Protein adaptation and biogeography: Threshold effects on molecular evolution

Protein adaptations to the physical environment play critical roles in determining the biogeographical distributions of species. The study of closely related species in habitats differing slightly in temperature or pressure offers an excellent experimental approach for discerning environmental thresholds of protein perturbation and the types of amino acid substitutions that are effective in maintaining optimal protein properties. These adaptations may involve amino acid replacements other than at the active site residues involved in catalysis or binding, a discovery with implications for the debate between adherents to the Neutralist and Selectionist points of view.