In mammals, sexual size dimorphism often reflects the intensity of sexual selection, yet its connection to genomic evolution remains unexplored. Gene family size evolution can reflect shifts in the relative importance of different molecular functions. Here, we investigate the associate between brain development gene repertoire to sexual size dimorphism using 124 mammalian species. We reveal significant changes in gene family size associations with sexual size dimorphism. High levels of dimorphism correlate with an expansion of gene families enriched in olfactory sensory perception and a contraction of gene families associated with brain development functions, many of which exhibited particularly high expression in the human adult brain. These findings suggest a relationship between intense sexual selection and alterations in gene family size. These insights illustrate the complex interplay between sexual dimorphism, gene family size evolution, and their roles in mammalian brain development and function, offering a valuable understanding of mammalian genome evolution.

在哺乳动物中，性别大小二态性通常反映了性选择的强度，但其与基因组进化的联系仍未被探索。基因家族大小的进化可以反映不同分子功能的相对重要性的变化。在这里，我们利用 124 种哺乳动物研究了大脑发育基因库与性别大小二态性之间的关联。我们揭示了基因家族大小与性别大小二态性关联的显着变化。高水平的二态性与富含嗅觉感官知觉的基因家族的扩张和与大脑发育功能相关的基因家族的收缩相关，其中许多基因家族在成人大脑中表现出特别高的表达。这些发现表明强烈的性选择与基因家族大小的改变之间存在关系。这些见解说明了性二态性、基因家族大小进化及其在哺乳动物大脑发育和功能中的作用之间复杂的相互作用，为哺乳动物基因组进化提供了宝贵的理解。