Whole-genome re-sequencing of the Baikal seal and other phocid seals for a glimpse into their genetic diversity, demographic history, and phylogeny

The Baikal seal (<i>Pusa sibirica</i>) is a freshwater seal endemic to Lake Baikal, where it became landlocked million years ago. It is an abundant species of least concern despite the limited habitat. Research on its genetic diversity had only been done on mitochondrial genes, restriction fragment analyses, and microsatellites, before its reference genome was published. Here, we report the genome sequences of six Baikal seals, and one individual of the Caspian, ringed, and harbor seal, re-sequenced from Illumina paired-end short read data. Heterozygosity calculations of the six newly sequenced individuals are similar to previously reported genomes. Also, the novel genome data of the other species contributed to a more complete phocid seal phylogeny based on whole-genome data. Despite the isolation of the land-locked Baikal seal, its genetic diversity is comparable to that of other seal species. Future targeted genome studies need to explore the genomic diversity throughout their distribution.