title: 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.
abstract: In Drosophila there is limited evidence on the nature of evolutionary forces affecting chromosomal arrangements other than inversions. The study of the X/4 fusion polymorphism of Drosophila americana is thus of interest. Polymorphism patterns at the paralytic (para) gene, located at the base of the X chromosome, suggest that there is suppressed crossing over in this region between fusion and nonfusion chromosomes but not within fusion and nonfusion chromosomes. These data are thus compatible with previous claims that within fusion chromosomes the amino acid clines found at fused1 (also located at the base of the X chromosome) are likely maintained by local selection. The para data set also suggests a young age of the X/4 fusion. Polymorphism data on para and elav (located at the middle region of the X chromosome) suggest that there is no population structure other than that caused by the X/4 fusion itself. These findings are therefore compatible with previous claims that selection maintains the strong association observed between the methionine/threonine variants at fused1 and the status of the X chromosome as fused or unfused to the fourth chromosome.
authors.affiliation: Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, Porto 4150-180, Portugal. cgvieira@ibmc.up.pt
authors.forename: Cristina P
authors.initials: CP
authors.lastname: Vieira
authors.forename: Paula A
authors.initials: PA
authors.lastname: Coelho
authors.forename: Jorge
authors.initials: J
authors.lastname: Vieira
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002875:Chromosomes; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D051959:ELAV Proteins; D017344:Genes, Insect; D008040:Genetic Linkage; D006239:Haplotypes; D006570:Heterochromatin / Q000235:genetics; D017403:In Situ Hybridization; D007438:Introns; D008297:Male; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D012261:Ribonucleoproteins / Q000235:genetics*; D015222:Sodium Channels / Q000235:genetics*; D014960:X Chromosome
chemical_list: D029721:Drosophila Proteins; D051959:ELAV Proteins; D006570:Heterochromatin; D012261:Ribonucleoproteins; D015222:Sodium Channels; C469950:para protein, Drosophila; D000444:Aldehyde Dehydrogenase