HIERARCHICAL VERSUS NONHIERARCHICAL PATTERNS OF GENETIC DISTANCES AMONG POPULATIONS - A SIMULATION STUDY

A simulation study was made of the effects of mixing two evolutionary forces (natural selection and random genetic drift), combined in a sin gle data matrix of gene frequencies, on the resulting genetic distance s among populations. Twenty-one, kinds of simulated gene frequencies s urfaces, for 15 populations linearly distributed over geographic space , were used to construct 21 data matrices, combining different proport ions of two types of surfaces (gradients and random surfaces). These m atrices were analysed by Unweighted Pair-Group Method - Arithmetic Ave rages (UPGMA), clustering and Principal Coordinate Analysis. The resul ts obtained show that ordination is more accurate than UPGMA in reveal ing the spatial patterns in the genetic distances, in comparison with results obtained using the Mantel test comparing directly genetic and geographic distances.