Parthenogenesis in Reptiles

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Abstract
Synopsis. The discovery of parthenogenesis in reptiles came about through the casual observation of the lack of males in several species of lizards. Nineteen all female species and subspecies from five genera and three families of lizards have been nanied or recognized. Actual proof of parthenogenesis, however, has been demonstrated for only seven of these. Studies in variation of parthenogens versus the variation of sym? patric bisexual species have been made on six species. In general the parthenogens are much less variable than bisexual species. Males have been found in most of the parthenogens studied. At least some of these seem to result from crosses between parthenogens and males of sympatric bisexual species. In a few instances, however, this seems unlikely. The evidence supporting the hybrid origin of these males rests on a few studies which show that these males have one more genome than the female parthenogens they resemble. The evolution and origin of parthenogens probably is through hybridization fol? lowed by further hybridization in some genera leading to triploidy. Evidence for these hypotheses is provided by a number of karyotype studies, skin transplants, and studies of various proteins. One study indicates that the somatic chromosome number is restored during oogenesis by an endoduplication immediately preceeding meiosis. Cne- midophorus uniparens, the species in which this phenomenon was demonstrated, is a triploid. Evolutionary aspects of parthenogenesis are discussed.

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