Genetic diversity and population structure in Echinacea laevigata (Boyntonand beadle) blake, an endangered plant species

Genetic considerations of diversity and structure are useful in management strategies for conserving threatened or endangered species. Echinacea laevi gata (Boynton and Beadle) Blake is an endangered plant species with populat ions currently found in only four states. We examined 11 populations of Ech inacea laevigata in North Carolina, South Carolina, and Virginia, USA, for genetic diversity and population genetic structure. These 11 populations co ntain moderate levels of genetic diversity, on average (H-e = 0.178), which compares favorably with that of Echinacea angustifolia DC., a widespread c ongener. Significant population structure (G(ST) = 0.109) and significant a nd positive correlation of genetic and geographic distances (rho = 0.380, p less than or equal to 0.025) suggest that genetic variation is not partiti oned evenly among all populations of E. laevigata and that population struc ture follows an isolation-by-distance model. In addition, a hierarchical an alysis of population structure (Analysis of Molecular Variance) is also sig nificant at all three levels (Phi (ST) = 0.219, Phi (CT) = 0.105, and Phi ( SC) = 0.127). This suggests that E. laevigata populations may be adapting t o local environments. The unequal partitioning of genetic variation suggest s that all populations should be maintained to conserve genetic diversity b ecause each population contains only a subset of the total genetic variatio n. Regional population differentiation may be important in the selection of material to establish new populations.