Potential role of pollinators in microhabitat structure within a large population of Echinacea laevigata (Asteraceae)1

Abstract

Understanding the linkages among population spatial, demographic, and genetic structure is a priority for threatened or endangered species, particularly when the physical or biotic landscape influences key processes such as pollinator behavior or plant establishment, growth, and flowering. We investigated spatial, demographic, and genetic structure, and followed activity of insect visitors within a large population of a federally endangered herb, Echinacea laevigata (C.L.Boynton & Beadle) S.F.Blake, distributed among microhabitats from an open powerline right-of-way across a narrow dirt road and into adjacent forest. Population and genetic structure differed among the microhabitats, but these differences were not due to clonal growth. Most genetic variation was within rather than among microhabitats. Plants differed in size (number of leaves) and the percentage of flowering plants among microhabitats, with smaller plants and lower flowering in the edge, larger plants and intermediate flowering in the forest and powerline, and smaller plants, but higher flowering, along the open road. Observations of insect visitors suggest activity of potential pollinators can interact with demographic structure contribute to, or reinforce, genetic structure in the population. Collectively, results of this research indicate that microhabitat effects on population structure and pollinator activity should be considered in species management plans for E. laevigata.