GEOGRAPHIC VARIATION IN CRANIAL MORPHOLOGY IN THRICHOMYS APEREOIDES (RODENTIA: ECHIMYIDAE). I. GEOMETRIC DESCRIPTORS AND PATTERNS OF VARIATION IN SHAPE

Abstract

Geometric descriptors were used to describe variation in cranial shape within and among populations of the echimyid rodent Thrichomys apereoides from localities in northeastern, central, and southeastern Brazil. Variation in shape based on dorsal, ventral, and lateral views of the skull, as inferred from contribution of uniform components and partial warps, was attributable to localized rather than global changes in morphology of the skull. Each view of the skull showed characteristic variability in shape among populations and provided different perspectives on patterns of geographic variation. The lateral view of the skull provided the most information content in terms of populations that share similarity in cranial shape and continuity over geographic space.