Electrophoretic Evidence of Triploidy Associated with Populations of the Gynogenetic Teleost Poecilia formosa
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American Society of Ichthyologists and Herpetologists
The all-female, gynogenetic teleost Poecilia formosa is a species of presumed hybrid origin that exists in nature as a series of histocompatibility clones. Occasional triploids have been observed in laboratory populations as well as offspring that exhibited some paternal inheritance. Recently triploids were obtained from natural populations of P. formosa. When electrophoretically separated in polyacrylamide gels, the plasma proteins of the known triploids exhibited an albumin phenotype that differed from that of P. formosa and sympatric congeners. Consequently, it is possible to determine the frequency of triploidy by screening the albumin phenotypes of natural populations. The ratio of P. formosa to triploid phenotypes ranged from 1:0.24 to1:34.0 in at least five different populations sampled throughout its known range. Two other inland populations had P. formosa but no triploids. Electrophoretic data are in agreement with cytological and morphological data. This report indicates that triploids are frequently associated in large numbers with natural populations of P. formosa. Hence, support is given to recent suggestions that the role of hybridization and polyploidy in animal speciation must be re-examined.