of how the genetic architecture of local adaptation has contributed to range expansion, for one of the most problematic invasive species in the United States.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.