REV I EWS AND SYNTHESES Connections between species diversity and genetic diversity

Mark Vellend* and Monica A. Geber National Center for Ecological Analysis and Synthesis, 735 State Street, Suite 300, Santa Barbara, CA 93101, USA Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA *Correspondence and present address: Departments of Botany and Zoology, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada V6T 1Z4. E-mail: [email protected] Abstract Species diversity and genetic diversity remain the nearly exclusive domains of community ecology and population genetics, respectively, despite repeated recognition in the literature over the past 30 years of close parallels between these two levels of diversity. Species diversity within communities and genetic diversity within populations are hypothesized to co-vary in space or time because of locality characteristics that influence the two levels of diversity via parallel processes, or because of direct effects of one level of diversity on the other via several different mechanisms. Here, we draw on a wide range of studies in ecology and evolution to examine the theoretical underpinnings of these hypotheses, review relevant empirical literature, and outline an agenda for future research. The plausibility of species diversity–genetic diversity relationships is supported by a variety of theoretical and empirical studies, and several recent studies provide direct, though preliminary support. Focusing on potential connections between species diversity and genetic diversity complements other approaches to synthesis at the ecology– evolution interface, and should contribute to conceptual unification of biodiversity research at the levels of genes and species.