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EVOLUTIONARY GENETICS OF A GYNOGENETIC FISH, POECILIA FORMOSA , THE AMAZON MOLLY
Author(s) -
Turner Bruce J.,
Brett BettyLou H.,
Rasch Ellen M.,
Balsano Joseph S.
Publication year - 1980
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1980.tb04813.x
Subject(s) - reprint , state (computer science) , library science , biology , sociology , computer science , physics , algorithm , astronomy
The application of allozyme and other genetic techniques to the study of unisexual vertebrates has led to the realization that all or nearly all of them possess genomes with a relatively high proportion of loci essentially fixed in the heterozygous state (e.g., Parker and Selander, 1976; Schultz, 1977; Vrijenhoek et al., 1977, 1978); this is apparently a consequence of their interspecific hybrid ancestry coupled with thelytokous breeding systems. The "Amazon Molly," Poecilia (formerly Mollienesia) formosa (Fig. 1), the first known unisexual vertebrate (Hubbs and Hubbs, 1932), has been under more or less continuous study since the discovery of its unusual reproductive biology (Table 1), but several basic features of its evolutionary biology have not yet been elucidated. For example, hybrid ancestry is strongly suggested by morphological evidence and by electrophoretic data from a single serum albumin locus, but a detailed analysis of the heterozygosity or possible ancestry of the P. formosa genome has not been available. What proportion of loci are heterozygous? What proportion of loci are variable within populations? Is a particular hybrid ancestry unambiguously suggested by the specific alleles at fixed heterozygous loci? This paper presents the results of an allozyme survey of the protein products of more than 30 loci in samples of P. formosa, its putative ancestral bisexual species, and some other forms closely related to them. The data reveal that while some aspects of the evolutionary genetics of P. formosa are rather similar to those of other unisexual animals, others appear unique: there are several seemingly invariant components of the P. formosa genome that are thus far not identifiable in the genomes of any potential parental bisexual species which we have been able to survey. The results thus suggest that the origin of vertebrate parthenoforms by interspecific hybridization may be biologically more complex than hitherto appreciated.