Morphology and Foods of Arizona Catostomid Fishes: Catostomus insignis, Pantosteus clarki, and Their Putative Hybrids

Morphology and food habits of putative hybrids between two widespread western American catostomid fishes, Catostomus insignis (Sonora sucker) and Pantosteus clarki (desert sucker), were compared with their parental forms. Hybrid intermediacy was demonstrable in morphological characters that differed between parental fishes, although tendencies were toward C. insignis. Coefficients of variation were similar in hybrid and parental samples, which, along with relatively low variation in canonical variables of discriminant function analysis, implied a lack of backcrossing. Foods of hybrids averaged intermediate to parental forms, but variation was high. Hybrids utilized a broad food base, with feeding habits that collectively spanned those of each parent. Additive inheritance of morphological and behavioral traits seems influenced by dominance and/or interallelic suppression that tend to produce deviations from often-assumed intermediacy in hybrid fishes.