No abstract

Geographic variation of 11 measurable cranial traits was studied on a set of 37 local samples of the Libyan jird, Meriones libycus, over its entire distribution area. MANOVA, cluster, canonical discriminant, and regression analyses were applied to consider both scalar and vector parameters of variation. It is shown that the Libyan jird is divided craniometrically into tree principal clusters, African, SWN Caspian, and main Asian ones, which differ basically by auditory bulla size (the least in SWN Caspian cluster) and incisive foramen length (the least in some subsamples of main Asian cluster). Auditory bulla size is shown to be negatively, though not very strongly, correlated with the aridity index. However, the SWN Caspian cluster is characterized by much smaller bulla than it is predicted by the regression with climatic parameter. This might be explained by some historical causes according to which a small size of auditory bulla in the jirds of that cluster reflects retention of the ancestral condition. It is suggested that subspecies M. l. caucasius from Azerbaijan is most conspicuously differentiated by cranial morphology, but its taxonomic relation to M. l. eversmanni from N Caspian region needs further clarification. The method of vector analysis of geographic trends within large portions of the areas of widely distributed species, such as M. libycus, seems to be useful in providing additional important information concerning biological specificity of respective territorial groupings.

No abstract

No abstract

No abstract