Department of Functional Biology, University of Oviedo, Oviedo, Asturias, Spain.
PLoS One. 2013 Aug 19;8(8):e69511. doi: 10.1371/journal.pone.0069511. eCollection 2013.
Visual species identification of cetacean strandings is difficult, especially when dead specimens are degraded and/or species are morphologically similar. The two recognised pilot whale species (Globicephala melas and Globicephala macrorhynchus) are sympatric in the North Atlantic Ocean. These species are very similar in external appearance and their morphometric characteristics partially overlap; thus visual identification is not always reliable. Genetic species identification ensures correct identification of specimens. Here we have employed one mitochondrial (D-Loop region) and eight nuclear loci (microsatellites) as genetic markers to identify six stranded pilot whales found in Galicia (Northwest Spain), one of them of ambiguous phenotype. DNA analyses yielded positive amplification of all loci and enabled species identification. Nuclear microsatellite DNA genotypes revealed mixed ancestry for one individual, identified as a post-F1 interspecific hybrid employing two different Bayesian methods. From the mitochondrial sequence the maternal species was Globicephala melas. This is the first hybrid documented between Globicephala melas and G. macrorhynchus, and the first post-F1 hybrid genetically identified between cetaceans, revealing interspecific genetic introgression in marine mammals. We propose to add nuclear loci to genetic databases for cetacean species identification in order to detect hybrid individuals.
目视鉴定搁浅鲸类物种较为困难，尤其是在死亡标本降解和/或物种形态相似的情况下。北大西洋海域中栖息着两种已确认的领航鲸物种（短肢领航鲸和长肢领航鲸）。这两种物种在外貌上非常相似，其形态特征部分重叠；因此，目视鉴定并不总是可靠的。遗传物种鉴定可确保标本的正确鉴定。在这里，我们使用了一个线粒体（D 环区）和 8 个核基因座（微卫星）作为遗传标记，对在西班牙西北部加利西亚发现的 6 头搁浅的领航鲸进行了鉴定，其中一头具有模糊的表型。所有基因座的 DNA 分析均产生了阳性扩增，从而实现了物种鉴定。核微卫星 DNA 基因型揭示了一个个体的混合血统，通过两种不同的贝叶斯方法鉴定为 F1 代后杂交种。从线粒体序列来看，母本物种为短肢领航鲸。这是首次记录到短肢领航鲸和长肢领航鲸之间的杂交种，也是首次在遗传上鉴定出的鲸目动物 F1 代后杂交种，揭示了海洋哺乳动物中的种间遗传渗透。我们建议在遗传数据库中添加核基因座，以便检测杂交个体，从而用于鲸类物种鉴定。
