Cheetahs Left North America During Last Ice Age, Say Researchers
Cheetahs roam the African plains today but that's not where the large and extremely fast felines first called home. A recent studyby researchers from St. Petersburg State University, Russia, revealed the animals actually migrating from North America to the Savannas 100,000 years ago during the last ice age before becoming isolated in Africa.
Modern African cheetahs are confined to habitats in eastern and southern Africa, a strikingly small range that has led to increased rates of inbreeding. The move to North America had already triggered a loss of diversity within the gene pool, according to a news release.
After sequencing the genomes of seven cheetahs from Tanzania and Namibia, including a male named "Chewbaaka," researchers identified a total of 18 cheetah genes with damaging mutations. One of these – KAP4 – showed a surprising number of mutations, suggesting it could be responsible for harming sperm development. This could explain why the animals have such difficulty breeding.
The university's study also found the mutations stem from two population bottlenecks, or simply an event triggered by environmental factors that ultimately results in a population decline.
The first of these two events took place roughly 100,000 years ago during the Pleistocene, a period iknown for repeated glaciations, which are believed to have initially caused cheetahs to relocate. They would have had to move toward Asia across the Beringian landbridge, before winding up in Africa. During this "big move" cheetah populations dwindled and incestuous mating increased.
The second population crash occurred only 10,000 to 12,000 years ago, when Cheetahs disappeared from North America following the last glacial retreat. At this time, other large mammals such as the saber-toothed tigers and pumas also left the continent.
"Cheetahs grew up in North America before they traversed the Bering Straits and wandered down to Africa," Stephen O'Brien, one of the study researchers from Saint Petersburg State University in Russia and Nova Southeastern University in Florida, said in a statement. "I don't think they were much different from the animals we see today, they developed into a sprinting hunter in North America. It's interesting that we lost about 40 species at the end of the ice age, including pumas and cheetahs. The pumas came back from South America and the cheetahs were fortunate to migrate into Asia and then into Africa. They have remained a top predator, unless they have had to deal with humans, of course."
Overall, researchers found cheetahs have lost between 90 and 99 percent of the genetic variation typically seen in outbred mammals. This lack of diversity has had a lasting impact on modern cheetahs and their ability to reproduce. As a result, cheetahs are listed as a vulnerable species, with only about 6,700 animals left in the wild.
The study, recently published in the journal Genome Biology, could be used to give cheetahs the population boost they need to survive.
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