Meeting Abstract

S9-1.2  Saturday, Jan. 7  Phenotypic plasticity and the evolutionary diversification of plant sexual systems. DIGGLE, PK; University of Colorado/Harvard University diggle@fas.harvard.edu

Andromonoecy, a sexual system in which individuals bear both hermaphroditic (bisexual) and male flowers, has evolved independently in numerous plant lineages, yet the advantages of this system remain poorly understood. I will report on a comparative ontogenetic study of multiple andromonoecious species within the genus Solanum. Experimental analyses of several species suggest that male flower production varies with resource availability, that is, male flower production is phenotypically plastic. Production of male flowers, however, is a fixed feature of the phenotype in a small number of species within each of two clades. Comparison of ontogenies within a phylogenetic framework suggests that plasticity is plesiomorphic, and that the environmentally induced production of male flowers has become fixed during the evolution of the non-plastic species.