The world's most isolated and distinct whale population? Humpback whales of the Arabian Sea

摘要

A clear understanding of population structure is essential for assessingconservation status and implementing management strategies. A small, nonmigratorypopulation of humpback whales in the Arabian Sea is classified as‘‘Endangered’’ on the IUCN Red List of Threatened Species, an assessmentconstrained by a lack of data, including limited understanding of its relationship toother populations. We analysed 11 microsatellite markers and mitochondrial DNAsequences extracted from 67 Arabian Sea humpback whale tissue samples andcompared them to equivalent datasets from the Southern Hemisphere and NorthPacific. Results show that the Arabian Sea population is highly distinct; estimates ofgene flow and divergence times suggest a Southern Indian Ocean origin butindicate that it has been isolated for approximately 70,000 years, remarkable for aspecies that is typically highly migratory. Genetic diversity values are significantlylower than those obtained for Southern Hemisphere populations and signatures ofancient and recent genetic bottlenecks were identified. Our findings suggest this isthe world’s most isolated humpback whale population, which, when combined withlow population abundance estimates and anthropogenic threats, raises concern for its survival. We recommend an amendment of the status of the population to‘‘Critically Endangered’’ on the IUCN Red List.