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Tylorrhynchus heterochaetus is a widespread benthic polychaete worm found in coastal brackish waters of the west Pacific. It has high ecological and economic value as a biomarker of water quality and as a high-quality feed in aquaculture and fisheries and is considered a delicacy in some areas of Asia. However, it has experienced a marked reduction in recent years due to overexploitation as well as changes in the environment and climate. Here, to comprehensively understand its genetic background and thus provide insights for better conservation and utilization of this species, we assessed the genetic variability and demographic history of T. heterochaetus individuals sampled from eight locations along the coasts of southeast China and north Vietnam based on mitochondrial cytochrome c oxidase I ( COI) sequences. We observed high haplotype diversity ( Hd), with an average of 0.926, but relatively low nucleotide diversity ( π), with a mean of 0.032 across all samples. A total of 94 polymorphic sites and 85 haplotypes were identified among 320 individuals. The pairwise genetic distances among haplotypes ranged from 0.001 to 0.067, with the high intraspecific divergence possibly reflecting geographic isolation and gene pool fragmentation. Significant genetic structures were revealed among the studied locations; specifically, the eight locations could be treated as six genetically different populations based on pairwise Φ ST results (0.026–0.951, P

Leopard coral groupers belong to the Plectropomus genus of the Epinephelidae family and are important fish for coral reef ecosystems and the marine aquaculture industry. To promote future research of this species, a high-quality chromosome-level genome was assembled using PacBio sequencing and Hi-C technology. A 787.06 Mb genome was assembled, with 99.7% (784.57 Mb) of bases anchored to 24 chromosomes. The leopard coral grouper genome size was smaller than that of other groupers, which may be related to its ancient status among grouper species. A total of 22 317 protein-coding genes were predicted. This high-quality genome of the leopard coral grouper is the first genomic resource for Plectropomus and should provide a pivotal genetic foundation for further research. Phylogenetic analysis of the leopard coral grouper and 12 other fish species showed that this fish is closely related to the brown-marbled grouper. Expanded genes in the leopard coral grouper genome were mainly associated with immune response and movement ability, which may be related to the adaptive evolution of this species to its habitat. In addition, we also identified differentially expressed genes (DEGs) associated with carotenoid metabolism between red and brown-colored leopard coral groupers. These genes may play roles in skin color decision by regulating carotenoid content in these groupers.

Tylorrhynchus heterochaetus is a widespread benthic polychaete worm found in coastal brackish waters of the west Pacific. It has high ecological and economic value as a biomarker of water quality and as a high-quality feed in aquaculture and fisheries and is considered a delicacy in some areas of Asia. However, it has experienced a marked reduction in recent years due to overexploitation as well as changes in the environment and climate. Here, to comprehensively understand its genetic background and thus provide insights for better conservation and utilization of this species, we assessed the genetic variability and demographic history of T. heterochaetus individuals sampled from eight locations along the coasts of southeast China and north Vietnam based on mitochondrial cytochrome c oxidase I (COI) sequences. We observed high haplotype diversity (Hd), with an average of 0.926, but relatively low nucleotide diversity (π), with a mean of 0.032 across all samples. A total of 94 polymorphic sites and 85 haplotypes were identified among 320 individuals. The pairwise genetic distances among haplotypes ranged from 0.001 to 0.067, with the high intraspecific divergence possibly reflecting geographic isolation and gene pool fragmentation. Significant genetic structures were revealed among the studied locations; specifically, the eight locations could be treated as six genetically different populations based on pairwise ΦST results (0.026–0.951, P