Refining Niche Metric Calculations: A Modified Weighting Approach to Colwell and Futuyma's Method.

Abstract

The niche concept is central to ecology, evolution, and conservation biology. To assess resource dynamics in biological communities, the most widely used niche metrics are niche breadth and niche overlap. Colwell and Futuyma (1971) were the first to propose niche metrics that incorporated resource distinctness. In their framework, niche breadth and overlap are calculated using either a relative weighting factor $\left(d_j\right)$ or an absolute weighting factor $\left({\delta }_j\right)$ . Hanski (1978) later introduced an alternative weighting factor $\left(\delta _j^{\ast }\right)$ , which accounts for both the quality and quantity of resource states in niche calculations. However, metrics based on $d_j$ , ${\delta }_j$ and $\delta _j^{\ast }$ have inherent mathematical and conceptual limitations. To overcome these issues, the present study introduces modified forms of these factors ( $e{d}_j$ , $e{\delta }_j$ and $e\delta _j^{\ast }$ ) and evaluates their performance using eight hypothetical and one empirical (ecological) resource matrix. The findings indicate that niche metrics incorporating the $e{d}_j$ factor represent the most coherent and biologically meaningful option.