Date of Award
Doctor of Philosophy (PhD)
Frederick H. Sheldon
This dissertation examined the molecular systematics and historical biogeography of tree shrews (Tupaiidae). Comparison of cytochrome b sequences and DNA hybridization data suggests that cytochrome b sequences evolved 7.9 to 13.4 times faster than single-copy nuclear DNA. These two data sets are taxonomically congruent. They indicate that the Mindanao tupaiid Urogale everetti is a member of Tupaia, and that there is lineage-based variation in rates of evolution among the tupaiids. A new species of Tupaia from Sarawak (Malaysia), T. stuebingi, was described using morphological, ecological, and cytochrome b sequence data. This lowland species is generally similar in size to the montane species, T. montana. Its coat coloration and fur texture resembles the common species, T. glis. Cytochrome b comparisons show that it is most closely related to T. montana at a proportional distance of 11.1%. Intrafamilial phylogenetic analyses placed the smooth-tailed Dendrogale as the outgroup of Tupaia, and the bushy-tailed Urogale everetti and the pen-tailed Ptilocercus lowii as members of Tupaia. All five taxa in the T. glis species group---belangeri, chinensis, glis, longipes , and salatana---should be recognized as full species based on their large degree of genetic and morphological differentiation, and their geographic separation. Maximum likelihood comparisons yielded three distinct tupaiid clades: a basal clade consisting of Asian mainland taxa, a middle clade of Philippine taxa, and a distal clade of Bornean taxa. This pattern suggests that the Bornean tupaiids originated on the Asian mainland, On Borneo, two phylogeographic patterns---one deep and one shallow---were found, suggesting that the island was colonized repeatedly. Based on cytochrome b data, the sister group of tupaiids is a clade consisting of rabbits, hedgehog, and elephant shrew. However, this sister relationship is likely the result of random long branch attraction between ingroup and distant outgroups. Thus, cytochrome b data cannot resolve the interordinal relationships of tupaiids, and their sister group remains unclear.
Han, Kwai Hin, "Molecular Systematics and Historical Biogeography of the Tree Shrews (Tupaiidae)." (2000). LSU Historical Dissertations and Theses. 7361.