Evidence for Selection at the fused1 Locus of Drosophila americana

Corresponding author: Jorge Vieira, Departamento de Genética Molecular, Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, Porto 4150-180, Portugal., jbvieira{at}ibmc.up.pt (E-mail)

Communicating editor: G. B. GOLDING

We analyze genetic variation at fused1, a locus that is close to the centromere of the X chromosome-autosome (X/4) fusion in Drosophila americana. In contrast to other X-linked and autosomal genes, for which a lack of population subdivision in D. americana has been observed at the DNA level, we find strong haplotype structure associated with the alternative chromosomal arrangements. There are several derived fixed differences at fused1 (including one amino acid replacement) between two haplotype classes of this locus. From these results, we obtain an estimate of an age of 0.61 million years for the origin of the two haplotypes of the fused1 gene. Haplotypes associated with the X/4 fusion have less DNA sequence variation at fused1 than haplotypes associated with the ancestral chromosome arrangement. The X/4 haplotypes also exhibit clinal variation for the allele frequencies of the three most common amino acid replacement polymorphisms, but not for adjacent silent polymorphisms. These patterns of variation are best explained as a result of selection acting on amino acid substitutions, with geographic variation in selection pressures.

This article has been cited by other articles:

				S. W. Schaeffer, A. Bhutkar, B. F. McAllister, M. Matsuda, L. M. Matzkin, P. M. O'Grady, C. Rohde, V. L. S. Valente, M. Aguade, W. W. Anderson, et al. Polytene Chromosomal Maps of 11 Drosophila Species: The Order of Genomic Scaffolds Inferred From Genetic and Physical Maps Genetics, July 1, 2008; 179(3): 1601 - 1655. [Abstract] [Full Text] [PDF]

				A. L. Evans, P. A. Mena, and B. F. McAllister Positive Selection Near an Inversion Breakpoint on the Neo-X Chromosome of Drosophila americana Genetics, November 1, 2007; 177(3): 1303 - 1319. [Abstract] [Full Text] [PDF]

				X. Maside and B. Charlesworth Patterns of Molecular Variation and Evolution in Drosophila americana and Its Relatives Genetics, August 1, 2007; 176(4): 2293 - 2305. [Abstract] [Full Text] [PDF]

				E. Santiago and A. Caballero Variation After a Selective Sweep in a Subdivided Population Genetics, January 1, 2005; 169(1): 475 - 483. [Abstract] [Full Text] [PDF]

				B. F. McAllister Sequence Differentiation Associated With an Inversion on the Neo-X Chromosome of Drosophila americana Genetics, November 1, 2003; 165(3): 1317 - 1328. [Abstract] [Full Text] [PDF]

				A. Navarro-Sabate, M. Aguade, and C. Segarra Excess of Nonsynonymous Polymorphism at Acph-1 in Different Gene Arrangements of Drosophila subobscura Mol. Biol. Evol., November 1, 2003; 20(11): 1833 - 1843. [Abstract] [Full Text] [PDF]

				C. P. Vieira, P. A. Coelho, and J. Vieira Inferences on the Evolutionary History of the Drosophila americana Polymorphic X/4 Fusion From Patterns of Polymorphism at the X-Linked paralytic and elav Genes Genetics, August 1, 2003; 164(4): 1459 - 1469. [Abstract] [Full Text] [PDF]

				A. Navarro and N. H. Barton Chromosomal Speciation and Molecular Divergence--Accelerated Evolution in Rearranged Chromosomes Science, April 11, 2003; 300(5617): 321 - 324. [Abstract] [Full Text] [PDF]

				J. Vieira Two Divergent Species of the Virilis Group, Drosophila littoralis and Drosophila virilis, Share a Replacement Polymorphism at the fused Locus Mol. Biol. Evol., April 1, 2002; 19(4): 579 - 581. [Full Text] [PDF]