There remain a number of questions about what maintains biodiversity in forest ecosystems. Substantial testing of competition for limiting resources, adaptation to specific local environmental conditions, and the role of... [ view full abstract ]
There remain a number of questions about what maintains biodiversity in forest ecosystems. Substantial testing of competition for limiting resources, adaptation to specific local environmental conditions, and the role of herbivory have produced largely inconclusive results; these forces seem insufficient to maintain biodiversity levels observed and often fail to explain relative abundance patterns in local communities. Increasingly, the role of pathogens has been explored as a means to explain maintenance of biodiversity, but this has been largely limited to specialist enemies, as described in the Janzen-Connell hypothesis. A recently proposed mechanism, known as the Enemies Susceptibility Hypothesis, has suggested generalist or quasi-generalist pathogens that infect phylogenetically related species may also contribute to maintenance of biodiversity.
This work uses R-based computer simulations of a forest community with trees affected by generalist, specialist, and phylogenetically driven pathogens to test the impact of their interactions in a spatially explicit environment. Various analyses consider the roles of spatial distances of tree and disease dispersal, degree of pathogen virulence, and frequency of reinfection. This work shows a number of different parameter combinations that can lead to long-term coexistence of multiple species. In particular, just two generalist pathogens, each infecting a different clade of trees, can maintain both biodiversity and relative abundance patterns in a stable fashion; the results are remarkably robust to altered model parameterization. A combination of a single generalist pathogen with species-specific specialist pathogens can also maintain both biodiversity and relative abundance patterns, but only under a narrower range of parameters.
This research ties to the Ribbon, “Thinking Critically” because the work required building a knowledge of the primary literature, combining those ideas in novel fashion, asking new questions based on that work, and then implementing those ideas in computer code. It also falls within the “Learning Throughout a Lifetime” ribbon because it involves continuing to ask fundamental questions of science, and requires the learning of new experiences and skills, including biodiversity and coding. Finally the research also “Crosses boundaries and disciplines” because it incorporates multiple disciplines including ecology, statistics, and computer programming.
