Geographical Variation in Skull Morphology of Gray-Bellied Squirrel Callosciurus caniceps

Abstract

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.

The Indochinese–Sundaic zoogeographic transition: a description and analysis of terrestrial mammal species distributions

“…Endo et al. , 2004; Hayashida et al. , 2007), and this will, in turn, increase the number of range limits that require consideration by perhaps 10%.…”

“…Some such taxa will, however, undoubtedly be elevated to species rank as a result of ongoing morphometric, karyotypic and molecular genetic analyses (e.g. Endo et al, 2004;Hayashida et al, 2007), and this will, in turn, increase the number of range limits that require consideration by perhaps 10%. However, we do not expect that changes in species designations will substantially alter our findings.…”

The systematics of the dusky striped squirrel,Funambulus sublineatus(Waterhouse, 1838) (Rodentia: Sciuridae) and its relationships to Layard's squirrel,Funambulus layardiBlyth, 1849

“…Three pertained to F. sublineatus including the original type as identified and listed in Table 1. Juvenile age classes with un-erupted molars (Morris 1972;Endo et al 2004;Hayashida et al 2007) were excluded from this selection.…”

“…): (1) the distance from the centre of the pale midline to the outer line on the right (as measured by Moore and Tate 1965) and (2) Multivariate analyses were performed under PAST (Hammer et al 2001) using log-transformed data. Hotelling's T 2 (Hammer and Harper 2006 -comparing multivariate means) tests conducted on a larger dataset using five intact variables for all adult specimens in these taxa revealed no significant sexual dimorphism and sexes were pooled (Dissanayake 2008) for further analysis as in similar studies (Heaney 1985;Hayashida et al 2007). Two morphometric analyses were performed after partitioning a selection of specimens that maximized available data and type material (Table 1).…”

Craniodental mechanics and the feeding ecology of two sympatric callosciurine squirrels in Vietnam

“…Considerable variation in the skull morphology of squirrels has been documented by a number of studies at inter-specific (Ball & Roth, 1995;Roth, 1996;Thorington & Darrow, 1996;Velhagen & Roth, 1997;Cardini, 2003;Cardini & O'Higgins, 2004;Cardini, Hoffmann & Thorington, 2005) and intra-specific levels (Swiderski, 2003;Endo et al, 2004a,b;Hayashida et al, 2007). Dietary differences between species or between populations have been suggested as an essential factor driving the cranial diversity within the family (Ball & Roth, 1995;Thorington & Darrow, 1996;Endo et al, 2003).…”