title: Geographical variation in skull morphology of gray-bellied squirrel Callosciurus caniceps.
abstract: The geographical variation of the gray-bellied squirrel (Callosciurus caniceps) was examined using osteometry of skull in Southeast Asia. From the principal component analysis (PCA), the plots of the northern localities from Nan to Kanchanaburi and those of the southern localities from Narathiwat to Kuala Lumpur in male were completely separated. In female, the plots of the locality from Uttradit to Kanchanaburi and those of the locality from Pattani to Negri Sembilan were completely separated. We called these northern localities and southern localities which are distinguished by the PCA as N group and S group. The size and shape of the skulls of these squirrels indicated the differences between N group and S group from t-test and U-test. These results may be influenced by the two transitions of the phytogeography around the southernmost locality in N group and the northernmost locality in S group in the peninsular Thailand and Malay Peninsula. Localities which are located between N and S groups were called the Middle (M) group. From the PCA among N, S groups and each locality of M group, the plots of localities such as Prachuap Khiri Khan, Chumphon, Krabi, Nakhon Si Thammarat and Trang in both sexes of M group could not be separated from those of N and S groups. We suggest that the sympatric distribution of N and S groups and the hybrid of N and S populations may be seen in these localities of M group.
authors.affiliation: Department of Basic Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Hayashida
authors.forename: Hideki
authors.initials: H
authors.lastname: Endo
authors.forename: Motoki
authors.initials: M
authors.lastname: Sasaki
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Oshida
authors.forename: Junpei
authors.initials: J
authors.lastname: Kimura
authors.forename: Surachit
authors.initials: S
authors.lastname: Waengsothorn
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kitamura
authors.forename: Junzo
authors.initials: J
authors.lastname: Yamada
mesh_terms: D000818:Animals; D001210:Asia, Southeastern; D002508:Cephalometry / Q000379:methods / Q000662:veterinary; D005260:Female; D008297:Male; D025341:Principal Component Analysis; D012589:Sciuridae / Q000033:anatomy & histology*; D012886:Skull / Q000033:anatomy & histology*