Data from: Mitogenomes and relatedness do not predict frequency of tool-use by sea otters

Many ecological aspects of tool-use in sea otters are similar to those in Indo-Pacific bottlenose dolphins. Within an area, most tool-using dolphins share a single mitochondrial haplotype and are more related to each other than to the population as a whole. We asked whether sea otters in California showed similar genetic patterns by sequencing mitogenomes of 43 otters and genotyping 154 otters at 38 microsatellite loci. There were six variable sites in the mitogenome that yielded three haplotypes, one found in only a single individual. The other two haplotypes contained similar percentages (33 and 36%) of frequent tool-users and a variety of diet types. Microsatellite analyses showed that snail specialists, the diet specialist group that most frequently used tools, were no more related to each other than to the population as a whole. The lack of genetic association among tool-using sea otters compared with dolphins may result from the length of time each species has been using tools. Tool-use in dolphins appears to be a relatively recent innovation (less than 200 years) but sea otters have probably been using tools for many thousands or even millions of years.

海獭（sea otter）使用工具的诸多生态学特征，与印太瓶鼻海豚（Indo-Pacific bottlenose dolphin）高度相似。在某一区域内，多数使用工具的海豚共享单一的线粒体单倍型（mitochondrial haplotype），且彼此间的亲缘关系较其与种群整体的亲缘关系更为紧密。本研究通过对43只海獭的线粒体基因组（mitogenome）进行测序，并对154只海獭的38个微卫星位点（microsatellite locus）进行基因分型，旨在探究加利福尼亚州的海獭是否呈现出类似的遗传模式。线粒体基因组中共存在6个变异位点，由此鉴定出3种单倍型，其中1种仅在单个个体中被检测到。剩余两种单倍型中，高频工具使用者的占比分别为33%与36%，且涵盖了多种食性类群。微卫星位点分析结果显示，作为最频繁使用工具的食性特化类群——蜗牛专食者，彼此间的亲缘关系并未较其与种群整体的亲缘关系更为紧密。与海豚相比，使用工具的海獭之间缺乏遗传关联，这一现象可能源于两个物种使用工具的时长差异。海豚的工具使用行为相对而言是较晚出现的创新（不足200年），而海獭使用工具的历史则可能长达数千年乃至数百万年。