Biomechanics and Strategies of Digging

Vassallo, Aldo Iván; Becerra, Federico; Echeverría, Alejandra Isabel; Buezas, Guido N.; Díaz, Alcira Ofélia; Longo, María Victoria; Cohen, Mariana

doi:10.1007/978-3-030-61679-3_7

Cited by 6 publications

(3 citation statements)

References 53 publications

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“…The genus Ctenomys has cranium adaptations for chiseltooth digger (Vassallo 1998(Vassallo , 2002Verzi and Olivares, 2006;Vassallo et al, 2021), especially the angle of incisor procumbency related to a longer rostrum (Mora et al, 2003;Vassallo and Mora, 2007). Our results show that C. lami specimens of the major group AB have a deeper and stronger rostrum and a larger zygomatic arch than CD karyotypic blocks (Figure 6B), this difference could be adaptative because AB karyotypic blocks with more robust cranium live in a region far away from the coast in relation to CD karyotypic blocks that are closer to sandy soils.…”

Section: Discussionmentioning

confidence: 99%

Cranial morphological variation of Ctenomys lami (Rodentia: Ctenomyidae) in a restricted geographical distribution

Fornel,

Maestri,

Cordeiro-Estrela

et al. 2023

Genet. Mol. Biol.

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The relationship between chromosomal and morphological variation in mammals is poorly understood. We analyzed the cranial size and shape variation in Ctenomys lami concerning to the geographic variation in their chromosome numbers. This subterranean rodent occurs in a narrow range of sand-dunes in the Coastal Plain of southern Brazil. This species presents a high karyotypic variation with diploid numbers varying from 2n = 54 to 2n = 58, involving the fission and fusion of chromosome pairs 1 and 2. Due to different chromosome rearrangement frequencies along their geographic distribution, four karyotypic blocks were proposed. This study, explored cranium shape and size variation in geographical, chromosomal polymorphism, and chromosome rearrangements contexts to test whether the four karyotypic blocks reflect morphologically distinct units. For this, we measured 89 craniums using geometric morphometrics and used uni and multivariate statistics to discriminate the predicted groups and test for an association among chromosomal and morphological variation. Our results show the size and shape of sexual dimorphism, with males larger than females, and support the existence of four karyotypic blocks for Ctenomys lami based on morphological variation. However, our results do not support a direct relationship between chromosomal and cranial morphological variation in C. lami.

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Section: Discussionmentioning

confidence: 99%

Cranial morphological variation of Ctenomys lami (Rodentia: Ctenomyidae) in a restricted geographical distribution

Fornel,

Maestri,

Cordeiro-Estrela

et al. 2023

Genet. Mol. Biol.

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“…Living in such soft substrate conditions could reduce the energetic requirements of digging (Vleck, 1979;Luna and Antinuchi, 2006;Zelová et al, 2010), and therefore preclude higher specialization. In this respect, important advances on the understanding of the digging habits and the postcranial morphology of subterranean mammals have been done in the South American tuco-tucos of the rodent family Ctenomyidae (Vassallo, 1998;Steiner-Souza et al, 2010;Vassallo et al, 2021). Several studies have found a more specialized (e.g., robust) humeral and cranial morphology in Ctenomys species inhabiting harder soils, whereas a more slender humeral morphology in species inhabiting softer soils (e.g., Steiner-Souza et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Functional anatomy and disparity of the postcranial skeleton of African mole-rats (Bathyergidae)

et al. 2022

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The burrowing adaptations of the appendicular system of African mole-rats (Bathyergidae) have been comparatively less investigated than their cranial adaptations. Because bathyergids exhibit different digging modes (scratch-digging and chisel-tooth digging) and social systems (from solitary to highly social), they are a unique group to assess the effects of distinct biomechanical regimes and social organization on morphology. We investigated the morphological diversity and intraspecific variation of the appendicular system of a large dataset of mole-rats (n = 244) including seven species and all six bathyergid genera. Seventeen morpho-functional indices from stylopodial (femur, humerus) and zeugopodial (ulna, tibia-fibula) elements were analyzed with multivariate analysis. We hypothesized that scratch-diggers (i.e., Bathyergus) would exhibit a more specialized skeletal phenotype favoring powerful forelimb digging as compared to the chisel-tooth diggers, and that among chisel-tooth diggers, the social taxa will exhibit decreased limb bone specializations as compared to solitary taxa due to colony members sharing the costs of digging. Our results show that most bathyergids have highly specialized fossorial traits, although such specializations were not more developed in Bathyergus (or solitary species), as predicted. Most chisel tooth-diggers are equally, or more specialized than scratch-diggers. Heterocephalus glaber contrasted significantly from other bathyergids, presenting a surprisingly less specialized fossorial morphology. Our data suggests that despite our expectations, chisel-tooth diggers have a suite of appendicular adaptations that have allowed them to maximize different aspects of burrowing, including shoulder and neck support for forward force production, transport and removal of soils out of the burrow, and bidirectional locomotion. It is probably that both postcranial and cranial adaptations in bathyergids have played an important role in the successful colonization of a wide range of habitats and soil conditions within their present distribution.

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“…Still, the preferred digging mode in the great majority of rodents is scratching the soil with their forelimbs (Vassallo et al, 2021). Indeed, forelimb digging is the primary digging mode in Geomys and Ctenomys, whilst many Spalax species are head-lift diggers (Lacey and Patton, 2000).…”

Section: The Subterranean Niche and Self-domesticationmentioning

confidence: 99%

Unusual occurrence of domestication syndrome amongst African mole-rats: Is the naked mole-rat a domestic animal?

Nájera

Kin

2022

Front. Ecol. Evol.

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The Naked mole-rat (NMR) is becoming a prominent model organism due to its peculiar traits, such as eusociality, extreme longevity, cancer resistance, and reduced pain sensitivity. It belongs to the African mole-rats (AMR), a family of subterranean rodents that includes solitary, cooperative breeding and eusocial species. We identified and quantified the domestication syndrome (DS) across AMR, a set of morphological and behavioural traits significantly more common and pronounced amongst domesticated animals than in their wild counterparts. Surprisingly, the NMR shows apparent DS traits when compared to the solitary AMR. Animals can self-domesticate when a reduction of the fear response is naturally selected, such as in islands with no predators, or to improve the group’s harmony in cooperative breeding species. The DS may be caused by alterations in the physiology of the neural crest cells (NCC), a transient population of cells that generate a full range of tissues during development. The NCC contribute to organs responsible for transmitting the fear response and various other tissues, including craniofacial bones. Therefore, mutations affecting the NCC can manifest as behavioural and morphological alterations in many structures across the body, as seen in neurocristopathies. We observed that all social AMRs are chisel-tooth diggers, an adaption to hard soils that requires the flattening of the skull. We hypothesise that chisel-tooth digging could impose a selective pressure on the NCC that triggered the DS’s appearance, possibly facilitating the evolution of sociality. Finally, we discuss how DS traits are neutral or beneficial for the subterranean niche, strategies to test this hypothesis and report well-studied mutations in the NMR that are associated with the NCC physiology or with the control of the fear response. In conclusion, we argue that many of the NMR’s unconventional traits are compatible with the DS and provide a hypothesis about its origins. Our model proposes a novel avenue to enhance the understanding of the extraordinary biology of the NMR.

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Biomechanics and Strategies of Digging

Cited by 6 publications

References 53 publications

Cranial morphological variation of Ctenomys lami (Rodentia: Ctenomyidae) in a restricted geographical distribution

Cranial morphological variation of Ctenomys lami (Rodentia: Ctenomyidae) in a restricted geographical distribution

Functional anatomy and disparity of the postcranial skeleton of African mole-rats (Bathyergidae)

Unusual occurrence of domestication syndrome amongst African mole-rats: Is the naked mole-rat a domestic animal?

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