Species richness, but not phylogenetic diversity, influences community biomass production and temporal stability in a re-examination of 16 grassland biodiversity studies

• Autores: Venail, Patrick; Gross, Kevin; Oakley, Todd H.; Narwani, Anita; Allan, Eric; Flombaum, Pedro; Isbell, Forest; Joshi, Jasmin; Reich, Peter B.; Tilman, David; Van Ruijven, Jasper; Cardinale, Bradley J.
• Año de publicación: 2015
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Biodiversity; Phylogenetic Diversity
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Hundreds of experiments have now manipulated species richness of various groups of organisms and examined how this aspect of biological diversity influences ecosystem functioning. Ecologists have recently expanded this field to look at whether genetic diversity among species, often quantified as the degree of evolutionary divergence on a molecular phylogeny, also predicts ecological function. Some have hypothesized that phylogenetic divergence should be a superior predictor of ecological function than species richness because evolutionary relatedness represents the degree of ecological and functional differentiation among species. But studies to date have provided mixed support for this hypothesis. Here, we re-analyze data from 16 experiments that have manipulated plant species richness in grassland ecosystems and examined the impact on aboveground biomass production over multiple time points. Using a new molecular phylogeny of the plant species used in these experiments, we quantified how the phylogenetic diversity of plants impacts average community biomass production as well as the stability of community biomass production through time. Using four complementary analyses we show that, after statistically controlling for variation in species richness, phylogenetic diversity (the sum of branches in a molecular phylogenetic tree connecting all species in a community) is neither related to mean community biomass nor to the temporal stability of biomass. These results run counter to past claims. After controlling for species richness, phylogenetic diversity was positively related to variation in community biomass over time via an increase in individual species variances but this relationship was not strong enough to influence community stability. In contrast to the non-significant relationships between phylogenetic diversity, biomass, and stability, after controlling for species richness, our analyses show that species richness tends to increase the mean biomass production of plant communities, after controlling for phylogenetic diversity. The relationship between species richness and temporal variation in community biomass was either non-significant or negative depending on which analysis was used. However, the increases in community biomass with species richness, independent of phylogenetic diversity, always led to increased stability. These results suggest that phylogenetic diversity is no better as a predictor of ecosystem functioning than species richness. Synthesis. Our study on grasslands offers a cautionary tale when trying to relate phylogenetic diversity to ecosystem functioning as there may be trait and functional variation among species that cannot be explained by their evolutionary relatedness. Management recommendations suggesting the conservation of evolutionarily distinct species will lead to more productive and more stable communities under changing environmental conditions are not well supported by the data explored in this study.
Fil: Venail, Patrick. University of Michigan. School of Natural Resources and Environment; Estados Unidos. University of Geneva. Institute F.-A. Forel. Section of Earth and Environmental Sciences; Suiza
Fil: Gross, Kevin. North Carolina State University. Statistics Department; Estados Unidos
Fil: Oakley, Todd H.. University of California. Department of Ecology, Evolution and Marine Biology; Estados Unidos
Fil: Narwani, Anita. University of Michigan. School of Natural Resources and Environment; Estados Unidos. Swiss Federal Institute of Aquatic Science and Technology. Aquatic Ecology; Suiza
Fil: Allan, Eric. University of Bern. Institute of Plant Sciences; Estados Unidos
Fil: Flombaum, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera; Argentina
Fil: Isbell, Forest. University of Georgia. Department of Plant Biology; Estados Unidos
Fil: Joshi, Jasmin. University of Potsdam. Biodiversity Research/Systematic Botany. Institute of Biochemistry and Biology; Alemania. Berlin-Brandenburg Institute of Advanced Biodiversity Research; Alemania
Fil: Reich, Peter B.. University of Minnesota. Department of Forest Resources; Estados Unidos. University of Western Sydney. Hawkesbury Institute for the Environment; Australia
Fil: Tilman, David. University of Minnesota. College of Biological Sciences; Estados Unidos. University of California. Bren School of Environmental Science and Management; Estados Unidos
Fil: Van Ruijven, Jasper. Wageningen University. Department of Nature Conservation and Plant Ecology; Países Bajos
Fil: Cardinale, Bradley J.. University of Michigan. School of Natural Resources and Environment; Estados Unidos