Genetic basis of phenotypic evolution
My group exploits the extensive experimental tools developed in C. hirsuta to ask how variation in the organisation of gene networks between C. hirsuta and A. thaliana drives the evolution of fruit and floral structures. Our reasons for focusing on these morphologies are four-fold: first, these are rapidly evolving traits that can be compared between related but reproductively isolated species; second, the direction of evolutionary change in these morphologies is known, third, these traits likely have adaptive value for mating and seed dispersal strategies, and finally, understanding these processes has potential translational value for Brassica crop improvement.
Explosive seed dispersal
Genetics and mechanics of development
C. hirsuta uses an explosive mechanism to disperse its seeds. Taking a combined biological and modeling approach, we showed that this trait evolved through morphomechanical innovations at different spatial scales. At the organ scale, tension within the fruit wall generates the elastic energy required for explosion. At the tissue scale, this tension is produced by differential contraction of exocarp and endocarp b tissues of the fruit wall. Explosive release of this tension is controlled at the cellular scale by asymmetric lignin deposition within endocarp b cells – a striking pattern that is strictly associated with explosive pod shatter across the Brassicaceae plant family. We bridged these different scales through modeling, to present an integrated mechanism for explosive seed dispersal. We aim to understand the genetic basis of this trait and how it evolved.
Petal number robustness
Inter- and intraspecific variation
Petal number is robust in A. thaliana but variable in C. hirsuta. We find petal number variation not only between these two species but also within C. hirsuta. We capitalize on this inter- and intraspecific variation to address fundamental questions about evolutionary change:
- Are single gene changes sufficient to explain species-specific form?
- What are the precise genetic changes?
- How are genetic changes translated into phenotypic differences?
- Do inter- and intraspecific variation have the same genetic basis?