In an attempt to understand the origin and population history of lions, scientists sequenced DNA from both living lions and museum-preserved lions, some of which are now extinct, from different geographical areas. They found that recent lion lineages began to diverge in the Late Pleistocene, and that the modern lion populations last shared a most recent common ancestor around 124,000 years ago. The results have been published in the journal BMC Evolutionary Biology.
Gathering information on the demographic history of a species is important because it can help to shed light on evolutionary processes. Not only that, but the results collected could also be applied to conservation efforts through predictions of how the animal may respond to certain pressures such as changes in the environment. Obtaining sequence data necessary to make such inferences for the lion, however, has been problematic since numerous hurdles exist. First, poor bone preservation in tropical areas has meant that the fossil record for lions is incomplete. Second, since the lion population has been artificially diminished by poaching, the remaining lions likely are not a sufficiently representative sample. Therefore, the scientists in this study used historically collected samples from museum-preserved lions to fill in the gaps.
By sequencing mitochondrial DNA from not only museum-preserved specimens from different geographical areas, but also lions currently living in Asia and across Africa, the scientists worked out how different subspecies of lion evolved. They estimated that recent lion lineages started to diverge in the Late Pleistocene, and that the most recent common ancestor of modern lions lived around 124,000 years ago. They also supported previous findings that suggested the modern lion, Panthera leo, first appeared in Eastern-Southern Africa.
During the Middle Pleistocene lions were likely widespread across Africa, but periods of high humidity caused tropical rainforest expansion across equatorial Africa, and the Sahara became savannah. This meant that southern and eastern African lion populations would have become isolated from western and northern populations. An increase in aridity also occurred, which caused the Sahara to expand and separated lions residing in North Africa and West Africa. During this time, lions in the west began to expand their range into Central Africa which was becoming more inhabitable. The data also suggested that during the end-Pleistocene, on two separate occasions lions entered Asia from North Africa.
Findings such as these could have implications for the conservation of lions living today. Asian lions are endangered, with fewer than 400 existing today. It is also estimated that there are as few as 400-800 West African lions and 900 Central African lions; there is concern that these lions may face extinction. But there is light at the end of the tunnel. The results found that the now thought to be extinct Barbary lion from North Africa is closely related to the extant Asian lion from India. This means that should efforts be made to restore lions to North Africa, closely-related Indian lions could potentially be reintroduced to this area.
Lions face numerous threats including climate change, loss of habitat due to agriculture and human population growth, and also poaching for products such as meat and bone. Over the last 20 years, it is thought that the African lion population has reduced by about one third. Hopefully these findings may aid conservation planning of these animals in order to prevent their further decline.
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