Reviewer #2 (Public review): Heterozygote advantage cannot explain MHC diversity, but MHC diversity can explain heterozygote advantage

This valuable study re-evaluates a published simulation model on the role of heterozygote advantage in shaping MHC diversity.By modifying key modeling assumptions, the author argues that the original conclusions depend on a narrow and potentially unrealistic parameter range.While the work is in principle solid, the robustness of this claim is viewed differently by the reviewers.The manuscript further proposes an alternative modeling framework in which expansion of the MHC gene family allows homozygotes to outperform heterozygotes, thereby challenging the idea that heterozygote advantage alone can account for high allelic diversity at MHC loci.The topic is highly relevant for eco-immunology and evolutionary genetics, although a clearer delineation of the model's scope would help readers assess its broader implications.