Genus Tupaia Research Articles

Tupaia belangeri as an experimental animal model for viral infection.

Tupaias, or tree shrews, are small mammals that are similar in appearance to squirrels. The morphological and behavioral characteristics of the group have been extensively characterized, and despite previously being classified as primates, recent studies have placed the group in its own family, the Tupaiidae. Genomic analysis has revealed that the genus Tupaia is closer to humans than it is to rodents. In addition, tupaias are susceptible to hepatitis B virus and hepatitis C virus. The only other experimental animal that has been demonstrated to be sensitive to both of these viruses is the chimpanzee, but restrictions on animal testing have meant that experiments using chimpanzees have become almost impossible. Consequently, the development of the tupaia for use as an animal infection model could become a powerful tool for hepatitis virus research and in preclinical studies on drug development.

Taxonomic Boundaries and Craniometric Variation in the Treeshrews (Scandentia, Tupaiidae) from the Palawan Faunal Region

The taxonomy of treeshrews (Order Scandentia) has long been complicated by ambiguous morphological species boundaries, and the treeshrews of the Palawan faunal region of the Philippines are no exception. Four named forms in the genus Tupaia Raffles, 1821, have been described from four island groups based on subtle qualitative morphological characters, and as many as three distinct species have been recognized. A recent molecular phylogenetic study of relationships among Tupaia species suggests that the two currently-recognized treeshrew species from the Palawan faunal region diverged very recently relative to other sister-species divergences within the genus and may not represent species-level taxonomic entities. Here we review the taxonomic and biogeographic histories of the Tupaia taxa from this region. We also collected craniodental data from 133 skulls of all four named forms, representing five island populations, and conducted univariate and multivariate analyses on these data. Our morphometric results are consistent with molecular results, further suggesting that there is insufficient evidence to recognize T. moellendorffi Matschie, 1898, as a separate species from T. palawanensis Thomas, 1894. Our analyses also revealed a craniodentally divergent population from the island of Balabac, which has never been considered a distinct subspecies (or species) from the population on Palawan. These results have conservation implications for the island populations in our analyses, but additional surveys and molecular evidence will be required to fully assess conservation priorities for the treeshrews of the Palawan faunal region.

Molecular profile of Treeshrew, a promising experimental animal for medical research

Scandentia order in Euarchontoglires consists of two families, Tupaiidae and Ptilocercidae , including five genera that contain 20 species. Genus Tupaia having 15 species is the largest genus in the order Scandentia . Most species in Scandentia have a karyotype 2n=52–68, therein, the well-known common treeshrew ( Tupaia glis ) has 2n=60; Northern treeshrew ( Tupaia belangeri chinensis , has 2n=62; pygmy treeshrew ( Tupaia minor ) has 2n=66 and mountain treeshrew ( Tupaia montana ) has 2=68, whereas only one species Mindanao treeshrew ( Urogaleeveretti ) has 2n=44. The whole genome Northern treeshrew ( Tupaia belangeri chinensis ) was sequenced and assembled recently. The size of a 2.86 GB genome was assembled that contains approximately 22 063 protein coding genes very closer to human gene number, and contains 35% of the repeat important element, and 14% of the dominated transposeon in the treeshrew genome. The functional annotation of some important genes and gene families will facilitate treeshrew becoming a promising experimental animal for medicine evaluation alternative to nonhuman primates.

Treeshrews, the primitive primate mammals for medical experimental animals

Treeshrews are small, squirrel-like mammals native to the tropical regions of Southeast Asia, which are placed in Scandentia order including two families, Tupaiidae and Ptilocercidae . There are five genera including 20 species. Genus Tupaia having 15 species is the largest genus in the order. Northern treeshrew ( Tupaia belangeri ) and common treeshrew ( Tupaia glis ) are two of the most famous treeshrews in the Tupaia genus. To date, there has been a great controversy as to whether treeshrews should be placed in the order of insectivore or primates. Treeshrews are generally considered to have a close genetic relationship to primates, and also have some unique characteristics suitable for laboratory animal, such as relatively small body mass, high brain-to-body mass ratio, short reproductive cycle and life span; treeshrews have been proposed to be used as an alternative experimental animal for nonhuman primates. In the past decades, treeshrews as an alternative animal model has been widely applied in biomedical research and safety testing for medicine.

Networks, trees, and treeshrews: assessing support and identifying conflict with multiple loci and a problematic root.

Multiple unlinked genetic loci often provide a more comprehensive picture of evolutionary history than any single gene can, but analyzing multigene data presents particular challenges. Differing rates and patterns of nucleotide substitution, combined with the limited information available in any data set, can make it difficult to specify a model of evolution. In addition, conflict among loci can be the result of real differences in evolutionary process or of stochastic variance and errors in reconstruction. We used 6 presumably unlinked nuclear loci to investigate relationships within the mammalian family Tupaiidae (Scandentia), containing all but one of the extant tupaiid genera. We used a phylogenetic mixture model to analyze the concatenated data and compared this with results using partitioned models. We found that more complex models were not necessarily preferred under tests using Bayes factors and that model complexity affected both tree length and parameter variance. We also compared the results of single-gene and multigene analyses and used splits networks to analyze the source and degree of conflict among genes. Networks can show specific relationships that are inconsistent with each other; these conflicting and minority relationships, which are implicitly ignored or collapsed by traditional consensus methods, can be useful in identifying the underlying causes of topological uncertainty. In our data, conflict is concentrated around particular relationships, not widespread throughout the tree. This pattern is further clarified by considering conflict surrounding the root separately from conflict within the ingroup. Uncertainty in rooting may be because of the apparent evolutionary distance separating these genera and our outgroup, the tupaiid genus Dendrogale. Unlike a previous mitochondrial study, these nuclear data strongly suggest that the genus Tupaia is not monophyletic with respect to the monotypic Urogale, even when uncertainty about rooting is taken into account. These data concur with mitochondrial DNA on other relationships, including the close affinity of Tupaia tana with the enigmatic Tupaia splendidula and of Tupaia belangeri with Tupaia glis. We also discuss the taxonomic and biogeographic implications of these results.

Species-Specificity in Communication Calls of Tree Shrews (Tupaia: Scandentia)

Tree shrews are small mammals living in the tropical forest of Southeast Asia. The habitus of species within the genus Tupaia is often quite similar, so that it is difficult to differentiate the species based on their morphology. We applied comparative bioacoustics, a tool successfully used to discriminate cryptic species of nocturnal mammals, to investigate whether species in the diurnal genus Tupaia can be recognized noninvasively on the basis of a conspicuous loud call, the chatter. We studied to what extent the chatter call of 2 tree shrew species, Tupaia glis and T. belangeri, differed in acoustic structure. We also acoustically analyzed the chatter call of T. chinensis, a subspecies or closely related parapatric species of T. belangeri. Analyzed acoustic features allowed assigning chatter calls with a probability of more than 73% to the species that produced them. Bioacoustical differences are in line with subtle morphological differences, supporting species status for all 3 studied tree shrew species and corroborating immunodiffusion and genetic data that differentiate T. glis and T. belangeri. Loud calls may offer a reliable noninvasive tool for species diagnosis and discrimination in cryptic species of this diurnal mammalian group.

Phylogenetic Relationships Among Treeshrews (Scandentia): A Review and Critique of the Morphological Evidence

Although the supraordinal relationships of Scandentia (treeshrews) have been studied in great detail from both morphological and molecular perspectives, the phylogenetic relationships among treeshrews have been largely ignored. Here we review several published studies of qualitative morphological variation among living treeshrews and their contribution to our understanding of intraordinal phylogenetic relationships. Reanalysis of the data from each of these studies demonstrates that none of the trees in the original publications represents the most parsimonious interpretation. In addition to performing new analyses, we argue that all such studies to date suffer from one or more fundamental shortcomings, notably the failure to include reference to nonscandentian outgroups and the a priori assumption of generic monophyly of the relatively speciose genus Tupaia. Parsimony analyses of these data sets fail to resolve either intergeneric or interspecific relationships. Finally, several inconsistencies and conflicts with respect to character coding both within and between published studies are discussed. We conclude that a more rigorous investigation of morphological character state variation is sorely needed, one that explicitly identifies voucher specimens and does not make any assumptions of generic monophyly. This is necessary not only for the purpose of resolving phylogenetic relationships, but also for inference of ancestral states in a group that continues to figure prominently in studies of placental mammal diversification.

Cytogenetic differentiation of two sympatric tree shrew taxa found in the southern part of the Isthmus of Kra.

Sympatric populations of the genus Tupaia encompassing two cytotypes (cyt60, 2n = 60 and cyt62, 2n = 62) were found in the southern part of the Isthmus of Kra (the middle region of the Malay Peninsula, Thailand). C-bands, location of rDNA, and location of non-essential telomeric repeats (TRs) were investigated in detail for 23 animals captured in the area. Such chromosomal traits definitely reveal that two distinct cytotypes exist in the sympatric population, though the external morphological traits are similar. Hybrid cytotypes were not observed; thus, these two cytotypes appear to be genetically isolated sibling species. Chromosomal results compared with previous data, geographic distribution and morphological data observed with new insight suggest that, in the sympatric population, 'cyt60' represents members of Tupaia glis, while 'cyt62' identifies individuals of Tupaia belangeri. The cytogenetic information discovered in the present study offers new insight to morphological classification and, further, may provide substantial diagnostic characteristics for the distinction of tree shrew species.

Interspecific relationships and biogeography of some Bornean tree shrews (Tupaiidae Tupaia), based on DNA hybridization and morphometric comparisons

The interspecific relationships and biogeography of seven southeast Asian tree shrew species in the genus Tupaia were examined by DNA hybridization and multivariate morphometric analysis. Urogale everetti served as the outgroup. DNA hybridization data indicate that T. tana is most closely related to T. montana, and they form a clade with T. minor. Morphometric comparisons indicate that T. tana and T. minor, and T. montana and T. palawanensis, form groups that, together, are most similar to T. glis. T. javanica and U. everetti cluster outside the rest of Tupaia. The DNA hybridization data support a model of Bornean speciation driven by sea-level changes. They also indicate either (1) that there is a large variation in the rate of tree shrew evolution or (2) that U. everetti may in fact be a member of the ingroup. When considered in light of the phylogenetic results, the morphometric data suggest substantial convergence in body size or correlation in character changes.

Interspecific relationships and biogeography of some Bornean tree shrews (Tupaiidae: Tupaia), based on DNA hybridization and morphometric comparisons1

The interspecific relationships and biogeography of seven southeast Asian tree shrew species in the genus Tupaia were examined by DNA hybridization and multivariate morphometric analysis. Urogale everetti served as the outgroup. DNA hybridization data indicate that T. tana is most closely related to T. montana, and they form a clade with T. minor. Morphometric comparisons indicate that T. tana and T. minor, and T. montana and T. palawanensis, form groups that, together, are most similar to T. glis. T. javanica and U. everetti cluster outside the rest of Tupaia. The DNA hybridization data support a model of Bornean speciation driven by sea-level changes. They also indicate either (1) that there is a large variation in the rate of tree shrew evolution or (2) that U. everetti may in fact be a member of the ingroup. When considered in light of the phylogenetic results, the morphometric data suggest substantial convergence in body size or correlation in character changes.

An Immunological Examination of the Systematics of Tupaioidea

The taxonomic position of Tupaioidea with respect to the order Primates and the remainder of Mammalia has been examined using an immunodiffusion technique in trefoil Ouchterlony plates. Antisera were made in rabbits to blood plasma proteins of six of the nine tree shrew species used in comparisons. Numerous non-tupaiid species were also included in experiments with these antisera. Computer analysis of the results of these comparisons indicate the existence of Tupaioidea as a distinct order, which is related to Primates and Dermoptera (flying lemurs). No similarity between Tupaioidea and Macroscelidea (elephant shrews) was observed. The members of the genus Tupaia, which were examined appeared to belong to two subgenera. Subgenus Tupaia included T. glis, T. chinensis, T. belangeri, and T. longipes, whereas subgenus Lyonogale included T. montana, T minor, and T. palawanensis, in addition to T. tana, which is generally considered to belong to this subgenus.

“Geographical Distribution of Animals”

I FIND that Mr. Wallace in his new work on the “Geographical Distribution of Animals” when stating the limits of his Ceylon sub-region (vol. i. p. 327), gives among mammals the genus Tupaia and among birds “a species of Mviophonus, whose nearest ally is in Java” as characteristic of that sub-region. Further, in the tabular statement (vol. ii. p. 187), Tupaia is altogether omitted from the Indian sub-region.