The goal of this project is to gain a better understanding of the role of gene arrangements on chromosomes in maintaining genetic diversity, which is fundamental to the process of evolution. Beyond adding to basic knowledge of evolution, these results have important implications for crop breeding, especially when crops occur in the presence of closely related non-crop species. The study will focus on monkeyflower, Mimulus guttatus, an herbaceous wildflower that is distributed predominantly in the Pacific Northwest. It occurs both as perennial and annual forms, which are distinct and locally adapted to their respective habitats. Through the use of genetic tools, the researchers will discover the bases of the differences between those forms and test hypotheses about how gene arrangements control evolution.
The researchers will use genetic tools to dissect a chromosomal inversion which varies between annual and perennial ecotypes of Mimulus guttatus. This inversion is strongly associated with life history expression, and has been shown to influence performance in nature significantly. Previous QTLs mapping has found that a large proportion of the genetic variance associated with life history maps to a large pericentric chromosomal inversion that separates the two ecotypes. However, since recombination is suppressed between inverted and collinear portions of a chromosome when found in a heterozygote, mapping within the inversion is impossible in this species pair. Using classical QTLs mapping, as well as NIL lines, the researchers will: (1) create a genome-wide map of life history divergence under multiple conditions, (2) test how the inversion contributes to life history divergence in the field, and (3) examine how selection acts on alleles within the inversion. The researchers will test whether the inversion has captured standing genetic variation for life history traits, and thus has potentially swept to fixation by indirect selection due to its recombination suppression properties. This work will help elucidate the mechanism by which inversions contribute to local adaptation, and ultimately, how inversions can maintain genetic diversity despite maladaptive gene flow.
