Egg Size as a Factor in Intergeneric Hybrid Success of Centrarchids

Abstract The diameter of eggs was measured for 4 species of sunfishes representing 4 genera. The egg size was compared to hybridization success reported for these species to evaluate egg size as a factor determining hybridization success. Average diameters were: Pomoxis nigromaculatus (Lesueur), black crappie (0.95 mm); Chaenobryttus gulosus (Cuvier), warmouth (1.01 mm); Lepomis macrochirus Rafinesque, bluegill (1.09 mm); and Micropterus salmoides (Lacepede), largemouth bass (1.74 mm). Highly significant differences (.01 level) existed between P. nigromaculatus and L. macrochirus eggs and between M. salmoides eggs and all other species measured. Hybrid success (hatching, deformities, embryonic death, etc.) did not show relationship to egg size for crosses among these species. Reciprocal cross data for L. macrochirus eggs, in particular, indicated that the causative factors determining hybridization success involve factors other than egg size.