Scientists confirm what we already know about elephants?

Contrary to the belief of many scientists (as well as many members of the public), new research confirms that Africa has two -- not one -- species of elephant. Scientists from Harvard Medical School, the University of Illinois, and the University of York in the United Kingdom used genetic analysis to prove that the African savanna elephant and the smaller African forest elephant have been largely separated for several million years.

---

"Experimentally, we had a major challenge to extract DNA sequences from two fossils -- mammoths and mastodons -- and line them up with DNA from modern elephants over hundreds of sections of the genome," says research scientist Nadin Rohland of the Department of Genetics at Harvard Medical School.

According to David Reich, associate professor in the same department, "The surprising finding is that forest and savanna elephants from Africa -- which some have argued are the same species -- are as distinct from each other as Asian elephants and mammoths."

Researchers only had DNA from a single elephant in each species, but had collected enough data from each genome to traverse millions of years of evolution to the time when elephants first diverged from each other.

"The divergence of the two species took place around the time of the divergence of the Asian elephant and woolly mammoths," says Professor Michi Hofreiter, who specializes in the study of ancient DNA in the Department of Biology at York. "The split between African savanna and forest elephants is almost as old as the split between humans and chimpanzees. This result amazed us all."

The possibility that the two might be separate species was first raised in 2001, but this is the most compelling scientific evidence so far that they are indeed distinct.

Previously, many naturalists believed that African savanna elephants and African forest elephants were two populations of the same species, despite the significant size differences. The savanna elephant has an average shoulder height of 3.5 meters whereas the forest elephant has an average shoulder height of 2.5 meters. The savanna elephant weighs between six and seven tons, roughly double the weight of the forest elephant.

DNA analysis revealed a wide range of genetic diversity within each species. The savanna elephant and woolly mammoth have very low genetic diversity, Asian elephants have medium diversity, and forest elephants have very high diversity. Researchers believe that this is due to varying levels of reproductive competition among males.

"We now have to treat the forest and savanna elephants as two different units for conservation purposes," says Alfred Roca, assistant professor in the Department of Animal Sciences at the University of Illinois. "Since 1950, all African elephants have been conserved as one species. Now that we know the forest and savanna elephants are two very distinctive animals, the forest elephant should become a bigger priority for conservation purposes."

This research was funded by the Max Planck Society and by a Burroughs Wellcome Career Development Award in Biomedical Science.

The researchers, whose findings appear online in PLoS Biology, compared the DNA of modern elephants from Africa and Asia to DNA that they extracted from two extinct species: the woolly mammoth and the mastodon. Not only is this the first time that anyone has generated sequences for the mastodon nuclear genome, but it is also the first time that the Asian elephant, African forest elephant, African savanna elephant, the extinct woolly mammoth, and the extinct American mastodon have been looked at together.

Have you ever wondered what happened that snakes lost their legs?

Some, if not all, snakes used to have legs, and now new research suggests snakes lost their limbs by growing them more slowly or for a shorter period of time.

The research, outlined in the latest issue of the Journal of Vertebrate Paleontology, strengthens the belief that snakes evolved from a lizard that either burrowed on land or swam in the ocean.

In either case, its legs must have become less useful as the animal evolved over time.

"If something is not useful it can regress without any impact on the (animal's) survival, or regression can even be positive, as for here if the leg was disturbing a kind of locomotion, like for burrowing snakes or swimming snakes," lead author Alexandra Houssaye told Discovery News.

For the study, Houssaye, from the National Museum of Natural History in Paris, and her colleagues analyzed a fossil snake named Eupodophis descouensi. The prehistoric snake lived during the Cretaceous Period in what is now Lebanon.

To better examine the snake, the scientists used a new imagining technique called synchrotron-radiation computed laminography (SRCL). With an intense, high-energy beam of X-rays, the SRCL deeply penetrated the fossil as the researchers rotated it. The result was thousands of two-dimensional images that were later compiled into a three-dimensional model of the ancient snake's hips and ultra tiny .8-inch legs.

"Synchrotrons are enormous machines and allow us to see microscopic details in fossils invisible to any other techniques without damage to these invaluable specimens," said co-author Paul Tafforeau from the European Synchrotron Radiation Facility.

The new 3-D model determined that Eupodophis, in its lifetime, had two small regressed hind limbs and no front limbs. The leg visible to the researchers was bent at the knee, possessing four anklebones but no foot or toe bones. The high tech imaging further showed that the internal architecture of the leg bones strongly resembled that of modern terrestrial lizard legs.

Houssaye said "the legs were very regressed" in this snake, which she added is not the world's oldest snake, but it comes pretty close.

"The oldest snake remains are dated to 112 to 94 million years ago, and this snake is dated to around 90 million years ago," she explained.

Yet another snake from the same time period, Najash rionegrina, is also thought to have had two small rear legs, strengthening the theory that snakes once had legs and evolved from a lizard with limbs. Hussam Zaher of the University of Sao Paolo in Brazil, and a colleague found Najash (which means "snake" in Hebrew) at the Rio Negro province ofArgentina.

Najash retained a sacrum, a bony feature that supported the pelvis. Zaher believes this feature was lost as snakes evolved from lizards. The fossil snake from Argentina is also thought to have lived on land, since it was found in what was once a terrestrial environment. Zaher said its anatomy suggests this snake lived in burrows.

Houssaye, however, does not think the case is yet closed as to whether or not snakes evolved from a marine or land-based lizard.

"The question of snake origin should not be resolved in the next 10 years," Houssaye said.

She is, however, hopeful that all of the separate teams working on this puzzle can one day pinpoint what species was the common ancestor of all snakes.