Non-Geographic Variation in Aethomys chrysophilus (De Winton, 1897) and A. namaquensis (A. Smith, 1834) (Rodentia: Muridae) from Southern Africa

Abstract

Prior to a systematic revision of African rock rats (genus AethomysThomas) in southern Africa, the nature and extent of non-geographic variation due to sex and age in two samples each of A. chrysophilus (De Winton, 1897) and A. namaquensis (A. Smith, 1834) were examined using both univariate and multivariate statistical procedures. Results of Model I two-way analysis of variance, % sum of squares and a series ol multivariate procedures were congruent and showed a lack ol sexual dimorphism in all samples examined, but marked variation between seven age categories based on the degree ol tooth wear on the maxillary tooth row. When univariate and multivariate results were considered together, pooling of sexes as well as individuals of tooth-wear classes IV, V and VI for subsequent recording and analysis was justified. Very few tooth-wear class VII individuals were available and their exclusion was largely arbitrary. Few measurements showed sexage interaction. The largest per cent contribution to the total variance was due to error. In general, variance partitioning indicated that if comparisons are to be made, caution needs to be exercised on the type of characters, number of factor levels and methodology used.