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Chromosomal and allelic variation in Drosophila americana: selective maintenance of a chromosomal cline
Journal article   Peer reviewed

Chromosomal and allelic variation in Drosophila americana: selective maintenance of a chromosomal cline

Bryant F McAllister
Genome, Vol.45(1), pp.13-21
02/2002
DOI: 10.1139/g01-112
PMID: 11908655
url
https://doi.org/10.1139/G01-112View
Open Access

Abstract

Geographically structured genetic variation, as represented by clines and hybrid zones, offers unique opportunities to study adaptation and speciation in natural populations. A hybrid zone has been reported between Drosophila americana americana and Drosophila americana texana, two taxa that are distinguished solely by the arrangement of their X and 4th chromosomes. In this study, samples of D. americana were collected along a latitudinal transect across the inferred hybrid zone, and the frequency of the alternative chromosomal arrangements is reported. These data illustrate that the alternative chromosomal arrangements are distributed along a shallow cline over a broad geographic region, and that the frequency of the arrangements is tightly correlated with latitude. Allelic variants at 13 RFLP loci in three genes on chromosome 4 exhibit no evidence of association with the cline. Presence of a cline for the chromosomal arrangements, as well as a general absence of geographic structure for variation at these genes, is interpreted as evidence that natural selection is responsible for the maintenance of this chromosomal cline. Furthermore, these results demonstrate that taxonomic subdivision of D. americana is unwarranted, because it exists as a cohesive species that is segregating a chromosomal fusion.
 Biological Evolution Genetic Variation Animals Polymorphism, Restriction Fragment Length Gene Frequency Karyotyping Chromosome Aberrations X Chromosome Linear Models Chromosomes Drosophila - genetics

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