Splitting Hairs to Save Gorillas : Science: S.D. Zoo researcher uses DNA analysis of hair from nesting sites to detect inbreeding that could lead to extinction.

Karen Garner keeps getting gorilla hairs in the mail--from friends.

Garner, a researcher with the San Diego Zoo, is using a new form of DNA analysis in an effort to learn more about the evolution of gorillas and to keep them from extinction.

While DNA analysis has been used in criminal investigations, among other things, Garner is among the first to use such techniques on wild gorillas.

In the past, scientists have been unwilling to drug the gorillas to obtain the needed blood samples. But today, through a method of genetic analysis, hair gathered from nesting sites is being used in a procedure that will tell scientists whether wild gorilla subspecies have the genetic variety to survive. The technique enables scientists to observe wild animals and conduct minute analysis without disrupting their habitat.

In examining one of Africa’s few remaining groups of mountain gorillas, Garner has uncovered perilous levels of inbreeding. She will unveil her findings today( at a Chicago meeting of the American Assn. for the Advancement of Science.

“We don’t want to interpret that they are hopelessly inbred,” said Garner, who works for the zoo’s Center for Reproduction of Endangered Species. “But it is cause for concern.”

Said Robert Dowler, a biology professor at Angelo State University in San Angelo, Tex.: “The new testing poses an ideal situation, because of the obvious impossibility of getting blood samples of gorillas in the wild.”

In the 1980s, Dowler supervised genetic study of captive gorillas in which the animals were sedated and blood samples were taken.

“We can now get good genetic information with hair samples, which are much easier to obtain without affecting the wild gorilla population,” Dowler said.

Using a recently developed process that extracts genetic information from extremely small biological samples, typically hair, Garner compared the DNA sequencing of a gorilla subspecies living in Africa’s western lowlands with the sequencing of the mountain subspecies, which number slightly more than 600.

DNA forms a basic genetic blueprint for people and animals. It is made of microscopic strands of bead-like shapes. In her work, Garner examined DNA segments, which revealed the gorillas’ genetic variability. Such variability is crucial to any species’ survival.

The tested samples from lowland gorillas, a more numerous and geographically dispersed population, recorded up to 20% variation. In the mountain gorillas, the variation was 1%, Garner said.

“It’s real scary to have to interpret this,” she said.

Although there is no hard and fast correlation between genetic variation and the gorilla’s actual ability to adapt, conservationists fear the wild mountain gorilla may inbreed to extinction.

“Often, you just see a species or subspecies start to die off,” said Amy Vedder, a forest ecologist with Wildlife Conservation International, a division of the New York Zoological Society. “There are really no behavioral or physiological traits that we can look at and determine if this population is better adapted than that one.

“This is the first crack at looking at gorilla subspecies on a genetic basis.”

Vedder said the information gleaned from the new testing may aid scientists in developing conservation-management policies to preserve the endangered species.

For example, if the genetic base in the eastern Virunga gorillas of Africa is different from those in the west Virunga region, then conservationists would try to encourage crossbreeding between the two groups, Vedder said. Even though they are a part of the same subspecies, the mixing may make the group more viable as a whole.

The new technique enabling this DNA analysis is referred to as the polymerase chain reaction, or PCR. The technique requires a small starting sample--five follicles of hair, a few drops of blood or saliva--from which the enzyme polymerase makes millions of copies of the genetic code, Garner said. The copies are analyzed, serving in place of larger, more difficult to obtain samples.

The report Garner plans to present today at the Chicago meeting compares information from 30 gorillas, representing the three known subspecies. The San Diego center has also received about 450 more hair samples from wild and captive gorillas around the world.

The plight of the shrinking gorilla populations was the subject of “Gorillas in the Mist,” a popular book by Dian Fossey and a Hollywood movie starring Sigourney Weaver. Garner analyzed hairs from gorillas named Peanuts and BeetsMe, two of the animals chronicled in Fossey’s work.

There are three confirmed subspecies of wild gorillas: the western lowland, eastern lowland and mountain gorillas. Gorillas from the lowlands are common in zoos.

Vedder, the forest ecologist, conducted a 1989 census of mountain gorillas of Africa, focusing on the subspecies concentrated in the Virunga Mountains range in Rwanda, Zaire and Uganda, and another group in the Bwindi Forest of Uganda, also referred to as the Impenetrable Forest.

In the 1989 census, Vedder estimated there were 306 to 322 gorillas in the Virunga Mountains and about 300 in the Bwindi Forest. Vedder said scientists are trying to determine if mountain gorillas represent two subspecies. The new DNA analysis may help find the answer, she said.

The PCR copying technique is also being used to compare DNA from preserved museum tissues and preserved pathology specimens, in an attempt to compare genetic traits of present-day gorillas with their ancestors.

Although the breakthrough in genetic analysis is viewed as an aid to conservation efforts, Vedder said a more pressing issue exists:

Gorilla habitats in the mountain and forest areas have been severely depleted, forcing gorilla populations into isolation and limiting the possibilities for any breeding.

“The most urgent issues facing the gorilla are loss of habitat and over-hunting,” Vedder said. “We know about those problems right now, without any knowledge of the gorilla’s genetics. Those issues need to be addressed right away.”