Meeting Abstract
The island rule states that large-bodied mammals generally undergo reduction in body size on islands (especially small ones) mostly due to resource limitation. But evolution of cranial morphology accompanying change in body size is poorly understood. Using 3D landmark data we analyzed cranial shape variation in three large-bodied taxa from Southeast Asia: 125 individuals from 11 gibbon species (family Hylobatidae), 64 individual longtailed macaques (Macaca fascicularis), and 32 individuals from six pig species (family Suidae). 75 landmarks were defined for the skull and 35 landmarks for the mandible. Sex, species, island type and island size were all taken into consideration. Size explains a large percentage of total variance in all three taxa (larger individuals have more cranial area for muscle attachment and more robust mandibles), indicating that functional aspects, such as diet, may be important in determining cranial shape on islands. However, comparison between islands faces the neglected problem of phylogenetic inertia within species. In a novel approach, intraspecific phylogenetic relationships have been determined and taken into account in analyzing the geometric morphometric data.
