Natural Sciences

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Publication Source

American Association of Anatomists Annual Meeting at Evolutionary Biology 2013 Conference (Boston, MA)

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Nile monitors (Varanus niloticus), most closely related to the Ornate monitor (V. ornatus), differs from its sister taxon primarily in geographic distribution, diet, and soft-tissues. The recent elevation of V. ornatus to species creates a problem for museums with osteological specimens that lack appropriate soft-tissue material, resulting in V. ornatus erroneously cataloged as V. niloticus. In order to identify osteological or dental characters that can be used to distinguish the two species, we examine tooth and jaw morphology using CT scans, digital and X-ray photography, in order to identify defining characters among wild-killed specimens of the two species, as well as from an invasive Florida population. V. niloticus exhibits significantly more pointed teeth along the mandible and among all size classes than those found in V. ornatus, though this may be obscured in the oldest specimens. Further, tooth form differs significantly between the two species, with V. niloticus teeth being more conical, with a more bulbous morphology found in V. ornatus. Florida V. niloticus are more homogeneous than their native African conspecifics, suggesting a founder effect. This research will allow clarification of museum specimen affinities, and supports on-going research into the morphological divergence of invasive animals from their parent populations.