Deforestation affects the web of plant-insect interactions affecting reproductive success in the Amazonian herb, Rapatea ulei

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)



First Committee Member

Theodore H. Fleming - Committee Chair


Much of the research surrounding the effects of deforestation has focused on effects on species diversity or populations of particular taxa. Currently, that focus is shifting towards the community processes that produce those effects, such as plant animal interactions. Recent ecological studies have emphasized the importance of considering the effects of multiple types of plant-animal interactions simultaneously, rather than as isolated phenomena. I considered the effects of deforestation on multiple types of plant-insect interactions and reproductive success in the herb Rapatea ulei (Rapateaceae: Poales). R. ulei occurs in riparian wetlands in Central Amazonian terra firme forest. I studied the reproductive ecology of R. ulei and the roles that numerous mutualistic and antagonistic insects played in limiting R. ulei seed production. I examined seed production and interactions including pollination, destructive pollen robbing, bud herbivory, and pre-dispersal seed predation. Rates of pollinator visitation were significantly reduced in deforested sites compared to intact forest - being between four to ten times lower in deforested habitats. Relative seed production per plant in deforested habitats was less than half of that in intact forest. Both petal and bud herbivory were far less common in deforested sites. Anther herbivory by destructive pollen thieves was significantly different between habitats in only one of the two study years, and was actually higher in deforested sites. In addition to this multivariate comparison across habitats, I used structural equation modeling to analyze the direct relationships between the interactions studied and plant reproductive success. I then compared path models of those relationships across intact and deforested habitats. Habitat context profoundly changed the relative importance of anther herbivory versus pollination in intact versus deforested habitats. Deforestation intensified the effects of plant-insect interactions on seed production and altered the balance between the relative importance of mutualistic versus antagonistic interactions.


Biology, Botany; Biology, Ecology; Environmental Sciences

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