Skeletal variation and taxonomic boundaries among mainland and island populations of the common treeshrew (Mammalia: Scandentia: Tupaiidae)

Sargis, Eric J.; Woodman, Neal; Morningstar, Natalie C.; Bell, Tiffany N.; Olson, Link E.

doi:10.1111/bij.12876

Cited by 13 publications

(19 citation statements)

References 21 publications

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“…Fooden and Albrecht () demonstrated similar variability among island groups and among islands within island groups in M. fascicularis throughout Southeast Asia, where different island populations variably exhibited a decrease, increase, or no change in skull length. Such variation was found both among and within island groups, and Fooden and Albrecht (, p. 533) attributed concordance among island populations to “common ancestry, parallel adaptation to local environmental conditions, or coincidence.” These factors may also apply to the variation we found both among and within the western, eastern, and southern island populations in our study (see also Sargis et al., ), again, with the assumption of vicariance. Closer comparison of habitat and other conditions on these islands may reveal some critical thresholds in island size that affect the magnitude and direction of change in body size.…”

Section: Discussionsupporting

confidence: 62%

“…Bivariate plot of the first two axes from canonical variate analysis of the 22 skull variables from the 13 island populations grouped by region as described in Table (see also Figure ; Sargis et al., ); circles: eastern islands, triangles: southern islands, squares: western islands. Open symbols indicate the centroid for each group.…”

Section: Resultsmentioning

confidence: 99%

“…To evaluate morphological variation within and among populations, EJS recorded 22 craniomandibular variables ( Table 2) employed in previous studies of treeshrews (Sargis, Woodman, Morningstar, et al, 2013;Sargis, Woodman, et al, 2014;Sargis, Campbell, et al, 2014;Sargis et al, 2017) from adult skulls (those with fully erupted permanent dentition) using digital calipers. Total length and body weight were recorded from skin tags or the original field notes of collectors.…”

Section: Methodsmentioning

confidence: 99%

“…Map of the Malay Peninsula and offshore islands discussed in the text (modified from Sargis et al., ). Black circles represent mainland localities (see Appendix )…”

Section: Introductionmentioning

confidence: 99%

“…Bergmann's rule describes the pattern in which species of a genus in colder climates (generally occurring at higher latitudes) have larger F I G U R E 1 Map of the Malay Peninsula and offshore islands discussed in the text (modified from Sargis et al, 2017). Black circles represent mainland localities (see Appendix 1) mean body sizes than congeners in warmer climates (at lower latitudes), and this rule has been extended to populations within a species (e.g., Ashton, Tracy, & Queiroz, 2000;Bergmann, 1847;Freckleton, Harvey, & Pagel, 2003;Mayr, 1956;Meiri & Dayan, 2003;Millien et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Rule reversal: Ecogeographical patterns of body size variation in the common treeshrew (Mammalia, Scandentia)

Sargis

Millien

Woodman

et al. 2018

Ecology and Evolution

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There are a number of ecogeographical “rules” that describe patterns of geographical variation among organisms. The island rule predicts that populations of larger mammals on islands evolve smaller mean body size than their mainland counterparts, whereas smaller‐bodied mammals evolve larger size. Bergmann's rule predicts that populations of a species in colder climates (generally at higher latitudes) have larger mean body sizes than conspecifics in warmer climates (at lower latitudes). These two rules are rarely tested together and neither has been rigorously tested in treeshrews, a clade of small‐bodied mammals in their own order (Scandentia) broadly distributed in mainland Southeast Asia and on islands throughout much of the Sunda Shelf. The common treeshrew, Tupaia glis, is an excellent candidate for study and was used to test these two rules simultaneously for the first time in treeshrews. This species is distributed on the Malay Peninsula and several offshore islands east, west, and south of the mainland. Using craniodental dimensions as a proxy for body size, we investigated how island size, distance from the mainland, and maximum sea depth between the mainland and the islands relate to body size of 13 insular T. glis populations while also controlling for latitude and correlation among variables. We found a strong negative effect of latitude on body size in the common treeshrew, indicating the inverse of Bergmann's rule. We did not detect any overall difference in body size between the island and mainland populations. However, there was an effect of island area and maximum sea depth on body size among island populations. Although there is a strong latitudinal effect on body size, neither Bergmann's rule nor the island rule applies to the common treeshrew. The results of our analyses demonstrate the necessity of assessing multiple variables simultaneously in studies of ecogeographical rules.

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Section: Discussionsupporting

confidence: 62%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…Map of the Malay Peninsula and offshore islands discussed in the text (modified from Sargis et al., ). Black circles represent mainland localities (see Appendix )…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Rule reversal: Ecogeographical patterns of body size variation in the common treeshrew (Mammalia, Scandentia)

Sargis

Millien

Woodman

et al. 2018

Ecology and Evolution

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Three‐Dimensional Geometric Morphometric Analysis of Treeshrew (Scandentia) Lower Molars: Insight into Dental Variation and Systematics

Selig

Sargis

Silcox

2019

The Anatomical Record

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Scandentia (treeshrews) is an order of small‐bodied Indomalayan mammals generally agreed to be a member of Euarchonta with Primates and Dermoptera (colugos). However, intraordinal relationships among treeshrews are less well understood. Although recent studies have begun to clarify treeshrew taxonomy using morphological and molecular datasets, previous analysis of treeshrew dentition has yielded little clarity in terms of species‐level relationships within the order. However, these studies made use of character‐based methods, scoring traits across the dental arcade, which depend on there being clear differences among taxa that can be encapsulated in coding schemes. Geometric morphometrics has the potential to capture subtler shape variation, so it may be better for examining similarities among closely related taxa whose teeth have a similar bauplan. We used three‐dimensional geometric morphometrics on a sample of treeshrew lower second molars and compared the patterns of variation to the results of previous studies. We captured 19 landmarks on a sample of 43 specimens representing 15 species. Using specimen‐based principal components analysis and between‐group principal component analysis, the two treeshrew families (Tupaiidae and Ptilocercidae) were well separated in morphospace. Moreover, several treeshrew species plot in morphospace according to the clades established in previous molecular work, with closely related species plotting closer to one another than to more distantly related species, suggesting that dental morphology can be useful when studying relationships among treeshrews. As most extinct treeshrews are known only from teeth, understanding morphological patterns in treeshrew molars is important for future work on the evolutionary history of Scandentia. Anat Rec, 302:1154–1168, 2019. © 2019 Wiley Periodicals, Inc.

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Craniometric variation and taxonomic boundaries in the Madras Treeshrew (Scandentia, Tupaiidae: Anathana ellioti [Waterhouse, 1850]) from India

Juman,

Olson,

Sargis

2024

J Mammal Evol

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The Madras Treeshrew, Anathana ellioti (Waterhouse, 1850), is a small, poorly studied mammal from South Asia. It is the only treeshrew found across the southern half of the Indian subcontinent and is the westernmost member of its order (Scandentia). The phylogenetic relationship between Anathana and its putative sister genus, Tupaia, remains unresolved, and the morphological differences between these two genera have yet to be analyzed with craniometric data. Here we describe some features that distinguish Anathana from other treeshrews. However, our comparative morphometric analyses reveal that Anathana overlaps with Tupaia in morphospace; it is smaller than most species (including the only other species found on the Indian mainland, T. belangeri) but larger than T. minor, Dendrogale melanura, and Ptilocercus lowii. At the infraspecific level, there is some separation between eastern and western populations, but this requires further investigation with larger sample sizes. Unfortunately, Anathana is disproportionately scarce in museum collections relative to other scandentians, and additional biological surveys across South India will be critical for future research on the taxonomy, distribution, and conservation of this elusive taxon.

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Skeletal variation and taxonomic boundaries among mainland and island populations of the common treeshrew (Mammalia: Scandentia: Tupaiidae)

Cited by 13 publications

References 21 publications

Rule reversal: Ecogeographical patterns of body size variation in the common treeshrew (Mammalia, Scandentia)

Rule reversal: Ecogeographical patterns of body size variation in the common treeshrew (Mammalia, Scandentia)

Three‐Dimensional Geometric Morphometric Analysis of Treeshrew (Scandentia) Lower Molars: Insight into Dental Variation and Systematics

Craniometric variation and taxonomic boundaries in the Madras Treeshrew (Scandentia, Tupaiidae: Anathana ellioti [Waterhouse, 1850]) from India

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