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<p><i>Taterillus</i> gerbils present significant taxonomic challenges due to morphological conservatism and unreliable diagnostic features. Following a prior geometric morphometric study that reported limited diagnostic utility for the cranium, this study reassessed taxonomic discrimination using increased specimen coverage, broader geographic sampling, and more comprehensive landmarking (64 landmarks on 192 adults across seven species from 47 African localities). The taxonomic status of <i>T. harringtoni</i> was also reexamined. Analyses included ANOVA with pairwise tests, principal component analysis, linear discriminant analysis, cluster analysis, and two-block partial least squares to assess interspecific cranial shape variation, and its associations with phylogeny, allometry, geography, and climate; and species classification accuracy based on cranial shape. This classification accuracy reached 56–57% overall, with highest rates for <i>T. congicus</i> (82%), <i>T. harringtoni</i> (62–74%), and <i>T. arenarius</i> (64–67%). Despite moderate classification accuracy, cranial morphology quantitatively supported traditional species boundaries and confirmed <i>T. harringtoni</i> as morphologically distinct from <i>T. emini</i>; their similar karyotypes highlight that cytogenetic and cranial morphology can vary independently. Significant cranial size and shape differences were detected between most species pairs, with shape variation patterns being associated with phylogeny, geography, and climate. Species-shared allometry explained 5–7% of shape variance, species-unique allometry added 3–4%, and interspecific shape differences remained after correcting for species-shared allometry but disappeared when both components were removed. An east–west geographic divide at E20° longitude marks a shift in climate, with eastern species (<i>T. congicus</i>, <i>T. emini</i>, <i>T. harringtoni</i>) found in cool, moist regions, and western species (<i>T. pygargus</i>, <i>T. arenarius</i>, <i>T. lacustris</i>) in hot, arid zones. Although cranial shape alone cannot reliably diagnose species, it retains significant phylogenetic signal. These findings explain persistent taxonomic challenges and emphasize the need for integrative approaches combining morphometric, molecular, and ecological data for robust species delimitation in morphologically conserved mammalian taxa.</p>

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Taterillus cranial shape variation is linked to allometry, geography, and climate (Gerbillinae, Rodentia)

  • 期刊论文

  • 发表日期：

    2025年9月25日

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  • Bader H. Alhajeri

摘要

Taterillus gerbils present significant taxonomic challenges due to morphological conservatism and unreliable diagnostic features. Following a prior geometric morphometric study that reported limited diagnostic utility for the cranium, this study reassessed taxonomic discrimination using increased specimen coverage, broader geographic sampling, and more comprehensive landmarking (64 landmarks on 192 adults across seven species from 47 African localities). The taxonomic status of T. harringtoni was also reexamined. Analyses included ANOVA with pairwise tests, principal component analysis, linear discriminant analysis, cluster analysis, and two-block partial least squares to assess interspecific cranial shape variation, and its associations with phylogeny, allometry, geography, and climate; and species classification accuracy based on cranial shape. This classification accuracy reached 56–57% overall, with highest rates for T. congicus (82%), T. harringtoni (62–74%), and T. arenarius (64–67%). Despite moderate classification accuracy, cranial morphology quantitatively supported traditional species boundaries and confirmed T. harringtoni as morphologically distinct from T. emini; their similar karyotypes highlight that cytogenetic and cranial morphology can vary independently. Significant cranial size and shape differences were detected between most species pairs, with shape variation patterns being associated with phylogeny, geography, and climate. Species-shared allometry explained 5–7% of shape variance, species-unique allometry added 3–4%, and interspecific shape differences remained after correcting for species-shared allometry but disappeared when both components were removed. An east–west geographic divide at E20° longitude marks a shift in climate, with eastern species (T. congicus, T. emini, T. harringtoni) found in cool, moist regions, and western species (T. pygargus, T. arenarius, T. lacustris) in hot, arid zones. Although cranial shape alone cannot reliably diagnose species, it retains significant phylogenetic signal. These findings explain persistent taxonomic challenges and emphasize the need for integrative approaches combining morphometric, molecular, and ecological data for robust species delimitation in morphologically conserved mammalian taxa.