The relative impact of genetic diversity versus species diversity on ecosystem function in plant communities.
Fridley, Jason*,1, 2, Grime, J. Philip2, 1 University of North Carolina at Chapel Hill, Chapel Hill, NC2 University of Sheffield, Sheffield, UK
ABSTRACT- Genetically-controlled phenotypic differences within plant populations have been found to be considerable within surprisingly small areas, and recent studies suggest local genotypic diversity can play an important role in local plant species dynamics. These results suggest that local genetic diversity has feedbacks to ecosystem functioning by means of controlling the abundance of local populations, but it remains unclear how such effects compare or interact with local diversity at the species level. If the fundamental unit of biodiversity is the gene, how does the partitioning of genetic (and thus phenotypic) differences into species and genotypes within species influence the functioning of ecosystems? We describe a microcosm experiment designed to examine the relative effects of genotypic and species diversity on ecosystem functioning for a perennial limestone grassland in northern England. Our design includes three levels of increasing simplification of a Festuca ovina pastureland (mixtures of eight and four herbaceous species and a monoculture of F. ovina), factorially combined with levels of one, four, and eight genotypes per species. Preliminary results indicate that, for several species, performance is strongly related to genotype composition, although there are no clear production patterns related to genetic diversity per se. We also document clear tradeoffs in vegetative and reproductive allocation at the genotype level for individuals derived from the same local community. We anticipate an increasing role for genotypic diversity in the maintenance of site productivity under a scenario of increasing drought stress, and suggest situations where local genetic diversity could well be a crucial component of the role of biodiversity in the response of ecosystems to climate change.
Key words: grassland, Festuca ovina , microcosm
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