XVI International Botanical Congess

The evolution of interspecies differences in morphology requires sufficient within-species variation in developmental regulatory systems for evolutionary forces to act upon. Genetic analyses indicates that variation in inflorescence architecture between different Arabidospis thaliana ecotypes is genetically-determined, and mapping analyses permit us to identify genomic regions that may harbor inflorescence quantitative trait loci. Molecular analyses of naturally-occuring alleles of floral developmental loci in Arabidopsis also reveal considerable intraspecific nucleotide diversity at floral homeotic genes. Some of these naturally-occuring molecular variation, such as in the meristem identity CAULIFLOWER gene, appear to be associated with functionally different alleles. Molecular studies at the population level may provide clues to the evolution of floral and inflorescence morphologies.