Meeting Abstract
Parallel evolution, or the independent evolution of similar phenotypes in organisms occupying similar environments, is strong evidence of adaptation. Whether convergent phenotypes are controlled by the same genetic loci and mutations, and therefore whether evolution is predictable at the molecular level, is a central question in evolutionary biology. To address this question we examine the genetic and adaptive significance of parallel leaf shape evolution across and within species in the Mimulus guttatus species complex. Lobed and narrow leaves have evolved from the entire, round leaves of M. guttatus in M. laciniatus, M. nudatus, and a polymorphic serpentine M. guttatus population. In addition to having divergent leaf shapes, all three of these taxa occur in harsh rocky habitats. We used (1) population genetics to detect local adaptation in leaf shape across altitudinal clines of M. laciniatus, (2) phenotypic selection analysis to test whether lobed leaf shape is adaptive in M. laciniatus’ granite habitat, and (3) quantitative trait locus (QTL) mapping and genome wide association to examine whether leaf shape evolution has a parallel genetic basis across three rocky outcrop Mimulus taxa. We found that (1) leaf lobing appears to be adaptive at high elevations across multiple altitudinal clines in M. laciniatus, (2) leaf shape is adaptive in rocky outcrops, and (3) leaf shape is controlled by overlapping genetic regions in all three Mimulus species. This overlap in QTL’s and harsh rocky habitats suggests that parallel genetic evolution is responsible for adaptive leaf shape evolution across Mimulus.
