Modern lions’ origin revealed by genetic analysis

lionThe origin and history of modern lions have been revealed by scientists.

A genetic analysis of living lions and museum specimens confirms modern lions’ most recent common ancestor lived around 124,000 years ago.

Modern lions evolved into two groups; one lives in Eastern and Southern Africa, the other includes lions in Central and West Africa, and in India.

This second group is now endangered, meaning half the genetic diversity of modern lions is at risk of extinction.

Details of the findings, which may aid the conservation of lions, are published in the journal BMC Evolutionary Biology.

Unravelling the history of the lion has been difficult. Animals living in tropical areas tend to leave fewer fossilised remains behind.

Lions have also been persecuted during their recent history, with whole populations being wiped out by human activity.

Such gaps in the fossil record, and in the distribution of lions, makes it difficult to reconstruct their past.

So an international team of scientists turned to the ancient DNA within lion specimens held in collections and museums around the world.

Led by Dr Ross Barnett of Durham University, UK, the team sequenced mitochondrial DNA from museum-held specimens, including from different subspecies, including the extinct Barbary lion of North Africa, the extinct Iranian lion, and lions from Central and West Africa.

The researchers compared these with genetic sequences drawn from other lions living in Asia, and across other parts of Africa, and then worked out how the different subspecies of lion evolved.

The study revealed that the single species of lion that persists today, Panthera leo, first appeared in Eastern-Southern Africa, supporting the conclusions of earlier research.

Around 124,000 years ago, in the Late Pleistocene, different subspecies began to evolve.

Around that time, tropical rainforests expanded across equatorial Africa, and the Sahara region turned to savannah.

Lions living in the south and east of the continent became separated from, and began to diverge from, those living in the west and north.

The genetic differences between these two groups of lions remain today.

Around 51,000 years ago, the continent dried and the Sahara expanded, cutting off lions in the west from those in the north.

At the same time, lions in the west expanded their range into Central Africa, which became more inhabitable.

Since then, Africa’s great rivers, including the Nile and Niger, have helped keep these lions apart.

Another detail only revealed by the study of ancient DNA in specimens, is that modern lions began their exodus out of Africa just 21,000 years ago.

At the end of the Pleistocene, lions left North Africa, eventually reaching as far as India.

Much later, just around 5,000 years ago, another group of lions left the continent, reaching what is today Iran, in the Middle East. These lions are now extinct.

These discoveries may have important implications for the conservation of modern lions.

Fewer than 400 Asian lions (P. leo persica) survive, living on the Kathiawar Peninsula of India, with the subspecies listed as Endangered by the International Union for the Conservation of Nature.

“Lion populations in West Africa and Central Africa, which have drastically declined over the past few decades, are actually more closely related to the Indian lion than to lions in, say, Somalia or Botswana,” Dr Barnett told BBC Nature.

Despite the large geographical distances between them, these lions also seem closely related to Iranian lions and the Barbary lions of North Africa.

“I was most surprised by the incredibly close relationship between the extinct Barbary lion from North Africa and the extant Asian lion from India,” said Dr Barnett.

The Barbary lion is one of the most enigmatic of all large predators, both due to its impressive appearance and uncertainty over its fate.

Once numerous across North Africa, the Barbary lion was the most physically distinctive type of lion, including those living elsewhere in Africa and Asia.

It had an extensive mane, and differences in the shape of its head included a more pointed crown and narrow muzzle. People at the time also talked of it being larger, with different coloured eyes to other lions, though it is unclear whether either difference was real.

It remains uncertain whether any Barbary lions exist today, and conservationists have talked of resurrecting the subspecies.

Circumstantial evidence suggested some may have survived in captivity, as part of a collection held by the royal family of Morocco.

But previous research and that by Dr Barnett’s team suggests there were not in fact true Barbary lions.

If so, and Barbary lions are in fact extinct, then the new study suggests that closely-related Indian lions could be reintroduced to their habitat, as a way to best restore lions to North Africa.

“This has implications for any future attempts to reintroduce lions into North Africa,” said Dr Barnett. “They could probably be re-seeded with Indian lions.”

Around a third of African lions are thought have disappeared in the past 20 years.

Of special concern, say Dr Barnett and colleagues, are West and Central African lions, which may be close to extinction in the wild, with around 400-800 and 900 lions living in each region respectively.

Relatively few lions of these subspecies are held within zoos for conservation.

“If you think of lion diversity as two distinct branches then the regions where lions are doing ok, in Eastern and Southern Africa, reflect only half the total diversity,” said Dr Barnett.

“The other half is represented by the diversity in India, West Africa, and Central Africa.

“If the West and Central African populations were to slip away, that whole branch would only survive in the tiny Indian lion population.”

Source: http://www.bbc.co.uk/nature/26736688

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