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<br />fish ~ith more obvious humps tended to be in the upper right <br /> <br />region of PC3 versus PC2 plots. <br /> <br />Overreliance on this single <br /> <br />character is avoided using the cur~ent approach, although some <br /> <br />hump quantification (e.g., perimeter as measured from the occiput <br /> <br />to the do~sal fin origin) may possibly enhance discrimination in <br /> <br />future analyses. <br /> <br />"Humpback" chubs from Blackrocks may be more variable than <br /> <br />currently perceived. Furthermore, variation may not be the <br /> <br />result of hybridization, since plots <br /> <br />for some hybrids would <br />. ~':rn <br /> <br />ha ve <br /> <br />been expected within the gap between clusters (Neff and Smith, <br /> <br />1979). <br /> <br />One-third <30 animals' of the Blackrocks study material <br /> <br />consisted of "unidentified" fish, a proportion larger than that <br /> <br />seen in nature. <br /> <br />This should have enhanced the possibility of <br /> <br />finding morphological/multivariate intermediates were they to <br /> <br />exist. <br /> <br />This absence of obvious intermediates in the peA scatter- <br /> <br />plots does not disprove the presence of hybrids or otherwise <br /> <br />introgr'?ssed animals (Neff and Smith, 1979; Pimental, 1981) <br /> <br />Rather, it suggests that hybrids do not occur and this is <br /> <br />testable using biochemical techniques (e.g., electrophoresis, <br /> <br />cytogenetics, mitochondrial DNA). <br /> <br />The possible "bony tail" chub plotted within or near th':~ "hump- <br /> <br />back" cluster, but its taxonomic status is unclear. <br /> <br />If specia- <br /> <br />tion with respect to "humpback" chubs were incomplete, morpholo- <br /> <br />gical differentiation might also be in the same state. The <br /> <br />captured fiSh may r13ve been_ large "hur'"lpback" chub '.-Jithout a <br /> <br />1 1 <br />