Confirmation of gynogenesis in Phoxinus eos-neogaeus (Pisces: Cyprinidae)

Abstract

We have previously reported that the all-female species Phoxinus eos-neogaeus is perpetuated at Norton Pool, New Hampshire, by clonal reproduction. Genetically identical diploid eos-neogaeus ova develop into diploid offspring if congeneric sperm stimulates development, and into triploid or diploid-triploid mosaic offspring if syngamy occurs. Some individuals produce both genetically identical and unique diploid ova, resulting in clonal and nonclonal offspring. In a third, very different type of gametogenesis, other females produce haploid eos ova that yield diploid ‘‘P. eos’’ offspring if fertilized by P. eos sperm. In this study we confirmed all three types of gametogenesis by mating two females of P. eos-neogaeus to a male of a related species, P. oreas, whose distinctive contribution to the offspring was revealed through morphology, genome size, and tissue graft analysis. In a second set of experiments we show that the same clone has existed at Norton Pool for 11 years. Lastly, we show that gynogenetic reproduction is not restricted to Norton Pool, but that hybrids from Algonquin Park, Ontario, also reproduce clonally.