Transcriptome Analyses Revealed the Genetic Advantages in Polygynous Males of <scp><i>Tylonycteris pachypus</i></scp>

Sexual selection is widely recognized as a key driver of evolutionary processes; However, research on this topic in bats remains limited despite their considerable ecological importance. The flat-headed bat <i>Tylonycteris pachypus</i>, a small bamboo-roosting species, typically forms either polygynous groups (one male with multiple females) or male-only groups. Previous studies have shown that males roosting with females experience significantly higher reproductive success, despite the absence of documented morphological sexual dimorphism. In this study, we constructed a reference transcriptome for <i>T. pachypus</i> using RNA-seq, combining <i>de novo</i> assembly and transcript-guided assembly based on a closely related species. We compared gene expression profiles of brain tissue between solitary males and polygynous males from the Chongzuo region in Guangxi, China. A total of 107 differentially expressed genes (DEGs) were identified, including <i>SEMA6A</i>, <i>KCTD12</i>, <i>CLTC</i> and <i>ALDH1L1</i>, etc., upregulated in polygynous males, while <i>VANGL2</i>, COTL1 and <i>IL10RB</i> were upregulated in solitary males. These results suggest that polygynous males may possess superior survival and reproductive potential compared to solitary males. KEGG enrichment analysis revealed that polygynous males were significantly enriched in pathways including "lysosome" and "endocrine and other factor-regulated calcium reabsorption". GO enrichment analysis also indicated various differences between the two male groups. Our results demonstrate distinct gene expression patterns between the two male groups, offering preliminary molecular evidence for adaptive evolution driven by sexual selection in <i>T. pachypus</i>.