PATTERNS OF SKULL SHAPE VARIATION IN MERIONES PERSICUS (RODENTIA: MURIDAE) IN RELATION TO GEOCLIMATICAL CONDITIONS

This study investigates skull variation in Persian jird, Meriones persicus (Blanford, 1875) in relation to the geoclimatical conditions across its distribution range. The pattern of correlations between geoclimatical variables and geometric shape descriptors for 221 ventral crania was studied by landmark-based geometric morphometric techniques. The covariation between shape and geoclimatical variables was explored using the Two-Block Partial Least-Squares (2B-PLS) method. The studied geoclimatical variables are: altitude, temperature (mean annual, monthly maximum and monthly minimum), annual rainfall and seasonal variation in rainfall represented by the Shannon rainfall diversity index. The phenotypes of this species reflect a particular pattern of correlated shape variation to the geoclimatical variation. The Persian jirds from the Southern populations living in lower, warmer and drier localities are characterized by bulla hypertrophy, less convex zygomatic arch, narrower zygomatic plate, longer incisive foramen and slightly a shorter nasal. The studied populations which belong to different subspecies differ from each other through a smooth variation in cranial characters.