Paysonia
Evolution and Genetics of Fruit Diversity in Paysonia (Brassicaceae)
Above: P. stonensis, P. lescurii, and P. stonensis X lescurii
Below: Fruit of P. stonensis and P. lescurii
I am interested in the evolution and diversification of fruit morphology in the Brassicaceae, and in using genomic, developmental and phylogenetic techniques to address this question. Fruit morphology has long been the most distinctive and widely used character to distinguish groups within this important family, yet is now proving to be highly homoplastic when mapped onto molecular phylogenies. There are a number of genes which have been shown to affect fruit morphology, but their relevance to the evolution of fruit diversity in the family is not known. I am focusing on a small monophyletic group of species that show significant differences in fruit morphology within the genus Paysonia (formerly Lesquerella). These differences relate both to the degree and orientation of flattening of the silique with respect to the false septum, as well as to differing patterns and types of trichomes. The evolutionary relationships of the species have been previously investigated, cross-ability and chromosome number has been examined, greenhouse collections of the species have been established, and F2 and backcross populations have been produced. The genus is phylogenetically close to Arabidopsis, which will allow the use of the completed Arabidopsis genome sequence and other molecular tools. The species have been reproductively isolated for approximately one million years, but now are coming into contact through man-made disturbance, resulting in large hybrid swarms. Thus there are opportunities both to dissect the genes responsible for the evolution of fruit morphology as well as the population dynamics of the species and their hybrids.