Adaptation and ecological tradeoffs in invasive species

Invasive species are defined by their ability to establish populations in new locations, yet novel environments will often pose unique challenges in terms of the nature and/or strength of selection on colonizers.  Our work draws on the natural experiments provided by human-mediated species introductions to understand how the genetic variation in these populations translates into phenotypic diversity, adaptation, and changes in ecology.  We are using comparative and population genomic techniques to gain insight into the traits that facilitate the establishment and local adaptation of plant invaders, with particular attention to the evolution of responses to environmental stresses.  To do this, we are employing common garden, gene expression, genomic sequencing, and genetic mapping approaches across a variety of species. Results to date indicate that changes in resource allocation and stress response have been a significant feature of evolution in weedy and invasive populations, and that elucidating the genomic basis of these changes is likely to be informative for our larger understanding of ecological and evolutionary trade-offs in plants.  In particular, I will present recent results from efforts to understand the evolution of increased size in invading populations of the noxious weed yellow starthistle, Centaurea solstitialis (Asteraceae; Compositae).