Biology, Science Education, Faculty of Education, University of Miyazaki. Gakuen-Kibanadai-Nishi, Miyazaki, Miyazaki, Japan.
Biology, Science Education, Faculty of Education, University of Miyazaki. Gakuen-Kibanadai-Nishi, Miyazaki, Miyazaki, Japan.
Adv Mar Biol. 2023;96:25-37. doi: 10.1016/bs.amb.2023.08.002. Epub 2023 Sep 26.
The two Kogia species, the pygmy sperm whale (K. breviceps) and the dwarf sperm whale (K. sima), have similar morphological and biological features as well as diets. Both species are deep divers, and both have wide distributions from tropical to warm-temperate zones. Although K. breviceps is larger than K. sima, there are few reports of habitat differentiation between the two species. The distribution of K. breviceps is concentrated in higher-latitudes, and this species dives deeper than K. sima. We investigated whether these two species differ in their population structures in the western North Pacific. Using stranded specimens from Japan, we compared the population genetic patterns of the two Kogia species using mtDNA control region variation (941 bp). In total, 34 K. breviceps samples and 54 K. sima samples from stranded individuals around Japan were successfully sequenced. Thirty haplotypes were detected in K. breviceps and 34 in K. sima, indicating high genetic diversity for both. Almost all these haplotypes are unique to the western North Pacific, but did not constitute distinct phylogeographic clades within either species. We detected differences between the species in the shape of haplotype networks and in the potential time of population expansion, indicating that the western North Pacific population of the two biologically similar species could have different population demographies. This may reflect differences in evolutionary histories and in the details of their ecological niches.
两种抹香鲸科物种，小抹香鲸（Kogia breviceps）和倭抹香鲸（K. sima），具有相似的形态学和生物学特征以及饮食。这两个物种都是深海潜水者，分布范围从热带到温带都很广泛。虽然 K. breviceps 比 K. sima 大，但很少有关于这两个物种栖息地分化的报道。K. breviceps 的分布集中在高纬度地区，而且这个物种比 K. sima 潜水更深。我们研究了这两个物种在西北太平洋的种群结构是否存在差异。我们利用从日本搁浅的标本，通过 mtDNA 控制区变异（941bp）比较了两种抹香鲸的种群遗传模式。总共对来自日本周围搁浅个体的 34 个 K. breviceps 样本和 54 个 K. sima 样本进行了测序。在 K. breviceps 中检测到 30 个单倍型，在 K. sima 中检测到 34 个单倍型，表明两个物种都具有高度的遗传多样性。几乎所有这些单倍型都是西北太平洋特有的，但在两个物种中都没有构成明显的系统地理分支。我们在单倍型网络的形状和种群扩张的潜在时间上检测到了物种之间的差异，表明这两个在生物学上相似的物种的西北太平洋种群可能具有不同的种群动态。这可能反映了它们进化历史和生态位细节的差异。
