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Nature | Science | World

May 23, 2005

A Primate Explosion

New monkey species are being discovered at a staggering rate. Here's why our long-lost cousins keep turning up.

David Goldenberg

Carolyn Ehardt, a primatologist from the University of Georgia, has been looking for monkeys in the Udzungwa Mountains of Tanzania off and on for over 10 years. But the ones she eventually located, earlier this year, weren't the ones she thought she would find. In fact, the highland mangabeys she found have never been described by science, and are most likely an entirely new species of primate.

Ordinarily, this would be huge news. Primates are very rare—just over 400 species exist in the world. Plus, they're cute and share an order with humans, so it doesn't take a wildlife-conservation activist to appreciate them. But this year, finding new primate species has been no big deal. First, there was the hubbub surrounding the naming of the new Golden Palace titi monkey from Brazil. Then, a couple of new lemur species were identified in Madagascar (Mail & Guardian). Later, scientists in India identified a new species of macaque—the first new macaque species found in over 100 years. Then there are the giant chimpanzee-type primates that were identified in Congo, but remain in new-species-limbo for lack of evidence (New Scientist via rfthomas.clara.net).

new mangabey
The highland mangabey, caught on camera in its native habitat. Click on the image for video, courtesy Carolyn Ehardt, the University of Georgia, and the National Science Foundation.
In fact, when Ehardt talked to other primate researchers in Tanzania, she found out that they, too, had found a new monkey species at a site 370 kilometers away from hers. It turns out the researchers, including Tim Davenport from the Wildlife Conservation Society, had simply found a different group of highland mangabeys. (Disclosure: I used to work for WCS.) After Ehardt went to Davenport's site (click on the picture at left to see her video of the mangabeys from there), she was convinced they had simultaneously discovered the same species, so she pulled the paper she had submitted with her collaborators to Science, and together the groups submitted a jointly authored piece.

Why are so many new primate species being found? Such a simple question has some intricate and interrelated answers. For starters, a renewed focus on conservation means that more scientists are spending more time in more places where they are likely to encounter new animals. It doesn't hurt that defining a new species means more funding and recognition for the area in which the animals live and the organization that found them. Additionally, a shift in how the scientific establishment defines species means that the classification is broader; some believe it is easier for scientists to gain new species status for groups of animals that previously wouldn't have been eligible.

Conservation Concentration

Colin Groves, a professor of biological anthropology at the Australian National University, is one of the world's leading experts on primate taxonomy, and he believes a changed research focus has sparked the discovery of the new species. "I think that people are probably surveying much more carefully than before, staying for longer in the more isolated places, things like that," he told Gelf over email. "Of course many of them are turning up in places never before surveyed: the deep Amazon rainforests, the Annamite Range along the Vietnam and Laos border, and I must say that the Eastern Arc forests of East Africa have never been properly surveyed."

Those forests are where Ehardt found her mangabeys. "I think there is and has been for a while now concern about loss of biodiversity," Ehardt says. "It's led to intensified research and conservation effort and sources of funding. This growing support is causing more people to be in biodiversity hotspots, like the one I've been working in."

Thanks to targeted funding, more scientists are spending time in these "hotspots," a term first used by British Ecologist Norman Meyers to describe areas that contain a high level of endemic biodiversity and face extreme threats. These 34 regions contain only about 2% of the world's land area but about 40% of its terrestrial-vertebrate species. Ehardt was in the Eastern Afromontane hotspot. Focusing on hotspots is a way for organizations to get the most bang for their conservation buck, says Ehardt.

Ehardt and her team were originally searching for the extremely endangered Sanje mangabey, of which she expects there are less than 1,300 remaining. The highland mangabeys probably number less than 1,000, she says. As Ehardt's experience demonstrates, new species are often discovered serendipitously by researchers involved in other projects. When these new species are found, they can sometimes tell us important new facts about the ecosystem in which they live. The highland mangabeys, for example, are extremely quiet in the presence of humans and are the only known mangabey species to communicate without using the distinctive "whoop-gobble" call. Both traits may be related to predation pressures.

The Arunachal macaque, first spotted by scientists earlier this year in the highlands of the Arunachal Pradesh province in eastern India, is located in the Indo-Burma hotspot. Identified by researchers from the Nature Conservation Foundation (NCF) working jointly with researchers from the Wildlife Conservation Society (WCS), this dark and heavyset animal is the first new species of macaque found since the Pagai macaque was discovered in 1903. Researchers affiliated with groups in the area also found two new species of deer and a primitive mountain goat previously unknown to science, as well as several new reptile and amphibian species—all a testament to the effectiveness of hotspot-centered research.

All of the newly found primate species are located in or very near to one of these hotspots. "It's probably similar to when a new diagnostic tool is found in medicine," Ehardt says. "All of a sudden rates of certain diseases start shooting up, but it's not because there are actually more cases."

New (To Us)

One related reason for the spate of species discoveries is that researchers are interacting more with local populations, especially hunters. Though Ehardt's group was probably the first in her area of the Udzungwa Mountains to see the highland mangabey, her experience is the exception. Almost all other researchers who find new species learn about them through locals. In fact, the highland monkey is also known as the kipunji, because that's what the local hunters around Davenport's site called the strange, shy monkey they encountered deep in the forest. Ehardt says that the first genetic sample they will get of the mangabey will probably come from a skin owned by a hunter from another section of the mountain range.

The Arunachal macaque is not eaten by locals, but is occasionally killed for crop-raiding gardens; its species name, mun zala, means "deep-forest monkey" in the vernacular of the local Dirang Monpa people. The Golden Palace titi monkey is known by villagers around Madidi National Park in Bolivia as "Luca, Luca" because of its vocalizations.

Biologists often rely on the knowledge of local hunters, who as a rule are informed about the behavior patterns of the various species they encounter. And not just the hunters' prey: Hunters I worked with in Zambia could identify the different vocalizations for all the bird and primate species we heard, and extrapolate from them to get an accurate picture of the landscape ahead. Closely related species often have very different calls and are worried about very different things; learning those minute differences are one way for hunters to protect themselves. (It's important for hunters to dodge leopards, for example, but they need not waste their time worrying about eagles. Vervet monkeys have different calls for the different predators, as Dorothy Cheney and Robert Seyfarth elaborate on in their excellent book, How Monkeys see The World.)

It might seem counterproductive for hunters to work with conservationists in locating new species—after all, the hunters risk having their meat source labeled "endangered" and hence off-limits. But hunters who cooperate with scientists can often gain long-term employment as trackers, field assistants, and forest guards, all positions that are considerably better-paying and safer than subsistence hunting.

Some new species are even found in food stalls in village markets, like the new rodents recently discovered in Laos (National Geographic News). As The Onion pointed out last week, new species can be delicious.

Specious Species?

New York University anthropology professor Todd Disotell, a primate taxonomy specialist, is going to start analyzing DNA from the highland mangabey over the next few weeks, as soon as he receives fecal samples from Ehardt's group. Disotell's main job will be to figure out where the new species fits among the current mangabey evolutionary tree, but he also wants to confirm one important point: that the highland mangabey is actually genetically different from other known species.

"I have very bright colleagues and the animal does look very different," says Disotell, "but I won't be 100% convinced until I have samples in hand."

Disotell feels he has legitimate reason to question whether the explosion of recently discovered primate species is a real phenomenon. "It's called the conservation-species concept," Disotell says. "If you can get species status, you can get protection [for the animals]. If it's just a subpopulation, well, it's difficult. Some people, trying to do good, might stretch the definition of species."

So Disotell sticks to DNA to tell the difference, though he acknowledges that there is no true definition of what makes a species. Besides, different genes evolve at different rates, so it would be impossible to say that different species must be a certain distance apart genetically speaking. "It's as much philosophy as it is data," he says. "There's no universal yardstick."

That said, Disotell thinks that the case can be made that if a new "species" is less differentiated from another species than two subspecies within the same genus, it should not be awarded species status.

"Of all the ones that have been announced in the last several years, if molecular results back it up, this [mangabey] is the best of those," says Disotell. "Some others, like the macaque and the New World monkeys—my opinion is those are conservation species. Sometimes when you do genetic testing later on, you see they're not actually species. Looking at a picture of a chubby stubby macaque, I'm not impressed." Researchers who found the Arunachal macaque haven't replied to emails from Gelf.

Groves disagrees with Disotell's thinking. "They are genuine species alright," he told Gelf. "While it is true that there has been a rethink of what we mean by species, and this has increased the total number of species that are recognized, the ones which hit the headlines are genuinely new discoveries, not simply reclassifications." (That said, Groves has nixed the idea that the ape found in Congo is a new species. "There is no doubt from the measurements that this is the skull of a chimp," he told the Daily Telegraph of London.)

Groves says that while it's true more species are being identified, there is another reason behind the change:

There has been a new view of species which has been gradually sweeping through biology in the past 15 years or so. Formerly everybody seemed to be operating on the basis of the concept that a species was reproductively isolated—meaning that in the field different species did not interbreed. This definition has gradually proved to be untenable. The concept of fixed heritable differences is much easier to maintain and more accurate. This is why, even without all the new discoveries that have happened over the past 15 or 20 years, the number of recognized species of primates probably has increased by about a third over that time—that simply is reclassification.

Ehardt thinks the highland mangabey will prove to be a distinct species, but she acknowledges the confused of state of species classification. "In any profession, there are those who are lumpers and those who are splitters," she says. "Colin's a splitter. He tends to see most of them as distinct species."

Environmental Focus

The legitimacy of their new finds notwithstanding, conservation groups like WCS use the publicity surrounding the discovery of new species to focus resources on preserving their habitats. When major new species finally are found, they are often in critically small populations. (Their scarcity is, of course, often why they evaded scientists for so long.)

Robert Wallace, who found the new titi monkey in Bolivia, auctioned off the naming rights for the new species, eventually earning $650,000 for the nonprofit organization that protects the monkey's habitat (WCS). The Golden Palace casino, the same online company that bought the grilled-cheese sandwich with the image of the Virgin Mary and has paid a woman to name her baby GoldenPalace.com, eventually outbid Ellen DeGeneres for the honor (official site); unsurprisingly, the new species has the scientific name Callicebus aureipalatii, the Golden Palace monkey.

The highland mangabey and the Arunachal macaque were named in more typical fashion: Their species names are the names the monkeys are referred to by the local populations. Nonetheless, finding a new species still means more potential for funding and protection. Ehardt is currently pushing the Tanzanian government to incorporate the sites where the mangabey is found into Udzungwa Mountains National Park, and WCS is asking to upgrade the mangabeys' protective status to critically endangered. "We finally have a bit of leverage with the Tanzanian government," says Ehardt.

Similar efforts have taken place in India. From the press release that the NCF and WCS, among others, put out after the discovery of the Arunachal macaque: "Work by NCF and its partners in the high altitude areas of Arunchal Pradesh have also recently led to the creation of the Tsangyang Gyatso Biosphere Reserve by the Arunachal Pradesh government. ...The discovery of the Arunachal macaque demonstrates that there is much to be explored and found yet."

"When you're looking at this from a conservation standpoint, it makes sense," says Ehardt. "If [Conservation International President] Russell Mittermeier feels good reason to think a taxon is distinct, he's going to go with it." When asked if she thought that finding a new species was important to energizing conservation efforts, Ehardt replied, "I'm certain it does. A new primate is something a lot of people can relate to. It's a flagship species."

Ehardt doesn't advocate forsaking science for conservation, but instead argues that scientists and conservationists must work together. She said to Gelf, "If you're trying to conserve an animal, and you don't know basic things about it, how in the world are you going to save it?"

David Goldenberg

David Goldenberg is the co-founder and editor of Gelf, and the host of Geeking Out, Gelf's monthly science speaking series.







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- Nature
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Please exclude the letter shown 'posted by Atonu Choudhurri'.With due respect,I would like to clarify my stand that I am not supposed to write for your magazine as am not eager to do that.
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Article by David Goldenberg

David Goldenberg is the co-founder and editor of Gelf, and the host of Geeking Out, Gelf's monthly science speaking series.

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