XVI International Botanical Congess
Achene dimorphism is a strategy in which ray and disc florets produce ecologically distinct achenes. Locally dispersed ray achenes maintain populations, and distantly dispersed disc achenes establish populations. Via dimorphism, ray and disc achenes offset spatial risks of distant dispersal and temporal risks of local dispersal. Genetic diversity and structure were compared between ray and disc achene pools of two species to evaluate whether there are genotypic differences related to ecological differences between achene types. Ray and disc achenes of both species had significant heterozygote deficiency. Levels of genetic diversity were similar between ray and disc achenes, but there were differences in partitioning of genetic diversity among ray and disc achenes. Genetic differences among achene pools are attributed to differences in ray and disc floret mating system.