Abstract: The amazing diversity of flowers and their relationships with pollinators have been proposed as major explanations for the considerably greater number of species in angiosperms versus gymnosperms. A specialized type of floral morphology that has fascinated botanists ever since Darwin’s seminal studies in Primula is heterostyly. Heterostyly is a floral heteromorphism consisting in the reciprocal arrangement of sexual organs in different individuals of the same species. It is often linked with a form of heteromorphic self-incompatibility that prevents pollen germination on the stigma of the same flower or floral morph. It occurs in 28 families of flowering plants and is thought to promote outcrossing via disassortative pollination between compatible floral morphs. Despite having been the subject of intensive research for over 150 years, multiple aspects of the function, evolution, and loss of heterostyly remain obscure. Recently, the advent of new experimental and analytical methods has greatly advanced our knowledge of heterostyly. I will review our cross-disciplinary studies of heterostyly at different hierarchical scales in Primulaceae, the prime model for this floral heteromorphism. The main questions addressed in my talk include: How does heterostyly work? Does variation in sexual organ reciprocity contribute to reproductive isolation? Does heterostyly spur diversification at macroevolutionary scales? What are the evolutionary implications of the loss of heterostyly? What are the genetic and molecular bases of heterostyly? I will conclude with an overview of comparative genomic analyses in our lab aimed at elucidating the assembly and breakdown of the heterostyly supergene in Primulaceae and a summary of current challenges and prospects in the study of this fascinating floral heteromorphism.
Read more about Elena Contis research (University of Zurich).