1
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Khannoon ER, Borczyk B, Alahmadi BA, Aloufi A, Skawiński T. Ontogeny of the autopodial skeleton of the gecko Tarentola (Squamata: Phyllodactylidae). ZOOLOGY 2024; 164:126160. [PMID: 38574691 DOI: 10.1016/j.zool.2024.126160] [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: 09/22/2023] [Revised: 03/24/2024] [Accepted: 03/26/2024] [Indexed: 04/06/2024]
Abstract
Squamates exhibit evident diversity in their limb morphology. Gekkotans are a particularly diverse group in this respect. The appearance of toepads in gekkotans usually cooccurs with the reduction or loss of claws. The gecko Tarentola (Phyllodactylidae) shows a unique combination of features among geckos, with toepads, hyperphalangy, and dimorphism of claw expression (claws are retained on digits III and IV, but lost (manus) or strongly reduced (pes) on the remaining digits). Despite being a candidate model for studying embryonic skeletal development of the autopodium, no studies have investigated the autopodial development of the gecko Tarentola in detail. Here, we aim to follow up the development of the autopodial skeleton in T. annularis and T. mauritanica using acid-free double staining. The results indicate that the terminal phalanges of claw-bearing digits III and IV ossify earlier than in the remaining digits. This confirms the differential ossification as a result of claw regression in Tarentola. The strongly reduced second phalanges of digits IV in both the fore- and hindlimbs are the last ossifying phalanges. Such late ossification may precede the evolutionary loss of this phalanx. If this is correct, the autopodia of Tarentola would be an interesting example of both the hyperphalangy in digit I and the process of phalanx loss in digit IV. Delay in ossification of the miniaturised phalanx probably represents an example of paedomorphosis.
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Affiliation(s)
- Eraqi R Khannoon
- Department of Biology, College of Science, Taibah University, Al-Madinah, Al-Munawwarah 344, Saudi Arabia; Department of Zoology, Faculty of Science, Fayoum University, Fayoum 63514, Egypt.
| | - Bartosz Borczyk
- Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Sienkiewicza 21, Wrocław 50-335, Poland
| | - Bassam A Alahmadi
- Department of Biology, College of Science, Taibah University, Al-Madinah, Al-Munawwarah 344, Saudi Arabia
| | - Abdulhadi Aloufi
- Department of Biology, College of Science, Taibah University, Al-Madinah, Al-Munawwarah 344, Saudi Arabia
| | - Tomasz Skawiński
- Museum of Natural History, Faculty of Biological Sciences, University of Wrocław,, Sienkiewicza 21, Wrocław 50-335, Poland
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2
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Riedel J, Klemm M, Higham T, Grismer LL, Ziegler T, Russell A, Rödder D, Reinhold K. Variation in claw morphology among the digits of Bent-toed geckos (Cyrtodactylus: Gekkota: Gekkonidae). BMC ZOOL 2023; 8:19. [PMID: 37684659 PMCID: PMC10492352 DOI: 10.1186/s40850-023-00180-x] [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: 01/23/2023] [Accepted: 08/31/2023] [Indexed: 09/10/2023] Open
Abstract
BACKGROUND Ecomorphological studies of lizards have increasingly employed comparison of claw morphology among species in relation to spatial niche use. Typically, such studies focus on digit IV of the autopodia, especially the pes. Uniformity of claw morphology among digits is more often implicitly assumed than tested. RESULTS Using four species of Cyrtodactylus, comprising two generalist and two scansorial taxa that use different substrates, we examined whether claw morphology is uniform among digits and among species. We found that, within each species, ventral claw curvature is uniform across all digits whereas there are small but insignificant differences in ventral claw length and claw depth. The claws of the pes of each species are longer and deeper than those of the corresponding digits of the manus. The claw of digit I of each species is significantly shorter and shallower on both autopodia compared to those on digits IV and V (digit I, including its claw, is idiosyncratically variable among lizards in general). CONCLUSIONS We conclude that digit IV is an adequate representative of claw form in each species and exhibits variation among species, thereby serving as an exemplar for use in studies of potential discrimination between ecomorphological types in studies of Cyrtodactylus.
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Affiliation(s)
- Jendrian Riedel
- Section Herpetology, Leibniz Institute for the Analysis of Biodiversity Change - Museum Koenig, Bonn, Germany.
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany.
| | - Melinda Klemm
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
| | - Timothy Higham
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
| | - L Lee Grismer
- Department of Biology, La Sierra University, Riverside, CA, USA
- Department of Herpetology, San Diego Natural History Museum, San Diego, CA, USA
| | - Thomas Ziegler
- Cologne Zoo, Cologne, Germany
- Institute of Zoology, University of Cologne, Cologne, Germany
| | - Anthony Russell
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Dennis Rödder
- Section Herpetology, Leibniz Institute for the Analysis of Biodiversity Change - Museum Koenig, Bonn, Germany
| | - Klaus Reinhold
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
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3
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Jenkins KM, Meyer DL, Lewis PJ, Choiniere JN, Bhullar BAS. Re-description of the early Triassic diapsid Palacrodon from the lower Fremouw formation of Antarctica. J Anat 2022; 241:1441-1458. [PMID: 36168715 DOI: 10.1111/joa.13770] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 09/06/2022] [Accepted: 09/07/2022] [Indexed: 12/01/2022] Open
Abstract
The rapid radiation and dispersal of crown reptiles following the end-Permian mass extinction characterizes the earliest phase of the Mesozoic. Phylogenetically, this early radiation is difficult to interpret, with polytomies near the crown node, long ghost lineages, and enigmatic origins for crown group clades. Better understanding of poorly known taxa from this time can aid in our understanding of this radiation and Permo-Triassic ecology. Here, we describe an Early Triassic specimen of the diapsid Palacrodon from the Fremouw Formation of Antarctica. While Palacrodon is known throughout the Triassic and exhibits a cosmopolitan geographic range, little is known of its evolutionary relationships. We recover Palacrodon outside of crown reptiles (Sauria) but more crownward than Youngina capensis and other late Permian diapsids. Furthermore, Palacrodon possesses anatomical features that add clarity to the evolution of the stapes within the reptilian lineage, as well as incipient adaptations for arboreality and herbivory during the earliest phases of the Permo-Triassic recovery.
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Affiliation(s)
- Kelsey M Jenkins
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA.,Peabody Museum of Natural History, Yale University, New Haven, Connecticut, USA
| | - Dalton L Meyer
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
| | - Patrick J Lewis
- Department of Biological Sciences, Sam Houston State University, Huntsville, Texas, USA
| | - Jonah N Choiniere
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Bhart-Anjan S Bhullar
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA.,Peabody Museum of Natural History, Yale University, New Haven, Connecticut, USA
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4
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Griffing AH, Gamble T, Cohn MJ, Sanger TJ. Convergent developmental patterns underlie the repeated evolution of adhesive toe pads among lizards. Biol J Linn Soc Lond 2022; 135:518-532. [PMID: 35185322 PMCID: PMC8842688 DOI: 10.1093/biolinnean/blab164] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/24/2021] [Accepted: 11/25/2021] [Indexed: 01/07/2023]
Abstract
How developmental modifications produce key innovations, which subsequently allow for rapid diversification of a clade into new adaptive zones, has received much attention. However, few studies have used a robust comparative framework to investigate the influence of evolutionary and developmental constraints on the origin of key innovations, such as the adhesive toe pad of lizards. Adhesive toe pads evolved independently at least 16 times in lizards, allowing us to examine whether the patterns observed are general evolutionary phenomena or unique, lineage-specific events. We performed a high-resolution comparison of plantar scale development in 14 lizard species in Anolis and geckos, encompassing five independent origins of toe pads (one in Anolis, four in geckos). Despite substantial evolutionary divergence between Anolis and geckos, we find that these clades have undergone similar developmental modifications to generate their adhesive toe pads. Relative to the ancestral plantar scale development, in which scale ridges form synchronously along the digit, both padded geckos and Anolis exhibit scansor formation in a distal-to-proximal direction. Both clades have undergone developmental repatterning and, following their origin, modifications in toe pad morphology occurred through relatively minor developmental modifications, suggesting that developmental constraints governed the diversification of the adhesive toe pad in lizards.
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Affiliation(s)
- Aaron H Griffing
- Department of Biological Sciences, Marquette University, PO Box 1881, Milwaukee, WI 53201, USA,Corresponding author. E-mail:
| | - Tony Gamble
- Department of Biological Sciences, Marquette University, PO Box 1881, Milwaukee, WI 53201, USA,Milwaukee Public Museum, 800 W. Wells St., Milwaukee, WI 53233, USA,Bell Museum of Natural History, University of Minnesota, 2088 Larpenteur Ave. W., St. Paul, MN 55113, USA
| | - Martin J Cohn
- Department of Molecular Genetics and Microbiology, UF Genetics Institute, University of Florida, Gainesville, FL 32610, USA
| | - Thomas J Sanger
- Department of Molecular Genetics and Microbiology, UF Genetics Institute, University of Florida, Gainesville, FL 32610, USA,Department of Biology, Loyola University Chicago, 1032 W. Sheridan Rd, Chicago, IL 60660, USA
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5
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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: 8] [Impact Index Per Article: 2.7] [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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Alibardi L. Development, structure, and protein composition of reptilian claws and hypotheses of their evolution. Anat Rec (Hoboken) 2020; 304:732-757. [PMID: 33015957 DOI: 10.1002/ar.24515] [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: 04/28/2020] [Revised: 06/23/2020] [Accepted: 07/10/2020] [Indexed: 11/06/2022]
Abstract
Here, we review the development, morphology, genes, and proteins of claws in reptiles. Claws likely form owing to the inductive influence of phalangeal mesenchyme on the apical epidermis of developing digits, resulting in hyperproliferation and intense protein synthesis in the dorsal epidermis, which forms the unguis. The tip of claws results from prevalent cell proliferation and distal movement along most of the ungueal epidermis in comparison to the ventral surface forming the subunguis. Asymmetrical growth between the unguis and subunguis forces beta-cells from the unguis to rotate into the apical part of the subunguis, sharpening the claw tip. Further sharpening occurs by scratching and mechanical wearing. Ungueal keratinocytes elongate, form an intricate perimeter and cementing junctions, and remain united impeding desquamation. In contrast, thin keratinocytes in the subunguis form a smooth perimeter, accumulate less corneous beta proteins (CBPs) and cysteine-poor intermediate filament (IF)-keratins, and desquamate. In addition to prevalent glycine-cysteine-tyrosine rich CBPs, special cysteine-rich IF-keratins are also synthesized in the claw, generating numerous SS bonds that harden the thick and compact corneous material. Desquamation and mechanical wear at the tip ensure that the unguis curvature remains approximately stable over time. Reptilian claws are likely very ancient in evolution, although the unguis differentiated like the outer scale surface of scales, while the subunguis might have derived from the inner scale surface. The few hair-like IF-keratins synthesized in reptilian claws indicate that ancestors of sauropsids and mammals shared cysteine-rich IF-keratins. However, the number of these keratins remained low in reptiles, while new types of CBPs function to strengthen claws.
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7
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Falvey CH, Aviles-Rodriguez KJ, Hagey TJ, Winchell KM. The finer points of urban adaptation: intraspecific variation in lizard claw morphology. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa123] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Abstract
Human activity drastically transforms landscapes, generating novel habitats to which species must adaptively respond. Consequently, urbanization is increasingly recognized as a driver of phenotypic change. The structural environment of urban habitats presents a replicated natural experiment to examine trait–environment relationships and phenotypic variation related to locomotion. We use geometric morphometrics to examine claw morphology of five species of Anolis lizards in urban and forest habitats. We find that urban lizards undergo a shift in claw shape in the same direction but varying magnitude across species. Urban claws are overall taller, less curved, less pointed and shorter in length than those of forest lizards. These differences may enable more effective attachment or reduce interference with toepad function on smooth anthropogenic substrates. We also find an increase in shape disparity, a measurement of variation, in urban populations, suggesting relaxed selection or niche expansion rather than directional selection. This study expands our understanding of the relatively understudied trait of claw morphology and adds to a growing number of studies demonstrating phenotypic changes in urban lizards. The consistency in the direction of the shape changes we observed supports the intriguing possibility that urban environments may lead to predictable convergent adaptive change.
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Affiliation(s)
- Cleo H Falvey
- Department of Biology, University of Massachusetts Boston, Boston, MA, USA
| | | | - Travis J Hagey
- Department of Sciences & Mathematics, Mississippi University for Women, Columbus, MS, USA
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8
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Alibardi L. Differential cell proliferation and differentiation in developing and growing claws of turtles and alligator determine their shape. ACTA ZOOL-STOCKHOLM 2020. [DOI: 10.1111/azo.12343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Lorenzo Alibardi
- Comparative Histolab Padova and University of Bologna Bologna Italy
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9
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Alibardi L. Corneous beta proteins of the epidermal differentiation complex (EDC) form large part of the corneous material of claws and rhamphothecae in turtles. PROTOPLASMA 2020; 257:1123-1138. [PMID: 32166360 DOI: 10.1007/s00709-020-01494-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 02/19/2020] [Indexed: 06/10/2023]
Abstract
The presence of specific protein types in claws and beaks of turtles is poorly known. The present immunological study describes the localization of some of the main corneous beta proteins (CBPs) coded in the epidermal differentiation complex of turtles. Three antibodies here utilized revealed that glycine-, cysteine-, tyrosine-, and valine-rich CBPs are present in differentiating keratinocytes of the beak and of the dorsal (unguis) and ventral (sub-unguis) sides of the claw in different species, semi-aquatic and terrestrial. These proteins provide mechanical resilience to the horny material of claws and beaks through the formation of numerous -S-S- bonds and also hydrophobicity that contributes to preserve wearing of the horny material. The thicker corneous layer of the unguis is made of elongated and partially merged corneocytes, and no or few cells desquamate superficially. Unknown junctional proteins may contribute to maintain corneocytes connected one to another. In contrast, corneocytes of the sub-unguis show an elongated but lenticular shape and form a looser corneous layer whose cells remain separate and desquamate superficially. This suggests that other specific corneous proteins are present in the unguis in comparison with the sub-unguis to determine this different compaction. The wearing process present in the sub-unguis creates a loss of tissue that may favor the slow by continuous apical migration of corneocytes from the unguis into the initial part of the sub-unguis. Beak corneocytes form a compact corneous layer like the unguis but numerous superficial cells desquamate on both outer (epidermal) and inner (oral) sides.
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Affiliation(s)
- Lorenzo Alibardi
- Comparative Histolab Padova and University of Bologna, L.A., Dipartimento di Biologia, via Selmi 3, Univ Bologna, 40126, Bologna, Italy.
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10
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Alturk WIM, Khannoon ER. Ontogeny of the Moorish gecko Tarentola mauritanica with emphasis on morphogenesis of the skin and its derivatives. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2020; 334:294-310. [PMID: 32410344 DOI: 10.1002/jez.b.22951] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 04/05/2020] [Accepted: 04/27/2020] [Indexed: 01/08/2023]
Abstract
Studying reptilian embryonic development provides answers to many questions related to the development of tetrapods. Reptilian skin has been recently considered in studies at the evo-devo level. The lizard epidermis has to be shed periodically. At the embryonic level, contention exists regarding the first layers to appear, whether the oberhautchen or the clear layer, and whether the shedding complex develops before hatching. Geckos exhibit diverse morphologies independently evolved multiple times within the clade, such as subdigital pad lamellae. Here we investigate the embryonic development of Tarentola mauritanica and establishing its embryonic table. Primarily we follow the development of the integument. This is a closely related species to Tarentola annularis and it is crucial to investigate whether it has the same derived digital condition of claw regression. Eleven embryonic stages are described according to the external morphological characteristics of the embryos. Interestingly, the oviposition stage appears earlier than its close relative T. annularis, and the total incubation time is less. We also describe skin development, adding clear evidence to the debate on the development of the shedding complex, which we found is developed before hatching. We describe one layer of periderm and the clear layer as the first embryonic epidermal layers. Generally, our results show the genus Tarentola to have the advantage of being a unique taxon, easily breed at the laboratory, with multiple clutches per year, and with an earlier stage at oviposition. That could be a model animal for embryonic development and experimental embryology studies.
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Affiliation(s)
- Wafaa I M Alturk
- Biology Department, College of Science, Taibah University, Medina, Saudi Arabia
| | - Eraqi R Khannoon
- Biology Department, College of Science, Taibah University, Medina, Saudi Arabia.,Zoology Department, Faculty of Science, Fayoum University, Fayoum, Egypt
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11
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Alibardi L. Immunolocalization of corneous beta proteins of the Epidermal Differentiation Complex in the developing claw of the alligator. Ann Anat 2020; 231:151513. [PMID: 32229243 DOI: 10.1016/j.aanat.2020.151513] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/06/2020] [Accepted: 03/08/2020] [Indexed: 12/20/2022]
Abstract
Knowledge on the sharpness, mechanical and hydration resistance of the corneous material of claws requires information on its constituent proteins. The present immunohistochemical study has localized some of the main corneous beta proteins (CBPs, formerly termed beta-keratins) indicated to be present in alligator claws only by genomic data. Using specific antibodies we show the immunolocalization of representative claws CBPs of the Epidermal Differentiation Complex (Beta A1 group) during late stages of claw development in alligator. Intense but asymmetric proliferation, revealed by 5BrdU-immunolabeling, determines the formation of a curved dorsal part (unguis) and a linear ventral part (sub-unguis). The large beta-cells generated in the unguis and their packing into a solid corneous layer occur before thinner beta-cells appear in the sub-unguis. In the latter, CBPs are also immune-detected but with less intensity compared to the unguis, and corneocytes remain separated and desquamate. It is suggested that at the tip of the developing claw beta-corneocytes move downward into the initial part of the sub-unguis. This circular movement contributes to sharpen the claw as these cells fully cornify and are desquamated from the sub-unguis. Corneocytes of the unguis contain 10-16 kDa proline-serine-rich proteins that also possess high percentages of glycine, cysteine, tyrosine, valine and leucine. Cysteines likely give rise to numerous SS bonds in the constituent hard horny material, tyrosine contribute to packing proteins into a dense horny material while glycine, valine and leucine increase the hydrophobic property of claws in these water-adapted predators.
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Affiliation(s)
- Lorenzo Alibardi
- Comparative Histolab Padova and Department of Biology, University of Bologna, Italy.
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12
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Naylor ER, Higham TE. Attachment Beyond the Adhesive System: The Contribution of Claws to Gecko Clinging and Locomotion. Integr Comp Biol 2019; 59:168-181. [DOI: 10.1093/icb/icz027] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Abstract
Attachment is imperative for many biological functions, such as holding position and climbing, but can be challenged by natural conditions. Adhesive toe pads and claws have evolved in multiple terrestrial lineages as important dynamic attachment mechanisms, and some clades (e.g., geckos) exhibit both features. The functional relationship of these features that comprise a complex attachment system is not well-understood, particularly within lizards (i.e., if pads and claws are redundant or multifunctional). Geckos exhibit highly adept frictional adhesive toe pads that continue to fuel biological inquiry and inspiration. However, gecko claws (the ancestral lizard clinging condition) have received little attention in terms of their functional or evolutionary significance. We assessed claw function in Thecadactylus rapicauda using assays of clinging performance and locomotor trials on different surfaces (artificial and natural) and inclines with claws intact, then partially removed. Area root mean square height (Sq), a metric of 3D surface roughness, was later quantified for all test surfaces, including acrylic, sandpaper, and two types of leaves (smooth and hairy). Maximum clinging force significantly declined on all non-acrylic surfaces after claw removal, indicating a substantial contribution to static clinging on rough and soft surfaces. With and without claws, clinging force exhibited a negative relationship with Sq. However, claw removal had relatively little impact on locomotor function on surfaces of different roughness at low inclines (≤30°). High static and dynamic safety factor estimates support these observations and demonstrate the species’ robust frictional adhesive system. However, maximum station-holding capacity significantly declined on the rough test surface after partial claw removal, showing that geckos rely on their claws to maintain purchase on rough, steeply inclined surfaces. Our results point to a context-dependent complex attachment system within geckos, in which pads dominate on relatively smooth surfaces and claws on relatively rough surfaces, but also that these features function redundantly, possibly synergistically, on surfaces that allow attachment of both the setae and the claw (as in some insects). Our study provides important novel perspectives on gecko attachment, which we hope will spur future functional studies, new evolutionary hypotheses, and biomimetic innovation, along with collaboration and integration of perspectives across disciplines.
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Affiliation(s)
- Emily R Naylor
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA 92521, USA
| | - Timothy E Higham
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA 92521, USA
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13
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Yuan ML, Wake MH, Wang IJ. Phenotypic integration between claw and toepad traits promotes microhabitat specialization in the
Anolis
adaptive radiation. Evolution 2019; 73:231-244. [DOI: 10.1111/evo.13673] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/29/2018] [Indexed: 12/25/2022]
Affiliation(s)
- Michael L. Yuan
- Department of Environmental Science, Policy, and Management, College of Natural Resources University of California Berkeley California 94720
- Museum of Vertebrate Zoology University of California Berkeley California 94720
- Department of Vertebrate Zoology, National Museum of Natural History Smithsonian Institution Washington District of Columbia 20560
| | - Marvalee H. Wake
- Museum of Vertebrate Zoology University of California Berkeley California 94720
- Department of Integrative Biology, College of Letters and Sciences University of California Berkeley California 94720
| | - Ian J. Wang
- Department of Environmental Science, Policy, and Management, College of Natural Resources University of California Berkeley California 94720
- Museum of Vertebrate Zoology University of California Berkeley California 94720
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14
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Russell AP, Delaugerre MJ. Left in the dust: differential effectiveness of the two alternative adhesive pad configurations in geckos (Reptilia: Gekkota). J Zool (1987) 2016. [DOI: 10.1111/jzo.12390] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- A. P. Russell
- Department of Biological Sciences; University of Calgary; Calgary AB Canada
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15
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Khannoon ER, Zahradnicek O. Postovipositional development of the sand snakePsammophis sibilans(Serpentes:Lamprophiidae) in comparison with other snake species. ACTA ZOOL-STOCKHOLM 2016. [DOI: 10.1111/azo.12157] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Eraqi R. Khannoon
- Department of Biology; Faculty of Science; Taibah University; PO Box 30002, Al Madinah Al Munawarah Saudi Arabia
- Zoology Department; Faculty of Science; Fayoum University; Fayoum 63514 Egypt
| | - Oldrich Zahradnicek
- Department of Teratology; Institute of Experimental Medicine; Academy of Sciences of the Czech Republic; Vídeňská, 1083 Prague 4 142 20 Czech Republic
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Khannoon ER. Developmental stages of the climbing geckoTarentola annulariswith special reference to the claws, pad lamellae, and subdigital setae. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2015; 324:450-64. [DOI: 10.1002/jez.b.22630] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 04/18/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Eraqi R. Khannoon
- Department of Zoology; Faculty of Science; Fayoum University; Fayoum 63514 Egypt
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