DOI: 10.5061/dryad.kf401
title: Data from: Phylogenetic structure and host abundance drive disease pressure in communities

description: Pathogens play an important part in shaping the structure and dynamics of
 natural communities, because species are not affected by them equally. A
 shared goal of ecology and epidemiology is to predict when a species is
 most vulnerable to disease. A leading hypothesis asserts that the impact
 of disease should increase with host abundance, producing a ‘rare-species
 advantage. However, the impact of a pathogen may be decoupled from host
 abundance, because most pathogens infect more than one species, leading to
 pathogen spillover onto closely related species. Here we show that the
 phylogenetic and ecological structure of the surrounding community can be
 important predictors of disease pressure. We found that the amount of
 tissue lost to disease increased with the relative abundance of a species
 across a grassland plant community, and that this rare-species advantage
 had an additional phylogenetic component: disease pressure was stronger on
 species with many close relatives. We used a global model of pathogen
 sharing as a function of relatedness between hosts, which provided a
 robust predictor of relative disease pressure at the local scale. In our
 grassland, the total amount of disease was most accurately explained not
 by the abundance of the focal host alone, but by the abundance of all
 species in the community weighted by their phylogenetic distance to the
 host. Furthermore, the model strongly predicted observed disease pressure
 for 44 novel host species we introduced experimentally to our study site,
 providing evidence for a mechanism to explain why phylogenetically rare
 species are more likely to become invasive when introduced. Our results
 demonstrate how the phylogenetic and ecological structure of communities
 can have a key role in disease dynamics, with implications for the
 maintenance of biodiversity, biotic resistance against introduced weeds,
 and the success of managed plants in agriculture and forestry.
description: Meadow_traitstableAttributes of the wild and experimentally introduced plant species from the study in grassland on the University of California Santa Cruz campus, Santa Cruz, CA USA (36°59'18.09"N, 122° 3'31.29"W) in 2011 and 2012. Used for Fig 2 and Fig 3 source: plant species found wild or experimentally introduced in grassland community origin: plant species native to Santa Cruz region or nonnative genus: genus of plant species: species of plant name: aggregate genus species name of plant code: 6-letter mnemonic code for plant species family: family of plant species phyloname: phylomatic-style family/genus/name of plant speciesMeadow_wildabunddiseaseEstimates of percent cover of plant species and percent of leaf area lost to disease for wild plants in ten 20-m diameter circular plots in grassland on the University of California Santa Cruz campus, Santa Cruz, CA USA (36°59'18.09"N, 122° 3'31.29"W). Data were collected in April and May 2011. (Used for Fig 2) plot: Plot number (1 to 10) for estimates of cover and disease genus: Plant genus species: plant species coverpercent: Percent cover of plant species in that plot diseasepercent: Percent of foliar tissue lost to disease (necrosis and chlorosis). Blanks indicate that we have no disease data for that species in that plotMeadow_ExperimentalPlant_visualdiseaseEstimates of percent of leaf area lost to disease for experimentally introduced plant species in each of 10 plots in grassland on the University of California Santa Cruz campus, Santa Cruz, CA USA (36°59'18.09"N, 122° 3'31.29"W). Data were collected in April 2012. (Used for Fig 3) plot: Plot number (1 to 10) for estimates of cover and disease genus: Plant genus species: plant species visualdisease: Percent of foliar tissue lost to disease (necrosis and chlorosis)Meadow_sentinelvisualdisease.csvRSAmeadow phylogenetic distance matrixPhylogenetic distances (in My of independent evolution) between all pairs of wild and experimentally introduced plant species. (Used for Fig 2 and Fig 3)RSAmeadow_phydist_respolytomy.csvReadMe_ParkerEtAl_Data2015NatureMetadata for four sets of data used in Parker et al. 2015. Phylogenetic structure drives disease pressure in communities. Nature. In press.