Genomics of adaptation over space and time

Medicago truncatula, or barrel medick, a close relative of the alfalfa sprouts you’ve seen in salad bars, is a model for research on the legume-rhizobium mutualism nitrogen fixation mutualism. It is native to the Mediterranean, which includes regions that have seen substantial increases in average annual temperature due to climate change over the few decades. This makes barrel medick a uniquely useful species in which to study the genome-wide effects of evolution by natural selection, or adaptation, due to coevolution with rhizobia and changing climate.

Barrel medick grows quickly and can tolerate cramped quarters in big greenhouse experiments, and its genome is relatively small and structurally simple, so it can be sequenced for relatively little expense. Excellent genomic resources for barrel medick have allowed identification of genes that important for the symbiosis, and some of these genes show signs of local adaptation to different populations of rhizobia. Other studies have identified genes adapted to different climates across the species’ native range. This is a starting point to study the role these genes — which have adapted to different environments in space — will play in the adaptation of populations over time, as they coevolve with rhizobia and cope with changing climate.

Interested students can help with many aspects of this work, and potentially develop independent projects within the broader research program, in the context of

- raising barrel medick in the greenhouse to maintain seed stocks and conduct experiments
- extracting DNA and preparing libraries for genomic sequencing
- bioinformatic processing and population genomic analysis with genomic data