Fast molecular evolution associated with high active metabolic rates in poison frogs

Molecular evolution is simultaneously paced by mutation rate, genetic drift, and natural selection. Life history traits also affect the speed of accumulation of nucleotide changes. For instance, small body size, rapid generation time, production of reactive oxygen species, and high resting metabolic rate (RMR) are suggested to be associated with faster rates of molecular evolution. However, phylogenetic correlation analyses failed to support a relationship between RMR and molecular evolution in ectotherms. In addition, resting metabolic rate might underestimate the metabolic budget (e.g., digestion, reproduction or escaping predation). An alternative is to test other metabolic rates, such as active metabolic rate (AMR), and their association with molecular evolution. Here, I present comparative analyses of the associations between life history traits (i.e., AMR, RMR, body mass, and fecundity) with rates of molecular evolution of nuclear and mitochondrial loci from a large ectotherm clade, the poison frogs. My results support a strong positive association between mass-specific AMR and rates of molecular evolution for both mitochondrial and nuclear loci. In addition, I found weaker and genome specific covariates such as mass and fecundity for mitochondrial and nuclear loci, respectively. No direct association was found between mass-specific RMR and rates of molecular evolution. Therefore, a multifactorial model that includes AMR might explain the rates of molecular evolution in ectothermic lineages.