Eco-evolutionary drivers of species distributions: Seed dispersal evolution
Dispersal is a key process influencing species persistence and geographic range limits. Most species’ distribution models assume that organisms of the same species have identical dispersal rates, but some models suggest that variation in dispersal across a species’ range may have significant consequences for the evolution of range limits. Patterns of variation in dispersal throughout a species’ range, the environmental drivers of that variation, and the influence dispersal variation has on the size and extent of species’ geographic distributions has been largely unexplored. Understanding the processes driving species’ distribution patterns is critical for conservation, as scientists strive to anticipate how organisms will respond to climate change, habitat loss, and land use change.
My PhD research investigated dispersal trait variation in a Great Lakes beach plant, American sea rocket (Cakile edentula var. lacustris, Brassicaceae), and the potential onsequences of that variation for range shifting of the species under projected climate change scenarios. Cakile edentula is an early colonist of the beach habitat along the Great Lakes, a highly dynamic habitat because of frequent disturbance by strong wind, waves, and shifting substrate. In order to persist on the dynamic beach habitat, C. edentula has a dimorphic fruit with two seed types adapted for dispersal via wind and water vectors. I am testing the hypothesis that environmental gradients in habitat quality and quantity across the Great Lakes range of C. edentula have caused different patterns of selection on dispersal traits at different positions within the species’ range, which in turn will play a role in the tracking of future climate.