Functional convergence in gastric lysozymes of foregut-fermenting rodents, ruminants, and primates is not attributed to convergent molecular evolution

• Published in: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology Vol. 271; p. 110949
• Main Authors: Barts, Nick, Bhatt, Roshni H., Toner, Chelsea, Meyer, Wynn K., Durrant, Jacob D., Kohl, Kevin D.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.04.2024
• Subjects: C-type lysozyme; Convergent evolution; Foregut fermentation; Molecular evolution; Molecular evolution; Foregut fermentation; Convergent evolution; C-type lysozyme
• ISSN: 1096-4959; 1879-1107
• DOI: 10.1016/j.cbpb.2024.110949

Convergent evolution is a widespread phenomenon. While there are many examples of convergent evolution at the phenotypic scale, convergence at the molecular level has been more difficult to identify. A classic example of convergent evolution across scales is that of the digestive lysozyme found in ruminants and Colobine monkeys. These herbivorous species rely on foregut fermentation, which has evolved to function more optimally under acidic conditions. Here, we explored if rodents with similar dietary strategies and digestive morphologies have convergently evolved a lysozyme with digestive functions. At the phenotypic level, we find that rodents with bilocular stomach morphologies exhibited a lysozyme that maintained higher relative activities at low pH values, similar to the lysozymes of ruminants and Colobine monkeys. Additionally, the lysozyme of Peromyscus leucopus shared a similar predicted protonation state as that observed in previously identified digestive lysozymes. However, we found limited evidence of positive selection acting on the lysozyme gene in foregut-fermenting species and did not identify patterns of convergent molecular evolution in this gene. This study emphasizes that phenotypic convergence need not be the result of convergent genetic modifications, and we encourage further exploration into the mechanisms regulating convergence across biological scales. [Display omitted] •Lysozyme is a model for convergent evolution in foregut fermenting mammals.•Herbivorous rodents with distinct foreguts may also possess a digestive lysozyme.•Rodent lysozymes are active at low pH, similar to other foregut fermenters.•Convergence of lysozyme function is not explained by molecular convergence.