LDH-A and alpha-actin as tools to assess the effects of temperature on the vertebrate genome: some problems

In a recent paper written with the purpose of shedding light on the question of whether genomic GC levels are related to temperature in vertebrates, Ream et al. [Mol. Biol. Evol. 20 (2003) 105] offered an analysis of two sets of homologous genes: those coding for alpha-actin and lactate dehydrogenase-A (LDH-A). The conclusion was that "there is no consistent relationship between adaptation temperature and the percentage of thermal stability-enhancing G+C base pairs in protein-coding genes". We argue here that the data presented neither prove nor suggest such a conclusion because of conceptual and methodological errors.