eLife Assessment
The is a valuable evaluation of a previously published simulation model on the role of heterozygote advantage in shaping MHC diversity, showing that the conclusions from this model hold only within a narrow parameter range that might be unrealistic. The author presents an alternative model, in which MHC homozygotes with duplicated MHC genes outperform heterozygotes with single genes, thereby challenging the explanation that heterozygote advantage will lead to high allelic variation at a given MHC gene. The topic is highly relevant for eco-immunology and evolutionary genetics, but several major aspects of the author's claim need to be clarified to make the model interpretable. While the work has the potential to improve our understanding of the question of how the extraordinary diversity at the MHC locus evolves, without this addition, the conclusions remain incomplete.