According to recent reports, shell morphology is unreliable for the identification of oysters because of the high phenotypic plasticity of these bivalves. Using COI DNA barcoding and sperm morphology, we reinvestigated the species validity of wild Pacific oyster Crassostrea gigas habituating the Peter the Great Bay (Sea of Japan). DNA barcoding confirmed the species validity of samples collected. Application of the single sperm pattern was not possible for species identification due to pronounced sperm plasticity being found. Six sperm morphs were discovered in the testes of each oyster collected. The amount of abundant sperm morphs and the type of the most dominant sperm pattern are particular to geographical localities that are individual depending on the environmental factors. Ecological monitoring of marine areas and commercially assigned intraspecific geo-authentification of the Pacific oyster seems possible based on the analysis of this species’ heterogenic sperm. Further work will be needed to test if sperm heterogeneity exists in other Ostreidae species and if heterogenic sperms could be used for interspecific analysis.

中文翻译：

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太平洋牡蛎精子形态的变化使其无法用作物种标记，但可以进行种内地理鉴定和水生监测

根据最近的报道，由于这些双壳类动物的高表型可塑性，壳的形态对于鉴定牡蛎是不可靠的。使用COI DNA条形码和精子形态，我们重新研究了习惯于彼得大帝海湾（日本海）的太平洋太平洋牡蛎Crassostrea gigas的物种有效性。DNA条形码证实了所收集样品的物种有效性。由于发现了明显的精子可塑性，因此无法使用单个精子模式进行物种鉴定。在收集的每个牡蛎的睾丸中发现了六个精子形态。丰富的精子形态数量和最占优势的精子模式类型取决于环境因素，这些地理位置因地区而异。根据对该物种异质精子的分析，似乎有可能对海洋区域进行生态监测，并进行商业分配的太平洋牡蛎种内地理鉴定。还需要进一步的工作来测试其他鸵鸟科物种中是否存在精子异质性，以及是否可以将异源性精子用于种间分析。