ID: 613 / 192

Category: Symposia

Track: Pending


Abstract: Flowers usually exhibit continuous variation in sexual organ position. But some species have discrete patterns of sex-organ variation. Since Darwin’s (1877) classic book on heterostyly, floral biologists have struggled to understand the evolution and functional significance of stylar polymorphisms. There are six classes of stylar polymorphisms: the heterostylous conditions distyly and tristyly, stigma-height dimorphism, enantiostyly, flexistyly and inversostyly. Of these the most well-known is heterostyly in which stigma and anther heights are reciprocally positioned in either two or three floral morphs. The remaining polymorphisms differ in the particular locations of styles and anthers but all have been interpreted as floral designs that through the geometry of flower-pollinator contacts increase the precision of cross-pollination and reduce lost mating opportunities. Since the monograph “Evolution and Function of Heterostyly” (Barrett 1992), novel findings on the ecology, evolution and molecular genetics of stylar polymorphisms have increased rapidly. Our symposium will review experimental work on the function and adaptive significance of polymorphisms, provide new information on the less well-known stylar polymorphisms, provide evidence on how changes in the pollination environment destabilize polymorphisms leading to alternative mating strategies, and showcase recent molecular genetic analyses aimed at determining the genetic architecture and genes governing stylar polymorphism. A hallmark of these studies is that they integrate information from a variety of fields including ecology, comparative biology and genomics, often within a theoretical framework. Our symposium will demonstrate how these integrated studies using a diversity of taxa, methods and approaches can provide novel insights into how and why stylar polymorphisms have evolved. Our goal in this symposium is therefore to provide both a foundation and future road map for a more comprehensive understanding of the ecology and evolution of floral polymorphisms that will be of interest to all plant biologists.

Speaker 1: Spencer C.H. Barrett Department of Ecology and Evolutionary Biology. University of Toronto (Canada). "What we know and don’t know about the biology of stylar polymorphisms."

Speaker 2: Elena Conti Department of Systematic and Evolutionary Botany, Herbarium, and Botanic Gardens University of Zurich, Switzerland “Convergence or deep homology? Comparative genomics elucidates the origins of the heterostyly supergene”

Speaker 3: Paulo Eugênio Oliveira Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais (Brazil) "Breakdown of distyly in tropical Rubiaceae: breeding system and morphometric changes."

Topics (Up to three): Reproductive Biology

Topic 2: Phylogenetics and Phylogenomics

Topic 3: Functional Genetics

Justification: Determining the mechanisms governing plant sexual diversification is a central problem in evolutionary biology. Stylar polymorphisms provide outstanding model systems for linking form to function and for understanding how the pollination process governs mating. The broad scope of our symposium will attract a wide range of participants including ecologists, comparative biologists and those interested in the molecular basis of floral variation. It will raise new questions on floral polymorphisms and expand our knowledge of the ecology and evolution of plant reproductive systems. Our symposium will also provide a future research agenda for studies on Darwin’s “most complex marriage arrangement”