Spontaneous parthenogenesis in a fish.

Abstract

THE guppy, Lebistes reticulatus, is a viviparous fish the reproductive physiology of which has been well studied (bibliography in Gordon1). A female, D9, of English domestic stock of this species born October 5, 1950, was separated from adult males twelve days after birth. The litter of which she was a member were placed in separate jars when thirty-nine days old. The first sign of differentiation of the anal fin into a gonopodium was seen in one of her brothers twelve days later, the family being raised at 20° C. The isolated female, at the age of 216 days, bore a female offspring which died at the age of 304 days. The mother was then mated to a male litter-mate, and bore four litters of at least twenty-six, of which twenty-four were females and one male. The male mated with D9 died before the birth of the second litter, consisting of seven females and one male which were separated from each other at the age of four days. One of these females, DD20, gave birth to three young at the age of 193 days.