Molecular Ecology (2008) 17, 20–29 doi: 10.1111/j.1365-294X.2007.03428.x © 2007 The Authors Journal compilation © 2007 Blackwell Publishing Ltd Blackwell Publishing Ltd Human influences on rates of phenotypic change in wild animal populations ANDREW P. HENDRY,* THOMAS J. FARRUGIA * and MICHAEL T. KINNISON † *Redpath Museum and Department of Biology, McGill University, 859 Sherbrooke Street West, Montréal, QC, Canada H3A 2K6, †Department of Biological Sciences, University of Maine, Orono, ME 04469-5751, USA Abstract Human activities can expose populations to dramatic environmental perturbations, which may then precipitate adaptive phenotypic change . We ask whether or not phenotypic changes associated with human-disturbed (anthropogenic) contexts are greater than those associated with more ‘natural’ contexts. Our meta-analysis is based on more than 3000 rates of phenotypic change in 68 ‘systems’, each representing a given species in a particular geographical area. We find that rates of phenotypic change are greater in anthropogenic contexts than in natural contexts. This difference may be influenced by phenotypic plasticity — because it was evident for studies of wild-caught individuals (which integrate both genetic and plastic effects) but not for common-garden or quantitative genetic studies (which minimize plastic effects). We also find that phenotypic changes in response to disturbance can be remarkably abrupt, perhaps again because of plasticity. In short, humans are an important agent driving phenotypic change in contemporary populations. Although these changes sometimes have a genetic basis, our analyses suggest a particularly important contribution from phenotypic plasticity. Keywords: contemporary evolution, Darwins, Haldanes, invasion, microevolution, rapid evolution Received 8 February 2007; revision accepted 16 May 2007 Introduction Natural populations are at least partly adapted to their local selective environments (Endler 1986; Rose & Lauder 1996; Schluter 2000). At any particular location, however, the intensity and direction of selection will fluctuate through time, making adaptation an ongoing and ever-changing necessity. This dynamic nature of adaptation has now been confirmed through numerous demonstrations of apparently adaptive phenotypic change on timescales as short as a few generations (reviews: Hendry & Kinnison 1999; Kinnison & Hendry 2001; Palumbi 2001; Reznick & Ghalambor 2001; Stockwell et al. 2003; Hairston et al. 2005). A remaining question, however, is whether or not adaptive phenotypic change can keep pace with the increasingly rapid and dramatic changes in selection that characterize our world. Our goal is to gain some insights into this question by examining phenotypic changes in populations experiencing environmental change, with the ‘environment’ construed broadly so as to include abiotic effects (e.g. temperature, moisture, light, nutrients, toxins), biotic effects (e.g. resources, competitors, predators), and other effects (e.g. harvesting of wild populations). Environmental changes that alter selection may be par- ticularly extreme in the case of human-caused disturbance (Pimm et al. 1995; Hughes et al. 1997; Vitousek et al. 1997). Populations facing these greater-than-normal disturbances may therefore manifest greater-than-normal phenotypic responses. Dramatic responses are certainly known for some populations facing human disturbance (Palumbi 2001; Stockwell et al. 2003) — but is this a general phenom- enon? We address this question by comparing rates of phenotypic change between populations experiencing either human-induced (anthropogenic) or natural environ- mental change. We specifically test whether phenotypic changes associated with human disturbances rise above the baseline typical of more ‘natural’ environmental variation. We discuss our findings in relation to whether or not populations can adapt to the environmental changes wrought by humans. Correspondence: Andrew P. Hendry, Fax: 514-398-3185; E-mail: andrew.hendry@mcgill.ca