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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13154

Implications of using different metrics for niche analysis in ecological communities

Adam Gouraguine*, Carlos J. Melián, Olga Reñones, Hilmar Hinz, Heather Baxter, Luis Cardona, Joan Moranta

*Corresponding author:

ABSTRACT: Explaining the mechanisms driving niche partitioning between species is of great importance to ecology. Unlike the fundamental niche, species’ realised niche can only be measured in situ, as a result of biotic and abiotic interactions defining its size. Due to the current methodology, the realised niche of a species is often characterised by the rare and divergent individuals of the community sampled. In this study, using fish on coral and temperate reefs as an example, behavioural empirical data were collected to estimate realised niche sizes and niche overlaps. The niche measurements were made using the Total Area of the convex hull (TA), but as an alternative, a metric not as strongly influenced by the sample size (Standard Ellipse Area (SEA)) was also used. A comprehensive description and context-dependent pros and cons of using either metric were discussed. Additionally, an alternative sample size correction was presented for both metrics. The analyses revealed large differences in the sizes of realised niches and their overlaps between species depending on the measurement metric. Regardless of the species, the niche size and overlap were always larger for TA than SEA. Increasing sample size reduced the niche size variability for both TA and SEA, and the variation was always smaller for SEA than TA. We successfully adapted SEA metric for analysis of behavioural niche components and demonstrated that measuring niche sizes using the two metrics, each with their own strengths and weaknesses, produces contradictory results, the ecological consequences of which are likely to be important.