Joseph Walloch Biology
Elizabeth Danka Assistant Professor of Biology
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Abstract
Keystone species are important for a number of ecological and evolutionary processes, and therefore influence economic and political decision making. However, studies highlighting the context dependency of keystone species have relativized the keystone concept, obfuscating the concept’s usefulness. A clear, quantitative definition and application of the keystone species concept could remove skepticism around the term and increase its utility for ecological research and environmental policy. In this study, we used the quantitative definition of keystone species from Power et al (1996) to perform a meta-analysis of 35 studies covering 23 species toward two objectives: 1) to test whether common scientific uses of the term match the quantitative definition, and 2) to examine the context dependency of true keystone species. We found that only 26% of species listed as keystone species in peer-reviewed literature fit the quantitative definition. We also found that of those 26% of species, 83% fit the definition only under certain environmental contexts. Our results are evidence that keystone species are more rare than previously thought. However, because of the quantitative definition’s narrow scope, the keystone concept retains its usefulness. Our results also show that environmental context is critical for determining whether a species fits the keystone designation. We suggest the keystone concept needs to be more narrowly applied, and should only be applied within an environmental context. These results provide evidence to ecosystem managers and policy makers to move away from broad, species focused policies to policies focused at the organism-environment interface.
