Event Dates: November 12, 2013 - 4:00pm - 5:00pm
My group is addressing fundamental questions in evolutionary biology: (i) How, and how frequently, do new genetic variants arise? (ii) Why do some variants increase in frequency? (iii) And why are some combinations of new variants incompatible with each other?
In collaboration with several other labs, we are describing whole-genome variation in natural accessions of Arabidopsis thaliana, under the auspices of the 1001 Genomes project (http://1001genomes.org). To better understand the patterns we observe in A. thaliana, we are comparing within-species variation with differences to the closest relatives, A. lyrata, and to variation in a closely related genus, Capsella. On the other end of the spectrum, we are analyzing new mutations that have arisen spontaneously under laboratory conditions or in a natural mutation accumulation experiment. The latter studies take advantage of an A. thaliana lineage that was apparently introduced to North America in historic times and accounts for about half of the population here. We have been able to support what we see in the extant North American population by whole-genome sequencing of herbarium samples from the 19th century. Since there has been much recent excitement about the potential contribution of heritable epigenetic variation, we are complementing our studies of genetic variation with analyses of DNA methylation differences, again over different time scales: in isogenic laboratory lines, in isogenic natural lines and across species boundaries.
The motivation for our top-down studies is to understand how new genetic and epigenetic variation interacts with reassortment of variants after crosses and natural selection to shape geographic patterns of genetic and epigenetic diversity. To this end, our population genomic work is complemented by forward genetic analyses, especially of detrimental combinations of sequence variants found in separate lineages. The ultimate goal is to understand at the molecular and biochemical level how changes in DNA sequence increase or decrease the fitness of organisms through their effects on protein levels and activity.
Additional information about our work can be found on our website, http://weigelworld.org.