Natural Hybridization of Cyprinid Fishes in Little Patuxent River, Maryland

Abstract

Three natural combinations of cyprinid hybrids were found in the Little Patuxent River, Maryland in the vicinity of the Fall Line. They resulted from the spawning ofNotropis cornutus, Notropis rubellus andClinostomus funduloides over the nests ofNocomis micropogon. The hybridN. rubellus ×C. funduloides was an unreported hybrid combination. It was rare; its characteristics were intermediate between the parental species. The hybridN. cornutus ×N. rubellus was common whileN. cornutus ×C. funduloides occurred rarely. The particular ecology, including the high stream gradient and generally sandy bottom with boulders and bedrock, appeared to contribute to the hybridization. The rarity of hybrids involvingC. funduloides is attributed to the greater genetic isolation. There appeared to be no relationship between the frequency of hybridization and the distance between the precise positions of the parental species as they spawned over theNocomis nest.