Many animal and plant species are suffering, their numbers dropping. Luckily, several groups and individuals consider this a sad turn of events and various conservation efforts are being undertaken. Yet, in order to make sure those efforts are as efficient as possible, understanding the evolutionary history of the target animals or plants is of crucial importance.
For many large tropical animal species, however, this isn’t always that easy. Often, extensive fossil material is missing and the small, isolated and fragmented nature of their populations makes the genetic data difficult to interpret clearly. This is especially true for the king of all animals, the lion.
A new study, performed by an international group of researchers and published in BMC Evolutionary Biology, used mitochondrial DNA to reconstruct the history of lions. Since mitochondria (little biological energy factories in cells) are passed on via the mother, this case is a maternal history. DNA from museum specimens was sequenced and added to a broader sample of lion sequences so that the researchers were able to construct a dataset encompassing recent lion history.
Using this combination of ancient and modern DNA sequences, the authors applied computational analyses to the data in the hopes of learning more about the evolution of lions and their current demography. Based on the analyses, five major groups could be identified among modern lions. A North African/Asian group, one in West Africa, another one in Central Africa, a South African one and a final one in East-South Africa. According to the mitochondrial DNA data on which this study is based, all these modern lion groups share a Late Pleistocene origin (estimated at roughly 125 000 years ago), probably in South-East Africa.
Since then, changes in climate and the accompanying growing and shrinking of tropical forests have probably been a major force in shaping the current division of lions into the five identified groups. First, the South and South-East African lions were separated from the others due to an expanding equatorial rainforest. Next, the western representatives spread into Central Africa as the forests there dwindled. Finally, the North African lions found their way into Asia on two separate occasions, first into India and later into the Middle East. The current division into five groups is maintained by several barriers, such as the Great Rift Valley, rainforest, the Sahara, the river Niger and the Nile.
Recognizing these different populations could have implications for lion conservation. At the moment, international conservation efforts focus on two lion groups: an African and an Asian one. This study, however, suggests that it may be better to bring five distinct groups to the fore in conservation planning. And not only in the field, but also in zoos. By paying attention to the maintenance of genetic diversity, the chances of the lion can only improve.
The authors acknowledge that this study is based solely on mitochondrial DNA and call for more work, specifically the inclusion of nuclear DNA and morphological data to further strengthen and support their findings.
All hail the king of beasts, in all of its newly identified diversity.
Photo: Flickr, fanz
Barnett R, Yamaguchi N, Shapiro B, Ho SY, Barnes I, Sabin R, Werdelin L, Cuisin J, & Larson G (2014). Revealing the maternal demographic history of Panthera leo using ancient DNA and a spatially explicit genealogical analysis. BMC evolutionary biology, 14 (1) PMID: 24690312
lion, dna, evolutionary biology, conservation, mitochondrial dna, nuclear dna