ASSESSMENT OF DNA FINGERPRINTING FOR STUDIES OF SMALL-MAMMAL POPULATIONS

We examined the use of DNA fingerprinting for determining degree of genetic relatedness and kin relationships of small mammals. We examined the utility of three DNA probes: a "mouse" probe, a repeat sequence from a Mus musculus genomic library; (CAC)5, a synthesized probe consisting of cytosine-adenine-cytosine repeated five times; and the SNAP probe, a synthesized probe containing a 22 base pair sequence. All three probes provided DNA fingerprints for montane voles (Microtus montanus), although the number of bands per individual varied among probes. We could obtain bands only with the SNAP probe for deer mice (Peromyscus maniculatus) and pocket mice (Perognathus parvus). Successful modifications of protocols for DNA extraction from small blood samples and for nonradioactive detection of bands suggest that DNA fingerprinting should be useful for in situ studies of natural populations by many research laboratories. To determine genetic similarity we calculated the probability of band sharing between individuals. The average probability varied among probes for the same unrelated M. montanus individuals and among species for the SNAP probe. For all probes the average probability of band sharing was significantly greater for related than for unrelated individuals of M. montanus. Unrelated individuals usually share an unpredictable number of bands, and the probability of band sharing may reach that of related individuals. Average band sharing for related M. montanus individuals was greater than the expected 0.5 only for (CAC)5. Average probability of band sharing between unrelated and related individuals and the variance of this value must be known before an attempt is made to determine general relationships in field populations. When maternity was known, paternity could be determined with a low probability of misassignment by identifying obligate paternal bands.