Adaptation to selfing in the genus Capsella: Inferring the evolutionary history and adaptive value of selfing-syndrome alleles
Project code: SI 1967/1-1
A common event in the evolution of flowering plants is the transition from outbreeding to selfing. In many cases, this transition has been followed by convergent evolution of floral morphology towards a dramatically reduced flower size and less opened structure. Several adaptive hypotheses have been formulated to explain the emergence of this so-called selfing syndrome. They have however been difficult to test rigorously up to now due to the lack of identified casual underlying genes. Also, the extent to which recurrent mutations in orthologous loci have contributed to the frequent independent emergence of the selfing syndrome is currently unknown. The genus Capsella has recently emerged as a model to study the evolution of the selfing syndrome. The transition to selfing has occurred independently twice in this genus, and in both cases this has been followed by a strong reduction of flower size. Using a quantitative-genetics approach, we have identified a gene underlying the reduction of petal size in the selfing species C. rubella relative to the closely related outbreeding species C. grandiflora. This project will pursue two major objectives: (1) to investigate the effects of the small-petal allele on fitness and (2) to assess whether the independent emergence of the selfing syndrome in C. orientalis involved mutations to the same loci identified in C. rubella. As a result, the proposed project will help to understand why selfing-syndrome alleles become fixed in selfing species, and will define the genetic basis underlying the convergent evolution of floral morphology after the transition to selfing
Photograph of C. grandiflora, C. rubella and C. orientalis flowers (from left to the right). The flowers are shown at the same magnification.
Publications related to the project
- Sicard A, Stacey N, Hermann K, Dessoly J, Neuffer B, Bäurle I, Lenhard M. (2011). Genetics, evolution, and adaptive significance of the selfing syndrome in the genus Capsella. Plant Cell 23(9):3156-71.
- Sicard A, Lenhard M. (2011). The selfing syndrome: a model for studying the genetic and evolutionary basis of morphological adaptation in plants. Ann Bot. 107(9):1433-43.
