Friend, Tim, National Wildlife
Want to measure genetic diversity? Trace migration routes? Paint a picture of a species' social structure? Reconstruct a crime scene? These days, the tool of choice for all these endeavors is DNA research.
A computer-generated model of deoxyribonucleic acid (DNA) reveals the molecule's trademark twisting double helix. The beads represent atoms, which are arranged in remarkably similar ways in the DNA of all organisms - but with enough variation that the differences allow researchers to obtain "fingerprints" from samples such as hair, skin or feathers. Blue depicts the structure's backbone. The gray, green, red and purple sections represent the four bases that comprise an alphabet for the genetic code.
Just before sunset in Tanzania's Gombe National Park, the chimpanzees made famous by Jane Goodall begin folding branches and collecting leaves to make nighttime nests like cradles in the boughs of trees. Molecular biologist Phillip Morin follows a single chimp, watches it build its nest and notes the location.
After sunrise, the chimp embarks on its day, and Morin climbs the tree to snatch the coarse, dark hairs the animal has left behind. He tucks them in an envelope so he can study components of their DNA - the genetic code of life in every cell of all living things - when he returns to the lab at the University of California, San Diego. "Genetics can tell us a lot about the history of animals that we can apply to their conservation," says Morin.
By "genetics," Morin means that the same molecular study of life that yielded critical evidence in the infamous O.J. Simpson trial has revolutionized our understanding of human disease and is even helping match pieces of the 2,000-year-old Dead Sea Scrolls, which were written on animal skins. DNA analysis has become one of the most dynamic and powerful tools for wildlife biologists working to maintain biodiversity, understand social structure and reproductive behavior, and learn how species and their habitats can be managed more effectively.
One of the more dramatic uses of DNA studies in wildlife is for crime solving. The technology is already helping authorities catch poachers and make people think twice before breaking the law, according to Ken Goddard, director of the unique U.S. Fish and Wildlife Service Forensics Laboratory in Ashland, Oregon. "We're basically breaking brand-new ground," he says. From tiny samples, the lab can distinguish genus, species, subspecies and gender - as well as identify an individual animal. Sleuths can now match a gut pile at a kill site with a head on a wall, meat in a freezer or blood on a car. "That is truly a revolutionary capability for wildlife forensics," says Goddard.
Before DNA analysis, starting about three decades ago, biologists studied blood proteins, which hold clues to animals' individual charateristics and yield crude tissue matches. The ability to study DNA has become widespread only in the last few years. The most important techniques are DNA fingerprinting - which reveals the unique genetic pattern of an individual - and the polymerase chain reaction (PCR). Using PCR techniques, scientists can take a tiny fragment of DNA and copy it a million times so they can examine it.
Before the DNA can be studied, researchers must, of course, obtain samples. With wild animals, in most cases that means using dart guns to sedate an animal to draw blood or firing special darts that pierce the skin and then pop out beating a small biopsy. For biologists in the field, the technique represents a challenge, if not a real danger of harming or being harmed by the animal.
Conservation biologist David Woodruff of the University of California, San Diego, and his colleague Morin solved that problem - at least where hairy animals are concerned - by using PCR to isolate and amplify DNA from animal hair. That breakthrough led Morin to Jane Goodall's chimps in Africa and to the first study of genetic variation in wild chimpanzees, reported last year. …