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Ollonen J, Khannoon ER, Macrì S, Vergilov V, Kuurne J, Saarikivi J, Soukainen A, Aalto IM, Werneburg I, Diaz RE, Di-Poï N. Dynamic evolutionary interplay between ontogenetic skull patterning and whole-head integration. Nat Ecol Evol 2024; 8:536-551. [PMID: 38200368 DOI: 10.1038/s41559-023-02295-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 11/29/2023] [Indexed: 01/12/2024]
Abstract
The arrangement and morphology of the vertebrate skull reflect functional and ecological demands, making it a highly adaptable structure. However, the fundamental developmental and macroevolutionary mechanisms leading to different vertebrate skull phenotypes remain unclear. Here we exploit the morphological diversity of squamate reptiles to assess the developmental and evolutionary patterns of skull variation and covariation in the whole head. Our geometric morphometric analysis of a complex squamate ontogenetic dataset (209 specimens, 169 embryos, 44 species), covering stages from craniofacial primordia to fully ossified bones, reveals that morphological differences between snake and lizard skulls arose gradually through changes in spatial relationships (heterotopy) followed by alterations in developmental timing or rate (heterochrony). Along with dynamic spatiotemporal changes in the integration pattern of skull bone shape and topology with surrounding brain tissues and sensory organs, we identify a relatively higher phenotypic integration of the developing snake head compared with lizards. The eye, nasal cavity and Jacobson's organ are pivotal in skull morphogenesis, highlighting the importance of sensory rearrangements in snake evolution. Furthermore, our findings demonstrate the importance of early embryonic, ontogenetic and tissue interactions in shaping craniofacial evolution and ecological diversification in squamates, with implications for the nature of cranio-cerebral relations across vertebrates.
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Affiliation(s)
- Joni Ollonen
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Eraqi R Khannoon
- Biology Department, College of Science, Taibah University, Al Madinah Al Munawwarah, Saudi Arabia
- Zoology Department, Faculty of Science, Fayoum University, Fayoum, Egypt
| | - Simone Macrì
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Vladislav Vergilov
- National Museum of Natural History, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Jaakko Kuurne
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Jarmo Saarikivi
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Arttu Soukainen
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Ida-Maria Aalto
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Ingmar Werneburg
- Senckenberg Centre for Human Evolution and Palaeoenvironment, Eberhard Karls Universität, Tübingen, Germany
- Fachbereich Geowissenschaften, Eberhard Karls Universität, Tübingen, Germany
| | - Raul E Diaz
- Department of Biological Sciences, California State University, Los Angeles, CA, USA
- Department of Herpetology, Natural History Museum of Los Angeles County, Los Angeles, CA, USA
| | - Nicolas Di-Poï
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.
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Allemand R, Abdul-Sater J, Macrì S, Di-Poï N, Daghfous G, Silcox MT. Endocast, brain, and bones: Correspondences and spatial relationships in squamates. Anat Rec (Hoboken) 2023; 306:2443-2465. [PMID: 36602153 DOI: 10.1002/ar.25142] [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: 10/13/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 01/06/2023]
Abstract
Vertebrate endocasts are widely used in the fields of paleoneurology and comparative neuroanatomy. The validity of endocranial studies is dependent upon the extent to which an endocast reflects brain morphology. Due to the variable neuroanatomical resolution of vertebrate endocasts, direct information about the brain morphology can be sometimes difficult to assess and needs to be investigated across lineages. Here, we employ X-ray computed tomography (CT), including diffusible iodine-based contrast-enhanced CT, to qualitatively compare brains and endocasts in different species of squamates. The relative position of the squamate brain within the skull, as well as the variability that may exist in such spatial relationships, was examined to help clarify the neurological regions evidence on their endocasts. Our results indicate that squamate endocasts provide variable representation of the brain, depending on species and neuroanatomical regions. The olfactory bulbs and peduncles, cerebral hemispheres, as well as the medulla oblongata represent the most easily discernable brain regions from squamate endocasts. In contrast, the position of the optic lobes, the ventral diencephalon and the pituitary may be difficult to determine depending on species. Finally, squamate endocasts provide very limited or no information about the cerebellum. The spatial relationships revealed here between the brain and the surrounding bones may help to identify each of the endocranial region. However, as one-to-one correspondences between a bone and a specific region appear limited, the exact delimitation of these regions may remain challenging according to species. This study provides a basis for further examination and interpretation of squamate endocast disparity.
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Affiliation(s)
- Rémi Allemand
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Jade Abdul-Sater
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Simone Macrì
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Nicolas Di-Poï
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | | | - Mary T Silcox
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
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Roscito JG, Sameith K, Kirilenko BM, Hecker N, Winkler S, Dahl A, Rodrigues MT, Hiller M. Convergent and lineage-specific genomic differences in limb regulatory elements in limbless reptile lineages. Cell Rep 2022; 38:110280. [DOI: 10.1016/j.celrep.2021.110280] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 11/24/2021] [Accepted: 12/27/2021] [Indexed: 01/02/2023] Open
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Sears KE, Gros J, Davey M. Limb development, evolution, and regeneration & repair: Part 1. Dev Dyn 2021; 250:1218-1219. [PMID: 34402127 DOI: 10.1002/dvdy.411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Karen E Sears
- Departments of Ecology and Evolutionary Biology and Molecular, Cell, and Developmental Biology, UCLA, California, Los Angeles, USA
| | - Jerome Gros
- Department of Developmental and Stem Biology, Institute Pasteur, Paris, France
| | - Megan Davey
- Functional Genetics and Development, The Roslin Institute, The University of Edinburgh, Midlothian, Scotland, UK
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Skawiński T, Skórzewski G, Borczyk B. Embryonic development and perinatal skeleton in a limbless, viviparous lizard, Anguis fragilis (Squamata: Anguimorpha). PeerJ 2021; 9:e11621. [PMID: 34178475 PMCID: PMC8214852 DOI: 10.7717/peerj.11621] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 05/25/2021] [Indexed: 11/21/2022] Open
Abstract
Despite the long history of embryological studies of squamates, many groups of this huge clade have received only limited attention. One such understudied group is the anguimorphs, a clade comprising morphologically and ecologically very diverse lizards. We describe several stages of embryonic development of Anguis fragilis, a limbless, viviparous anguimorph. Interestingly, in several clutches we observe high morphological variation in characters traditionally important in classifying embryos into developmental stages. The causes of this variation remain unknown but environmental factors do not seem to be very important. Additionally, we describe the state of ossification in several perinatal specimens of A. fragilis. The cranial skeleton is relatively poorly ossified around the time of birth, with all of the bones constituting the braincase unfused. On the other hand, the vertebral column is well ossified, with the neurocentral sutures closed and the neural arches fused in all postatlantal vertebrae. Such an advanced state of ossification may be related to the greater importance of the vertebral column in locomotion in limbless species than in ones with fully-developed limbs. Numerous factors seem to affect the state of ossification at the time of hatching or birth in squamates, including phylogenetic position, mode of reproduction and, potentially, limblessness. However, data from a greater number of species are needed to reach firmer conclusions about the relative importance of these variables in certain clades.
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Affiliation(s)
- Tomasz Skawiński
- Department of Evolutionary Biology and Conservation of Vertebrates, University of Wroclaw, Wrocław, Poland
| | | | - Bartosz Borczyk
- Department of Evolutionary Biology and Conservation of Vertebrates, University of Wroclaw, Wrocław, Poland
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