Humans Not Main Culprit in Musk Ox Population Decline After Last Ice Age
10.03.2010 - Flora & Fauna, Human Dimension, Arctic
A team of scientists found that human activity is not the reason behind the drastic decline in Arctic musk ox populations that began 12,000 years ago. The findings, to be published in the journal Proceedings of the National Academy of Sciences (PNAS), shows that while both human and musk ox populations overlapped in many parts of the Earth, the decline is due more to a warming climate than to humans hunting them.
Once present in great numbers all over the Northern Hemisphere, musk oxen now are concentrated mostly in Greenland.
The study also finds the oxen were not the only animals to suffer during the late Pleistocene. The end of the period was marked by rapid environmental change paired with human expansion throughout the Northern Hemisphere, and some species became extinct while others survived. While some scientists have previously thought this to be due to human hunting, musk oxen DNA might offer new insights into the reasons for the decline.
For their research, the scientists first drew mitochondrial DNA from musk ox bones and musk oxen of today as well as remains from animals that lived during different times across the former range of musk oxen. Thanks to advancements in DNA studies, which can now give insights into population size and dynamics of animals, the scientists were able to estimate the changes in genetic diversity of the musk oxen populations over time. They believe that a reduction in genetic diversity of an animal's population can reflect a decrease in the size of the population. With an estimate of the animal’s genetic diversity decline, they were then able to test whether it was due to human hunting or to something else. The scientists also found that while the genetic diversity of the musk ox was much higher during the Pleistocene, the genetic diversity of the species increased and decreased frequently over the past 65,000 years.
The study found that musk oxen witnessed a significant decline nearly 65,000 years ago. However it seems every species followed its own path, suggesting that it is changes in habitat that are responsible for the decline rather than human hunting. Historic data corroborated this theory by showing that musk oxen are sensitive to changes in the Arctic environment. While the precise factors behind the changes remain unknown, humans can be ruled out as a cause for local extinctions.
