Hybridization of Four Species of Sunfishes (Centrarchidae)

Abstract

Red-ear sunfish, Lepomis microlophus (Gunther); bluegill, L. macrochiris Rafinesque; green sunfish, L. cyanellus Rafinesque; and warmouth, Chaenobryttus gulosus (Cuvier) are present in a number of east-central Illinois lakes and ponds and are known to hybridize occasionally. During 1957 through 1964, the spawning seasons of these species were observed to extend from mid-May to August or September. Red-ear sunfish, bluegills, and green sunfish usually nested in colonies, and mixed colonies containing two and, less frequently, all three of these species were not uncommon. Warmouths tended to be more solitary in their nest site selections. Gametes stripped from the four species were paired in 16 different combinations to produce zygotes representing 12 kinds of F₁ hybrids and the four parental species.  warmouth male x bluegill female and warmouth male X red-ear female crosses were 100 percent lethal, and the warmouth male x green sunfish female cross was partially lethal.  Based on the percentages of zygotes that hatched and developed into normal-appearing fry, the viability of each of the remaining nine kinds of hybrids was not significantly different from that of its maternal parent.