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The Use of Niche Breadth and Proportional Similarity in Feeding to Stipulate Resource Utilization Strategies in Fish

1989; Taylor & Francis; Volume: 5; Issue: 1 Linguagem: Inglês

10.1080/02705060.1989.9665218

2156-6941

Joseph W. Rachlin, Barbara E. Warkentine, Antonios Pappantoniou,

Fish biology, ecology, and behavior

ABSTRACT A hypothetical data set was evaluated using algorithms to calculate niche breadth (Levins' index) and the proportional similarity in feeding between the species of interest and the resource base (the PS ratio of Feinsinger et al.). The results were then examined for the occurrence of concordance and non-concordance between information generated by these two algorithms. The nature of the concordance and non-concordance can be used to define strategies of resource utilization. That is, if the concordance results from both a high niche breadth value and a high proportional similarity in feeding, the foraging strategy is that of a classic “generalist.” If the values for proportional similarity in feeding and the niche breadth are both low, the foraging strategy is that of a classic “specialist.” In cases of non-concordance where the values for niche breadth is high but the value for proportional feeding is low, the foraging strategy is that of a “selectionist.” But if the niche breadth value is low and the proportional similarity in feeding is high, then the strategy is that of an “opportunist.” These definitions allow for the avoidance of the so called “paradox of niche breadth.” When applied to measurements derived from an empirical data set, these definitions were helpful in ordering the 12 species of the community by resource utilization strategy. Five of the species were specialists; three of the species were opportunists. The remaining four species exhibited feeding strategies which placed them on the resource utilization continuum between specialists and opportunists. No species was functioning as either a classic generalist or as a selectionist.