Life History Traits and the Rate of Molecular Evolution in Galliformes (Aves)

Rates of molecular evolution are known to vary widely among taxonomic groups. A number ofstudies, examining various taxonomic groups, have indicated that body size is negatively and clutch size ispositively correlated with the rates of nucleotide substitutions among vertebrate species. Generally, either smallerbody mass or larger clutch size is associated with shorter generation times and higher metabolic rates. However,this generality is subject to ongoing debate, and large-scale comparative studies of species below the Order levelare lacking. In this study, phylogenetically independent methods were used to test for relationships between ratesof the mitochondrial cytochrome b evolution and a range of life history traits, such as body mass and clutchsize in the Order Galliformes. This analysis included data from 67 species of Galliformes birds and 2 outgroupspecies in Anseriformes. In contrast to previous studies, taxa were limited to within-Order level, not to Classor higher. I found no evidence to support an effect of life history traits on the rate of molecular evolution withinthe Galliformes. These results suggest that such relationship may be too weak to be observed in comparisonsof closely related species or may not be a general pattern that is applicable to all nucleotide sequences or alltaxonomic groups.