Mediterranean monk seal (Monachus monachus) and leopard seal (Hydrurga leptonyx) de novo genomes to study the demographic history and genetic diversity of southern seals

Abstract

<p>Background: The Monachinae, or southern seals, are one of two subfamilies within the Phocidae and are home</p><p>to iconic pinnipeds such as the leopard seal, a fierce Antarctic top predator, and the Mediterranean monk seal, one</p><p>of the world’s most endangered mammals. These two species are difficult to study and sample, due to their hidden</p><p>lives in extreme environments or, in case of the monk seal, their critically reduced population sizes; consequently,</p><p>genetic data from these two species is scarce. However, cost developments and advances in genome sequencing</p><p>have made it possible to generate continuous genome assemblies from DNA of even stranded individuals, allowing</p><p>to assemble the first reference genomes of such rarely observed species.</p><p>Results: In this study, we have sequenced the genomes of the leopard seal and the Mediterranean monk seal using</p><p>PacBio’s CCS technology to assemble the very first genomes for these species. Four additional Mediterranean monk</p><p>seal individuals were sequenced using Illumina short-read technology. These data allowed analysis of their demography</p><p>and genomic diversity based on whole-genome data, confirming low genetic variability and small numbers</p><p>of individuals for the Mauritanian population of the Mediterranean monk seal. In contrast, the relatively abundant</p><p>leopard seal shows a high degree of heterozygosity, comparable in the range of other common carnivores.</p><p>Conclusions: The first genome assemblies for these seals will lay the groundwork for population-level and other studies</p><p>to better understand their evolutionary history and biology and to aid conservation efforts.</p>