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Transfer of genetic information in the rp49 region of Drosophila subobscura between different chromosomal gene arrangements.

ABSTRACT: Nucleotide variation in the region including the ribosomal protein 49 (rp49) gene was investigated by direct sequencing of 10 alleles of Drosophila subobscura from chromosomes differing in gene arrangements. Fifty-six nucleotide and seven length polymorphisms were detected over a 1.5-kb region. Of the 20 nucleotide polymorphisms present more than once in the sample, 13 were segregating in O[3 + 4], 9 in O[3 + 4 + 8], and 4 in O[st] chromosomal classes. Several of these polymorphisms were segregating in more than one chromosomal class, a strong indication of genetic transfer between different chromosomal gene arrangements either by double crossover or gene conversion. Given the probable role played by gene conversion in the history of the rp49 region in D. subobscura, estimates of nucleotide diversity within chromosomal class indicate that the O[3 + 4] chromosomal gene arrangement is older than the O[st] arrangement.

SUBMITTER: Rozas J

PROVIDER: S-EPMC47292 | biostudies-other | 1993 Sep

REPOSITORIES: biostudies-other

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Transfer of genetic information in the rp49 region of Drosophila subobscura between different chromosomal gene arrangements.

Rozas J J Aguadé M M

Proceedings of the National Academy of Sciences of the United States of America 19930901 17

Nucleotide variation in the region including the ribosomal protein 49 (rp49) gene was investigated by direct sequencing of 10 alleles of Drosophila subobscura from chromosomes differing in gene arrangements. Fifty-six nucleotide and seven length polymorphisms were detected over a 1.5-kb region. Of the 20 nucleotide polymorphisms present more than once in the sample, 13 were segregating in O[3 + 4], 9 in O[3 + 4 + 8], and 4 in O[st] chromosomal classes. Several of these polymorphisms were segrega ...[more]

PMID: 8367467

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Project description:BackgroundThe role of chromosomal arrangements in adaptation is supported by the repeatable clinal variation in inversion frequencies across continents in colonizing species such as Drosophila subobscura. However, there is a lack of knowledge on the genetic variation in genes within inversions, possibly targets of climatic selection, across a geographic latitudinal gradient. In the present study we analysed four candidate loci for thermal adaptation, located close to the breakpoints, in two chromosomal arrangements of the sex (A) chromosome of Drosophila subobscura with different thermal preferences. Individual chromosomes with A2 (the inverted arrangement considered warm adapted) or AST (the standard ancestral arrangement considered cold adapted) were sequenced across four European localities at varying latitudes, up to ~ 2500 Kms apart.ResultsImportantly, we found very low differentiation for each specific arrangement across populations as well as no clinal patterns of genomic variation. This suggests wide gene exchange along the cline. Differentiation between the sex chromosome arrangements was significant in the two more proximal regions relative to the AST orientation but not in the distal ones, independently of their location inside or outside the inversion. This can be possibly due to variation in the levels of gene flux and/or selection acting in these regions.ConclusionsGene flow appears to have homogenized the genetic content within-arrangement at a wide geographical scale, despite the expected diverse selective pressures in the specific natural environments of the different populations sampled. It is thus likely that the inversion frequency clines in this species are being maintained by local adaptation in face of gene flow. The differences between arrangements at non-coding regions might be associated with the previously observed differential gene expression in different thermal regimes. Higher resolution genomic scans for individual chromosomal arrangements performed over a large environmental gradient are needed to find the targets of selection and further elucidate the adaptive mechanisms maintaining chromosomal inversion polymorphisms.

Dataset Information

Transfer of genetic information in the rp49 region of Drosophila subobscura between different chromosomal gene arrangements.

Publications

Transfer of genetic information in the rp49 region of Drosophila subobscura between different chromosomal gene arrangements.

Similar Datasets

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