Degree of Selective Constraint as an Explanation of the Different Rates of Evolution of Gender-Specific Mitochondrial DNA Lineages in the Mussel Mytilus
AUTOR(ES)
Stewart, D. T.
RESUMO
Mussels of the genus Mytilus segregate for a maternally transmitted F lineage and a paternally transmitted M lineage of mitochondrial DNA. Previous studies demonstrated that these lineages are older than the species of the M. edulis complex and that the M lineage evolves faster than the F lineage. Here we show that the latter observation also applies to a region of the molecule with no assigned function. Sequence data for the mitochondrial COIII gene and the ``unassigned'' region of the F and M lineages of M. edulis and M. trossulus are used to evaluate various hypotheses that may account for the faster rate of evolution of the M lineage. Tests based on the proportion of synonymous and nonsynonymous substitutions suggest that the M lineage experiences relatively relaxed selection. Further support for this hypothesis comes from an examination of COIII amino acid substitutions at sites defined as either conserved or variable based on the pattern of variation in other mollusks and Drosophila. Most substitutions in the M lineage occur in regions that are also variable among non-Mytilus taxa. We suggest that these differences in selection pressure are a consequence of doubly uniparental mitochondrial DNA transmission in Mytilus.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1207403Documentos Relacionados
- Species-Specific Segregation of Gender-Associated Mitochondrial DNA Types in an Area Where Two Mussel Species (Mytilus Edulis and M. Trossulus) Hybridize
- An unusual type of mitochondrial DNA inheritance in the blue mussel Mytilus.
- Gender-specific risk factors for gout: a systematic review of cohort studies
- Effect of concurrent training on gender-specific biochemical variables and adiposity in obese adolescents
- Ageing and telomeres: a study into organ- and gender-specific telomere shortening