Sympatric Distribution of the Two Morphological Types of the Common Tree Shrew in Hat-Yai Districts(South Thailand).

Kimura

Oshida

et al. 2004

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ABSTRACT. The geographical variations of the skulls were osteometrically examined in the gray-bellied squirrel (Callosciurus caniceps) from the populations of Korat, Ranong, southernmost Thailand, and Terutau Island. The skull size was larger in northern population than in the southern population in the continental mainland. The zoogeographical influences of the Isthmus of Kra remained unclear, since the plots from Korat population were intermingled with those from southernmost Thailand population in the principal component charts. Although Korat population has been thought to belong to north group, we suggest that Ranong and southernmost Thailand p opulations may contain individuals from both north and south groups separated by the ancient Kra barrier. Terutau Island population was similar to southernmost Thailand population in skull size, although Terutau population has been isolated in the island and separ ated from the south group of the Isthmus of Kra. In the proportional analysis the interorbital space was narrower and the binocular sense has been well-developed in Terutau population. It suggests that this population has been highly adapted to arboreal behavior. In contrast, the skull with larger interorbital space was more adaptive for terrestrial life in Korat population. The canonical discriminant analysis could clearly separate the four populations in the scattergrams of discriminant scores.

Section: Discussionsupporting

confidence: 86%

Geographical and Functional-Morphological Variations of the Skull in the Gray-Bellied Squirrel

Kimura

Oshida

et al. 2004

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“…The common species in the northern region of the Isthmus of Kra consists of T. belangeri. This species is distinguishable from T. glis in the southern districts by external skin color, principal component plots, and karyological type [9,11,12,18,23,24], although we think that the similar behavioral adaptation has been established in both T. belangeri and T. glis.…”

Section: Discussionmentioning

confidence: 81%

Morphological Adaptation of the Skull for Various Behaviors in the Tree Shrews

Hikida

Motokawa

et al. 2003

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ABSTRACT. Skull size and shape were examined among 14 species of the tree shrews (Tupaia montana, T. picta, T. splendidula, T. mulleri, T. longipes, T. glis, T. javanica, T. minor, T. gracilis, T. dorsalis, T. tana, Dendrogale melanura, D. murina, and Ptilocercus lowii). The bones of face were rostro-caudally longer in T. tana and T. dorsalis, contrasting with T. minor and T. gracilis, D. melanura, D. murina and P. lowii which have smaller facial length ratios. The arbo-terrestrial species (T. longipes and T. glis) were similar to terrestrial species in length ratios of bones of face unlike the other arbo-terrestrial species (T. montana, T. picta, T. splendidula, and T. mulleri). We propose that T. longipes and T. glis have adapted to foraging for termites and ants as have T. tana and T. dorsalis. Additionally small body size in T. javanica may be the result of being isolated in Java. We separated the species into 5 groups from the measurment values of skulls: 1) Terrestrial species; T. tana and T. dorsalis, 2) Arboreal species; T. minor and T. gracilis, 3) Arbo-terrestrial species group 1: T. montana, T. splendidula, T. picta and T. mulleri, and T. javanica, 4) Arbo-terrestrial species group 2: T. glis and T. longipes, 5) Arboreal species of Dendrogale and Ptilocercus. Principal component analysis separated species into 8 clusters as follows: 1) T. tana, 2) T. dorsalis, 3) T. montana, T. splendidula, T. picta and T. mulleri, 4) T. glis and T. longipes, 5) T. javanica, 6) T. minor and T. gracilis, 7) D. melanura and D. murina, and 8) P. lowii. We suggest that these clusters correspond to behavioral strategies and peculiarities observed in foraging, feeding and locomotion in each species.

“…From the principal component charts the M, S and T groups were actually separated from the V and B ones. We think that it is due to the geographic barrier separation of the Isthmus of Kra, and that the M, S and T populations belong to the evolutionary southern lines in the history of the Kra separation [4,5,8]. The island-isolation effect in Tioman and Sumatra Islands was not obviously confirmed in this species, and we suggest that the principal component analysis did not clearly distinguish the island populations from the M population.…”

Section: Discussionmentioning

confidence: 76%

“…The origins of the M population were Surat Thani, Trang, Selangor and the neighboring districts of Kuala Lumpur. Although the sympatric distribution of two different populations was reported in tree shrews in the south side of the Isthmus of Kra [4,5,8], we should examine the genetic dis- Table 6. Significant differences of proportion indices among three populations of the black giant squirrel tance between M and the two other mainland populations in the future.…”

Section: Discussionmentioning

confidence: 99%

Geographical Variation of Skull Size and Shape in Various Populations in the Black Giant Squirrel

Kimura

Oshida

et al. 2004

Self Cite

ABSTRACT. We osteometrically examined the skulls of the black giant squirrel (Ratufa bicolor) from three mainland populations (M. Malayan Peninsula, V. South Vietnam, and B. Burma, India and North Thailand) and from two island populations (T. Tioman, and S. Sumatra Islands). The skull in the Malayan peninsula population was significantly smaller than that of the two other mainland populations. It is consistent with Bergmann's rule as shown in the gray-bellied squirrel. The two island populations did not show obvious differences in comparison with the Malayan population in many measurements. In the proportion analysis eliminating the size factor, the differences among populations were not easily confirmed and we concluded that the osteological characters peculiar to each population could not be shown in this species. The first and second principal component scores of M, S, and T populations were intermingled, whereas the V and B populations of V and B were not separated in the chart. We pointed out that the morphological differences were demonstrated between northern and southern groups of the Isthmus of Kra in the mainland populations, and that the two island populations did not show the island-isolation effect in comparison with the M population. The adaptational variation related to feeding and locomotion could not be confirmed among populations of the black giant squirrel as shown in the proportion analysis.