Abstract
Plans and proposals for the restoration of gray wolves (Canis lupus) in Yellowstone National Park are being considered. An important aspect that is contemplated within these plans is the monitoring of the genetic structure of the pack(s) which might be reintroduced. This means that the restored animals, which have known and defined genotypes, could be distinguished from other unrelated and genetically different gray wolves that could be found in the Park. It also means that for every offspring observed within the pack(s) its genetic relationship with the translocated animals could be monitored; that is, establishment of parentage could be routinely carried out. Because distinguishing unrelated wolves phenotypically is practically impossible, it is necessary to rely on a technique capable of revealing sufficient genetic variation to allow individual identification of the relocated wolves, and assignment of parents to the offspring produced within the pack(s). We used the molecular biological technique called DNA fingerprinting (Jeffreys et al. 1985a) to address this aspect of the gray wolf relocation plans. This technique is based on finding particular DNA regions called hypervariable minisatellites (Jeffreys et al. 1985b), that consist of very short nucleotide sequences repeated many times in tandem and show multiallelic variation in the number of repeating units in each allele. DNA fingerprinting involves the extraction of DNA from almost any fresh tissue (blood, skin, semen, etc.), followed by its digestion with an enzyme (restriction endonuclease), that cuts the DNA molecule at specific base sequences. The DNA fragments produced by this enzymatic digestion are then separated by size along an electrical gradient in an agarose gel. A record of the fragment distribution pattern within the gel is made by blotting the DNA onto a nylon membrane (Southern blotting), to which it is permanently bonded. Those fragments among the total that carry a particular nucleotide sequence are identified via hybridization with a radioactively labeled "probe" molecule carrying the complementary nucleotide sequence (in this case, the core sequence of the tandem repetitive units). The positions at which the probe attaches are recorded by exposing X-ray film to the hybridized membrane. The resulting autoradiograph shows dozens of bands that correspond to the many different fragment sizes bearing the core sequence. This is the "fingerprint".