The Journal of Heredity 1985:76(4):251-257
© 1985 The American Genetic Association 76:251-257
research-article |
Triploid progeny of pumpkinseed X green sunfish hybrids
Two of the authors (R.M.D. and R.J.S.) are affiliated with the Biological Sciences Group, the University of Connecticut, Storrs, CT 06268 and one (J.H.G.) with the Department of Biological Sciences, Rutgers University, Piscataway, NJ 08854. The current address of Dr. Dawley is Division of Biological Sciences, Section of Ecology and Systematics, Cornell University, Ithaca, NY 14853. The authors gratefully acknowledge the help of Walter Whitworth for assistance in developing this project, Robert C. Vrijenhoek for use of his laboratory facilities that are currently funded in part by the National Science Foundation (NSF BSR82-12150), and Ellen Dawley, Kentwood Wells, and an anonymous reviewer for comments on the manuscript. Research was supported by the Biological Sciences Group of the University of Connecticut and by grants to the senior author from the Raney Fund of the American Society of Ichthyologists and Herpetologists and the Theodore Roosevelt Memorial Fund of the American Museum of Natural History.
Abstract
Female pumpkinseed X green sunfish hybrids from Hall's Pond, Connecticut, were backcrossed to male pumpkinseed and male green sunfish. Offspring from these crosses are triploid and starch-gel electrophoresls shows they carry a double dose of the maternal genome. Thus, the female hybrids must produce unreduced, diploid eggs that are subsequently fertilized to yield triploid progeny. This is similar to the situation in parthenogenetic and gynogenetic vertebrates, where unreduced gametes are produced that develop, without fertilization, into female clones. However, because the fertilized eggs of the female sunfish yield sterile triploids, a self-perpetuating diploid unisexual "species" has not arisen from these hybrids.