Walsh Justin, Junker Ian P, Chen Yu-Chieh David, Chen Yen-Chung, Gifford Helena, Ding Yun
Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
Current address: Department of Biological and Biomedical Sciences, Vanderbilt University, Nashville, TN, USA.
bioRxiv. 2025 May 10:2025.05.06.652433. doi: 10.1101/2025.05.06.652433.
Understanding how the cellular and molecular composition of neural circuits change during evolution is essential for deciphering how behavior evolves. Male sexual behaviors in species are remarkably diverse, and the underlying sexual circuits are specified by sex determination genes. Here, we employed single-cell transcriptomics to systematically characterize and compare neuron cell types that express the sex determination gene in adult males across species with divergent sexual behaviors. High-resolution profiling to delineate cellular diversity revealed a largely conserved set of cell types across four species, with minimal evolutionary gain or loss and potentially more prevalent changes in cell type abundance. In-depth comparisons between and showed that transcriptomic conservation and differentially expressed genes between species are highly cell-type-specific, suggesting that cell types evolve as highly independent units. We identified widespread species differences in gene expression, particularly in the neuromodulatory signaling pathway, while preserving a conserved circuit layout in sexual identity and neurotransmitter properties. We further generated a female dataset in to define sex differences in cell types and examine species divergence in relation to sex differences. Finally, we reported marker gene combinations that uniquely define each cell type, providing a foundational resource that enables the design of cell -type-specific genetic reagents. Overall, our study provides fundamental insights into the cellular diversity of sexual circuits and how evolution shapes cell types and gene expression in behavioral adaptations.
了解神经回路的细胞和分子组成在进化过程中如何变化，对于解读行为如何进化至关重要。物种间的雄性性行为差异显著，其潜在的性回路由性别决定基因指定。在这里，我们采用单细胞转录组学系统地表征和比较了在具有不同性行为的多个物种的成年雄性中表达性别决定基因的神经元细胞类型。通过高分辨率分析来描绘细胞多样性，结果显示在四个物种中存在一组基本保守的细胞类型，细胞类型的进化增减极少，而细胞类型丰度的变化可能更为普遍。对两个物种的深入比较表明，物种间的转录组保守性和差异表达基因具有高度的细胞类型特异性，这表明细胞类型作为高度独立的单位进化。我们确定了基因表达中广泛存在的物种差异，特别是在神经调节信号通路中，同时在性别身份和神经递质特性方面保留了保守的回路布局。我们进一步在一个物种中生成了雌性数据集，以定义细胞类型中的性别差异，并研究与性别差异相关的物种差异。最后，我们报告了唯一定义每种细胞类型的标记基因组合，提供了一种基础资源，能够用于设计细胞类型特异性的遗传试剂。总的来说，我们的研究为性回路的细胞多样性以及进化如何塑造行为适应中的细胞类型和基因表达提供了基本见解。
