Center for Conservation and Sustainable Development
• Conservation Genetics
• Quantitative Genetics
• Species-level molecular systematics
The relationship between population size and fecundity in Mead’s milkweed. Dr. Edwards is a population geneticist whose research includes studies of the genetic diversity of endangered species. Mead’s milkweed (Asclepias meadii, Apocynaceae) is a federally threatened, long-lived perennial plant that occupies mature tallgrass prairie habitats in Kansas, Missouri, Iowa, and Illinois. Plants reproduce sexually by producing a single terminal umbel inflorescence composed of 8-20 flowers, and successful sexual reproduction typically results in a single seed pod (follicle) with about 60 seeds. Mead’s milkweed has a genetic self-incompatibility mechanism that prevents self-fertilization and crossing between close relatives. It also reproduces vegetatively through rhizomes, particularly when habitats are subjected to midsummer haying, such that several neighboring stems may be genetically identical. Although the initial cause of declines in the species was loss of habitat and adverse land management practices, another important factor preventing the recovery of the species is low fecundity, with some populations producing only a few or no seed pods each year despite the abundance of flowering stems. Fecundity varies among populations, with some populations successfully producing seed pods each year and others producing none. One hypothesis for the low fecundity in some populations is that they suffer from low mate availability, which would also suggest that small populations would have lower fecundity rates. In this study, the REU student will conduct field work (with a technician or PI) to comprehensively map individuals in 10 populations of varying size, periodically revisit them to quantify flowering and fruiting rates, and finally analyze the relationship between population size and fecundity.