title: The effect of soil-borne pathogens depends on the abundance of host tree species.
abstract: The overarching issue for understanding biodiversity maintenance is how fitness advantages accrue to a species as it becomes rare, as this is the defining feature of stable coexistence mechanisms. Without these fitness advantages, average fitness differences between species will lead to exclusion. However, empirical evidence is lacking, especially for forests, due to the difficulty of manipulating density on a large-enough scale. Here we took advantage of naturally occurring contrasts in abundance between sites of a subtropical tree species, Ormosia glaberrima, to demonstrate how low-density fitness advantages accrue by the Janzen-Connell mechanism. The results showed that soil pathogens suppressed seedling recruitment of O. glaberrima when it is abundant but had little effect on the seedlings when it is at low density due to the lack of pathogens. The difference in seedling survival between abundant and low-density sites demonstrates strong dependence of pathogenic effect on the abundance of host species.
authors.affiliation: SYSU-Alberta Joint Lab for Biodiversity Conservation, Sun Yat-sen University, Guangzhou 510275, China.|Guangdong Key Laboratory for Biodiversity Dynamics and Conservation, and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
authors.forename: Yu
authors.identifier: http://orcid.org/0000-0001-8588-1537
authors.initials: Y
authors.lastname: Liu
authors.affiliation: SYSU-Alberta Joint Lab for Biodiversity Conservation, Sun Yat-sen University, Guangzhou 510275, China.|Guangdong Key Laboratory for Biodiversity Dynamics and Conservation, and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
authors.forename: Suqin
authors.initials: S
authors.lastname: Fang
authors.affiliation: Department of Ecology and Evolutionary Biology, The University of Arizona, Tucson, Arizona 85721, USA.|Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan.
authors.forename: Peter
authors.identifier: http://orcid.org/0000-0001-8931-8012
authors.initials: P
authors.lastname: Chesson
authors.affiliation: SYSU-Alberta Joint Lab for Biodiversity Conservation, Sun Yat-sen University, Guangzhou 510275, China.|Department of Renewable Resources, University of Alberta, 114St-89 Avenue, Edmonton, Alberta, Canada T6G 2H1.
authors.forename: Fangliang
authors.initials: F
authors.lastname: He
mesh_terms: D044822:Biodiversity; D007887:Fabaceae / Q000382:microbiology*; D065928:Forests; D058507:Host Specificity; D010935:Plant Diseases / Q000382:microbiology*; D012988:Soil Microbiology; D014197:Trees / Q000382:microbiology