Hybridization Between Species of the Rana pipiens Complex in Central Texas

Sage, Richard D.; Selander, Robert K.

doi:10.2307/2407468

Cited by 55 publications

(46 citation statements)

References 25 publications

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“…The allele always occurs at low frequency outside the hybrid zone, but is found at relatively high frequency in most of the mixed/intermediate populations. Other hybrid zone studies have documented similar phenomena (the "rare allele phenomenon"-see Sage and Selander, 1979). One explanation for this pattern is that the allele is of hybrid origin, perhaps having arisen via intragenic recombination in an individual of mixed ancestry (see Watt, 1972).…”

Section: Consequences Of a Mosaic Hybrid Zonementioning

confidence: 83%

Pattern and process in a narrow hybrid zone

1986

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This paper examines variation in morphology and allozymes in a hybrid zone between two closely related eastern North American species of field cricket (genus Gryllus). I show that patterns of variation across the zone do not conform to a simple model of monotonic clinal variation. In fact, the hybrid zone is a mosaic of populations. Pockets of "pure" parental forms are found within the hybrid zone, and striking reversals in mean character index score occur along transects across the zone. Treating hybrid zones as mosaics has important consequences for thinking about the dynamics of such zones.Patterns of variation in morphology and allozymes are not concordant across the hybrid zone. Rather, there is strong evidence for differential and asymmetric introgression, with morphological integrity maintained despite considerable introgression of alleles at allozyme loci. Species boundaries must be thought of as semipermeable, the permeability varying with he genetic marker used.I also show that there is strong positive assortative mating at one site within the hybrid zone and that assortative mating persists despite introgression at allozyme loci. Habitat isolation and behavioural differences may both affect the extent of assortative mating.

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Section: Consequences Of a Mosaic Hybrid Zonementioning

confidence: 83%

Pattern and process in a narrow hybrid zone

1986

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“…As an indication of the possible impact of hybrid release on the rate of genetic change in nature, Woodruff and Thompson (1982b, and in preparation) have observed that the progeny from 25 of 90 crosses between natural population lines of D. melanogaster have a significantly higher frequency of spontaneous lethal mutations than do the base populations, and similar values have been observed for spontaneous breakage in hybrid progeny. One consequence of the intraspecific release of mutator activity is that high levels of rare genetic variants observed in hybrid zones (Hunt and Selander, 1973;Avise and Smith, 1974;Kilpatrick and Zimmerman, 1976;Gould and Woodruff, 1978;Sage and Selander, 1979;Smith, 1979;Moran et a!., 1980;Greenbaum, 1981;Hafner, 1982;Peters, 1982;Barton et aL, 1983) may be due to increased rates of mutation (Woodruff et aL, 1979;Thompson and Woodruff, 1980), although intragenic recombination could also explain these variants (Golding and Strobeck, 1983). Support for increased rates of mutation as the cause of the increased genetic variation in hybrid zones comes from the observation that high frequencies of novel chromosome re-arrangements are observed in hybrid zones of grasshoppers and the re-arrangements are derived only from hybrid parents (Shaw et aL, 1983).…”

Section: Discussionmentioning

confidence: 99%

Variation in spontaneous mutation and repair in natural population lines of Drosophila melanogaster

et al. 1984

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SUMMARYTo measure the possible correlation between genetic damage and repair ability in natural populations of a eukaryote, we compared the spontaneous frequency of sex-linked recessive lethal mutations and male recombination, which is associated with DNA transposable element induced chromosome breakage, with DNA repair efficiency in isofemale lines of a winery population of Drosophila melanogaster from Australia. Repair efficiency was measured by maternal effects on ring-X chromosome loss. Significant amounts of genetic variability for spontaneous rates of genetic change and for repair ability were observed in the isofemale lines collected during periods of low and high population density. However, there were no correlations between repair ability and rates of genetic damage. Possible reasons for the absence of correlation are discussed, along with the observations that: (a) the frequency of lethal mutations and ring-X chromosome losses were significantly higher in the small, resident population; (b) the rates of ring chromosome losses and especially lethal mutations are uniform over periods of time; (c) and inbreeding of isofemale lines leads to a reduction of the high spontaneous mutation rates.

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“…According to Sage and Selander (1979), protein electrophoresis can reveal hybridization zones because they sometimes contain rare alleles not found in any of the parental semi-species. Such alleles may have resulted from a high mutation index in the hybrid genoma, or be formed by intra-genetic recombination between different alleles of the parental populations.…”

Section: Seroprotein Electrophoresismentioning

confidence: 99%

Comparative cytogenetic studies of Bufo ictericus, B. paracnemis (Amphibia, Anura) and an intermediate form in sympatry

et al. 2003

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Specimens of Bufo ictericus, Bufo paracnemis and a third type, considered an intermediate subgroup between these species, were cytogenetically studied by conventional Giemsa staining, C-banding and staining of the nucleolus organizer region (NOR). The nuclear DNA content and seroproteins were also analyzed to characterize these species, and verify the possibility of hybridization between them. Karyotypes and cytogenetic markers were essentially equal on the basis of the methods used. The DNA nuclear content found was 6.25 ± 0.30 pg/DNA in Bufo ictericus; 7.57 ± 0.40 pg/DNA in Bufo paracnemis and 7.04 ± 0.29 pg/DNA in the intermediate subgroup.Eletrophoresis of total blood serum in Bufo ictericus, Bufo paracnemis and the intermediate specimens revealed a remarkable difference in the patterns of the protein bands whose molecular weight corresponded to that of albumin. While the parental species presented two different bands, the intermediate form presented 4. However, only three of these bands were seen in each specimen. The results obtained pointed to a high probability for natural hybridization between Bufo ictericus and Bufo paracnemis in the site and specimens studied.

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Hybridization Between Species of the Rana pipiens Complex in Central Texas

Cited by 55 publications

References 25 publications

Pattern and process in a narrow hybrid zone

Pattern and process in a narrow hybrid zone

Variation in spontaneous mutation and repair in natural population lines of Drosophila melanogaster

Comparative cytogenetic studies of Bufo ictericus, B. paracnemis (Amphibia, Anura) and an intermediate form in sympatry

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