Table_2_Identification of Main Oyster Species and Comparison of Their Genetic Diversity in Zhejiang Coast, South of Yangtze River Estuary.xlsx

Oysters are an important aquaculture species distributed worldwide, including in Zhejiang Province, located on the east coast of China. Because of the high diversity and complicated introduction history of oysters and their seedlings, there has been much disagreement regarding the origin of each species, and the dominant and indigenous species remain unclear. We sampled 16 batches of oysters from seven sites in three aquaculture bays and found two main oyster species, Crassostrea sikamea and Crassostrea angulata. The former occupied the higher intertidal zone and comprised more than 70% of the cultured oysters. Based on the cytochrome oxidase C subunit I (COI) and mitochondrial noncoding region (MNR), C. sikamea showed higher genetic diversity than C. angulata. The analysis of molecular variance among COI sequences of these species from the Xiangshan Bay populations were comparable to those of other populations and showed that most of the molecular variance was within groups, which was consistent with the low pairwise fixation index FST values. The neutrality test revealed that C. sikamea experienced population expansion events, whereas for C. angulata, the significant Fu’s Fs and non-significant Tajima’s D test results may indicate a possible population expansion event, implying that C. sikamea is likely an indigenous species. The method established based on internal transcribed spacer 1 digestion by the HindIII restriction enzyme is useful for identifying C. sikamea and C. angulata in the local region. The specific primers on the MNR sequence show potential for distinguishing C. sikamea from four other important Crassostrea oysters. These results highlight the abundance of C. sikamea on the Zhejiang coast and lay the foundation for protecting and utilizing the local oyster germplasm resources and for the sustainable development of the oyster industry.

牡蛎作为一种全球范围内广泛分布的养殖物种，包括中国东部沿海的浙江省，在海洋养殖业中占据着举足轻重的地位。鉴于牡蛎及其苗种所具有的高度多样性和复杂的引入历史，关于各个物种起源的争议颇多，而优势种和原生种尚不明确。本研究从三个养殖湾的七个地点采集了16批牡蛎样本，鉴定出两种主要的牡蛎物种：Crassostrea sikamea和Crassostrea angulata。前者占据较高的潮间带区域，占据了养殖牡蛎的70%以上。基于细胞色素氧化酶C亚基I（COI）和线粒体非编码区（MNR）的分析，C. sikamea的遗传多样性高于C. angulata。对这些物种的Xiangshan Bay种群COI序列进行的多态性分析，其结果与其他种群相当，表明大部分分子变异发生在群体内部，这与较低的成对固定指数FST值相一致。中性测试表明，C. sikamea经历了种群扩张事件，而C. angulata的显著Fu’s Fs和非显著Tajima’s D测试结果可能暗示了可能的种群扩张事件，这表明C. sikamea可能是原生种。基于HindIII限制性内切酶对内部转录间隔区1的消化所建立的方法，对于在本地区域鉴定C. sikamea和C. angulata是有效的。针对MNR序列的特异性引物显示出区分C. sikamea与其他四种重要Crassostrea牡蛎的潜力。这些研究结果突显了C. sikamea在浙江沿海的丰富度，并为保护和利用当地牡蛎种质资源以及牡蛎产业的可持续发展奠定了基础。