Fungal pathogen species richness: why do some plant species have more pathogens than others?

Variation among plant species in the number of associated herbivore and pathogen species is predicted to fit a species-area relationship in which the area or biomass embodied by a plant species is a function of individual size and geographic range size. This hypothesis is tested using published estimates of geographic range, individual size, and species richness of fungal-pathogens for 490 plant species occurring in the United States and controlling for sampling intensity and phylogenetic effects. The number of pathogens found on a plant species increases with the metrics of plant species' area and/or habitat diversity and their effects are similar between gymnosperm and angiosperm lineages. The strength of this pattern across a diverse set of plant lineages suggests that accumulation and persistence of pathogen species on plant species are governed by the same processes among temperate plants.