Abstract: The last two centuries have seen remarkable rates of environmental change, as is evidenced by the conversion of our landscape to agriculture. Native plants that predate this transition and persist in the face of extreme human-mediated disturbance present a remarkable opportunity to learn about the evolutionary consequences of contemporary land-use regimes. Integrating landscape and herbarium genomics with population genetic inference, my lab looks to dissect the mode and tempo of contemporary evolution using a pervasive agricultural weed, common waterhemp (Amaranthus tuberculatus). To examine these concepts, I will discuss work that pinpoints alleles with antagonistic effects across contemporary natural and agricultural environments, and directly tracks their rate of change through time in sequenced herbarium samples dating back to 1830. This time series also reveals concurrent shifts in population structure—highlighting a strong link between demographic and selective processes. I will then turn to a case study on herbicide resistance evolution to demonstrate how spatial processes, from multiple independent local origins to migration, contribute to this rate of evolution. Together, this work demonstrates how the intensification of agriculture and reliance on herbicides have had extensive evolutionary impacts on both genome-wide diversity and variation for fitness in this native plant, facilitating its success as a 21st-century agricultural weed.
For more information or to request a meeting with Professor Kreiner contact: Patrick Tranel, tranel@illinois.edu