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How to Render Species Comparable Taxonomic Units Through Deep Time: a Case Study on Intraspecific Osteological Variability in Extant and Extinct Lacertid Lizards

Tschopp, E; Napoli, J; Wencker, L; Delfino, M; Upchurch, P; (2022) How to Render Species Comparable Taxonomic Units Through Deep Time: a Case Study on Intraspecific Osteological Variability in Extant and Extinct Lacertid Lizards. Systematic Biology , Article syab078. 10.1093/sysbio/syab078. (In press).

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Abstract

Generally, the species is considered to be the only naturally occurring taxon. However, species recognized and defined using different species delimitation criteria cannot readily be compared, impacting studies of biodiversity through Deep Time. This comparability issue is particularly marked when comparing extant with extinct species because the only available data for species delimitation in fossils are derived from their preserved morphology, which is generally restricted to osteology in vertebrates. Here, we quantify intraspecific, intrageneric, and intergeneric osteological variability in extant species of lacertid lizards using pairwise dissimilarity scores based on a data set of 253 discrete osteological characters for 99 specimens referred to 24 species. Variability is always significantly lower intraspecifically than between individuals belonging to distinct species of a single genus, which is in turn significantly lower than intergeneric variability. Average values of intraspecific variability and associated standard deviations are consistent (with few exceptions), with an overall average within a species of 0.208 changes per character scored. Application of the same methods to six extinct lacertid species (represented by 40 fossil specimens) revealed that intraspecific osteological variability is inconsistent, which can at least in part be attributed to different researchers having unequal expectations of the skeletal dissimilarity within species units. Such a divergent interpretation of intraspecific and interspecific variability among extant and extinct species reinforces the incomparability of the species unit. Lacertidae is an example where extant species recognized and defined based on a number of delimitation criteria show comparable and consistent intraspecific osteological variability. Here, as well as in equivalent cases, application of those skeletal dissimilarity values to paleontological species delimitation potentially provides a way to ameliorate inconsistencies created by the use of morphology to define species. [Intraspecific variation; Lacertidae; morphological disparity; osteology; species delimitation; taxonomic bias.]

Type: Article
Title: How to Render Species Comparable Taxonomic Units Through Deep Time: a Case Study on Intraspecific Osteological Variability in Extant and Extinct Lacertid Lizards
DOI: 10.1093/sysbio/syab078
Publisher version: https://doi.org/10.1093/sysbio/syab078
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10136011
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