For decades, the multitude of species roaming North America and Siberia neck in neck with our forefathers have captivated the imagination of the scientific community. Researchers have tried on countless occasions to come up with answers as to why most of the ancient species never made it into the modern era. Preliminary theories blamed mass extinction on humans, calamities, or sudden shifts in climate. However, new evidence suggests that the real answer may lie deep within the extinct species’ genome. Hence, rather than excessive hunting or global warming, some species crossed the threshold into extinction as a direct result of genetic flaws slowly piling up. Researchers say the wooly mammoth was, in fact, a victim of such genetic meltdown.
For their study, the researchers gathered samples from two mammoths. One of the subjects was a member of a thriving mainland population, while the other one was born into a community that slowly succumbed to isolation. Details of the study have been published on Thursday, March 2nd, in the journal PLOS Genetics.
As it turned out, the size of the population had a direct impact on both specimens’ genetic fitness. Analyzing the results, the scientists could come up with better ways of protecting surviving species better in the future. It is only natural that climate change and human activity had a say in the wooly mammoth’s extinction, no questions there. However, as most mainland specimens went extinct approximately 10,000 years ago, there were two communities that managed to survive several more millenniums longer. On St. Paul island, a scarce population made their last stand for 4,400 years more, until the lack of fresh water did them in, while on the remote Wrangel Island, wooly mammoths managed to survive for twice as long, compared to their St. Paul counterparts.
Researchers compared genetic evidence of a Wrangel Island specimen against that of a 45,000-year-old mainland mammoth. As opposed to the stranded individuals, the mainland mammoth was part of a breeding population 43 times larger. Looking at the genetic pool of both individuals, the researchers concluded the genetic diversity was almost non-existent for stranded specimens, hence the genetic meltdown that led to their extinction. While mainland mammoths kept their thick coats and sharp senses, it appears that isolated specimens suffered from a poor sense of smell, and thin coats. Furthermore, as Dr. Rogers underscores, it seems the genetic mutations that led to these deficiencies were accumulating in the mammoth genome right before they went extinct.
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