ORCID Profile
0000-0002-4874-4848
Current Organisation
University of Queensland
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Publisher: Wiley
Date: 18-08-2020
DOI: 10.1002/ECE3.6593
Publisher: Wiley
Date: 03-2023
DOI: 10.1002/ECE3.9698
Abstract: Morphology‐based taxonomic research frequently applies linear morphometrics (LMM) in skulls to quantify species distinctions. The choice of which measurements to collect generally relies on the expertise of the investigators or a set of standard measurements, but this practice may ignore less obvious or common discriminatory characteristics. In addition, taxonomic analyses often ignore the potential for subgroups of an otherwise cohesive population to differ in shape purely due to size differences (or allometry). Geometric morphometrics (GMM) is more complicated as an acquisition technique but can offer a more holistic characterization of shape and provides a rigorous toolkit for accounting for allometry. In this study, we used linear discriminant analysis (LDA) to assess the discriminatory performance of four published LMM protocols and a 3D GMM dataset for three clades of antechinus known to differ subtly in shape. We assessed discrimination of raw data (which are frequently used by taxonomists) data with isometry (i.e., overall size) removed and data after allometric correction (i.e., with nonuniform effects of size removed). When we visualized the principal component analysis (PCA) plots, we found that group discrimination among raw data was high for LMM. However, LMM datasets may inflate PC variance accounted in the first two PCs, relative to GMM. GMM discriminated groups better after isometry and allometry were removed in both PCA and LDA. Although LMM can be a powerful tool to discriminate taxonomic groups, we show that there is substantial risk that this discrimination comes from variation in size, rather than shape. This suggests that taxonomic measurement protocols might benefit from GMM‐based pilot studies, because this offers the option of differentiating allometric and nonallometric shape differences between species, which can then inform on the development of the easier‐to‐apply LMM protocols.
Publisher: University of Queensland Library
Date: 2021
DOI: 10.14264/16366DC
Publisher: Cold Spring Harbor Laboratory
Date: 28-04-2021
DOI: 10.1101/2021.04.28.441717
Abstract: Taxonomic distinction of species forms the foundation of bio ersity assessments and conservation priorities. However, traditional morphological and/or genetics-based taxonomic assessments frequently miss the opportunity of elaborating on the ecological and functional context of species ersification. Here, we used 3D geometric morphometrics of the cranium to improve taxonomic differentiation and add eco-morphological characterisation of a young cryptic ergence within the marsupial carnivorous genus Antechinus . Specifically, we used 168 museum specimens to characterise the recently proposed clades A. stuartii “south”, A. stuartii “north” and A. subtropicus . Beyond slight differences attributable to overall size (and therefore not necessarily diagnostic), we also found clear allometry-independent shape variation. This allowed us to define new, easily measured diagnostic traits in the palate, which differentiate the three clades. Contrary to previous suggestions, we found no support for a latitudinal gradient as causing the differentiation between the clades. However, skull shape co-varied with temperature and precipitation seasonality, suggesting that the clades may be adapted to environmental variables that are likely to be impacted by climate change. Our study demonstrates the use of 3D geometric morphometrics to improve taxonomic diagnosis of cryptic mammalian species, while providing perspectives on the adaptive origins and potential future threats of mammalian ersity.
Publisher: Authorea, Inc.
Date: 20-06-2022
DOI: 10.22541/AU.165573736.65712166/V1
Abstract: Morphology-based taxonomic research frequently applies linear morphometrics (LMM) in skulls to quantify species distinctions. The choice of which measurements to collect generally relies on the expertise of the investigators or a set of standard measurements, but this practice may ignore less obvious or common discriminatory characters. In addition, taxonomic analyses often ignore the potential for subgroups of an otherwise cohesive population to differ in shape purely due to size differences (or allometry). Geometric morphometrics (GMM) is more complicated as an acquisition technique, but can offer a more holistic characterization of shape and provides a rigorous toolkit for accounting for allometry. In this study, we used linear discriminant analysis to assess the discriminatory performance of four published LMM protocols and a 3D GMM dataset for three clades of antechinus known to differ subtly in shape. We assessed discrimination of raw data (which are frequently used by taxonomists) data with isometry removed and data after allometric correction. We found that group discrimination among raw data was high for LMM, possibly inflated relative to GMM when visualised in PCA plots. However, GMM produced better results in group discrimination after the size and allometry treatments. High measurement redundancy in LMM protocols appears to result in relatively high allometry but low discriminatory performance. These findings suggest that taxonomic measurement protocols might benefit from GMM-based pilot studies, because this offers the option of differentiating allometric and non-allometric shape differences between species, which can then inform on the development of the easier-to-apply LMM protocols.
Publisher: Oxford University Press (OUP)
Date: 28-08-2021
DOI: 10.1093/ZOOLINNEAN/ZLAB048
Abstract: Taxonomic distinction of species forms the foundation of bio ersity assessments and conservation priorities. However, traditional morphological and/or genetics-based taxonomic assessments frequently miss the opportunity of elaborating on the ecological and functional context of species ersification. Here, we used 3D geometric morphometrics of the cranium to improve taxonomic differentiation and add ecomorphological characterization of a young cryptic ergence within the carnivorous marsupial genus Antechinus. Specifically, we used 168 museum specimens to characterize the recently proposed clades A. stuartii ‘south’, A. stuartii ‘north’ and A. subtropicus. Beyond slight differences attributable to overall size (and, therefore, not necessarily diagnostic), we also found clear allometry-independent shape variation. This allowed us to define new, easily measured diagnostic traits in the palate, which differentiate the three clades. Contrary to previous suggestions, we found no support for a latitudinal gradient as causing the differentiation between the clades. However, skull shape co-varied with temperature and precipitation seasonality, suggesting that the clades may be adapted to environmental variables that are likely to be impacted by climate change. Our study demonstrates the use of 3D geometric morphometrics to improve taxonomic diagnosis of cryptic mammalian species, while providing perspectives on the adaptive origins and potential future threats of mammalian ersity.
No related grants have been discovered for Pietro Viacava.