LETTER Diversity–stability relationship varies with latitude in zooplankton Jonathan B. Shurin, 1 * Shelley E. Arnott, 2 Helmut Hillebrand, 3 Allyson Longmuir, 1 Bernadette Pinel-Alloul, 4 Monika Winder 5 and Norman D. Yan 6 1 Department of Zoology and Biodiversity Research Centre, University of British Columbia, 6270 University Blvd, Vancouver, BC, Canada V6T 1Z4 2 Department of Biology, Queen’s University, Kingston, ON, Canada K7L 3N6 3 Institute for Botany, University of Cologne, Gyrhofstrasse 15, D-50931 Koln, Germany Abstract Analyses of temporal patterns of diversity across a wide range of taxa have found that more diverse communities often show smaller compositional changes over time. This generality indicates that high diversity is associated with greater temporal stability in species composition. We examined patterns of diversity and community stability in zooplankton time series data from 36 lakes sampled over a combined 483 years. The species–time relationship was flatter in more species-rich lakes in the temperate zone. However, high-latitude lakes had both low richness and low turnover. These patterns were consistent for turnover both within and among years. Daily, annual and long-term richness were all higher in large lakes while turnover was unaffected by the surface area. Richness on all time scales, as well as turnover within and among years, all declined at high latitude. Species–area relations and latitudinal gradients in richness therefore reflect different temporal components of diversity. Our results suggest that diversity shows strong associations with compositional stability that vary qualitatively across biogeo- graphical provinces. Community stability increases with diversity among lakes in the temperate zone; however, the two are negatively correlated across latitudinal gradients. These patterns indicate that either the direct effects of diversity on stability or their covariance with environmental fluctuations vary with latitude. Keywords Extinction, invasion, latitudinal gradients, species–time relationship. Ecology Letters (2007) 10: 127–134 INTRODUCTION Ecologists have uncovered few generalities in the relation- ship between community diversity and stability. Elton (1958) first proposed that diversity buffers assemblages against perturbations by providing species with a range of traits and tolerances that thrive under varying conditions (see also MacArthur 1955). By contrast, May (1974) found that model communities with more species had greater chances of including unstable combinations that showed cycles, chaos or extinctions, leading to reduced stability in rich communities. However, populations in diverse com- munities may be more stable if most species interact weakly (Yodzis 1981; McCann et al. 1998). Thus, theory provides plausible scenarios leading to either positive or negative relationships between community diversity and population stability depending on the particular configuration of species interactions. Reflecting the lack of theoretical consensus, empirical studies have shown examples where stability either increases or decreases with species diversity (McCann 2000). Virtually all studies of diversity and stability have been experimental and cover a narrow range of richness relative to natural variation due to methodological constraints on manipulating large numbers of species (Cottingham et al. 2001). The existing literature therefore provides equivocal evidence for a general relationship between diversity and stability. In addition, we know little about how the two co-vary in natural, unmanipulated communities. 4 De ´ partement de Sciences Biologiques, Universite ´ de Montre ´ al, C.P. 6128, Succ. Centre ville, Montreal, QC, Canada H3C 3J7 5 Center for Watershed Sciences, University of California, Davis One Shields Ave., Davis, CA 95616-8803, USA 6 Department of Biology, York University, Toronto, ON, Canada M3J 1P3, and Ontario Ministry of the Environment, Dorset Environmental Science Centre, Dorset, ON, Canada P0A 1E0 *Correspondence: E-mail: shurin@zoology.ubc.ca Ecology Letters, (2007) 10: 127–134 doi: 10.1111/j.1461-0248.2006.01009.x Ó 2007 Blackwell Publishing Ltd/CNRS