Post date: Jun 26, 2014 1:22:59 PM
Nicolas Galtier and I just published a highlight on this interesting paper in F1000 Biology.
In this study, Qiu et al. (2014) report that both body mass and mass-specific metabolic rate are negatively correlated with substitution rate in Scombroid fishes. The originality of this work stands on the fact that, in contrast to most animals, the mass-specific metabolic rate scales positively with body mass in Scombroid fishes, thus providing a unique opportunity to tease apart their effect on the rate of molecular evolution.
Scombroid fishes include large pelagic species (e.g. tunas, sailfishes and swordfish) that are "regionally endothermic" (i.e. able to warm specific organs above the ambient temperature) and other, often smaller, ectothermic species. This creates a positive correlation between body mass and mass-specific metabolic rate.
Estimating substitution rate using both nuclear and mitochondrial markers, the authors demonstrate that the mass-specific metabolic rate is negatively associated with substitution rate – a result contradicting the metabolic rate hypothesis (e.g., Gillooly et al. 2005). Additionally, there is a clear negative association between body mass and substitution rate, thus supporting alternative hypotheses such as the generation time hypothesis.
References :
Qiu F, Kitchen A, Burleigh JG, Miyamoto MM (2014) Scombroid Fishes Provide Novel Insights into the Trait/Rate Associations of Molecular Evolution. Journal of Molecular Evolution, 1–11.
Gillooly JF, Allen AP, West GB, Brown JH (2005) The rate of DNA evolution: effects of body size and temperature on the molecular clock. Proceedings of the National Academy of Sciences of the United States of America, 102, 140–145.