<div style="text-align:justify">Background: Chinese pond turtle (CPT, Mauremys reevesii) is a typical species with temperature-dependent sex determination (TSD). Pond slider turtle (PST, Trachemys scripta) is considered one of the worst invasive species in the world. In order to analyze the adaptive evolution of fecundity traits in CPT and TSD, the rapidly evolving gene families were obtained and functional enrichment analysis was performed. At the same time, CPT and PST species-specific genes were also enriched for their fecundity traits. 
 
Methods: Orthofinder software was employed to search homologous genes based on protein sequence. CAF&Eacute; software was used to obtain the expansion and contraction gene families of CPT and PST. Then, GO terms and pathway enrichment analyses were performed using TBtools software and Swissprot database.&nbsp; 
 
Result: In CPT, 159 rapid expansion gene families GO enrichment results showed that the reproductive activities related pathways were mainly three significant enrichment process, spermatogenesis, steroid hormone mediated signaling pathway and male gamete generation. 2 rapidly contraction gene families showed that there was no significant enrichment pathway related to reproduction. The pathway of significant enrichment were RNA biosynthetic process, regulation of RNA metabolic process and regulation of cellular metabolic process. The gene families unique to the species were significantly enriched in pathways DNA replication-dependent nucleosome organization, DNA replication-dependent nucleosome assembly and negative regulation of megakaryocyte differentiation. In PST, 15 rapid expansion gene families GO enrichment results showed that the most significant GO terms mainly consisted of biological processes which were involved in endocrine process, regulation of endocrine process and cellular response to steroid hormone stimulus, but spermatogenesis and male gamete generation gene families also expanded. 58 rapidly contraction gene families showed that the pathways of significant enrichment were endocrine process, cellular response to steroid hormone stimulus and regulation of endocrine process. At the same time, estrogen secretion, binding of sperm to zona pellucida and sperm-egg recognition gene family also rapidly contraction. The gene families unique to the species were significantly enriched in pathways adenylate cyclase-activating G protein-coupled receptor signaling pathway, double-strand break repair and regulation of potassium ion transport.</div>

Comparison of Fecundity Traits between Mauremys reevesii and Trachemys scripta based on Gene Family Analysis