The genetic architecture and evolution of life history divergence among perennials in the Mimulus guttatus species complex

Abstract

AbstractEcological divergence is a main source of trait divergence between closely related species. Despite its importance in generating phenotypic diversity, the genetic architecture of most ecologically relevant traits is poorly understood. Differences in elevation can impose substantial selection for phenotypic divergence of both complex, correlated suites of traits (such as life history), as well as novel adaptations. Here, we use the Mimulus guttatus species complex to assess if divergence in elevation is accompanied by trait divergence in a group of closely related perennial species, and determine the genetic architecture of this divergence. We find that divergence in elevation is associated with differences in multivariate quantitative life history traits, as well as a unique trait; the production of rhizomes, which may play an important role in overwintering survival. However, the extent of phenotypic divergence among species depended on ontogeny, suggesting that species also diverged in investment strategies across development. Lastly, we show that the genetic architecture of life history divergence between two species is simple, involving few mid to large effect Quantitative Trait Loci (QTLs), and that the genetic architecture of the ability to produce rhizomes changes through development, which has potential implications for hybrid fitness in the wild.