Ecology: Inbreeding may hinder killer whale conservation Ecology and evolution

Inbreeding between isolated populations may be responsible for the disappearance of the southern population, a population of killer whales off the western coasts of the United States and Canada. This report sheetnature and its evolutionThe findings may help explain why conservation measures that have worked for other populations of killer whales have not worked in this group.

Killer whales (also known as orcas) have been hunted and culled in the North Pacific Ocean. Legal protections since the early 1970s have helped restore many of the area’s residents, but not the smaller group known as the Southerners. Populations of fewer than 100 animals have lower survival and fertility rates than other populations of killer whales, and genetic problems have been partly to blame.

Marty Cardos and his colleagues sequenced the genomes of 100 live and dead killer whales from the Southern Population. Comparison of its genome with that of killer whales from other North Pacific populations reveals that the southern population has the lowest level of genetic diversity and the highest level of inbreeding. Evaluation of survival data for control individuals showed an association between this low level of genetic diversity and a shorter lifespan. The researchers suggest that female killer whales take about 20 years to reach reproductive age, so females in southern populations may not live long enough to ensure population growth.

Cardus and colleagues suggest that a combination of natural and anthropogenic factors, such as geographic habitats and population influences resulting from neighborhood capture in the 1960s and 1970s, may have led to increased inbreeding within resident groups in the South. While he says inbreeding may not be directly eradicated, he stresses the importance of killer whale conservation efforts in this region.

doi: 10.1038/s41559-023-01995-0

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