Genetic evidence for natural hybridization and apparent introgression between freshwater snail species (Viviparus ater and V. contectus)

Autor: G. Ribi, M. Katoh
Rok vydání: 1996
Předmět:
Zdroj: Journal of Evolutionary Biology. 9:67-82
ISSN: 1420-9101
1010-061X
DOI: 10.1046/j.1420-9101.1996.9010067.x
Popis: We examined six allozyme markers and shell morphology to study gene flow between the naturally sympatric freshwater snail species Viviparus ater and V. contectus in Lake Garda, Italy, using offspring from experimental crosses and snails collected from natural populations. Hybrid offspring obtained from experimental crosses and hybrids collected from natural populations were heterozygous at four or five out of five diagnostic loci. Shell morphology was a poor predictor of the hybrid status of individual snails. Backcrossed offspring from experimentally bred hybrids and either of the parental species morphologically resembled the parental species. There was no evidence of segregation distortion at the six loci. Linkage analysis revealed one pair of linked loci (GPI and PNP). These cross experiments indicated a Mendelian type hybrid system in which gene introgression may occur. F1 hybrids were found at four out of six sampling sites of Lake Garda, Italy. Local frequencies of F1 hybrids ranged from 0% to 1.6% (estimated average = 0.74%) of the total population including both species. Alleles typical of V. ater were found at low frequencies in V. contectus at all six sampling sites. Alleles typical of V. contectus were found at low frequencies in V. ater at three out of six sampling sites. This is consistent with the hypothesis of introgression in both directions.
Databáze: OpenAIRE
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