Northern elephant seals show genetic effects of near-extinction despite population recovery

Northern elephant seals have recovered after being hunted nearly to extinction in the early 20th century. However, a recent study reveals lasting genetic effects, including loss of genetic diversity, which may impact their future adaptability.

Marine mammals face long-term challenges as researchers study the impacts of historical population declines.

A study reveals that the near-extinction of northern elephant seals has led to a significant loss of genetic diversity, raising concerns for their long-term health.

Northern elephant seals, genetic diversity, near-extinction, population recovery, conservation, genetic health

Northern elephant seals have made a remarkable recovery after nearly being hunted to extinction for their blubber oil, but a new study reveals enduring genetic impacts on the current population.

Historically, the population of northern elephant seals in the Pacific Ocean was in the hundreds of thousands. However, genetic analyses suggest that by the early 20th century, hunting had reduced this population to fewer than 25 individuals. Since then, the population has rebounded to approximately 225,000, but this drastic decline has left lasting marks on their genetic pool.

The research, led by the Universities of York and Bielefeld (Germany) and published in Nature Ecology and Evolution, indicates that this near-extinction event resulted in the loss of numerous genes from the northern elephant seal's gene pool. This loss has significantly reduced their genetic diversity, potentially affecting their overall health and future adaptability.

The researchers conducted the study by combining genetic data, health records, population size models, and genetic simulations. Interestingly, they did not observe a similar genetic pattern in the southern elephant seal, a closely related species that did not experience such a drastic population decline.

The findings demonstrate how severe population declines can reduce a species' genetic diversity, increasing the risk of inbreeding and threatening its long-term survival. These insights are crucial for species conservation and ecosystem management.

The study's lead author, Professor Kanchon Dasmahapatra from the Department of Biology at the University of York, explained, "Our study illustrates how the unique population history of a species shapes its genetic diversity. The highly reduced genetic diversity, including the loss of copies of beneficial genes, may hinder the northern elephant seals' ability to cope with future environmental changes, including those caused by anthropogenic climate change, habitat alterations, or even natural threats such as disease outbreaks."

Professor Joseph Hoffman from Bielefeld University, a co-author of the study, added, "All individuals of a species carry some harmful mutations, although their effects are usually hidden. However, inbred individuals may face health issues as these mutations become exposed. We observed several key health traits in these seals, including body weight, blubber thickness, and susceptibility to diseases. Surprisingly, we found no signs of health problems related to inbreeding. We believe that the severe population decline might have removed many harmful mutations."

The research emphasizes the complex relationship between population history and genetic health in species. While the northern elephant seals have shown an impressive comeback in terms of numbers, the genetic consequences of their near-extinction may pose challenges to their future adaptability and survival.

This study highlights the importance of maintaining genetic diversity within species, offering critical information for future conservation efforts and ecosystem management strategies to ensure the resilience of wildlife populations.