Department of Pathology, Stellenbosch University, South Africa.
Whale Unit, Mammal Research Institute c/o Iziko Museum, Cape Town, South Africa.
Adv Mar Biol. 2023;96:85-114. doi: 10.1016/bs.amb.2023.09.001. Epub 2023 Nov 10.
Little is known about the biology of pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales as these animals are difficult to observe in the wild. However, both species strand frequently along the South African, Australian and New Zealand coastlines, providing samples for these otherwise inaccessible species. The use of DNA samples from tissue and DNA extracted from historical material, such as teeth and bone, allowed a first analysis of the population structure of both species in the Southern Hemisphere. A 279 base pair consensus region of the mitochondrial cytochrome b gene was sequenced for 96 K. breviceps (53 tissue and 43 teeth or bone samples) and 29 K. sima (3 tissue and 26 teeth or bone samples), and 26 and 12 unique haplotypes were identified, respectively. K. breviceps showed a higher nucleotide diversity of 0.82% compared to 0.40% in K. sima. Significant genetic differentiation was detected in the Southern Hemisphere between K. breviceps from South Africa and New Zealand (Ф = 0.042, p < 0.05). Mitochondrial control region sequences (505 bp) were available for 44 individuals (41 K. breviceps and 3 K. sima) for comparative purposes. A comprehensive global phylogenetic analysis (maternal lineage) of our sequences together with all available Kogia mtDNA sequences largely supported previously published phylogenetic findings, but highlighted some changed inferences about oceanic divergences within both species. The higher nucleotide diversity and low population differentiation observed in K. breviceps may result from its broad foraging ecology and wide distribution, which may indicate a more opportunistic feeding behaviour and tolerance towards a larger range of water temperatures than K. sima.
关于侏儒（Kogia breviceps）和小抹香鲸（K. sima）的生物学知识知之甚少，因为这些动物在野外很难观察到。然而，这两个物种经常在南非、澳大利亚和新西兰的海岸线搁浅，为这些难以接近的物种提供了样本。利用组织中的 DNA 样本和来自牙齿和骨骼等历史材料的 DNA，可以首次分析南半球这两个物种的种群结构。对来自 96 头侏儒抹香鲸（53 个组织和 43 个牙齿或骨骼样本）和 29 头小抹香鲸（3 个组织和 26 个牙齿或骨骼样本）的线粒体细胞色素 b 基因的 279 个碱基对的共识区域进行了测序，并分别鉴定出 26 和 12 个独特的单倍型。与小抹香鲸的 0.40%相比，侏儒抹香鲸的核苷酸多样性更高，为 0.82%。在南半球，南非和新西兰的侏儒抹香鲸之间检测到显著的遗传分化（Ф = 0.042，p < 0.05）。为了进行比较，还获得了 44 个个体（41 头侏儒抹香鲸和 3 头小抹香鲸）的线粒体控制区序列（505bp）。我们的序列与所有可用的抹香鲸 mtDNA 序列一起进行了全面的全球系统发育分析（母系谱系），这在很大程度上支持了以前发表的系统发育研究结果，但突出了一些关于这两个物种内部海洋分歧的推断变化。侏儒抹香鲸观察到的较高核苷酸多样性和较低的种群分化可能是由于其广泛的觅食生态和广泛的分布，这可能表明其具有更具机会主义的觅食行为和对更大范围水温的耐受性，而小抹香鲸则不然。
