A method of obtaining indices of distance and similarity from observations on differences in electrophoretic mobility of population samples

Abstract

A new index of distance is introduced which is believed to overcome objections to the Nei index of genetic distance. The new index is the length of the vector between samples in a space with dimensions equal to the number of enzyme loci investigated. This vector length can be calculated on rm‐values directly (Vrm), or the rm‐values can be interpretated in terms of the assumed number of mutations separating the different phenotypes at each locus, and a new vector length (Vrv) can thus be calculated. For the Vrv measure an index called VL (average vector length per locus) is derived in order to be able to compare values obtained in studies using different numbers of enzyme loci. An index of genetic similarity (SI) is derived from the index VL using the formula SI = exp. (– VL). The Nei indices were compared with VL and SI on two different sets of data. In the first set of data it was shown that the new indices differentiate more than the Nei indices. In the second set of data it was shown that dendrograms calculated from genetic similarity values using the two methods are not identical. Copyright © 1983, Wiley Blackwell. All rights reserved