Research

My work aims to understand the evolution of floral diversity, particularly in the African violet family Gesneriaceae. Understanding the genetic mechanisms that produce diversity is one of the central goals of evolutionary biology. Flowers, with their vast array of shapes and colors, represent one of the most amazing and visible products of evolution. Floral biology can be studied through both an adaptive perspective, particulary as a function of reproductive biology and pollination, or a genetic perspective, particularly molecular analyses of developmental and biochemical pathways. I aim to understand the diversification of floral form using comparative genomics, phylogenetics, and developmental genetics.

Comparative genomics in Achimenes

Using comparative genomics in a phylogenetic and developmental context allows us to begin understanding how the molecular mechanisms underlying floral diversification. Achimenes is a small genus of 26 species native to Mexico that contains huge variation in floral form and pollination syndrome. We have already sequenced, assembled, and annotated floral transcriptomes for 4 species of Achimenes (A. cettoana, A. erecta, A. misera, and A. patens) across 3 developmental timepoints (Roberts and Roalson 2017, accepted). These provide valuable resources to perform inter- and intraspecies comparisons of gene sequence orthology, gene expression, and molecular evolution. Our sampling will soon be expanded to include an additional 6 species of Achimenes as well as 2 outgroup species. This will allow to test hypotheses related to the evolution of gene expression across species that share similar pollinators.

Comparative Phylogenetics

Gesneriaceae represent a large lineage (~3500 species) with an enormous amount of diversity, particularly in floral form. Constructing the largest dated phylogeny for gesneriads (nearly a quarter of species) and inferring divergence times has allowed us to test hypotheses related to the affect of geography, floral traits, epiphytism, and growth form on diversification (Roalson and Roberts 2016). Broad-scale patterns of macroevolution can provide evidence for distinct patterns of evolution in different lineages.

Developmental genetics

In order to test the functional role of genes in planta, it is useful to have an efficient regeneration and transformation system. We have developed an successful micropropagation and Agrobacterium-mediated transformation for Achimenes erecta (Roberts et al., in prep). The ability to efficiently transform plant species with high successful will be useful to develop Achimenes into a model for evolutionary-developmental studies.