I’m excited by recent advances in our ability to see clear signatures of selection in natural populations in response to intense selective pressures. Examples we are currently working on include adaptation to whole genome duplication and extreme edaphic conditions, such as lead, zinc, and serpentine soil tolerance.
We are particularly interested in the repeatability of evolution in response to intense selection. We are therefore concentrating on focused genome scans for selective sweeps in many independently genome-duplicated and also in stress tolerant lineages. For example, we are working on multiple independently derived auto- and allopolyploid Mimulus populations to test for within-species repeated evolution, as well as for between-species repeated evolution by looking in distantly related species, such as Chamerion (Fireweed). We are also broadly scanning separate cases of serpentine and lead-tolerant populations in the Brassicaceae. Thus far, we have seen striking cases of repeated evolution in response to serpentine challenge.
Results from these scans are providing some clear parallels to studies in other species, such as Arabidopsis Arenosa, but also rather surprising differences, providing fruitful inroads for detailed functional analyses of the consequences of genome evolution. Our overall goal is to understand how the cell adapts to the sudden internal upheaval by investigating many independently-evolved natural solutions. Initial results have surprised us by indicating that even conserved meiotic processes are capable of nimble evolutionary shifts when required.