DNA fingerprinting in birds

Several regions of the human genome are highly variable in populations because the number of repeats in these regions of a short 'minisatellite' sequence varies at high frequency. Different minisatellites have a core sequence1,2 in common, however, and probes made up of tandem repeats of this core sequence detect many highly variable DNA fragments in several species including humans1,3, cats4, dogs4 and mice5. The hypervariable sequences detected in this way are dispersed in the genome and their variability means that they can be used as a DNA 'fingerprint', providing a novel method for the identification of individuals2,6, confirmation of biological relationships7,8 and human genetic analysis9,10. We show here that human minisatellite-derived probes also detect highly variable regions in bird DNAs. Segregation analysis in a house sparrow family confirms that these regions comprise many mostly heterozygous dispersed loci and we conclude that house sparrow DNA fingerprints are analagous to those of humans. Fingerprint analysis identified one nestling, with fingerprint bands not present in the parent pair's fingerprints, which we conclude resulted from an extrapair copulation. Extrabond copulations have been described in many wild bird species11–13, but their success and hence adaptive significance have rarely been quantifiable14–20. DNA fingerprinting will be of great significance to studies of the sociobiology, demography and ecology of wild birds