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Węgrzyn K, Pauwels OSG, Brecko J, Georgalis GL. Vertebral morphology and intracolumnar variation of the iconic African viperid snake Atheris (Serpentes, Viperidae). Anat Rec (Hoboken) 2024. [PMID: 39360337 DOI: 10.1002/ar.25579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Revised: 09/09/2024] [Accepted: 09/12/2024] [Indexed: 10/04/2024]
Abstract
We here provide a detailed description of the vertebral morphology of the African arboreal viperid snakes of the genus Atheris. Vertebrae of three different species of the genus, i.e., Atheris desaixi, Atheris hispida, and Atheris katangensis, were investigated via the aid of μCT (micro-computed tomography) scanning. We describe several vertebrae from different regions of the vertebral column for all three species, starting from the atlas-axis complex to the caudal tip, in order to demonstrate important differences regarding the intracolumnar variation. Comparison of these three species shows an overall similar general morphology of the trunk vertebrae among the Atheris species. We extensively compare Atheris with other known viperids. As the sole arboreal genus of Viperinae the prehensile nature of the tail of Atheris is reflected in its caudal vertebral morphology, which is characterized by a high number of caudal vertebrae but also robust and anteroventrally oriented pleurapophyses as a skeletal adaptation, linked with the myology of the tail, to an arboreal lifestyle. We anticipate that the extensive figuring of these viperid specimens will also aid identifications in paleontology.
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Affiliation(s)
- Kacper Węgrzyn
- Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Kraków, Poland
- Faculty of Biology, Jagiellonian University, Kraków, Poland
- Faculty of Biology and Biotechnology, Warsaw University of Life Sciences, Warsaw, Poland
| | - Olivier S G Pauwels
- Department of Recent Vertebrates, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Jonathan Brecko
- Department of Recent Vertebrates, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
- Biological Collections, Royal Museum for Central Africa, Tervuren, Belgium
| | - Georgios L Georgalis
- Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Kraków, Poland
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2
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Riedel J, Schwarzkopf L. Variation in density, but not morphology, of cutaneous sensilla among body regions in nine species of Australian geckos. J Morphol 2022; 283:637-652. [PMID: 35174531 DOI: 10.1002/jmor.21462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/07/2022] [Accepted: 02/13/2022] [Indexed: 11/07/2022]
Abstract
Skin sense organs, i.e., cutaneous sensilla, are a well-known feature of the integument of squamate reptiles, and particularly geckos. They vary widely in morphology among species, and are thought to be mechanosensitive, associated with prey capture and handling, tail autotomy, and placement of the adhesive toepads in pad-bearing species. Some authors suggest that they may also sense abiotic environmental features, such as temperature, or humidity. Here, we describe the morphology and distribution of cutaneous sensilla among body regions of nine Australian gecko species, in four genera. We hypothesised that if sensilla morphology was distinct, or sensilla density high, around the mouth, on the tail, and on extremities, sensilla were likely used for these direct tactile functions. We found that sensilla morphology was uniform among body regions within species, but varied among species, while sensilla densities varied among species and body regions. In gecko species studied, sensilla density was highest on the labials and the dorsal tail scales, and low on the feet, head and body, providing strong support for the hypothesis that sensilla serve tactile mechanoreceptive functions for prey capture and handling and for predator avoidance, but not for toepad placement. We suggest sensilla density may be explained by mechanoreception, whereas structure may be influenced by other factors.
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Affiliation(s)
- Jendrian Riedel
- College of Science and Engineering, James Cook University, Townsville, QLD, Australia.,Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany.,Herpetology Section, Zoological Research Museum Alexander Koenig (ZFMK) - Leibniz Institute for the Analysis of Biodiversity Change (LIB), Bonn, Germany
| | - Lin Schwarzkopf
- College of Science and Engineering, James Cook University, Townsville, QLD, Australia
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3
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Rothier PS, Simon MN, Marroig G, Herrel A, Kohlsdorf T. Development and function explain the modular evolution of phalanges in gecko lizards. Proc Biol Sci 2022; 289:20212300. [PMID: 35016544 PMCID: PMC8753168 DOI: 10.1098/rspb.2021.2300] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 12/06/2021] [Indexed: 01/14/2023] Open
Abstract
Selective regimes favouring the evolution of functional specialization probably affect covariation among phenotypic traits. Phalanges of most tetrapods develop from a conserved module that constrains their relative proportions. In geckos, however, biomechanical specializations associated with adhesive toepads involve morphological variation in the autopodium and might reorganize such modular structures. We tested two hypotheses to explain the modular architecture of hand bones in geckos, one based on developmental interactions and another incorporating functional associations related to locomotion, and compared the empirical support for each hypothetical module between padded and padless lineages. We found strong evidence for developmental modules in most species, which probably reflects embryological constraints during phalangeal formation. Although padded geckos exhibit a functional specialization involving the hyperextension of the distal phalanges that is absent in padless species, the padless species are the ones that show a distal functional module with high integration. Some ancestrally padless geckos apparently deviate from developmental predictions and present a relatively weak developmental module of phalanges and a strongly integrated distal module, which may reflect selective regimes involving incipient frictional adhesion in digit morphology. Modularity of digit elements seems dynamic along the evolutionary history of geckos, being associated with the presence/absence of adhesive toepads.
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Affiliation(s)
- Priscila S. Rothier
- Department of Biology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 3900 Avenida dos Bandeirantes, 14040-901, Ribeirão Preto, SP, Brazil
- Département Adaptations du Vivant, Muséum National d'Histoire Naturelle, 55 Rue Buffon 75005, Paris, France
| | - Monique N. Simon
- Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, 277 Rua do Matão, 05508-090, São Paulo, SP, Brazil
| | - Gabriel Marroig
- Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, 277 Rua do Matão, 05508-090, São Paulo, SP, Brazil
| | - Anthony Herrel
- Département Adaptations du Vivant, Muséum National d'Histoire Naturelle, 55 Rue Buffon 75005, Paris, France
| | - Tiana Kohlsdorf
- Department of Biology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 3900 Avenida dos Bandeirantes, 14040-901, Ribeirão Preto, SP, Brazil
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4
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Büscher TH, Gorb SN. Physical constraints lead to parallel evolution of micro- and nanostructures of animal adhesive pads: a review. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2021; 12:725-743. [PMID: 34354900 PMCID: PMC8290099 DOI: 10.3762/bjnano.12.57] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 06/30/2021] [Indexed: 05/25/2023]
Abstract
Adhesive pads are functional systems with specific micro- and nanostructures which evolved as a response to specific environmental conditions and therefore exhibit convergent traits. The functional constraints that shape systems for the attachment to a surface are general requirements. Different strategies to solve similar problems often follow similar physical principles, hence, the morphology of attachment devices is affected by physical constraints. This resulted in two main types of attachment devices in animals: hairy and smooth. They differ in morphology and ultrastructure but achieve mechanical adaptation to substrates with different roughness and maximise the actual contact area with them. Species-specific environmental surface conditions resulted in different solutions for the specific ecological surroundings of different animals. As the conditions are similar in discrete environments unrelated to the group of animals, the micro- and nanostructural adaptations of the attachment systems of different animal groups reveal similar mechanisms. Consequently, similar attachment organs evolved in a convergent manner and different attachment solutions can occur within closely related lineages. In this review, we present a summary of the literature on structural and functional principles of attachment pads with a special focus on insects, describe micro- and nanostructures, surface patterns, origin of different pads and their evolution, discuss the material properties (elasticity, viscoelasticity, adhesion, friction) and basic physical forces contributing to adhesion, show the influence of different factors, such as substrate roughness and pad stiffness, on contact forces, and review the chemical composition of pad fluids, which is an important component of an adhesive function. Attachment systems are omnipresent in animals. We show parallel evolution of attachment structures on micro- and nanoscales at different phylogenetic levels, focus on insects as the largest animal group on earth, and subsequently zoom into the attachment pads of the stick and leaf insects (Phasmatodea) to explore convergent evolution of attachment pads at even smaller scales. Since convergent events might be potentially interesting for engineers as a kind of optimal solution by nature, the biomimetic implications of the discussed results are briefly presented.
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Affiliation(s)
- Thies H Büscher
- Department of Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
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Griffing AH, Sanger TJ, Epperlein L, Bauer AM, Cobos A, Higham TE, Naylor E, Gamble T. And thereby hangs a tail: morphology, developmental patterns and biomechanics of the adhesive tails of crested geckos ( Correlophus ciliatus). Proc Biol Sci 2021; 288:20210650. [PMID: 34130507 DOI: 10.1098/rspb.2021.0650] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Among the most specialized integumentary outgrowths in amniotes are the adhesive, scale-like scansors and lamellae on the digits of anoles and geckos. Less well-known are adhesive tail pads exhibited by 21 gecko genera. While described over 120 years ago, no studies have quantified their possible adhesive function or described their embryonic development. Here, we characterize adult and embryonic morphology and adhesive performance of crested gecko (Correlophus ciliatus) tail pads. Additionally, we use embryonic data to test whether tail pads are serial homologues to toe pads. External morphology and histology of C. ciliatus tail pads are largely similar to tail pads of closely related geckos. Functionally, C. ciliatus tail pads exhibit impressive adhesive ability, hypothetically capable of holding up to five times their own mass. Tail pads develop at approximately the same time during embryogenesis as toe pads. Further, tail pads exhibit similar developmental patterns to toe pads, which are markedly different from non-adhesive gecko toes and tails. Our data provide support for the serial homology of adhesive tail pads with toe pads.
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Affiliation(s)
- Aaron H Griffing
- Department of Biological Sciences, Marquette University, PO Box 1881, Milwaukee, WI 53201, USA
| | - Thomas J Sanger
- Department of Biology, Loyola University Chicago, 1032 W. Sheridan Road, Chicago, IL 60660, USA
| | - Lilian Epperlein
- Department of Biology, Loyola University Chicago, 1032 W. Sheridan Road, Chicago, IL 60660, USA
| | - Aaron M Bauer
- Department of Biology and Center for Biodiversity and Ecosystem Stewardship, Villanova University, 800 Lancaster Avenue, Villanova, PA, USA
| | - Anthony Cobos
- Department of Evolution, Ecology, and Organismal Biology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Timothy E Higham
- Department of Evolution, Ecology, and Organismal Biology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Emily Naylor
- Department of Evolution, Ecology, and Organismal Biology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Tony Gamble
- Department of Biological Sciences, Marquette University, PO Box 1881, Milwaukee, WI 53201, USA.,Milwaukee Public Museum, 800 W. Wells Street, Milwaukee, WI 53233, USA.,Bell Museum of Natural History, University of Minnesota, Saint Paul, MN 55108, USA
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6
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Garner AM, Russell AP. Revisiting the classification of squamate adhesive setae: historical, morphological and functional perspectives. ROYAL SOCIETY OPEN SCIENCE 2021; 8:202039. [PMID: 33972877 PMCID: PMC8074656 DOI: 10.1098/rsos.202039] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
Research on gecko-based adhesion has become a truly interdisciplinary endeavour, encompassing many disciplines within the natural and physical sciences. Gecko adhesion occurs by the induction of van der Waals intermolecular (and possibly other) forces between substrata and integumentary filaments (setae) terminating in at least one spatulate tip. Gecko setae have increasingly been idealized as structures with uniform dimensions and a particular branching pattern. Approaches to developing synthetic simulacra have largely adopted such an idealized form as a foundational template. Observations of entire setal fields of geckos and anoles have, however, revealed extensive, predictable variation in setal form. Some filaments of these fields do not fulfil the morphological criteria that characterize setae and, problematically, recent authors have applied the term 'seta' to structurally simpler and likely non-adhesively competent fibrils. Herein we briefly review the history of the definition of squamate setae and propose a standardized classificatory scheme for epidermal outgrowths based on a combination of whole animal performance and morphology. Our review is by no means comprehensive of the literature regarding the form, function, and development of the adhesive setae of squamates and we do not address significant advances that have been made in many areas (e.g. cell biology of setae) that are largely tangential to their classification and identification. We contend that those who aspire to simulate the form and function of squamate setae will benefit from a fuller appreciation of the diversity of these structures, thereby assisting in the identification of features most relevant to their objectives.
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Affiliation(s)
- Austin M. Garner
- Integrated Bioscience Program, Department of Biology, The University of Akron, Akron, OH 44325-3908, USA
| | - Anthony P. Russell
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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