No abstract

Atlantic slope of Mexico and Guatemala. The stocks of shortfin mollies used by the Hubbses (and by Meyer, who obtained his material from them) were descended largely from progenitors collected on the Pacific coast of Mexico near Acapulco (L. C. Hubbs, pers. comm.). They were therefore most likely P. butleri or P. sphenops (both sensu Schultz and Miller, 1971), or perhaps inadvertent laboratory hybrids of one of these species with the other or with P. mexicana. In other words, the attempts to produce gynogenetic P. formosa in the laboratory by interspecific hybridization were probably done with what later turned out to be at least one "wrong" species.To our knowledge, there have been no subsequent attempts to produce gynogens by interspecific hybridization of Poecilia species. Prompted by this, and by the successful laboratory "synthesis" of hybridogenetic unisexual Poeciliopsis by direct hybridization of bisexual progenitor species (Schultz, 1973(Schultz, , 1977, we hypothesized that hybridization of the "correct" Poecilia species should produce at least some gynogenetic progeny. Moreover, if gynogens could be easily synthesized, the interfertility of other shortfin mollies in laboratory crosses would provide a ready-made system (complete with allozyme markers) in which the genetic bases of hybrid unisexuality could be studied in detail. The results presented here, however, indicate that our hypothesis was incorrect or at least incomplete; laboratory hybrid progeny of P. latipinna and P. mexicana are not gynogenetic. MATERIALS AND METHODSOur experiments took advantage of the relative ease with which mollies can be cultivated and interbred in laboratory aquaria. Hybridization was accomplished 917

No abstract

Atlantic slope of Mexico and Guatemala. The stocks of shortfin mollies used by the Hubbses (and by Meyer, who obtained his material from them) were descended largely from progenitors collected on the Pacific coast of Mexico near Acapulco (L. C. Hubbs, pers. comm.). They were therefore most likely P. butleri or P. sphenops (both sensu Schultz and Miller, 1971), or perhaps inadvertent laboratory hybrids of one of these species with the other or with P. mexicana. In other words, the attempts to produce gynogenetic P. formosa in the laboratory by interspecific hybridization were probably done with what later turned out to be at least one "wrong" species.To our knowledge, there have been no subsequent attempts to produce gynogens by interspecific hybridization of Poecilia species. Prompted by this, and by the successful laboratory "synthesis" of hybridogenetic unisexual Poeciliopsis by direct hybridization of bisexual progenitor species (Schultz, 1973(Schultz, , 1977, we hypothesized that hybridization of the "correct" Poecilia species should produce at least some gynogenetic progeny. Moreover, if gynogens could be easily synthesized, the interfertility of other shortfin mollies in laboratory crosses would provide a ready-made system (complete with allozyme markers) in which the genetic bases of hybrid unisexuality could be studied in detail. The results presented here, however, indicate that our hypothesis was incorrect or at least incomplete; laboratory hybrid progeny of P. latipinna and P. mexicana are not gynogenetic. MATERIALS AND METHODSOur experiments took advantage of the relative ease with which mollies can be cultivated and interbred in laboratory aquaria. Hybridization was accomplished 917

No abstract