Strong regional heterogeneity in base composition evolution on the Drosophila X chromosome.

ABSTRACT: Fluctuations in base composition appear to be prevalent in Drosophila and mammal genome evolution, but their timescale, genomic breadth, and causes remain obscure. Here, we study base composition evolution within the X chromosomes of Drosophila melanogaster and five of its close relatives. Substitutions were inferred on six extant and two ancestral lineages for 14 near-telomeric and 9 nontelomeric genes. GC content evolution is highly variable both within the genome and within the phylogenetic tree. In the lineages leading to D. yakuba and D. orena, GC content at silent sites has increased rapidly near telomeres, but has decreased in more proximal (nontelomeric) regions. D. orena shows a 17-fold excess of GC-increasing vs. AT-increasing synonymous changes within a small (approximately 130-

SUBMITTER: Ko WY 

PROVIDER: S-EPMC1569809 | biostudies-literature | 2006 Sep

REPOSITORIES: biostudies-literature