Fluctuating Mutation Bias and the Evolution of Base Composition in Drosophila |
| |
Authors: | Francisco Rodríguez-Trelles Rosa Tarrío Francisco J Ayala |
| |
Institution: | (1) Department of Ecology and Evolutionary Biology, 321 Steinhaus Hall, University of California, Irvine, CA 92697-2525, USA, US |
| |
Abstract: | The idea that the pattern of point mutation in Drosophila has remained constant during the evolution of the genus has recently been challenged. A study of the nucleotide composition
focused on the Drosophila
saltans group has evidenced unsuspected nucleotide composition differences among lineages. Compositional differences are associated
with an accelerated rate of amino acid replacement in functionally less constrained regions. Here we reassess this issue from
a different perspective. Adopting a maximum-likelihood estimation approach, we focus on the different predictions that mutation
and selection make about the nonsynonymous-to-synonymous rate ratio. We investigate two gene regions, alcohol dehydrogenase
(Adh) and xanthine dehydrogenase (Xdh), using a balanced data set that comprises representatives from the melangaster, obscura, saltans, and willistoni groups. We also consider representatives of the Hawaiian picture-winged group. These Hawaiian species are known to have experienced
repeated bottlenecks and are included as a reference for comparison. Our results confirm patterns previously detected. The
branch ancestral to the fast-evolving willistoni/saltans lineage, where most of the change in GC content has occurred, exhibits an excess of synonymous substitutions. The shift in
mutation bias has affected the extent of the rate variation among sites in Xdh.
Received: 4 May 1999 / Accepted: 26 July 1999 |
| |
Keywords: | : Mutation bias — Nucleotide composition — Nonsynonymous/synonymous rate ratio — Among-site rate heterogeneity — willistoni group — saltans group |
本文献已被 PubMed SpringerLink 等数据库收录! |
|