Towards a more exact definition of the importance of competition – a reply to Freckleton et al. (2009)

Kikvidze, Zaal and Brooker, Rob (2010) Towards a more exact definition of the importance of competition – a reply to Freckleton et al. (2009). Journal of Ecology, 98. pp. 719-724. ISSN 1365-2745

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1. Freckleton, Watkinson & Rees (2009) criticize a recent paper by ourselves in this journal (Brooker & Kikvidze 2008) as well as our earlier work on competition importance (Brooker et al. 2005). In response, here we clarify our ideas with the aim of defining more clearly the key points of scientific debate, specifically (i) the definition of the importance of competition and (ii) its measurement. 2. Freckleton, Watkinson & Rees (2009) interpret the classic paper by Welden & Slauson (1986) such that importance as a concept relates to long-term, population-level consequences of competition. However, we consider competition importance to be the proportional impact of competition relative to the overall impact of the environment, and our index Cimp expresses changes in competition importance – as defined by ourselves – along productivity gradients. We argue that our definition more accurately reflects the work of Welden & Slauson, as well as a more recent use of the concept (Grace 1991), which precedes the work of Freckleton & Watkinson (2001). 3. We highlight that Cimp was never proposed as a general index of competition importance, but is readily applicable in certain circumstances. Notably, our index and the approaches to measuring competition importance as set out by Freckleton, Watkinson & Rees (2009) are not unrelated. 4. We also discuss some recent additional responses to both our (2008) paper and that by Freckleton, Watkinson & Rees (2009), including applications of the concept of competition importance. Although the authors of these papers may not have used our index Cimp, they follow the same definitions for the overall concept of competition importance as ourselves. 5. Synthesis. We conclude that the complex topic of biotic interactions, including the specific issue of the importance of competition, invites a range of approaches. Importantly, these approaches can be complementary and not conflicting. Here, we propose what we see as a sensible resolution to the current debate concerning the definition of competition importance, a resolution which is backed by the original source article, literature precedent and current usage.

Item Type: Article
Subjects: Q Science > Ecology
Divisions: Institutes > 4D Research Institute
Depositing User: Prof. Zaal Kikvidze
Date Deposited: 16 Apr 2015 06:20
Last Modified: 16 Apr 2015 06:20

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