Editor, Earth NewsAn intimate portraitThe tiger may be more ancient and distinct than we thought. Tigers are less closely related to lions, leopards and jaguars than these other big cats are to each other, according to a new comprehensive study. The genetic analysis also reveals the tiger began evolving 3.2 million years ago, and its closest living relative is the equally endangered snow leopard. The discovery comes as the BBC launches a collection of intimate videos of wild tigers and the threats they face. Despite the popularity and endangered status of tigers, much remains to be discovered about them, including how they evolved. It has long been known that the five species of big cat – the tiger, lion, leopard, jaguar and snow leopard, which belong to the Panthera genus – and the two species of clouded leopard are more closely related to each other than to other smaller cats.
But it has been difficult to pin down the exact relationships between them. So to find out more, scientists Mr Brian Davis, Dr Gang Li and Professor William Murphy conducted an analysis of the DNA of all these species. By looking at similarities in DNA held in mitochondria and within the sex chromosomes among other places, the researchers found that the five big cat species are related to each other in a different way to previously thought. Their data strongly suggests that lions, leopards and jaguars are most closely related to each other. Their ancestor split from other cats around 4.3 to 3.8 million years ago. About 3.6 to 2.5 million years ago, the jaguar began to evolve, while lions and leopards split from one other about 3.1 to 1.95 million years ago. But the tiger had already emerged by this point. The ancestor of tigers and snow leopards also branched off around 3.9 million years ago. The tiger then began to evolve into a unique species toward the end of the Pliocene epoch, about 3.2 million years ago.
According to the study published in the journal Molecular Phylogenetics and Evolution, the tiger and snow leopard are “sister species.”
DNA studies revealed that tigers are more ancient than other big cats such as lions, leopards and jaguars, which belong to the Panthera genus, BBC reported.
Brian Davis, Gang Li and Professor William Murphy, who studied all these species, came to the conclusion that lions, leopards and jaguars are more closely related to each other than to tigers.
Their findings showed that the jaguar began to evolve about 3.6 to 2.5 million years ago and lions and leopards split from one other about 3.1 to 1.95 million years ago.
The tiger, however, began evolving 3.2 million years ago and therefore emerged by this point. http://news.softpedia.com/news/The-Origins-of-Tigers-Revealed-134874.shtml
The Origins of Tigers Revealed
New genetic study clears the mysteryBy Tudor Vieru, Science EditorFebruary 13th, 2010, 09:47 GMT
Tigers have a very weird situation right now, in the sense that they are some of the most popular and widely known animals in the world, while at the same time being severely endangered. Although many researchers have devoted years of their lives to studying these magnificent creatures, a lot of data about them still remains obscured. These missing pieces of information also include more details as to how the animals evolved.
Up until now, experts investigating big cats thought that tigers, lions, leopards, jaguars, snow leopards and two species of clouded leopards were more closely linked to each other genetically than to any other species of smaller cats. However, there appear to be intricate relationships between these predators, and experts have had a tough time figuring them out up to this point. The only way out was to conduct a DNA analysis of all these species, and this is precisely what researcher Brian Davis, Dr. Gang Li and professor William Murphy did.
They looked at the differences and similarities that existed between these species in terms of the genetic information stored in their mitochondrial DNA, and the gender chromosomes. This investigation revealed that the big cats are actually related to each other in different patterns than the ones researches had suggested in previous studies. Lions, leopards and jaguars were found to be the most tightly linked, with a common ancestor probably living about 4.3 to 3.8 million years ago. At around the same time, the common ancestor of snow leopards and tigers appeared, the experts write in the latest issue of the respected scientific journal Molecular Phylogenetics and Evolution.