 |
|
Parasites a key to the decline of red colobus monkeys in forest fragments
October 25, 2007CHAMPAIGN, Ill. - Forest fragmentation threatens biodiversity, often causing declines or local extinctions in a majority of species while enhancing the prospects of a few. A new study from the University of Illinois shows that parasites can play a pivotal role in the decline of species in fragmented forests. This is the first study to look at how forest fragmentation increases the burden of infectious parasites on animals already stressed by disturbances to their habitat.
The study, of black-and-white colobus monkeys and red colobus monkeys in tropical forests in western Uganda, appears in the American Journal of Primatology.
Once dominated by vast forests, Uganda now has less than one-twentieth of its original forest cover. According to the World Resources Institute, its tropical forests are being logged and converted to agricultural land at a rate that outpaces sub-Saharan Africa as a whole. Small tracts remain, however, hemmed in by pastures and croplands. Many of the species that thrived in the original forests are struggling to survive in these parcels, which can be as small as one hectare in size.
"In Uganda, just looking at the primates, it's one of the most biodiverse places on the earth," said Thomas Gillespie, a professor of pathobiology and of anthropology, who is principal investigator on the study. "You've got 12 to 13 species of primates in a core undisturbed forest. But if you go into these forest fragments, you'll find only three or four species of primates."
Populations of black-and-white colobus monkeys appear to be stable in the Ugandan forest remnants, while their cousins, the red colobus monkeys, are in decline.
Gillespie and his colleague, Colin Chapman, of McGill University in Montreal, surveyed 20 forest fragments near the western boundary of Kibale National Park, in western Uganda.
They compared the abundance, variety and density of potentially harmful parasites in these fragments to the undisturbed "core forest" of the park.
The researchers followed the monkeys for four years, collecting data on how far the animals ranged, what they ate and which parasites were infecting them.
In those four years, red colobus populations in forest fragments declined 20 percent, whereas populations of black-and-white colobus monkeys remained relatively stable. Both species maintained stable populations in the undisturbed forest.
Scientists have struggled to explain why closely related animals, like these two species of monkeys, can fare so differently in forest fragments. The answer, Gillespie said, lies in a complex interplay of factors, with parasites and nutrition playing key roles.
The researchers focused on two nematodes known to cause significant pathology in monkeys: a whipworm, (Trichuris sp.), and a nodule worm (Oesophagostomum sp.). While feeding on leaves, the monkeys ingest the larval forms of these worms. The larvae mature in the intestines, where they can cause blockages or other damage. The nematodes migrate through blood vessels, causing inflammation, organ damage and, sometimes, death.
The researchers found a higher density of parasites in the forest fragments than in the undisturbed forest. They also found new parasites not seen in the undisturbed forest.
"Several of the parasites in these animals in the fragments never occur in undisturbed forest, and some of these novel parasites are definitely from livestock or people," Gillespie said. The red colobus monkeys were infected with five of these human or livestock parasites; the black and white colobus carried only two.
Other differences between the two species affect their vulnerability to parasitic infection. Red colobus monkeys congregate and live in large groups, with up to 50 members, compared with about 10 members in the black-and-white groups. Red colobus monkeys eat a much more varied diet. This causes them to travel farther, searching for the foods they need. But many of the plants that make up their diet simply aren't available in disturbed forest fragments.
"The red colobus typically eat 40 to 50 species of plants, but in these forest fragments we might only have 12 tree species, so there's a dramatic reduction in what we typically would see them feed on," Gillespie said.
"The black-and-white colobus tend to feed on whatever's dominant. They make do with what's there."
The black-and-white colobus monkeys' ability to eat well under a variety of circumstances enhances their ability to withstand parasitic infections, Gillespie said.
Red colobus monkeys' travels bring them into contact with more parasites. Their compromised nutritional status also weakens them, giving parasites the edge, Gillespie said.
"We asked how parasitism plays into this dynamic of some species doing well and others not doing well after forest fragmentation," Gillespie said. "This is giving us a new window into what's happening."
University of Illinois at Urbana-Champaign
"In Uganda, just looking at the primates, it's one of the most biodiverse places on the earth," said Thomas Gillespie, a professor of pathobiology and of anthropology, who is principal investigator on the study. "You've got 12 to 13 species of primates in a core undisturbed forest. But if you go into these forest fragments, you'll find only three or four species of primates."
Populations of black-and-white colobus monkeys appear to be stable in the Ugandan forest remnants, while their cousins, the red colobus monkeys, are in decline.
Gillespie and his colleague, Colin Chapman, of McGill University in Montreal, surveyed 20 forest fragments near the western boundary of Kibale National Park, in western Uganda.
They compared the abundance, variety and density of potentially harmful parasites in these fragments to the undisturbed "core forest" of the park.
The researchers followed the monkeys for four years, collecting data on how far the animals ranged, what they ate and which parasites were infecting them.
In those four years, red colobus populations in forest fragments declined 20 percent, whereas populations of black-and-white colobus monkeys remained relatively stable. Both species maintained stable populations in the undisturbed forest.
Scientists have struggled to explain why closely related animals, like these two species of monkeys, can fare so differently in forest fragments. The answer, Gillespie said, lies in a complex interplay of factors, with parasites and nutrition playing key roles.
The researchers focused on two nematodes known to cause significant pathology in monkeys: a whipworm, (Trichuris sp.), and a nodule worm (Oesophagostomum sp.). While feeding on leaves, the monkeys ingest the larval forms of these worms. The larvae mature in the intestines, where they can cause blockages or other damage. The nematodes migrate through blood vessels, causing inflammation, organ damage and, sometimes, death.
The researchers found a higher density of parasites in the forest fragments than in the undisturbed forest. They also found new parasites not seen in the undisturbed forest.
"Several of the parasites in these animals in the fragments never occur in undisturbed forest, and some of these novel parasites are definitely from livestock or people," Gillespie said. The red colobus monkeys were infected with five of these human or livestock parasites; the black and white colobus carried only two.
Other differences between the two species affect their vulnerability to parasitic infection. Red colobus monkeys congregate and live in large groups, with up to 50 members, compared with about 10 members in the black-and-white groups. Red colobus monkeys eat a much more varied diet. This causes them to travel farther, searching for the foods they need. But many of the plants that make up their diet simply aren't available in disturbed forest fragments.
"The red colobus typically eat 40 to 50 species of plants, but in these forest fragments we might only have 12 tree species, so there's a dramatic reduction in what we typically would see them feed on," Gillespie said.
"The black-and-white colobus tend to feed on whatever's dominant. They make do with what's there."
The black-and-white colobus monkeys' ability to eat well under a variety of circumstances enhances their ability to withstand parasitic infections, Gillespie said.
Red colobus monkeys' travels bring them into contact with more parasites. Their compromised nutritional status also weakens them, giving parasites the edge, Gillespie said.
"We asked how parasitism plays into this dynamic of some species doing well and others not doing well after forest fragmentation," Gillespie said. "This is giving us a new window into what's happening."
University of Illinois at Urbana-Champaign
Colobus Monkeys Current Events and Colobus Monkeys News RSSExtinction threat growing for mankind's closest relatives
Mankind's closest relatives - the world's monkeys, apes and other primates - are disappearing from the face of the Earth, with some literally being eaten into extinction.
Ugandan monkeys harbor evidence of infection with unknown poxvirus
Researchers report this month that red colobus monkeys in a park in western Uganda have been exposed to an unknown orthopoxvirus, a pathogen related to the viruses that cause smallpox, monkeypox and cowpox.
Key 'impact hunters' catalyze hunting among male chimpanzees
While hunting among chimpanzees is a group effort, key males, known as "impact hunters" are highly influential within the group. They are more likely to initiate a hunt, and hunts rarely occur in their absence, according to a new study.
Chimpanzees found to use tools to hunt mammalian prey
Reporting findings that help shape our understanding of how tool use has evolved among primates, researchers have discovered evidence that chimpanzees, at least under some conditions, are capable of habitually fashioning and using tools to hunt mammalian prey.
Hominid fossils from Ethiopia link ape-men to more distant human ancestors
New fossils discovered in the Afar desert of eastern Ethiopia are a missing link between our ape-man ancestors some 3.5 million years ago and more primitive hominids a million years older.
Monkey-dung study offers clues about land-use, wildlife ecology
Fecal matter of red colobus monkeys collected in western Uganda has yielded a wealth of knowledge about human land-use change and wildlife health and conservation.
Logging changed ecological balance for monkeys, damaged health
Twenty-eight years after intense selective logging stopped in the region now known as Uganda's Kibale National Park, the red-tailed guenon (Cercophithecus ascanius) is a primate still in decline.
Why Sloths Do Not Sleep Upside Down
Several mammal species other than ruminants and camels have a multi-chambered forestomach - kangaroos, hippos, colobus monkeys, peccaries, sloths - but they do not ruminate. As studies on the digestive physiology of these species are largely missing, it is generally assumed that their forestomach functions in the same way as that of ruminants, the most prominent characteristic of which is the selective retention of larger particles. However, retaining larger particles (which are more difficult to digest due to their unfavourable surface:volume-ratio) only makes sense if you can chew on them again, i.e. ruminate, and thus reduce their size. In rodents and other small hindgut-fermenting he
More Colobus Monkeys Current Events and Colobus Monkeys News Articles
| The Red Colobus Monkey. Wildlife Behavior and Ecology Series by Thomas T. Struhsaker | |
 | Inferring extinction from biological records: Were we too quick to write off Miss Waldron's Red Colobus Monkey (Piliocolobus badius waldronae)? [An article from: Biological Conservation] by D.L. Roberts, A.C. Kitchener This digital document is a journal article from Biological Conservation, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.Description: We are now entering a time of immense environmental upheaval where experts are increasingly required to provide conservation... |
| Colobus monkeys: An entry from Thomson Gale's Gale Encyclopedia of Science, 3rd ed. by Jean F. Blashfield The “Gale Encyclopedia of Science” is written at a level somewhere between the introductory sources and the highly technical texts currently available. This six-volume set covers all major areas of science and engineering, as well as mathematics and the medical and health sciences, while providing a comprehensive overview of current scientific knowledge and technology. Alphabetically arranged... | |
| Plant Chemical Defenses and the Feeding and Ranging Behavior of Colobus Monkeys in African Rainforests by Doyle Benton McKey | |
| Mortality trends in the African cherry (Prunus africana) and the implications for colobus monkeys (Colobus guereza) in Kakamega Forest, Kenya [An article from: Biological Conservation] by P.J. Fashing This digital document is a journal article from Biological Conservation, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.Description: Prunus africana (Hook.f.) Kalkm. is a secondary forest canopy tree species that has been declining over much of its... |
| The Red Colobus Monkey. by Thomas T. Struhsaker | |
| Red Colobus Monkey (Wildlife Behavior and Ecology) by Thomas T. Struhsaker | |
 | Chimpanzee and Red Colobus: The Ecology of Predator and Prey by Craig B. Stanford, Richard W. Wrangham Our closest living relatives, the chimpanzees, are familiar enough - bright and ornery and promiscuous. But they also kill and eat their kin, in this case the red colobus monkey, which may say something about primate - even hominid - evolution. This book, the first detailed account of a predator-prey relationship involving two wild primates, documents a six-year investigation into how the risk of... |
| Behavioral observations of feral colobus monkeys: A bibliography by Jean Balch Williams | |
| Red Colobus Monkey. by Thomas T. Struhsaker |
| © 2009 BrightSurf.com |