Last Woolly Mammoths Reveal New Extinction Clues
Four thousand years ago, the last woolly mammoth on an island off the coast of modern-day Siberia died. This isolation could have led to fatal inbreeding and population declines, contributing to the species’ extinction.
However, a new study reveals that while the Wrangel Island mammoths were indeed inbred, this alone did not seal their fate. The population had gradually lost harmful genetic mutations, suggesting “another random event, like disease or environmental changes, led to their extinction, according to researchers in a June 27 Cell report.”
Research Praise and Modern Conservation Implications
Joshua Miller, a paleontologist at the University of Cincinnati who was not involved in the study, commended the research for providing valuable insights into the end of the Wrangel Island mammoths. He noted that “the study also has implications for modern conservation efforts, emphasizing the importance of monitoring genetic health in endangered species to prevent similar fates.”
Woolly mammoths roamed mainland Siberia until around 10,000 years ago when rising sea levels stranded populations on isolated islands. This geographic separation likely limited genetic mixing among the mammoths, reducing genetic diversity and increasing vulnerability to environmental changes.
Love Dalén, an evolutionary geneticist at the Centre for Palaeogenetics in Stockholm and co-author of the study, emphasized the importance of genetic variation for adaptation to environmental changes. Previous theories suggested that isolation increased inbreeding and genetic vulnerability. However, Dalén and his colleagues have disputed this for over a decade, arguing that other factors were at play.
Comprehensive Genetic Analysis
The research team analyzed 21 mammoth genomes, including eight previously published, covering the last 50,000 years of the species’ existence. This comprehensive genetic analysis revealed that while the isolated mammoths on Wrangel Island were inbred, they were not doomed solely by genetic factors. “The study provides a nuanced understanding of the complex interplay between genetics and environmental factors in the extinction of the woolly mammoth.”
Using computer modeling software, the team compared the genomes of woolly mammoths with those of elephants and humans to assess the impact of harmful genetic mutations on mammoths and whether these mutations were eliminated over time.
The analysis revealed that while Wrangel Island’s mammoth population began with as few as eight individuals, it grew to about 200-300 and remained stable until its extinction. The researchers found that the most harmful genetic mutations became less frequent, likely because affected animals failed to reproduce.
Unresolved Questions and Future Research Directions
Despite this, Vincent Lynch, an evolutionary biologist at the University at Buffalo, cautions that while the study provides strong evidence against the genetic meltdown model, it doesn’t entirely rule it out. He suggests that “the accumulation of minor genetic mutations could have increased the mammoths’ vulnerability to other environmental changes such as disease, climate shifts, and human activity, contributing to their eventual extinction.”
Challenges in obtaining high-quality DNA limited the team’s ability to analyze the genetic condition of the Wrangel Island mammoths during their final 300 years, or roughly five generations, according to study coauthor Marianne Dehasque. With advances in sequencing technologies, the researchers aim to complete their analysis of the mammoths’ genetic trajectory in the future.
As scientists continue to investigate, the final moments of the woolly mammoth remain a mystery. “Maybe they were just unlucky,” speculates Love Dalén. He suggests that without a catastrophic event, “we might still have mammoths walking around today.”
Read the Original Article on: Science News
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