Genomic analyses reveal trans-generational haul out site fidelity in leopard seals

As top predators, leopard seals (Hydrurga leptonyx) have a key role in Southern Ocean ecosystems. For example, this species has driven the local collapse of Antarctic fur seals (Arctocephalus gazella) at Cape Shirreff, in the northern Antarctic Peninsula. However, little is known about leopard seal haul out site fidelity and social behavior. Here, we employ “genomic tagging” and relatedness analyses from a genome-wide single nucleotide polymorphism (SNP) dataset obtained from 88 leopard seal tissue samples to investigate patterns of seasonal haul out site fidelity and social structure at Cape Shirreff, a leopard seal hotspot during austral summers. Although many seals were observed only once, some females had remarkably high site fidelity returning to the same location across timeframes of up to eight years. Most leopard seals were unrelated, but we identified a trio of closely related females, including a mother-daughter pair, indicating that seasonal site fidelity can span generations. Interestingly, the mother leopard seal identified through our relatedness analyses is a foraging specialist that targets Antarctic fur seal pups; her diet changed very little over the past decade. Our findings suggest high individual variability in leopard seal behavior regarding site fidelity and social structure. Such flexibility may play a key role in this species’ responses to environmental change.

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