Density-dependent competition for insect resources in two sympatric species of Drosera

Boyd, Amy
Tom Wessels, MA
Department of Environmental Studies
Populations of two species of sundew plants, Drosera rotundifolia and Drosera intermedia, were studied over a three-month summer period. For each of three study sites, data were collected on prey capture success rate and density of the two Drosera species. Theses data were then analyzed to determine whether of not density-dependent competition for insect resources exist in these sundew populations. In both of the D. rotundifolia sites, and in one of the two D. intermedia sites, data indicated a strong relationship between leaf density and prey capture success, which shows the presence of density-development intraspecific competition. The second D. intermedia site demonstrated so such relationship; this may be due to a larger insect population at that site, making prey less limited for plants. Data from a site where the two species grow together indicated that while there was no demonstrable relationship between density and capture rate, there was a difference between the capture rates of the two species. D. intermedia had a significantly higher capture rate that D. rotundifolia in the mixed-species plots, probably due to difference in morphology.

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