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assemblages, the index of competitive ability permitted interspecific <br />comparison of ability of each competitor to obtain limited resources. Values <br />of competitive ability were negative for seven of nine mixed-species <br />treatments suggesting that fathead minnow were superior competitors in those <br />experimental treatments, and that Colorado squawfish were superior in the <br />remaining two experimental treatments. These conclusions are consistent with <br />those from analysis of d. Competitive ability values were positive for two of <br />the three experimental treatments where d values for Colorado squawfish were <br />greater than those for fathead minnow. <br />Diet overlap <br />Diet overlap estimates based on Colorado squawfish and fathead minnow in <br />single-species assemblages ranged from 0.92 to 0.99 (Table 1). These values <br />provide a basis for comparing diet overlap in mixed-species assemblages by <br />showing the range of responses that occurred in absence of interspecific <br />resource competition. There was a variable response of diet overlap in <br />mixed-species assemblages to resource availability. In the two highest <br />feeding regimes there was no relation between diet overlap and resource <br />availability or relative abundance. Overlap at these feeding regimes ranged <br />from 0.70 to 0.98, and four of six values were greater than or equal to 0.91. <br />In contrast, diet overlap in mixed-species assemblages in the lowest feeding <br />regime ranged from 0.66 to 0.88 and was reduced compared to single-species <br />assemblages. There was no apparent relation between diet overlap and relative <br />abundance. <br />16 <br />