Uncertainty resurfaces in the economics behind the extinction of Woolly Mammoths
lets dive into the last mammoths to grace our planet, the ones persisting on Wrangel Island off the coast of Siberia. These behemoths, fondly known as woolly mammoths, held on for hundreds of generations, defying the common fate of inbreeding that plagues isolated populations. But how did they do it?
A groundbreaking study, published today in Cell, explores this question by analyzing 21 woolly mammoth genomes. Researchers scrutinized the genetic diversity of the Wrangel Island mammoths to figure out if it played a role in their unexpected longevity and, eventually, their extinction.
" Genetic diversity is vital for a population's resilience against environmental changes," says Marianne Dehasque, lead author of the study and a geneticist at the Center for Paleogenetics in Stockholm. The study suggests that while the Wrangel Island mammoth population faced adversity, it was not their reduced genetic diversity that spelled their doom. Instead, "something very short and sudden" is suspected to have triggered their abrupt extinction.
Digging deeper, the team observed that the Wrangel Island population had started with just 8 individuals, give or take a few, following a near-extinction event. Despite this inauspicious beginning, the population swelled to hundreds over the next 20 generations, persisting for another 6,000 years before their demise. Interestingly, the genomes revealed that individual mammoths experienced harmful effects of inbreeding, but the population as a whole managed to endure.
" The Wrangel Island populations showed signs of purging the most harmful mutations from its genetics," says Love Dalén, an evolutionary geneticist and co-author of the paper. "However, they continued to accumulate mildly harmful mutations until the animals' extinction." These findings debunk earlier hypotheses that genetic problems caused the extinction and instead point towards a rapid, environmental catastrophe as the culprit.
The researchers are not quite sure what transpired, but they plan to analyze even younger mammoth DNA, closer to the moment of extinction, to shed more light on the last days of the woolly mammoths.
While the exact cause of the Wrangel Island mammoths' extinction remains veiled, the signs were there. A 2021 study revealed that the rapid warming at the end of the last Ice Age, reducing the food sources of mammoths, likely brought about their demise[2].
Currently, other endangered species like the adorable, highly inbred kākāpō of New Zealand and the critically endangered vaquita of Baja California serve as reminders of the delicate balance of survival, emphasizing the importance of preserving genetic diversity in our modern world.
- The study on the Wrangel Island mammoths suggests that their reduced genetic diversity did not lead to their extinction, but instead a rapid and sudden environmental change might have been the cause.
- Geneticist Marianne Dehasque, lead author of the study, states that genetic diversity is crucial for a population's resilience against environmental changes.
- The genomes of the Wrangel Island mammoths showed signs of purging the most harmful mutations from its genetics, however, they continued to accumulate mildly harmful mutations until the animals' extinction.
- The research team plans to analyze even younger mammoth DNA, closer to the moment of extinction, to gain more insights into the last days of the woolly mammoths, which are likely to have been caused by rapid warming at the end of the last Ice Age.
