Differentiation of closely related species by DNA hybridization.

The specificity of genomic DNA probes for species differentiation by slot blot hybridization has been investigated. Experiments have been performed investigating species differentiation between monkey and human and between cattle, goat and sheep. It is demonstrated that cross hybridization between probe and DNA sequences from closely related species is reduced by addition of unlabelled DNA from the cross hybridizing species. Quantitative species differentiation is shown possible for all species although with different detection limits. For differentiation between cattle and sheep or goat the detection limits are determined to less than 0·01% whereas the detection limits for differentiation between the closely related species sheep and goat are about 10%.