Non-neutral processes drive the nucleotide composition of non-coding sequences in Drosophila

Penelope R. Haddrill, Brian Charlesworth

Research output: Contribution to journalArticlepeer-review


The nature of the forces affecting base composition is a key question in genome evolution. There is uncertainty as to whether differences in the GC contents of non-coding sequences reflect differences in mutational bias, or in the intensity of selection or biased gene conversion. We have used a polymorphism dataset for non-coding sequences on the X chromosome of Drosophila simulans to examine this question. The proportion of GC --> AT versus AT --> GC polymorphic mutations in a locus is correlated with its GC content. This implies the action of forces that favour GC over AT base pairs, which are apparently strongest in GC-rich sequences.

Original languageEnglish
Pages (from-to)438-441
Number of pages4
JournalBiology letters
Issue number4
Early online date27 May 2008
Publication statusPublished - 23 Aug 2008


  • GC content
  • biased gene conversion
  • selection
  • Drosophila

Cite this