Clines
Mostrando 1-12 de 46 artigos, teses e dissertações.
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1. Chromosomal inversion polymorphism in Drosophila mediopunctata : seasonal, altitudinal, and latitudinal variation
The most polymorphic chromosome for inversions in Drosophila mediopunctata is the chromosome II, where 17 inversions have been found, eight of which occurring in the distal region and nine in the proximal region. We present an analysis of the chromosome II inversion polymorphism with respect to seasonal, altitudinal and latitudinal variation. In D. mediopunc
Publicado em: 2010
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2. Variação morfologica em populações brasileiras de Drosophila melanogaster : variação latitudinal e temporal, herdabilidade e associação com inversões cromossomicas / Morphological variation in Brazilian populations of Drosophila melanogaster: latitudinal and temporal variation, heritability and association with chromossomal inversions
O presente trabalho tem como objetivo caracterizar a variação do tamanho e forma das asas de populações de Drosophila melanogaster em três pontos ao longo de uma grande amplitude latitudinal na costa brasileira. O trabalho foi feito a partir de coletas realizadas no Recife, Rio de Janeiro e Porto Alegre, e os seguintes aspectos foram abordados: 1) varia
Publicado em: 2006
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3. Chromosomal inversion polymorphism in Drosophila mediopunctata: seasonal, altitudinal, and latitudinal variation
The most polymorphic chromosome for inversions in Drosophila mediopunctata is the chromosome II, where 17 inversions have been found, eight of which occurring in the distal region and nine in the proximal region. We present an analysis of the chromosome II inversion polymorphism with respect to seasonal, altitudinal and latitudinal variation. In D. mediopunc
Genetics and Molecular Biology. Publicado em: 2004
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4. Inversions Fail to Account for Allozyme Clines
Allozyme and inversion data from natural populations of Drosophila melanogaster from the eastern United States were analyzed to determine whether the clines at allozyme loci are due to nonrandom associations with common cosmopolitan inversions. All inversions show strong clines. Clines were large and significant for half of the eight allozyme loci. An analy
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5. The Genetic Structure of a Tribal Population, the Yanomama Indians. Xiv. Clines and Their Interpretation
The Yanomama Indians are a South American tribe distributed over an irregular area approximately 200 x 300 miles. The gene frequencies observed at 12 loci in 47 villages within this area have been analyzed for the occurrence of clines. Apparently significant clines are observed for alleles of the Rh, MNSs, Kidd, Gm, Inv and serum albumin system. Available da
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6. Chromosome Inversion Polymorphisms in DROSOPHILA MELANOGASTER. I. Latitudinal Clines and Associations between Inversions in Australasian Populations
Nineteen Australasian populations of Drosophila melanogaster have been screened for chromosome inversion polymorphisms. All 15 of the inversion types found are paracentric and autosomal, but only four of these, one on each of the major autosome arms, are common and cosmopolitan. North-south clines occur, with the frequencies of all four of the common cosmopo
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7. Inference from Clines Stabilized by Frequency-Dependent Selection
Frequency-dependent selection against rare forms can maintain clines. For weak selection, s, in simple linear models of frequency-dependence, single locus clines are stabilized with a maximum slope of between &s/ &8 σ and &s/ &12 δ, where σ is the dispersal distance. These clines are similar to those maintained by heterozygote disadvantage. Using comput
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8. Inversion Clines in Populations of DROSOPHILA MELANOGASTER
Twenty different natural populations of Drosophila melanogaster were sampled to determine the frequencies of inversions. Based on their frequencies and geographical distributions, the inversions could be classified as follows: (1) Common cosmopolitan inversions that are present in many populations in frequencies exceeding five percent and that may exhibit f
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9. Structural analysis of an electrophoretically cryptic alcohol dehydrogenase variant from an Australian population of Drosophila melanogaster.
The existence of geographically widespread clines in genetic polymorphisms is persuasive evidence that the distribution of such genetic variance is determined by natural selection. However, when comparing clines it is important to be certain that identical structural genes are involved. We report a structural difference (proline-214 to serine) between the pr
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10. Allopatric genetic origins for sympatric host-plant shifts and race formation in Rhagoletis
Tephritid fruit flies belonging to the Rhagoletis pomonella sibling species complex are controversial because they have been proposed to diverge in sympatry (in the absence of geographic isolation) by shifting and adapting to new host plants. Here, we report evidence suggesting a surprising source of genetic variation contributing to sympatric host shift
National Academy of Sciences.
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11. Variance Component Analysis of Allozyme Frequency Data from Eastern Populations of DROSOPHILA MELANOGASTER
Gene frequency variation at eight polymorphic allozyme loci in Drosophila melanogaster populations in North Carolina and the east coast of the United States were analyzed utilizing the variance component estimation procedures suggested by Cockerham (1969, 1973). These variance components were used to estimate correlations of genes within small geographic re
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12. Genetic Drift in Clines Which Are Maintained by Migration and Natural Selection
Genetic drift will cause a migration-selection cline to wobble about its expected position. A rough linear approximation is developed, valid when local populations are large. This is used to calculate effects of genetic drift on clines in a stepping-stone model with abrupt and with gradual changes of selection coefficients at a single haploid locus. Among th