Linnea Meier, 2008

Earlham College

The effects of isolation and plant population size on host-specialist interactions and plant fitness in two species of Physalis (Solanaceae)

The study of population and community dynamics in isolated habitats is a matter of increasing importance as urban development and other anthropogenic factors fragment the landscape. This study examined how isolation affects the spatial distribution of specialist pollinators. We have also examined how isolation affects levels of herbivory, and how all these interactions impact plant fitness. Physalis longifolia and Physalis heterophylla and their associated specialist insects were used as a study system. Locations of patches of both species of Physalis and Solanum dulcamara, a plant which also hosts the herbivore, were recorded with GPS. Proportion of plants occupied by the herbivore did not vary with level of isolation, patch size or presence of a patch edge. In one case the number of pollinators was predicted by level of isolation and patches with more edge had more flowers. Fruit and seed set were very high and did not vary isolation, patch size or presence of a patch edge.


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