Symbioses: Plant, Animal, and Microbe Interactions
Gilbert, Gregory , Webb, Campbell .
The structure of plant pathogen host range is a function of local host density and phylogenetic distance between plant species.
DENSITY-DEPENDENT mortality from host-specialist plant pathogens is often invoked as a mechanism for the maintenance of high plant diversity in tropical forests. Because most plant pathogens are polyphagous, understanding how host relationships and local abundances affect the host ranges of plant pathogens is essential for evaluating the strength of influence of pathogens in plant communities. Working in a semi-deciduous tropical forest in Panama, we used in-field inoculations to test the ability of several dozen foliar plant pathogens to infect a phylogenetically diverse range of forest plant species. We also measured the local abundance of plant species in the forest understory and overstory. As expected, there was a strong phylogenetic signal, with pathogens most likely to infect plant species most closely related to the host of origin. However, the phylogenetic signal showed strong interactions with local host density, such that pathogens from locally rare plant species were more likely to be broad generalists than species from locally common hosts, and locally rare plant species are more likely to develop disease symptoms than are common hosts. The evolutionary and ecological signals in pathogen host range have significant implications for understanding plant community dynamics and disease epidemiology in natural communities.
Log in to add this item to your schedule
1 - University of California, Environmental Studies, 1156 High St. - 405 ISB, Santa Cruz, California, 95064, USA
2 - Harvard University, Arnold Arboretum, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, Massachusetts, 02138, USA
tropical rain forest
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 31st, 2006
Time: 8:15 AM