LOW METABOLIC RATES IN SALAMANDERS ARE CORRELATED WITH WEAK SELECTIVE CONSTRAINTS ON MITOCHONDRIAL GENES
Version of Record online: 16 NOV 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 67, Issue 3, pages 894–899, March 2013
How to Cite
Chong, R. A. and Mueller, R. L. (2013), LOW METABOLIC RATES IN SALAMANDERS ARE CORRELATED WITH WEAK SELECTIVE CONSTRAINTS ON MITOCHONDRIAL GENES. Evolution, 67: 894–899. doi: 10.1111/j.1558-5646.2012.01830.x
- Issue online: 5 MAR 2013
- Version of Record online: 16 NOV 2012
- Accepted manuscript online: 22 OCT 2012 08:49AM EST
- Received November 1, 2011 Accepted September 22, 2012
- substitution rates
Mitochondria are the site for the citric acid cycle and oxidative phosphorylation (OXPHOS), the final steps of ATP synthesis via cellular respiration. Each mitochondrion contains its own genome; in vertebrates, this is a small, circular DNA molecule that encodes 13 subunits of the multiprotein OXPHOS electron transport complexes. Vertebrate lineages vary dramatically in metabolic rates; thus, functional constraints on mitochondrial-encoded proteins likely differ, potentially impacting mitochondrial genome evolution. Here, we examine mitochondrial genome evolution in salamanders, which have the lowest metabolic requirements among tetrapods. We show that salamanders experience weaker purifying selection on protein-coding sequences than do frogs, a comparable amphibian clade with higher metabolic rates. In contrast, we find no evidence for weaker selection against mitochondrial genome expansion in salamanders. Together, these results suggest that different aspects of mitochondrial genome evolution (i.e., nucleotide substitution, accumulation of noncoding sequences) are differently affected by metabolic variation across tetrapod lineages.