Compositional genetic differentiation among populations at three levels of genetic integration

Based on: Gillet EM. (2013) DifferInt: Compositional differentiation among populations at three levels of genetic integration. Molecular Ecology Resources 13, 953-964. http://dx.doi.org/10.1111/1755-0998.12145

    PURPOSE of DifferInt

    Species often occur in subdivided populations that differ in their genetic compositions due to genetic adaptation or other forces of fragmentation. These differences may be present at the allelic level, or they may become apparent at higher levels of genic association. For a set of codominantly expressed, diploid gene loci, the computer program DifferInt calculates and compares the compositional genetic differentiation among populations at three levels of genetic integration: gene-pool, single-locus genotypes, and multilocus genotypes.

    Four measures of compositional differentiation are calculated at each level of genetic integration:

    • dispersive genic differentiation bigdeltabar.gif
    • dispersive genotypic differentiation deltabar.gif
    • complementary genic differentiation ΔSD
    • complementary genotypic differentiation δSD

    All four measures are based on the minimum extent to which the distribution of genetic types in one of the two populations must be altered in order to match the distribution of genetic types in the other. Minimization for two of the measures is additionally based on an elementary genic difference between individuals that is applicable to any level of genetic integration. A measure of covariation expresses the correspondence of the single populations' contributions between two levels of integration. An increase from one level to the next indicates differences in forms of gene association. Effects of gene-pools and gene association on differentiation are compared by permutation analysis. Snail diagrams depict the contribution of each population to differentiation. These diagrams are useful, for example, for conservation decisions, recognition of introgression or migration, provenance identification, or breeding.

    Email differint@uni-goettingen.de. URL http://www.uni-goettingen.de/forstgenetik/differint