1
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Taewcharoen N, Norris R, Sherratt E. Small- to medium-sized mammals show greater morphological disparity in cervical than lumbar vertebrae across different terrestrial modes of locomotion. Ecol Evol 2024; 14:e11478. [PMID: 38835523 PMCID: PMC11148397 DOI: 10.1002/ece3.11478] [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: 02/29/2024] [Revised: 05/08/2024] [Accepted: 05/10/2024] [Indexed: 06/06/2024] Open
Abstract
During mammalian terrestrial locomotion, body flexibility facilitated by the vertebral column is expected to be correlated with observed modes of locomotion, known as gait (e.g., sprawl, trot, hop, bound, gallop). In small- to medium-sized mammals (average weight up to 5 kg), the relationship between locomotive mode and vertebral morphology is largely unexplored. Here we studied the vertebral column from 46 small- to medium-sized mammals. Nine vertebrae across cervical, thoracic, and lumbar regions were chosen to represent the whole vertebral column. Vertebra shape was analysed using three-dimensional geometric morphometrics with the phylogenetic comparative method. We also applied the multi-block method, which can consider all vertebrae as a single structure for analysis. We calculated morphological disparity, phylogenetic signal, and evaluated the effects of allometry and gait on vertebral shape. We also investigated the pattern of integration in the column. We found the cervical vertebrae show the highest degree of morphological disparity, and the first thoracic vertebra shows the highest phylogenetic signal. A significant effect of gait type on vertebrae shape was found, with the lumbar vertebrae having the strongest correlation; but this effect was not significant after taking phylogeny into account. On the other hand, allometry has a significant effect on all vertebrae regardless of the contribution from phylogeny. The regions showed differing degrees of integration, with cervical vertebrae most strongly correlated. With these results, we have revealed novel information that cannot be captured from study of a single vertebra alone: although the lumbar vertebrae are the most correlated with gait, the cervical vertebrae are more morphologically diverse and drive the diversity among species when considering whole column shape.
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Affiliation(s)
- Nuttakorn Taewcharoen
- School of Biological Sciences The University of Adelaide Adelaide South Australia Australia
| | - Rachel Norris
- School of Animal and Veterinary Sciences The University of Adelaide Roseworthy South Australia Australia
| | - Emma Sherratt
- School of Biological Sciences The University of Adelaide Adelaide South Australia Australia
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2
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Marek RD. A surrogate forelimb: Evolution, function and development of the avian cervical spine. J Morphol 2023; 284:e21638. [PMID: 37708511 DOI: 10.1002/jmor.21638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/17/2023] [Accepted: 08/21/2023] [Indexed: 09/16/2023]
Abstract
The neck is a critical portion of the avian spine, one that works in tandem with the beak to act as a surrogate forelimb and allows birds to manipulate their surroundings despite the lack of a grasping capable hand. Birds display an incredible amount of diversity in neck morphology across multiple anatomical scales-from varying cervical counts down to intricate adaptations of individual vertebrae. Despite this morphofunctional disparity, little is known about the drivers of this enormous variation, nor how neck evolution has shaped avian macroevolution. To promote interest in this system, I review the development, function and evolution of the avian cervical spine. The musculoskeletal anatomy, basic kinematics and development of the avian neck are all documented, but focus primarily upon commercially available taxa. In addition, recent work has quantified the drivers of extant morphological variation across the avian neck, as well as patterns of integration between the neck and other skeletal elements. However, the evolutionary history of the avian cervical spine, and its contribution to the diversification and success of modern birds is currently unknown. Future work should aim to broaden our understanding of the cervical anatomy, development and kinematics to include a more diverse selection of extant birds, while also considering the macroevolutionary drivers and consequences of this important section of the avian spine.
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Affiliation(s)
- Ryan D Marek
- Department of Cell and Developmental Biology, Centre for Integrative Anatomy, University College London, London, UK
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3
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Auerbach BM, Savell KRR, Agosto ER. Morphology, evolution, and the whole organism imperative: Why evolutionary questions need multi-trait evolutionary quantitative genetics. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023. [PMID: 37060292 DOI: 10.1002/ajpa.24733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 03/13/2023] [Accepted: 03/14/2023] [Indexed: 04/16/2023]
Abstract
Since Washburn's New Physical Anthropology, researchers have sought to understand the complexities of morphological evolution among anatomical regions in human and non-human primates. Researchers continue, however, to preferentially use comparative and functional approaches to examine complex traits, but these methods cannot address questions about evolutionary process and often conflate function with fitness. Moreover, researchers also tend to examine anatomical elements in isolation, which implicitly assumes independent evolution among different body regions. In this paper, we argue that questions asked in primate evolution are best examined using multiple anatomical regions subjected to model-bound methods built from an understanding of evolutionary quantitative genetics. A nascent but expanding number of studies over the last two decades use this approach, examining morphological integration, evolvability, and selection modeling. To help readers learn how to use these methods, we review fundamentals of evolutionary processes within a quantitative genetic framework, explore the importance of neutral evolutionary theory, and explain the basics of evolutionary quantitative genetics, namely the calculation of evolutionary potential for multiple traits in response to selection. Leveraging these methods, we demonstrate their use to understand non-independence in possible evolutionary responses across the limbs, limb girdles, and basicranium of humans. Our results show that model-bound quantitative genetic methods can reveal unexpected genetic covariances among traits that create a novel but measurable understanding of evolutionary complexity among multiple traits. We advocate for evolutionary quantitative genetic methods to be a standard whenever appropriate to keep studies of primate morphological evolution relevant for the next seventy years and beyond.
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Affiliation(s)
- Benjamin M Auerbach
- Department of Anthropology, The University of Tennessee, Knoxville, Tennessee, USA
- Department of Ecology and Evolutionary Biology, The University of Tennessee, Knoxville, Tennessee, USA
| | - Kristen R R Savell
- Department of Biology, Sacred Heart University, Fairfield, Connecticut, USA
| | - Elizabeth R Agosto
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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4
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Molnar J, Watanabe A. Morphological and functional regionalization of trunk vertebrae as an adaptation for arboreal locomotion in chameleons. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221509. [PMID: 36998764 PMCID: PMC10049746 DOI: 10.1098/rsos.221509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 03/10/2023] [Indexed: 06/19/2023]
Abstract
Regionalization of the vertebral column can help animals adapt to different kinds of locomotion, including arboreal locomotion. Although functional axial regionalization has been described in both chameleons and arboreal mammals, no morphological basis for this functional regionalization in chameleons has been proposed. However, recent studies have described regionalization in the presacral vertebral column of other extant squamates. To investigate possible morphological regionalization in the vertebral column of chameleons, we took morphometric measurements from the presacral vertebrae of 28 chameleon species representing all extant chameleon genera, both fully arboreal and ground-dwelling, and performed comparative analyses. Our results support chameleons exhibiting three or four presacral morphological regions that correspond closely to those in other sauropsids, but we detected evolutionary shifts in vertebral traits occurring in only arboreal chameleons. Specifically, the anterior dorsal region in arboreal chameleons has more vertically oriented zygapophyseal joints, predicting decreased mediolateral flexibility. This shift is functionally significant because stiffening of the anterior thoracic vertebral column has been proposed to help bridge gaps between supports in primates. Thus, specialization of existing morphological regions in the vertebral column of chameleons may have played an important role in the evolution of extreme arboreal locomotion, paralleling the adaptations of arboreal primates.
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Affiliation(s)
- Julia Molnar
- Department of Anatomy, New York Institute of Technology, College of Osteopathic Medicine, Old Westbury, NY 11568, USA
| | - Akinobu Watanabe
- Department of Anatomy, New York Institute of Technology, College of Osteopathic Medicine, Old Westbury, NY 11568, USA
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
- Life Sciences Department, Natural History Museum, London, SW7 5BD UK
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5
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Adler KA, De Nault DL, Cardoza CM, Womack M. Evolutionary rates and shape variation along the anuran vertebral column with attention to phylogeny, body size, and ecology. Evolution 2022; 76:2724-2738. [PMID: 36117276 DOI: 10.1111/evo.14614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 07/31/2022] [Accepted: 08/08/2022] [Indexed: 01/22/2023]
Abstract
The vertebral column is critical to a vertebrate species' flexibility and skeletal support, making vertebrae a clear target for selection. Anurans (frogs and toads) have a unique, truncated vertebral column that appears constrained to provide axial rigidity for efficient jumping. However, no study has examined how presacral vertebrae shape varies among anuran species at the macroevolutionary scale nor how intrinsic (developmental and phylogenetic) and extrinsic (ecological) factors may have influenced vertebrae shape evolution. We used microCT scans and phylogenetic comparative methods to examine the vertebrae of hundreds of anuran species that vary in body size as well as adult and larval ecology. We found variation in shape and evolutionary rates among anuran vertebrae, dispelling any notion that trunk vertebrae evolve uniformly. We discovered the highest evolutionary rates in the cervical vertebrae and in the more caudal trunk vertebrae. We found little evidence for selection pressures related to adult or larval ecology affecting vertebrae evolution, but we did find body size was highly associated with vertebrae shape and microhabitat (mainly burrowing) affected those allometric relationships. Our results provide an interesting comparison to vertebrae evolution in other clades and a jumping-off point for studies of anuran vertebrae evolution and development.
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Affiliation(s)
- Katie A Adler
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, 94720
| | - Diego L De Nault
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, 94720
| | - Cassandra M Cardoza
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, 94720
| | - Molly Womack
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California, 94720.,Department of Biology, Utah State University, Logan, Utah, 84322
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6
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Rhoda D, Segall M, Larouche O, Evans K, Angielczyk KD. Local superimpositions facilitate morphometric analysis of complex articulating structures. Integr Comp Biol 2021; 61:1892-1904. [PMID: 33905523 PMCID: PMC8699094 DOI: 10.1093/icb/icab031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Articulating structures, such as the vertebrate skeleton or the segmented arthropod exoskeleton, comprise a majority of the morphological diversity across the eukaryotic tree of life. Quantifying the form of articulating structures is therefore imperative for a fuller understanding of the factors influencing biological form. A wealth of freely available 3D data capturing this morphological diversity is stored in online repositories such as Morphosource, but the geometric morphometric analysis of an articulating structure is impeded by arbitrary differences in the resting positions of its individual articulating elements. In complex articulating structures, where the angles between articulating elements cannot be standardized, landmarks on articulating elements must be Procrustes superimposed independently (locally) and then recombined to quantify variation in the entire articulating structure simultaneously. Here, we discuss recent advances in local superimposition techniques, namely the “matched local superimpositions” approach, which incorporates anatomically accurate relative sizes, positions, and orientations of locally-superimposed landmarks, enabling clearer biological interpretation. We also use simulations to evaluate the consequences of choice of superimposition approach. Our results show that local superimpositions will isolate shape variation within locally-superimposed landmark subsets by sacrificing size and positional variation. They may also create morphometric “modules” when there are none by increasing integration within the locally-superimposed subsets; however, this effect is no greater than the spurious between-module integration created when superimposing landmark subsets (i.e., articulating elements) together. Taken together, our results show that local superimposition techniques differ from conventional Procrustes superimpositions in predictable ways. Finally, we use empirical datasets of the skulls of wrasses and colubriform snakes to highlight the promise of local superimpositions and their utility. Complex articulating structures must be studied, and the only current solution to do so is local superimpositions.
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Affiliation(s)
- Daniel Rhoda
- Committee on Evolutionary Biology, University of Chicago, 5801 S Ellis Ave, Chicago, IL 60637, USA
| | - Marion Segall
- Department of Herpetology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA
| | - Olivier Larouche
- Department of BioSciences, Rice University, 6100 Main St, Houston, TX 77005, USA
| | - Kory Evans
- Department of BioSciences, Rice University, 6100 Main St, Houston, TX 77005, USA
| | - Kenneth D Angielczyk
- Negaunee Integrative Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, Illinois 60605, USA
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7
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Marek RD, Falkingham PL, Benson RBJ, Gardiner JD, Maddox TW, Bates KT. Evolutionary versatility of the avian neck. Proc Biol Sci 2021; 288:20203150. [PMID: 33653136 PMCID: PMC7934994 DOI: 10.1098/rspb.2020.3150] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Bird necks display unparalleled levels of morphological diversity compared to other vertebrates, yet it is unclear what factors have structured this variation. Using three-dimensional geometric morphometrics and multivariate statistics, we show that the avian cervical column is a hierarchical morpho-functional appendage, with varying magnitudes of ecologically driven osteological variation at different scales of organization. Contrary to expectations given the widely varying ecological functions of necks in different species, we find that regional modularity of the avian neck is highly conserved, with an overall structural blueprint that is significantly altered only by the most mechanically demanding ecological functions. Nevertheless, the morphologies of vertebrae within subregions of the neck show more prominent signals of adaptation to ecological pressures. We also find that both neck length allometry and the nature of neck elongation in birds are different from other vertebrates. In contrast with mammals, neck length scales isometrically with head mass and, contrary to previous work, we show that neck elongation in birds is achieved predominantly by increasing vertebral lengths rather than counts. Birds therefore possess a cervical spine that may be unique in its versatility among extant vertebrates, one that, since the origin of flight, has adapted to function as a surrogate forelimb in varied ecological niches.
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Affiliation(s)
- Ryan D Marek
- Department of Musculoskeletal & Ageing Science, University of Liverpool, William Henry Duncan Building, 6 West Derby Street, Liverpool, L7 8TX, UK
| | - Peter L Falkingham
- Biological and Environmental Sciences, James Parsons Building, Byrom Street, Liverpool L3 3AF, UK
| | - Roger B J Benson
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - James D Gardiner
- Department of Musculoskeletal & Ageing Science, University of Liverpool, William Henry Duncan Building, 6 West Derby Street, Liverpool, L7 8TX, UK
| | - Thomas W Maddox
- Department of Musculoskeletal & Ageing Science, University of Liverpool, William Henry Duncan Building, 6 West Derby Street, Liverpool, L7 8TX, UK
| | - Karl T Bates
- Department of Musculoskeletal & Ageing Science, University of Liverpool, William Henry Duncan Building, 6 West Derby Street, Liverpool, L7 8TX, UK
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8
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Bjarnason A, Benson R. A 3D geometric morphometric dataset quantifying skeletal variation in birds. ACTA ACUST UNITED AC 2021. [DOI: 10.18563/journal.m3.125] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Nations JA, Mount GG, Morere SM, Achmadi AS, Rowe KC, Esselstyn JA. Locomotory mode transitions alter phenotypic evolution and lineage diversification in an ecologically rich clade of mammals. Evolution 2021; 75:376-393. [PMID: 33370843 DOI: 10.1111/evo.14156] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 12/04/2020] [Accepted: 12/20/2020] [Indexed: 11/30/2022]
Abstract
The relationship between organismal function and form is a cornerstone of biology because functional diversity is key to generating and maintaining ecological diversity. Morphological changes often occur in unison with behavioral or ecological transitions, and this process may foster diversification, but alternately could trap a species on an adaptive peak. We estimated the most comprehensive phylogenetic hypothesis of Murinae, a young (∼15 million years) and diverse (∼700 species) clade of mammals. We then tested for correlated evolution among four morphological traits with potential links to locomotor modes (Arboreal, General, Terrestrial, and Amphibious), then investigated the effects of locomotion on morphological and lineage diversification. We found unique combinations of trait values for each locomotor mode, including strong covariance between the tail and hindfoot lengths of specialized Arboreal and ecologically flexible General species. Low diversification rates and long branch lengths suggest that specialized lineages represent stable evolutionary "cul-de-sacs." General species, characterized by the classic "rat-like" body plan and broad locomotor abilities, have narrow optimal trait values and slow phenotypic evolution, but high lineage diversification rates. Our findings suggest that versatile, generalist forms act as seeds of species diversity and morphological specialization, which together build ecologically diverse radiations.
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Affiliation(s)
- Jonathan A Nations
- Museum of Natural Science, Louisiana State University, 119 Foster Hall, Baton Rouge, Louisiana, 70803.,Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, 70803
| | - Genevieve G Mount
- Museum of Natural Science, Louisiana State University, 119 Foster Hall, Baton Rouge, Louisiana, 70803.,Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, 70803
| | - Sara M Morere
- Museum of Natural Science, Louisiana State University, 119 Foster Hall, Baton Rouge, Louisiana, 70803
| | - Anang S Achmadi
- Museum Zoologicum Bogoriense, Research Centre for Biology, Cibinong, Jawa Barat, 16911, Indonesia
| | - Kevin C Rowe
- Sciences Department, Museums Victoria, Melbourne, Victoria, 3001, Australia
| | - Jacob A Esselstyn
- Museum of Natural Science, Louisiana State University, 119 Foster Hall, Baton Rouge, Louisiana, 70803.,Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, 70803
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10
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López-Aguirre C, Hand SJ, Koyabu D, Tu VT, Wilson LAB. Phylogeny and foraging behaviour shape modular morphological variation in bat humeri. J Anat 2020; 238:1312-1329. [PMID: 33372711 DOI: 10.1111/joa.13380] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 11/19/2020] [Accepted: 11/20/2020] [Indexed: 01/18/2023] Open
Abstract
Bats show a remarkable ecological diversity that is reflected both in dietary and foraging guilds (FGs). Cranial ecomorphological adaptations linked to diet have been widely studied in bats, using a variety of anatomical, computational and mathematical approaches. However, foraging-related ecomorphological adaptations and the concordance between cranial and postcranial morphological adaptations remain unexamined in bats and limited to the interpretation of traditional aerodynamic properties of the wing (e.g. wing loading [WL] and aspect ratio [AR]). For this reason, the postcranial ecomorphological diversity in bats and its drivers remain understudied. Using 3D virtual modelling and geometric morphometrics (GMM), we explored the phylogenetic, ecological and biological drivers of humeral morphology in bats, evaluating the presence and magnitude of modularity and integration. To explore decoupled patterns of variation across the bone, we analysed whole-bone shape, diaphyseal and epiphyseal shape. We also tested whether traditional aerodynamic wing traits correlate with humeral shape. By studying 37 species from 20 families (covering all FGs and 85% of dietary guilds), we found similar patterns of variation in whole-bone and diaphyseal shape and unique variation patterns in epiphyseal shape. Phylogeny, diet and FG significantly correlated with shape variation at all levels, whereas size only had a significant effect on epiphyseal morphology. We found a significant phylogenetic signal in all levels of humeral shape. Epiphyseal shape significantly correlated with wing AR. Statistical support for a diaphyseal-epiphyseal modular partition of the humerus suggests a functional partition of shape variability. Our study is the first to show within-structure modular morphological variation in the appendicular skeleton of any living tetrapod. Our results suggest that diaphyseal shape correlates more with phylogeny, whereas epiphyseal shape correlates with diet and FG.
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Affiliation(s)
- Camilo López-Aguirre
- Earth and Sustainability Science Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Suzanne J Hand
- Earth and Sustainability Science Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Daisuke Koyabu
- Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong.,Department of Molecular Craniofacial Embryology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Vuong Tan Tu
- Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, Hanoi, Vietnam.,Graduate University of Science and Technology, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Laura A B Wilson
- Earth and Sustainability Science Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, NSW, Australia.,School of Archaeology & Anthropology, Australian National University, Canberra, ACT, Australia
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11
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Rhoda D, Polly PD, Raxworthy C, Segall M. Morphological integration and modularity in the hyperkinetic feeding system of aquatic-foraging snakes. Evolution 2020; 75:56-72. [PMID: 33226114 DOI: 10.1111/evo.14130] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 11/05/2020] [Accepted: 11/13/2020] [Indexed: 12/12/2022]
Abstract
The kinetic skull is a key innovation that allowed snakes to capture, manipulate, and swallow prey exclusively using their heads using the coordinated movement of eight bones. Despite these unique feeding behaviors, patterns of evolutionary integration and modularity within the feeding bones of snakes in a phylogenetic framework have yet to be addressed. Here, we use a dataset of 60 μCT-scanned skulls and high-density geometric morphometric methods to address the origin and patterns of variation and integration in the feeding bones of aquatic-foraging snakes. By comparing alternate superimposition protocols allowing us to analyze the entire kinetic feeding system simultaneously, we find that the feeding bones are highly integrated, driven predominantly by functional selective pressures. The most supported pattern of modularity contains four modules, each associated with distinct functional roles: the mandible, the palatopterygoid arch, the maxilla, and the suspensorium. Further, the morphological disparity of each bone is not linked to its magnitude of integration, indicating that integration within the feeding system does not strongly constrain morphological evolution, and that adequate biomechanical solutions to a wide range of feeding ecologies and behaviors are readily evolvable within the constraint due to integration in the snake feeding system.
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Affiliation(s)
- Daniel Rhoda
- Department of Herpetology, American Museum of Natural History, New York, New York, 10024.,Committee on Evolutionary Biology, University of Chicago, Chicago, Illinois, 60637
| | - P David Polly
- Department of Geological Sciences, Indiana University, Bloomington, Indiana, 47405
| | - Christopher Raxworthy
- Department of Herpetology, American Museum of Natural History, New York, New York, 10024
| | - Marion Segall
- Department of Herpetology, American Museum of Natural History, New York, New York, 10024
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12
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Michaud M, Veron G, Fabre AC. Phenotypic integration in feliform carnivores: Covariation patterns and disparity in hypercarnivores versus generalists. Evolution 2020; 74:2681-2702. [PMID: 33085081 DOI: 10.1111/evo.14112] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 08/01/2020] [Accepted: 10/03/2020] [Indexed: 01/01/2023]
Abstract
The skeleton is a complex arrangement of anatomical structures that covary to various degrees depending on both intrinsic and extrinsic factors. Among the Feliformia, many species are characterized by predator lifestyles providing a unique opportunity to investigate the impact of highly specialized hypercarnivorous diet on phenotypic integration and shape diversity. To do so, we compared the shape of the skull, mandible, humerus, and femur of species in relation to their feeding strategies (hypercarnivorous vs. generalist species) and prey preference (predators of small vs. large prey) using three-dimensional geometric morphometric techniques. Our results highlight different degrees of morphological integration in the Feliformia depending on the functional implication of the anatomical structure, with an overall higher covariation of structures in hypercarnivorous species. The skull and the forelimb are not integrated in generalist species, whereas they are integrated in hypercarnivores. These results can potentially be explained by the different feeding strategies of these species. Contrary to our expectations, hypercarnivores display a higher disparity for the skull than generalist species. This is probably due to the fact that a specialization toward high-meat diet could be achieved through various phenotypes. Finally, humeri and femora display shape variations depending on relative prey size preference. Large species feeding on large prey tend to have robust long bones due to higher biomechanical constraints.
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Affiliation(s)
- Margot Michaud
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, Paris, 75231 cedex 05, France
| | - Géraldine Veron
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, Paris, 75231 cedex 05, France
| | - Anne-Claire Fabre
- Department of Life Sciences, The Natural History Museum, London, SW7 5BD, United Kingdom
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13
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Mallet C, Billet G, Houssaye A, Cornette R. A first glimpse at the influence of body mass in the morphological integration of the limb long bones: an investigation in modern rhinoceroses. J Anat 2020; 237:704-726. [PMID: 32519813 PMCID: PMC7495277 DOI: 10.1111/joa.13232] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/09/2020] [Accepted: 05/12/2020] [Indexed: 01/20/2023] Open
Abstract
The appendicular skeleton of tetrapods is a particularly integrated structure due to the shared developmental origin or similar functional constraints exerted on its elements. Among these constraints, body mass is considered strongly to influence its integration but its effect on shape covariation has rarely been addressed in mammals, especially in heavy taxa. Here, we propose to explore the covariation patterns of the long bones in heavy animals and their link to body mass. We investigate the five modern rhinoceros species, which display an important range of bodyweight. We used a 3D geometric morphometric approach to describe the shape covariation of the six bones composing the stylopodium and zeugopodium both among and within species. Our results indicate that the appendicular skeleton of modern rhinos is a strongly integrated structure. At the interspecific level, the shape covariation is roughly similar between all pairs of bones and mainly concerns the muscular insertions related to powerful flexion and extension movements. The forelimb integration appears higher and more related to body mass than that of the hind limb, suggesting a specialization for weight support. The integration of the stylopodium elements does not seem to relate to body mass in our sample, which suggests a greater effect of shared developmental factors. Conversely, the covariation of the zeugopodium bones seems more associated with body mass, particularly for the radius-ulna pair. The fibula appears poorly integrated with other bones, especially within non-Rhinoceros species, which may represent a case of parcellation due to a functional dissociation between the hind limb bones. The exploration of the integration patterns at the intraspecific level also highlights a more prominent effect of age over individual body mass on shape covariation within C. simum. This study lends support to previous hypotheses indicating a link between high body mass and high integration level.
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Affiliation(s)
- Christophe Mallet
- Mécanismes adaptatifs et évolution (MECADEV)UMR 7179, MNHN, CNRSParisFrance
| | - Guillaume Billet
- Centre de Recherche en Paléontologie – Paris (CR2P)UMR CNRS 7207, MNHN, CNRSFrance
| | - Alexandra Houssaye
- Mécanismes adaptatifs et évolution (MECADEV)UMR 7179, MNHN, CNRSParisFrance
| | - Raphaël Cornette
- Institut de Systématique, Evolution, Biodiversité (ISYEB)UMR 7205, MNHN, CNRS, SU, EPHE, UAParisFrance
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Karban ME. Occipital hemi-bun development and shape covariation in a longitudinal extant human growth sample. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2019; 172:123-134. [PMID: 31797354 DOI: 10.1002/ajpa.23981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 10/11/2019] [Accepted: 11/20/2019] [Indexed: 11/10/2022]
Abstract
OBJECTIVES Although the homology of the Neanderthal occipital bun and anatomically modern human "hemi-bun" has long been debated, little is known about the developmental timing and patterning of these two patterns of prominent occipital squama convexity. In this study, occipital hemi-bun ontogeny and cranial shape covariation are assessed in a comparative extant human sample. MATERIALS AND METHODS Two-dimensional geometric morphometric methods were used to investigate hemi-bun development in a longitudinal sample of growth study cephalograms representing extant human subjects predominantly of European ancestry. Subjects were each measured at three distinct age points, ranging from 3.0 to 20.4 years, and two-block partial least squares analysis was used to assess patterns of covariation between midsagittal occipital bone morphology and other aspects of craniofacial shape. RESULTS Occipital hemi-bun morphology, when present, was found to develop early in ontogeny, in association with anteroposterior elongation of the frontal and parietal bones. No significant pattern of covariation was found between occipital hemi-bun shape and cranial/basicranial breadth, basicranial length, basicranial angle, or midfacial prognathism. DISCUSSION This study suggests that the occipital hemi-bun, at least in this extant human population, should not be considered an independent trait, as its development is closely linked to shape variation in the frontal and parietal bones. Importantly, these results suggest that occipital hemi-bun morphology is not significantly influenced by basicranial morphology during development, but instead covaries with changes in midsagittal neurocranial vault shape.
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Arlegi M, Veschambre‐Couture C, Gómez‐Olivencia A. Evolutionary selection and morphological integration in the vertebral column of modern humans. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2019; 171:17-36. [DOI: 10.1002/ajpa.23950] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 07/03/2019] [Accepted: 09/26/2019] [Indexed: 01/22/2023]
Affiliation(s)
- Mikel Arlegi
- Departamento de Estratigrafía y Paleontología, Facultad de Ciencia y TecnologíaUniversidad del País Vasco‐Euskal Herriko Unibertsitatea (UPV/EHU) Leioa Spain
- Université de Bordeaux, PACEA UMR 5199 Pessac France
| | | | - Asier Gómez‐Olivencia
- Departamento de Estratigrafía y Paleontología, Facultad de Ciencia y TecnologíaUniversidad del País Vasco‐Euskal Herriko Unibertsitatea (UPV/EHU) Leioa Spain
- IKERBASQUE. Basque Foundation for Science Bizkaia Spain
- Centro UCM‐ISCIII de Investigación sobre Evolución y Comportamiento Humanos Madrid Spain
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Watanabe A, Fabre AC, Felice RN, Maisano JA, Müller J, Herrel A, Goswami A. Ecomorphological diversification in squamates from conserved pattern of cranial integration. Proc Natl Acad Sci U S A 2019; 116:14688-14697. [PMID: 31262818 PMCID: PMC6642379 DOI: 10.1073/pnas.1820967116] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Factors intrinsic and extrinsic to organisms dictate the course of morphological evolution but are seldom considered together in comparative analyses. Among vertebrates, squamates (lizards and snakes) exhibit remarkable morphological and developmental variations that parallel their incredible ecological spectrum. However, this exceptional diversity also makes systematic quantification and analysis of their morphological evolution challenging. We present a squamate-wide, high-density morphometric analysis of the skull across 181 modern and extinct species to identify the primary drivers of their cranial evolution within a unified, quantitative framework. Diet and habitat preferences, but not reproductive mode, are major influences on skull-shape evolution across squamates, with fossorial and aquatic taxa exhibiting convergent and rapid changes in skull shape. In lizards, diet is associated with the shape of the rostrum, reflecting its use in grasping prey, whereas snakes show a correlation between diet and the shape of posterior skull bones important for gape widening. Similarly, we observe the highest rates of evolution and greatest disparity in regions associated with jaw musculature in lizards, whereas those forming the jaw articulation evolve faster in snakes. In addition, high-resolution ancestral cranial reconstructions from these data support a terrestrial, nonfossorial origin for snakes. Despite their disparate evolutionary trends, lizards and snakes unexpectedly share a common pattern of trait integration, with the highest correlations in the occiput, jaw articulation, and palate. We thus demonstrate that highly diverse phenotypes, exemplified by lizards and snakes, can and do arise from differential selection acting on conserved patterns of phenotypic integration.
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Affiliation(s)
- Akinobu Watanabe
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, NY 11568;
- Life Sciences Department, Vertebrates Division, Natural History Museum, London SW7 5BD, United Kingdom
- Division of Paleontology, American Museum of Natural History, New York, NY 10024
| | - Anne-Claire Fabre
- Life Sciences Department, Vertebrates Division, Natural History Museum, London SW7 5BD, United Kingdom
| | - Ryan N Felice
- Life Sciences Department, Vertebrates Division, Natural History Museum, London SW7 5BD, United Kingdom
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London WC1E 6BT, United Kingdom
| | - Jessica A Maisano
- Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712
| | - Johannes Müller
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin 10115, Germany
| | - Anthony Herrel
- Département Adaptations du Vivant, Centre National de la Recherche Scientifique, Muséum National d'Histoire Naturelle, Paris 75005, France
| | - Anjali Goswami
- Life Sciences Department, Vertebrates Division, Natural History Museum, London SW7 5BD, United Kingdom
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom
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López-Aguirre C, Hand SJ, Koyabu D, Son NT, Wilson LAB. Postcranial heterochrony, modularity, integration and disparity in the prenatal ossification in bats (Chiroptera). BMC Evol Biol 2019; 19:75. [PMID: 30866800 PMCID: PMC6417144 DOI: 10.1186/s12862-019-1396-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 02/21/2019] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Self-powered flight is one of the most energy-intensive types of locomotion found in vertebrates. It is also associated with a range of extreme morpho-physiological adaptations that evolved independently in three different vertebrate groups. Considering that development acts as a bridge between the genotype and phenotype on which selection acts, studying the ossification of the postcranium can potentially illuminate our understanding of bat flight evolution. However, the ontogenetic basis of vertebrate flight remains largely understudied. Advances in quantitative analysis of sequence heterochrony and morphogenetic growth have created novel approaches to study the developmental basis of diversification and the evolvability of skeletal morphogenesis. Assessing the presence of ontogenetic disparity, integration and modularity from an evolutionary approach allows assessing whether flight may have resulted in evolutionary differences in the magnitude and mode of development in bats. RESULTS We quantitatively compared the prenatal ossification of the postcranium (24 bones) between bats (14 species), non-volant mammals (11 species) and birds (14 species), combining for the first time prenatal sequence heterochrony and developmental growth data. Sequence heterochrony was found across groups, showing that bat postcranial development shares patterns found in other flying vertebrates but also those in non-volant mammals. In bats, modularity was found as an axial-appendicular partition, resembling a mammalian pattern of developmental modularity and suggesting flight did not repattern prenatal postcranial covariance in bats. CONCLUSIONS Combining prenatal data from 14 bat species, this study represents the most comprehensive quantitative analysis of chiropteran ossification to date. Heterochrony between the wing and leg in bats could reflect functional needs of the newborn, rather than ecological aspects of the adult. Bats share similarities with birds in the development of structures involved in flight (i.e. handwing and sternum), suggesting that flight altriciality and early ossification of pedal phalanges and sternum are common across flying vertebrates. These results indicate that the developmental modularity found in bats facilitates intramodular phenotypic diversification of the skeleton. Integration and disparity increased across developmental time in bats. We also found a delay in the ossification of highly adaptable and evolvable regions (e.g. handwing and sternum) that are directly associated with flight performance.
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Affiliation(s)
- Camilo López-Aguirre
- PANGEA Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, NSW 2052 Australia
| | - Suzanne J. Hand
- PANGEA Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, NSW 2052 Australia
| | - Daisuke Koyabu
- University Museum, University of Tokyo, Tokyo, Japan
- Department of Humanities and Sciences, Musashino Art University, Tokyo, Japan
| | - Nguyen Truong Son
- Department of Vertebrate Zoology, Institute of Ecology and Biological Resources, Vietnam Academy of Sciences and Technology, Hanoi, Vietnam
- Vietnam Academy of Science and Technology, Graduate University of Science and Technology, Hanoi, Vietnam
| | - Laura A. B. Wilson
- PANGEA Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, NSW 2052 Australia
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Randau M, Sanfelice D, Goswami A. Shifts in cranial integration associated with ecological specialization in pinnipeds (Mammalia, Carnivora). ROYAL SOCIETY OPEN SCIENCE 2019; 6:190201. [PMID: 31032062 PMCID: PMC6458409 DOI: 10.1098/rsos.190201] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 02/15/2019] [Indexed: 05/08/2023]
Abstract
Patterns of trait integration reflect the underlying genetic and developmental architecture of morphology and significantly influence the direction of evolution. Nevertheless, the relationship between integration and disparity is complex and unlikely to be uniform across large phylogenetic and ecological scales. To date, there are little data comparing patterns of integration across major ecological transitions, limiting understanding of the processes driving changes in trait integration and their consequences. Here, we investigated patterns of cranial integration and disparity across pinnipeds, three closely related carnivoran families that have undergone a secondary adaptation to the aquatic niche with varying levels of ecological differentiation. With a three-dimensional geometric morphometric dataset of 677 specimens spanning 15 species, we compared five models of trait integration, and examined the effects of sexual dimorphism and allometry on model support. Pinnipeds varied greatly in patterns of cranial integration compared to terrestrial carnivorans. Interestingly, this variation is concentrated in phocids, which may reflect the broader range of ecological and life-history specializations across phocid species, and greater independence from the terrestrial habitat observed in that group, relative to otariids. Overall, these results indicate that major ecological transitions, and presumably large changes in selection pressures, may drive changes in phenotypic trait integration.
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Affiliation(s)
| | - Daniela Sanfelice
- Instituto Federal do Rio Grande do Sul, Campus Restinga, Porto Alegre, Brazil
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López‐Aguirre C, Hand SJ, Koyabu D, Son NT, Wilson LAB. Prenatal allometric trajectories and the developmental basis of postcranial phenotypic diversity in bats (Chiroptera). JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2019; 332:36-49. [DOI: 10.1002/jez.b.22846] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 01/17/2019] [Accepted: 01/31/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Camilo López‐Aguirre
- PANGEA Research Centre School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney New South Wales Australia
| | - Suzanne J. Hand
- PANGEA Research Centre School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney New South Wales Australia
| | - Daisuke Koyabu
- Department of Curatorial Studies University Museum, University of Tokyo Tokyo Japan
- Department of Humanities and Sciences Musashino Art University Tokyo Japan
| | - Nguyen Truong Son
- Department of Vertebrate Zoology Institute of Ecology and Biological Resources, Vietnam Academy of Sciences and Technology Hanoi Vietnam
- Faculty of Ecology and Biological Resources Graduate University of Science and Technology Hanoi Vietnam
| | - Laura A. B. Wilson
- PANGEA Research Centre School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney New South Wales Australia
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Bardua C, Wilkinson M, Gower DJ, Sherratt E, Goswami A. Morphological evolution and modularity of the caecilian skull. BMC Evol Biol 2019; 19:30. [PMID: 30669965 PMCID: PMC6343317 DOI: 10.1186/s12862-018-1342-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 12/21/2018] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Caecilians (Gymnophiona) are the least speciose extant lissamphibian order, yet living forms capture approximately 250 million years of evolution since their earliest divergences. This long history is reflected in the broad range of skull morphologies exhibited by this largely fossorial, but developmentally diverse, clade. However, this diversity of form makes quantification of caecilian cranial morphology challenging, with highly variable presence or absence of many structures. Consequently, few studies have examined morphological evolution across caecilians. This extensive variation also raises the question of degree of conservation of cranial modules (semi-autonomous subsets of highly-integrated traits) within this clade, allowing us to assess the importance of modular organisation in shaping morphological evolution. We used an intensive surface geometric morphometric approach to quantify cranial morphological variation across all 32 extant caecilian genera. We defined 16 cranial regions using 53 landmarks and 687 curve and 729 surface sliding semilandmarks. With these unprecedented high-dimensional data, we analysed cranial shape and modularity across caecilians assessing phylogenetic, allometric and ecological influences on cranial evolution, as well as investigating the relationships among integration, evolutionary rate, and morphological disparity. RESULTS We found highest support for a ten-module model, with greater integration of the posterior skull. Phylogenetic signal was significant (Kmult = 0.87, p < 0.01), but stronger in anterior modules, while allometric influences were also significant (R2 = 0.16, p < 0.01), but stronger posteriorly. Reproductive strategy and degree of fossoriality were small but significant influences on cranial morphology (R2 = 0.03-0.05), after phylogenetic (p < 0.03) and multiple-test (p < 0.05) corrections. The quadrate-squamosal 'cheek' module was the fastest evolving module, perhaps due to its pivotal role in the unique dual jaw-closing mechanism of caecilians. Highly integrated modules exhibited both high and low disparities, and no relationship was evident between integration and evolutionary rate. CONCLUSIONS Our high-dimensional approach robustly characterises caecilian cranial evolution and demonstrates that caecilian crania are highly modular and that cranial modules are shaped by differential phylogenetic, allometric, and ecological effects. More broadly, and in contrast to recent studies, this work suggests that there is no simple relationship between integration and evolutionary rate or disparity.
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Affiliation(s)
- Carla Bardua
- Department of Life Sciences, Natural History Museum, London, UK. .,Department of Genetics, Evolution and Environment, UCL, London, UK.
| | - Mark Wilkinson
- Department of Life Sciences, Natural History Museum, London, UK
| | - David J Gower
- Department of Life Sciences, Natural History Museum, London, UK
| | - Emma Sherratt
- School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Anjali Goswami
- Department of Life Sciences, Natural History Museum, London, UK.,Department of Genetics, Evolution and Environment, UCL, London, UK
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Felice RN, Randau M, Goswami A. A fly in a tube: Macroevolutionary expectations for integrated phenotypes. Evolution 2018; 72:2580-2594. [PMID: 30246245 PMCID: PMC6585935 DOI: 10.1111/evo.13608] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 09/07/2018] [Accepted: 09/13/2018] [Indexed: 02/03/2023]
Abstract
Phenotypic integration and modularity are ubiquitous features of complex organisms, describing the magnitude and pattern of relationships among biological traits. A key prediction is that these relationships, reflecting genetic, developmental, and functional interactions, shape evolutionary processes by governing evolvability and constraint. Over the last 60 years, a rich literature of research has quantified patterns of integration and modularity across a variety of clades and systems. Only recently has it become possible to contextualize these findings in a phylogenetic framework to understand how trait integration interacts with evolutionary tempo and mode. Here, we review the state of macroevolutionary studies of integration and modularity, synthesizing empirical and theoretical work into a conceptual framework for predicting the effects of integration on evolutionary rate and disparity: a fly in a tube. While magnitude of integration is expected to influence the potential for phenotypic variation to be produced and maintained, thus defining the shape and size of a tube in morphospace, evolutionary rate, or the speed at which a fly moves around the tube, is not necessarily controlled by trait interactions. Finally, we demonstrate this reduced disparity relative to the Brownian expectation for a given rate of evolution with an empirical example: the avian cranium.
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Affiliation(s)
- Ryan N Felice
- Department of Life Sciences, The Natural History Museum, London SW7 5DB, United Kingdom.,Department of Genetics, Evolution, and Environment, University College London, London WC1E 6BT, United Kingdom
| | - Marcela Randau
- Department of Life Sciences, The Natural History Museum, London SW7 5DB, United Kingdom.,Department of Genetics, Evolution, and Environment, University College London, London WC1E 6BT, United Kingdom
| | - Anjali Goswami
- Department of Life Sciences, The Natural History Museum, London SW7 5DB, United Kingdom.,Department of Genetics, Evolution, and Environment, University College London, London WC1E 6BT, United Kingdom
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