title: Competitive exclusion, beta diversity, and deterministic vs. stochastic drivers of community assembly.
abstract: Species diversity has two components - number of species and spatial turnover in species composition (beta-diversity). Using a field experiment focusing on a system of Mediterranean grasslands, we show that interspecific competition may influence the two components in the same direction or in opposite directions, depending on whether competitive exclusions are deterministic or stochastic. Deterministic exclusions reduce both patch-scale richness and beta-diversity, thereby homogenising the community. Stochastic extinctions reduce richness at the patch scale, but increase the differences in species composition among patches. These results indicate that studies of competitive effects on beta diversity may help to distinguish between deterministic and stochastic components of competitive exclusion. Such distinction is crucial for understanding the causal relationship between competition and species diversity, one of the oldest and most fundamental questions in ecology.
authors.affiliation: Department of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, 91904, Israel.
authors.forename: Hila
authors.initials: H
authors.lastname: Segre
authors.forename: Ronen
authors.initials: R
authors.lastname: Ron
authors.forename: Niv
authors.initials: N
authors.lastname: De Malach
authors.forename: Zalmen
authors.initials: Z
authors.lastname: Henkin
authors.forename: Micha
authors.initials: M
authors.lastname: Mandel
authors.forename: Ronen
authors.initials: R
authors.lastname: Kadmon
mesh_terms: D044822:Biodiversity; D065948:Grassland; D019083:Mediterranean Region; D008954:Models, Biological; D006109:Poaceae / Q000145:classification*; D013269:Stochastic Processes
keywords: Annual plants; Mediterranean grasslands; community ecology; functional groups; habitat productivity; niche vs. neutral processes; plant competition; removal experiment; species diversity