Spawning habitat, behavior, and morphology as isolating mechanisms of the golden redhorse, Moxostoma erythrurum, and the black redhorse M. duquesnei, two syntopic fishes

摘要: Golden redhorse, Moxostoma erythrurum, and black M. duquesnei, were observed spawning during the springs of 1984 through 1987 in Stony Creek, Illinois, at water temperatures ranging from 15–21°C. Both species spawned simultaneously within same stream reach 1987. Male golden redhorse aggressively defended territories on shoals joined by females an adjacent pool. Black also riffles displayed no agonistic behavior. throughout daylight hours groups two to five, night. Habitat utilization curves indicate that habitat was slightly deeper, much swifter, over coarser substrate than redhorse. Males both exhibited nuptial body color breeding tubercles anal caudal fins, while only males had head tubercles. We suggest these differences habitat, behavior, morphology act as reproductive isolating mechanisms between dichotomy behavior may be due competitive interactions.