Dissertation Research: Does the Presence and Spatial Arrangement of Co-flowering Species Affect Threshold Critical Population Densities in Plants?

Duke University, Durham NC

Investigators

Abstract

Plants in small or sparse populations may receive insufficient pollinator visits to produce enough seeds to replace dying individuals. Thus, populations below some threshold size or density may be doomed to extinction. If a co-occurring plant species shares pollinators, its presence may increase both visitation and seed production of plants in sparse populations by increasing local flower density. This may lower the threshold density above which populations persist. Experiments proposed will determine conditions under which plant species can lower or raise threshold population densities of other plant species, using experimental arrays of plants at different densities, with and without co-occurring plants, and measuring pollinator visitation, pollen receipt by flowers, and the numbers of fruits and seeds produced. Experimental data, combined with data on growth and survival of individuals in natural populations, will be used in population models to determine whether populations of each density and species treatment persist. Plant populations will likely become smaller and sparser as the landscape becomes more fragmented and degraded. This project will inform ecologists and conservationists about whether small or sparse populations are more likely to persist in the presence of other species. Also, this project will inform land managers working to re-establish populations of native plants in restored areas.