Department of Cell Biology, Curriculum Fellows Program, Harvard Medical School, 25 Shattuck St, Boston, Massachusetts, USA.
Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford St, Cambridge, Massachusetts, USA.
J Exp Zool B Mol Dev Evol. 2023 Mar;340(2):162-181. doi: 10.1002/jez.b.23125. Epub 2022 Mar 3.
The development of dimorphic adult sexes is a critical process for most animals, one that is subject to intense selection. Work in vertebrate and insect model species has revealed that sex determination mechanisms vary widely among animal groups. However, this variation is not uniform, with a limited number of conserved factors. Therefore, sex determination offers an excellent context to consider themes and variations in gene network evolution. Here we review the literature describing sex determination in diverse insects. We have screened public genomic sequence databases for orthologs and duplicates of 25 genes involved in insect sex determination, identifying patterns of presence and absence. These genes and a 3.5 reference set of 43 others were used to infer phylogenies and compared to accepted organismal relationships to examine patterns of congruence and divergence. The function of candidate genes for roles in sex determination (virilizer, female-lethal-2-d, transformer-2) and sex chromosome dosage compensation (male specific lethal-1, msl-2, msl-3) were tested using RNA interference in the milkweed bug, Oncopeltus fasciatus. None of these candidate genes exhibited conserved roles in these processes. Amidst this variation we wish to highlight the following themes for the evolution of sex determination: (1) Unique features within taxa influence network evolution. (2) Their position in the network influences a component's evolution. Our analyses also suggest an inverse association of protein sequence conservation with functional conservation.
两性成虫的发育是大多数动物的关键过程，这一过程受到强烈的选择。在脊椎动物和昆虫模式物种中的研究表明，性别决定机制在动物群体中差异很大。然而，这种变异并不均匀，只有有限的几个保守因素。因此，性别决定为研究基因网络进化的主题和变化提供了一个极好的背景。在这里，我们回顾了描述不同昆虫性别决定的文献。我们筛选了公共基因组序列数据库，以寻找参与昆虫性别决定的 25 个基因的直系同源物和重复物，确定了它们存在和缺失的模式。这些基因和 3.5 个参考集的 43 个其他基因被用于推断系统发育，并与公认的生物体关系进行比较，以检查一致性和分歧模式。使用 RNA 干扰在乳草虫 Oncopeltus fasciatus 中测试了候选基因在性别决定（雄性化，雌性致死 2-d，变形虫 2）和性染色体剂量补偿（雄性特异性致死 1，msl-2，msl-3）中的作用。这些候选基因在这些过程中没有表现出保守作用。在这种变化中，我们希望强调以下主题：（1）分类群中的独特特征影响网络进化。（2）它们在网络中的位置影响组成部分的进化。我们的分析还表明，蛋白质序列保守性与功能保守性呈负相关。
