北部湾涠洲岛海域栖息布氏鲸种群的物种鉴定

A PILOT STUDY ON SPECIES IDENTIFICATION OF BRYDE’S WHALES INHABITING IN THE WEIZHOU ISLAND WATERS, BEIBU GULF

  • 摘要: 布氏鲸(Bryde’s whale)是广泛分布于温带和热带海域的一类中等体型须鲸, 通常认为存在小布氏鲸(Balaenoptera edeni edeni)和布氏鲸(B. e. brydei)两个亚种。然而, 有研究表明它们应该被划分为两个独立物种, 即近岸小型布氏鲸(B. edeni)和远洋大型布氏鲸(B. brydei)。由于两者外部形态极其相似, 并且存在同域分布现象, 很难基于外观进行准确的物种鉴定。近年来, 广西北部湾涠洲岛海域出现一个稳定的布氏鲸栖息种群, 但目前尚不清楚属于哪种布氏鲸。研究采集了涠洲岛布氏鲸种群中两个体的粪便样品, 从其中一份样品成功提取基因组DNA, 并基于线粒体Cyt bCOΙ基因序列开展物种鉴定和遗传分析, 鉴定结果为小布氏鲸。此外, 还鉴定出涠洲岛海域同年死亡的一头须鲸也为小布氏鲸。据此推测涠洲岛水域栖息的布氏鲸种群可能是小布氏鲸。研究首次基于粪便样品, 采用分子生物学技术, 成功开展了活体布氏鲸的物种鉴定。这种基于非损伤采样的物种鉴定方法值得进一步优化并推广应用。

     

    Abstract: The Bryde’s whale is a medium sized baleen whale that is widely distributed in the tropical and subtropical waters. However, the taxonomy of the Bryde’s whale has long been controversial. Currently, both the IUCN (the International Union for Conservation of Nature and Natural Resources), and the IWC (the International Whaling Commission) assign the whale as two subspecies, Balaenoptera edeni edeni and B. e. brydei. Although, several studies indicate that they should be regarded as two separate species, B. e. edeni and B. e. brydei are so similar in their external morphology, and are sometimes sympatric, which make it is difficult to correctly identify them in the field just through observation. Therefore, accurate species delimitation usually requires molecular methods. Recently, a Bryde’s whale population was reported inhabiting in the Weizhou Island waters, Beibu Gulf. However, it is unclear which species these animals belong to. In this study, we collected two fecal samples from two individuals in this population, and tried to identify them using molecular methods. Genomic DNA was extracted from one of the two fecal samples. Fragments of the mitochondrial genes Cyt b and COⅠ were PCR amplified and sequenced. Based on the mitochondrial gene sequences, the whale was identified as B. e. edeni. In addition, a baleen whale that died in 2019 in the same waters was also identified as B. e. edeni using the same methods outline in this study. Thus, we infer that the population living in the Weizhou Island waters is B. e. edeni. This is the first study which successfully identified a living Bryde’s whale based on mitochondrial DNA present in fecal samples. This non-invasive sampling-based species identification method should be further developed and applied in the future. Additional studies, such as population genetics should be carried out to provide a scientific basis for the conservation of this Bryde’s whale population.

     

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