A microsatellite, despite its name, is not a small electronic ball orbiting the earth. It's something even tinier and more intricate -- part of a strand of the genetic material DNA.

Microsatellites are being used by a team of scientists in the Yukon and Alberta to determine how close the relationship is among three small herds of woodland caribou in the southern Yukon.

A microsatellite is a section of the DNA molecule where a DNA sequence is repeated over and over again, explains Dr. John Coffin, research associate with the Wildlife Conservation Genetics and Forensics Lab at the University of Alberta.

The number of repetitions varies from individual to individual and determines the length of the microsatellite. That number, and the resulting length, are inherited from one of the individual animal's two parents.

Measuring the length of microsatellites at several locations, or loci, creates a kind of bar code unique to the individual animal, Coffin says. The bar code -- called a genotype or genetic fingerprint -- also provides information about relationships between parent and offspring and about larger relationships at the herd level.

The study of the genetic relationships of Yukon woodland caribou was undertaken because Yukon government wildlife managers needed to know if they were dealing with several distinct herds of woodland caribou or shifting groupings of closely related animals. Many years of observations suggested that the Aishihik, Wolf Lake, and Chisana herds do not mix, even though their ranges are relatively close to each other.

Yukon biologists Rick Farnell and Gerry Kuzyk asked the highly-specialized University of Alberta lab, led by Dr. Curtis Strobeck, to do a genetic analysis of the three herds to confirm the observations.

The genetic material for the analysis came from blood samples taken when caribou were captured for radio-collaring. DNA was extracted from white blood cells, and a number of microsatellite loci were analyzed.

In order to get enough material to measure, a region containing a microsatellite is copied up to a million times, using an enzymatic reaction called PCR (polymerase chain reaction), Coffin says. Even then, the material can't be seen by the naked eye and can only be measured by using a system of fluorescent markers that can be detected by a laser.

Doctoral student Keri Zittlau performed the analysis. The procedure for one batch of samples takes about 24 hours, she says. So far she has analyzed samples taken from 83 individual animals at 10 different loci.

The results of the analysis confirm observations of the herds' behaviour, Zittlau says. The Aishihik, Chisana, and Wolf Lake herds live separately and breed separately, even though their ranges are, in some areas, less than a hundred kilometres apart.

This has important implications for the management and future of the herds. For example, the Aishihik herd has grown in the past few years, while the Chisana herd has declined rapidly. The genetic analysis confirms that the herds do not interact, so the healthy growth in the Aishihik herd does nothing to counteract the decline of the Chisana herd, only a short distance away.

The fact that the herds are separate, both geographically and genetically, means that wildlife managers have to adapt management measures to suit the needs of the particular herd. In fact, Yukon wildlife managers have been treating the herds as distinct, and the genetic analysis confirms that they are on the right track.

Expanding the DNA analysis of Yukon caribou could provide a clearer understanding of the genetic structure of the territory's various caribou populations, the scientists say. In addition, the information might eventually prove useful in controlling poaching by identifying which herd a carcass came from.

For more information about DNA analysis of Yukon caribou, contact the Yukon Department of Renewable Resources.