1
|
Marek RD, Felice RN. The neck as a keystone structure in avian macroevolution and mosaicism. BMC Biol 2023; 21:216. [PMID: 37833771 PMCID: PMC10576348 DOI: 10.1186/s12915-023-01715-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
BACKGROUND The origin of birds from non-avian theropod dinosaur ancestors required a comprehensive restructuring of the body plan to enable the evolution of powered flight. One of the proposed key mechanisms that allowed birds to acquire flight and modify the associated anatomical structures into diverse forms is mosaic evolution, which describes the parcelization of phenotypic traits into separate modules that evolve with heterogeneous tempo and mode. Avian mosaicism has been investigated with a focus on the cranial and appendicular skeleton, and as such, we do not understand the role of the axial column in avian macroevolution. The long, flexible neck of extant birds lies between the cranial and pectoral modules and represents an opportunity to study the contribution of the axial skeleton to avian mosaicism. RESULTS Here, we use 3D geometric morphometrics in tandem with phylogenetic comparative methods to provide, to our knowledge, the first integrative analysis of avian neck evolution in context with the head and wing and to interrogate how the interactions between these anatomical systems have influenced macroevolutionary trends across a broad sample of extant birds. We find that the neck is integrated with both the head and the forelimb. These patterns of integration are variable across clades, and only specific ecological groups exhibit either head-neck or neck-forelimb integration. Finally, we find that ecological groups that display head-neck and neck-forelimb integration tend to display significant shifts in the rate of neck morphological evolution. CONCLUSIONS Combined, these results suggest that the interaction between trophic ecology and head-neck-forelimb mosaicism influences the evolutionary variance of the avian neck. By linking together the biomechanical functions of these distinct anatomical systems, the cervical vertebral column serves as a keystone structure in avian mosaicism and macroevolution.
Collapse
Affiliation(s)
- Ryan D Marek
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, UK.
| | - Ryan N Felice
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, UK
- Department of Life Sciences, Natural History Museum, London, UK
- Department of Genetics, Evolution, and Environment, University College London, London, UK
| |
Collapse
|
2
|
Goswami A, Noirault E, Coombs EJ, Clavel J, Fabre AC, Halliday TJD, Churchill M, Curtis A, Watanabe A, Simmons NB, Beatty BL, Geisler JH, Fox DL, Felice RN. Developmental origin underlies evolutionary rate variation across the placental skull. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220083. [PMID: 37183904 PMCID: PMC10184245 DOI: 10.1098/rstb.2022.0083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023] Open
Abstract
The placental skull has evolved into myriad forms, from longirostrine whales to globular primates, and with a diverse array of appendages from antlers to tusks. This disparity has recently been studied from the perspective of the whole skull, but the skull is composed of numerous elements that have distinct developmental origins and varied functions. Here, we assess the evolution of the skull's major skeletal elements, decomposed into 17 individual regions. Using a high-dimensional morphometric approach for a dataset of 322 living and extinct eutherians (placental mammals and their stem relatives), we quantify patterns of variation and estimate phylogenetic, allometric and ecological signal across the skull. We further compare rates of evolution across ecological categories and ordinal-level clades and reconstruct rates of evolution along lineages and through time to assess whether developmental origin or function discriminate the evolutionary trajectories of individual cranial elements. Our results demonstrate distinct macroevolutionary patterns across cranial elements that reflect the ecological adaptations of major clades. Elements derived from neural crest show the fastest rates of evolution, but ecological signal is equally pronounced in bones derived from neural crest and paraxial mesoderm, suggesting that developmental origin may influence evolutionary tempo, but not capacity for specialisation. This article is part of the theme issue 'The mammalian skull: development, structure and function'.
Collapse
Affiliation(s)
- Anjali Goswami
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK
- Department of Genetics, Evolution, and Environment, University College London, London WC1E 6BT, UK
| | - Eve Noirault
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK
| | - Ellen J Coombs
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK
- Department of Genetics, Evolution, and Environment, University College London, London WC1E 6BT, UK
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA
| | - Julien Clavel
- Université Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, 69622 Villeurbanne, France
| | - Anne-Claire Fabre
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK
- Naturhistorisches Museum Bern, 3005 Bern, Switzerland
- Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Thomas J D Halliday
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Morgan Churchill
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, WI 54901, USA
| | - Abigail Curtis
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Akinobu Watanabe
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
| | - Nancy B Simmons
- Department of Mammalogy, Division of Vertebrate Zoology, American Museum of Natural History, New York, NY 10024, USA
| | - Brian L Beatty
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA
| | - Jonathan H Geisler
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA
| | - David L Fox
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ryan N Felice
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK
- Department of Genetics, Evolution, and Environment, University College London, London WC1E 6BT, UK
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| |
Collapse
|
3
|
Hunt ESE, Felice RN, Tobias JA, Goswami A. Ecological and life-history drivers of avian skull evolution. Evolution 2023; 77:1720-1729. [PMID: 37105944 DOI: 10.1093/evolut/qpad079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 04/04/2023] [Accepted: 04/26/2023] [Indexed: 04/29/2023]
Abstract
One of the most famous examples of adaptive radiation is that of the Galápagos finches, where skull morphology, particularly the beak, varies with feeding ecology. Yet increasingly studies are questioning the strength of this correlation between feeding ecology and morphology in relation to the entire neornithine radiation, suggesting that other factors also significantly affect skull evolution. Here, we broaden this debate to assess the influence of a range of ecological and life-history factors, specifically habitat density, migration, and developmental mode, in shaping avian skull evolution. Using 3D geometric morphometric data to robustly quantify skull shape for 354 extant species spanning avian diversity, we fitted flexible phylogenetic regressions and estimated evolutionary rates for each of these factors across the full data set. The results support a highly significant relationship between skull shape and both habitat density and migration, but not developmental mode. We further found heterogenous rates of evolution between different character states within habitat density, migration, and developmental mode, with rapid skull evolution in species that occupy dense habitats, are migratory, or are precocial. These patterns demonstrate that diverse factors affect the tempo and mode of avian phenotypic evolution and that skull evolution in birds is not simply a reflection of feeding ecology.
Collapse
Affiliation(s)
- Eloise S E Hunt
- Department of Life Sciences and Grantham Institute, Imperial College London, London, United Kingdom
- Department of Life Sciences, The Natural History Museum, London, United Kingdom
| | - Ryan N Felice
- Department of Life Sciences, The Natural History Museum, London, United Kingdom
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Joseph A Tobias
- Department of Life Sciences, Imperial College London, Ascot, United Kingdom
| | - Anjali Goswami
- Department of Life Sciences, The Natural History Museum, London, United Kingdom
- Department of Genetics, Evolution, and Environment, University College London, London, United Kingdom
| |
Collapse
|
4
|
Tharakan S, Shepherd N, Gower DJ, Stanley EL, Felice RN, Goswami A, Watanabe A. High-Density Geometric Morphometric Analysis of Intraspecific Cranial Integration in the Barred Grass Snake ( Natrix helvetica) and Green Anole ( Anolis carolinensis). Integr Org Biol 2023; 5:obad022. [PMID: 37397233 PMCID: PMC10311474 DOI: 10.1093/iob/obad022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 04/30/2023] [Accepted: 06/02/2023] [Indexed: 07/04/2023] Open
Abstract
How do phenotypic associations intrinsic to an organism, such as developmental and mechanical processes, direct morphological evolution? Comparisons of intraspecific and clade-wide patterns of phenotypic covariation could inform how population-level trends ultimately dictate macroevolutionary changes. However, most studies have focused on analyzing integration and modularity either at macroevolutionary or intraspecific levels, without a shared analytical framework unifying these temporal scales. In this study, we investigate the intraspecific patterns of cranial integration in two squamate species: Natrix helvetica and Anolis carolinensis. We analyze their cranial integration patterns using the same high-density three-dimensional geometric morphometric approach used in a prior squamate-wide evolutionary study. Our results indicate that Natrix and Anolis exhibit shared intraspecific cranial integration patterns, with some differences, including a more integrated rostrum in the latter. Notably, these differences in intraspecific patterns correspond to their respective interspecific patterns in snakes and lizards, with few exceptions. These results suggest that interspecific patterns of cranial integration reflect intraspecific patterns. Hence, our study suggests that the phenotypic associations that direct morphological variation within species extend across micro- and macroevolutionary levels, bridging these two scales.
Collapse
Affiliation(s)
- S Tharakan
- Department of Anatomy, New York Institute of Technology, College of Osteopathic Medicine, 100 Northern Boulevard, Old Westbury, NY 11568, USA
| | - N Shepherd
- Department of Genetics, Evolution, and Environment, University College London, Gower Street, London, WC1E 6BT, UK
| | - D J Gower
- Life Sciences Division, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
| | - E L Stanley
- Digital Imaging Division, Florida Museum of Natural History, University of Florida, Gainesville, FL 32611-0001, USA
| | - R N Felice
- Department of Genetics, Evolution, and Environment, University College London, Gower Street, London, WC1E 6BT, UK
- Life Sciences Division, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - A Goswami
- Department of Genetics, Evolution, and Environment, University College London, Gower Street, London, WC1E 6BT, UK
- Life Sciences Division, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
| | | |
Collapse
|
5
|
Goswami A, Noirault E, Coombs EJ, Clavel J, Fabre AC, Halliday TJD, Churchill M, Curtis A, Watanabe A, Simmons NB, Beatty BL, Geisler JH, Fox DL, Felice RN. Attenuated evolution of mammals through the Cenozoic. Science 2022; 378:377-383. [DOI: 10.1126/science.abm7525] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Cenozoic diversification of placental mammals is the archetypal adaptive radiation. Yet, discrepancies between molecular divergence estimates and the fossil record fuel ongoing debate around the timing, tempo, and drivers of this radiation. Analysis of a three-dimensional skull dataset for living and extinct placental mammals demonstrates that evolutionary rates peak early and attenuate quickly. This long-term decline in tempo is punctuated by bursts of innovation that decreased in amplitude over the past 66 million years. Social, precocial, aquatic, and herbivorous species evolve fastest, especially whales, elephants, sirenians, and extinct ungulates. Slow rates in rodents and bats indicate dissociation of taxonomic and morphological diversification. Frustratingly, highly similar ancestral shape estimates for placental mammal superorders suggest that their earliest representatives may continue to elude unequivocal identification.
Collapse
Affiliation(s)
- Anjali Goswami
- Department of Life Sciences, Natural History Museum, London, UK
- Department of Genetics, Evolution, and Environment, University College London, London, UK
| | - Eve Noirault
- Department of Life Sciences, Natural History Museum, London, UK
| | - Ellen J. Coombs
- Department of Life Sciences, Natural History Museum, London, UK
- Department of Genetics, Evolution, and Environment, University College London, London, UK
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Julien Clavel
- Université Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, Villeurbanne, France
| | - Anne-Claire Fabre
- Department of Life Sciences, Natural History Museum, London, UK
- Naturhistorisches Museum Bern, Bern, Switzerland
- Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
| | - Thomas J. D. Halliday
- Department of Life Sciences, Natural History Museum, London, UK
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
| | - Morgan Churchill
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, WI, USA
| | - Abigail Curtis
- Department of Biology, University of Washington, Seattle, WA, USA
| | - Akinobu Watanabe
- Department of Life Sciences, Natural History Museum, London, UK
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, NY, USA
- Division of Paleontology, American Museum of Natural History, New York, NY, USA
| | - Nancy B. Simmons
- Department of Mammalogy, Division of Vertebrate Zoology, American Museum of Natural History, New York, NY, USA
| | - Brian L. Beatty
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, NY, USA
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Jonathan H. Geisler
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, NY, USA
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - David L. Fox
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN, USA
| | - Ryan N. Felice
- Department of Life Sciences, Natural History Museum, London, UK
- Department of Genetics, Evolution, and Environment, University College London, London, UK
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, UK
| |
Collapse
|
6
|
Abstract
All modern crocodyliforms (alligators, crocodiles and the gharial) are semi-aquatic generalist carnivores that are relatively similar in cranial form and function. However, this homogeneity represents just a fraction of the variation that once existed in the clade, which includes extinct herbivorous and marine forms with divergent skull structure and function. Here, we use high-dimensional three-dimensional geometric morphometrics to quantify whole-skull morphology across modern and fossil crocodyliforms to untangle the factors that shaped the macroevolutionary history and relatively low phenotypic variation of this clade through time. Evolutionary modelling demonstrates that the pace of crocodyliform cranial evolution is initially high, particularly in the extinct Notosuchia, but slows near the base of Neosuchia, with a late burst of rapid evolution in crown-group crocodiles. Surprisingly, modern crocodiles, especially Australian, southeast Asian, Indo-Pacific species, have high rates of evolution, despite exhibiting low variation. Thus, extant lineages are not in evolutionary stasis but rather have rapidly fluctuated within a limited region of morphospace, resulting in significant convergence. The structures related to jaw closing and bite force production (e.g. pterygoid flange and quadrate) are highly variable, reinforcing the importance of function in driving phenotypic variation. Together, these findings illustrate that the apparent conservativeness of crocodyliform skulls betrays unappreciated complexity in their macroevolutionary dynamics.
Collapse
Affiliation(s)
- Ryan N Felice
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, UK.,Department of Life Sciences, The Natural History Museum, London, UK
| | - Diego Pol
- CONICET, Museo Paleontológico Egidio Feruglio, Trelew 9100, Chubut, Argentina
| | - Anjali Goswami
- Department of Life Sciences, The Natural History Museum, London, UK
| |
Collapse
|
7
|
Abstract
Abstract
The study of integration and modularity aims to describe the organization of components that make up organisms, and the evolutionary, developmental and functional relationships among them. Both have been studied at the interspecific (evolutionary) and intraspecific (phenotypic and ontogenetic) levels to different degrees across various clades. Although evolutionary modularity and integration are well-characterized across birds, knowledge of intraspecific patterns is lacking. Here, we use a high-density, three-dimensional geometric morphometric approach to investigate patterns of integration and modularity in Psittacula krameri, a highly successful invasive parrot species that exhibits the derived vertical palate and cranio-facial hinge of the Psittaciformes. Showing a pattern of nine distinct cranial modules, our results support findings from recent research that uses similar methods to investigate interspecific integration in birds. Allometry is not a significant influence on cranial shape variation within this species; however, within-module integration is significantly negatively correlated with disparity, with high variation concentrated in the weakly integrated rostrum, palate and vault modules. As previous studies have demonstrated differences in beak shape between invasive and native populations, variation in the weakly integrated palate and rostrum may have facilitated evolutionary change in these parts of the skull, contributing to the ring-necked parakeet’s success as an invasive species.
Collapse
Affiliation(s)
- Matthew J Mitchell
- Department of Life Sciences, Natural History Museum, Kensington, London, UK
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, Bloomsbury, London, UK
| | - Anjali Goswami
- Department of Life Sciences, Natural History Museum, Kensington, London, UK
| | - Ryan N Felice
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, Bloomsbury, London, UK
| |
Collapse
|
8
|
O'Connor PM, Turner AH, Groenke JR, Felice RN, Rogers RR, Krause DW, Rahantarisoa LJ. Late Cretaceous bird from Madagascar reveals unique development of beaks. Nature 2020; 588:272-276. [PMID: 33239782 DOI: 10.1038/s41586-020-2945-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 09/14/2020] [Indexed: 11/09/2022]
Abstract
Mesozoic birds display considerable diversity in size, flight adaptations and feather organization1-4, but exhibit relatively conserved patterns of beak shape and development5-7. Although Neornithine (that is, crown group) birds also exhibit constraint on facial development8,9, they have comparatively diverse beak morphologies associated with a range of feeding and behavioural ecologies, in contrast to Mesozoic birds. Here we describe a crow-sized stem bird, Falcatakely forsterae gen. et sp. nov., from the Late Cretaceous epoch of Madagascar that possesses a long and deep rostrum, an expression of beak morphology that was previously unknown among Mesozoic birds and is superficially similar to that of a variety of crown-group birds (for example, toucans). The rostrum of Falcatakely is composed of an expansive edentulous maxilla and a small tooth-bearing premaxilla. Morphometric analyses of individual bony elements and three-dimensional rostrum shape reveal the development of a neornithine-like facial anatomy despite the retention of a maxilla-premaxilla organization that is similar to that of nonavialan theropods. The patterning and increased height of the rostrum in Falcatakely reveals a degree of developmental lability and increased morphological disparity that was previously unknown in early branching avialans. Expression of this phenotype (and presumed ecology) in a stem bird underscores that consolidation to the neornithine-like, premaxilla-dominated rostrum was not an evolutionary prerequisite for beak enlargement.
Collapse
Affiliation(s)
- Patrick M O'Connor
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA. .,Ohio Center for Ecological and Evolutionary Studies, Ohio University, Athens, OH, USA. .,Department of Earth Sciences, Denver Museum of Nature & Science, Denver, CO, USA.
| | - Alan H Turner
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY, USA
| | - Joseph R Groenke
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Ryan N Felice
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, UK
| | - Raymond R Rogers
- Department of Earth Sciences, Denver Museum of Nature & Science, Denver, CO, USA.,Geology Department, Macalester College, St Paul, MN, USA
| | - David W Krause
- Department of Earth Sciences, Denver Museum of Nature & Science, Denver, CO, USA.,Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY, USA
| | - Lydia J Rahantarisoa
- Département de Sciences de la Terre et de l'Environnement, Université d'Antananarivo, Antananarivo, Madagascar
| |
Collapse
|
9
|
Felice RN, Watanabe A, Cuff AR, Hanson M, Bhullar BAS, Rayfield ER, Witmer LM, Norell MA, Goswami A. Decelerated dinosaur skull evolution with the origin of birds. PLoS Biol 2020; 18:e3000801. [PMID: 32810126 PMCID: PMC7437466 DOI: 10.1371/journal.pbio.3000801] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 07/13/2020] [Indexed: 12/30/2022] Open
Abstract
The evolutionary radiation of birds has produced incredible morphological variation, including a huge range of skull form and function. Investigating how this variation arose with respect to non-avian dinosaurs is key to understanding how birds achieved their remarkable success after the Cretaceous-Paleogene extinction event. Using a high-dimensional geometric morphometric approach, we quantified the shape of the skull in unprecedented detail across 354 extant and 37 extinct avian and non-avian dinosaurs. Comparative analyses reveal fundamental differences in how skull shape evolved in birds and non-avian dinosaurs. We find that the overall skull shape evolved faster in non-avian dinosaurs than in birds across all regions of the cranium. In birds, the anterior rostrum is the most rapidly evolving skull region, whereas more posterior regions-such as the parietal, squamosal, and quadrate-exhibited high rates in non-avian dinosaurs. These fast-evolving elements in dinosaurs are strongly associated with feeding biomechanics, forming the jaw joint and supporting the jaw adductor muscles. Rapid pulses of skull evolution coincide with changes to food acquisition strategies and diets, as well as the proliferation of bony skull ornaments. In contrast to the appendicular skeleton, which has been shown to evolve more rapidly in birds, avian cranial morphology is characterised by a striking deceleration in morphological evolution relative to non-avian dinosaurs. These results may be due to the reorganisation of skull structure in birds-including loss of a separate postorbital bone in adults and the emergence of new trade-offs with development and neurosensory demands. Taken together, the remarkable cranial shape diversity in birds was not a product of accelerated evolution from their non-avian relatives, despite their frequent portrayal as an icon of adaptive radiations.
Collapse
Affiliation(s)
- Ryan N. Felice
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, United Kingdom
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, United Kingdom
| | - Akinobu Watanabe
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, United Kingdom
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States of America
- Division of Paleontology, American Museum of Natural History, New York, New York, United States of America
| | - Andrew R. Cuff
- Hull York Medical School, University of York, York, United Kingdom
| | - Michael Hanson
- Department of Earth & Planetary Sciences, Yale University, New Haven, Connecticut, United States of America
| | - Bhart-Anjan S. Bhullar
- Department of Earth & Planetary Sciences, Yale University, New Haven, Connecticut, United States of America
- Yale Peabody Museum of Natural History, Yale University, New Haven, Connecticut, United States of America
| | - Emily R. Rayfield
- School of Earth Sciences, University of Bristol, Bristol, United Kingdom
| | - Lawrence M. Witmer
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio, United States of America
| | - Mark A. Norell
- Division of Paleontology, American Museum of Natural History, New York, New York, United States of America
| | - Anjali Goswami
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, United Kingdom
| |
Collapse
|
10
|
Abstract
Cranial morphology in birds is thought to be shaped by adaptive evolution for foraging performance. This understanding of ecomorphological evolution is supported by observations of avian island radiations, such as Darwin's finches, which display rapid evolution of skull shape in response to food resource availability and a strong fit between cranial phenotype and trophic ecology. However, a recent analysis of larger clades has suggested that diet is not necessarily a primary driver of cranial shape and that phylogeny and allometry are more significant factors in skull evolution. We use phenome-scale morphometric data across the breadth of extant bird diversity to test the influence of diet and foraging behaviour in shaping cranial evolution. We demonstrate that these trophic characters are significant but very weak predictors of cranial form at this scale. However, dietary groups exhibit significantly different rates of morphological evolution across multiple cranial regions. Granivores and nectarivores exhibit the highest rates of evolution in the face and cranial vault, whereas terrestrial carnivores evolve the slowest. The basisphenoid, occipital, and jaw joint regions have less extreme differences among dietary groups. These patterns demonstrate that dietary niche shapes the tempo and mode of phenotypic evolution in deep time, despite a weaker than expected form–function relationship across large clades.
Collapse
Affiliation(s)
- Ryan N Felice
- 1 Department of Cell and Developmental Biology, University College London , London WC1E 6BT , UK.,3 Department of Life Sciences, The Natural History Museum , London SW7 5DB , UK
| | - Joseph A Tobias
- 4 Department of Life Sciences, Imperial College London , Ascot , UK
| | - Alex L Pigot
- 2 Centre for Biodiversity and Environment Research, Department of Genetics, Evolution, and Environment, University College London , London WC1E 6BT , UK
| | - Anjali Goswami
- 2 Centre for Biodiversity and Environment Research, Department of Genetics, Evolution, and Environment, University College London , London WC1E 6BT , UK.,3 Department of Life Sciences, The Natural History Museum , London SW7 5DB , UK
| |
Collapse
|
11
|
Felice RN, Watanabe A, Cuff AR, Noirault E, Pol D, Witmer LM, Norell MA, O'Connor PM, Goswami A. Evolutionary Integration and Modularity in the Archosaur Cranium. Integr Comp Biol 2019; 59:371-382. [PMID: 31120528 DOI: 10.1093/icb/icz052] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Complex structures, like the vertebrate skull, are composed of numerous elements or traits that must develop and evolve in a coordinated manner to achieve multiple functions. The strength of association among phenotypic traits (i.e., integration), and their organization into highly-correlated, semi-independent subunits termed modules, is a result of the pleiotropic and genetic correlations that generate traits. As such, patterns of integration and modularity are thought to be key factors constraining or facilitating the evolution of phenotypic disparity by influencing the patterns of variation upon which selection can act. It is often hypothesized that selection can reshape patterns of integration, parceling single structures into multiple modules or merging ancestrally semi-independent traits into a strongly correlated unit. However, evolutionary shifts in patterns of trait integration are seldom assessed in a unified quantitative framework. Here, we quantify patterns of evolutionary integration among regions of the archosaur skull to investigate whether patterns of cranial integration are conserved or variable across this diverse group. Using high-dimensional geometric morphometric data from 3D surface scans and computed tomography scans of modern birds (n = 352), fossil non-avian dinosaurs (n = 27), and modern and fossil mesoeucrocodylians (n = 38), we demonstrate that some aspects of cranial integration are conserved across these taxonomic groups, despite their major differences in cranial form, function, and development. All three groups are highly modular and consistently exhibit high integration within the occipital region. However, there are also substantial divergences in correlation patterns. Birds uniquely exhibit high correlation between the pterygoid and quadrate, components of the cranial kinesis apparatus, whereas the non-avian dinosaur quadrate is more closely associated with the jugal and quadratojugal. Mesoeucrocodylians exhibit a slightly more integrated facial skeleton overall than the other grades. Overall, patterns of trait integration are shown to be stable among archosaurs, which is surprising given the cranial diversity exhibited by the clade. At the same time, evolutionary innovations such as cranial kinesis that reorganize the structure and function of complex traits can result in modifications of trait correlations and modularity.
Collapse
Affiliation(s)
- Ryan N Felice
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, UK.,Life Sciences Department, Vertebrates Division, Natural History Museum, London, SW7 5BD, UK
| | - Akinobu Watanabe
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, SW7 5BD, UK.,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
| | - Andrew R Cuff
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TA, UK
| | - Eve Noirault
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, SW7 5BD, UK
| | - Diego Pol
- CONICET. Museo Paleontológico Egidio Feruglio, Av. Fontana 140, Trelew, Chubut, U9100GYO, Argentina
| | - Lawrence M Witmer
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, OH, USA
| | - Mark A Norell
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
| | - Patrick M O'Connor
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, OH, USA.,Ohio Center for Ecology and Evolutionary Studies, Ohio University, Athens, OH, USA
| | - Anjali Goswami
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, SW7 5BD, UK.,Department of Genetics, Evolution, and Environment, University College London, London, WC1E 6BT, UK
| |
Collapse
|
12
|
Goswami A, Watanabe A, Felice RN, Bardua C, Fabre AC, Polly PD. High-Density Morphometric Analysis of Shape and Integration: The Good, the Bad, and the Not-Really-a-Problem. Integr Comp Biol 2019; 59:669-683. [PMID: 31243431 PMCID: PMC6754122 DOI: 10.1093/icb/icz120] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The field of comparative morphology has entered a new phase with the rapid generation of high-resolution three-dimensional (3D) data. With freely available 3D data of thousands of species, methods for quantifying morphology that harness this rich phenotypic information are quickly emerging. Among these techniques, high-density geometric morphometric approaches provide a powerful and versatile framework to robustly characterize shape and phenotypic integration, the covariances among morphological traits. These methods are particularly useful for analyses of complex structures and across disparate taxa, which may share few landmarks of unambiguous homology. However, high-density geometric morphometrics also brings challenges, for example, with statistical, but not biological, covariances imposed by placement and sliding of semilandmarks and registration methods such as Procrustes superimposition. Here, we present simulations and case studies of high-density datasets for squamates, birds, and caecilians that exemplify the promise and challenges of high-dimensional analyses of phenotypic integration and modularity. We assess: (1) the relative merits of "big" high-density geometric morphometrics data over traditional shape data; (2) the impact of Procrustes superimposition on analyses of integration and modularity; and (3) differences in patterns of integration between analyses using high-density geometric morphometrics and those using discrete landmarks. We demonstrate that for many skull regions, 20-30 landmarks and/or semilandmarks are needed to accurately characterize their shape variation, and landmark-only analyses do a particularly poor job of capturing shape variation in vault and rostrum bones. Procrustes superimposition can mask modularity, especially when landmarks covary in parallel directions, but this effect decreases with more biologically complex covariance patterns. The directional effect of landmark variation on the position of the centroid affects recovery of covariance patterns more than landmark number does. Landmark-only and landmark-plus-sliding-semilandmark analyses of integration are generally congruent in overall pattern of integration, but landmark-only analyses tend to show higher integration between adjacent bones, especially when landmarks placed on the sutures between bones introduces a boundary bias. Allometry may be a stronger influence on patterns of integration in landmark-only analyses, which show stronger integration prior to removal of allometric effects compared to analyses including semilandmarks. High-density geometric morphometrics has its challenges and drawbacks, but our analyses of simulated and empirical datasets demonstrate that these potential issues are unlikely to obscure genuine biological signal. Rather, high-density geometric morphometric data exceed traditional landmark-based methods in characterization of morphology and allow more nuanced comparisons across disparate taxa. Combined with the rapid increases in 3D data availability, high-density morphometric approaches have immense potential to propel a new class of studies of comparative morphology and phenotypic integration.
Collapse
Affiliation(s)
- Anjali Goswami
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, SW7 5BD, UK
- Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, UK
| | - Akinobu Watanabe
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, SW7 5BD, UK
- 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
| | - Ryan N Felice
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, SW7 5BD, UK
- Department of Cell and Developmental Biology, Centre for Integrative Anatomy, University College London, London, WC1E 6BT, UK
| | - Carla Bardua
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, SW7 5BD, UK
- Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, UK
| | - Anne-Claire Fabre
- Life Sciences Department, Vertebrates Division, Natural History Museum, London, SW7 5BD, UK
| | - P David Polly
- Departments of Earth and Atmospheric Sciences, Biology, and Anthropology, Indiana University, 1001 E. 10 Street, Bloomington, IN 47405, USA
| |
Collapse
|
13
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
14
|
Abstract
Advances in imaging technologies, such as computed tomography (CT) and surface scanning, have facilitated the rapid generation of large datasets of high-resolution three-dimensional (3D) specimen reconstructions in recent years. The wealth of phenotypic information available from these datasets has the potential to inform our understanding of morphological variation and evolution. However, the ever-increasing ease of compiling 3D datasets has created an urgent need for sophisticated methods of capturing high-density shape data that reflect the biological complexity in form. Landmarks often do not take full advantage of the rich shape information available from high-resolution 3D specimen reconstructions, as they are typically restricted to sutures or processes that can be reliably identified across specimens and exclude most of the surface morphology. The development of sliding and surface semilandmark techniques has greatly enhanced the quantification of shape, but their application to diverse datasets can be challenging, especially when dealing with the variable absence of some regions within a structure. Using comprehensive 3D datasets of crania that span the entire clades of birds, squamates and caecilians, we demonstrate methods for capturing morphology across incredibly diverse shapes. We detail many of the difficulties associated with applying semilandmarks to comparable regions across highly disparate structures, and provide solutions to some of these challenges, while considering the consequences of decisions one makes in applying these approaches. Finally, we analyze the benefits of high-density sliding semilandmark approaches over landmark-only studies for capturing shape across diverse organisms and discuss the promise of these approaches for the study of organismal form.
Collapse
Affiliation(s)
- C Bardua
- Department of Life Sciences, Natural History Museum, Cromwell Rd, Kensington, London, SW7 5BD, UK.,Department of Genetics, Evolution & Environment, University College London, Gower St, Bloomsbury, London, WC1E 6BT, UK
| | - R N Felice
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, Gower St, Bloomsbury, London, WC1E 6BT, UK
| | - A Watanabe
- Department of Life Sciences, Natural History Museum, Cromwell Rd, Kensington, London, SW7 5BD, UK.,Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd, Old Westbury, NY 11568, USA.,Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA
| | - A-C Fabre
- Department of Life Sciences, Natural History Museum, Cromwell Rd, Kensington, London, SW7 5BD, UK
| | - A Goswami
- Department of Life Sciences, Natural History Museum, Cromwell Rd, Kensington, London, SW7 5BD, UK.,Department of Genetics, Evolution & Environment, University College London, Gower St, Bloomsbury, London, WC1E 6BT, UK
| |
Collapse
|
15
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
16
|
Felice RN. Coevolution of caudal skeleton and tail feathers in birds. J Morphol 2014; 275:1431-40. [DOI: 10.1002/jmor.20321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/16/2014] [Accepted: 07/26/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Ryan N. Felice
- Department of Biological Sciences; 107 Irvine Hall, Ohio University; Athens Ohio 45701
- Ohio Center for Ecology and Evolutionary Studies; Irvine Hall, Ohio University; Athens Ohio 45701
| |
Collapse
|
17
|
Adams DC, Felice RN. Assessing trait covariation and morphological integration on phylogenies using evolutionary covariance matrices. PLoS One 2014; 9:e94335. [PMID: 24728003 PMCID: PMC3984176 DOI: 10.1371/journal.pone.0094335] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 03/12/2014] [Indexed: 12/21/2022] Open
Abstract
Morphological integration describes the degree to which sets of organismal traits covary with one another. Morphological covariation may be evaluated at various levels of biological organization, but when characterizing such patterns across species at the macroevolutionary level, phylogeny must be taken into account. We outline an analytical procedure based on the evolutionary covariance matrix that allows species-level patterns of morphological integration among structures defined by sets of traits to be evaluated while accounting for the phylogenetic relationships among taxa, providing a flexible and robust complement to related phylogenetic independent contrasts based approaches. Using computer simulations under a Brownian motion model we show that statistical tests based on the approach display appropriate Type I error rates and high statistical power for detecting known levels of integration, and these trends remain consistent for simulations using different numbers of species, and for simulations that differ in the number of trait dimensions. Thus, our procedure provides a useful means of testing hypotheses of morphological integration in a phylogenetic context. We illustrate the utility of this approach by evaluating evolutionary patterns of morphological integration in head shape for a lineage of Plethodon salamanders, and find significant integration between cranial shape and mandible shape. Finally, computer code written in R for implementing the procedure is provided.
Collapse
Affiliation(s)
- Dean C. Adams
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, United States of America
| | - Ryan N. Felice
- Department of Biological Sciences, Ohio University, Athens, Ohio, United States of America
| |
Collapse
|
18
|
Felice RN, O’Connor PM. Ecology and caudal skeletal morphology in birds: the convergent evolution of pygostyle shape in underwater foraging taxa. PLoS One 2014; 9:e89737. [PMID: 24586998 PMCID: PMC3935938 DOI: 10.1371/journal.pone.0089737] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 01/23/2014] [Indexed: 01/07/2023] Open
Abstract
Birds exhibit a specialized tail that serves as an integral part of the flight apparatus, supplementing the role of the wings in facilitating high performance aerial locomotion. The evolution of this function for the tail contributed to the diversification of birds by allowing them to utilize a wider range of flight behaviors and thus exploit a greater range of ecological niches. The shape of the wings and the tail feathers influence the aerodynamic properties of a bird. Accordingly, taxa that habitually utilize different flight behaviors are characterized by different flight apparatus morphologies. This study explores whether differences in flight behavior are also associated with variation in caudal vertebra and pygostyle morphology. Details of the tail skeleton were characterized in 51 Aequornithes and Charadriiformes species. Free caudal vertebral morphology was measured using linear metrics. Variation in pygostyle morphology was characterized using Elliptical Fourier Analysis, a geometric morphometric method for the analysis of outline shapes. Each taxon was categorized based on flight style (flap, flap-glide, dynamic soar, etc.) and foraging style (aerial, terrestrial, plunge dive, etc.). Phylogenetic MANOVAs and Flexible Discriminant Analyses were used to test whether caudal skeletal morphology can be used to predict flight behavior. Foraging style groups differ significantly in pygostyle shape, and pygostyle shape predicts foraging style with less than 4% misclassification error. Four distinct lineages of underwater foraging birds exhibit an elongate, straight pygostyle, whereas aerial and terrestrial birds are characterized by a short, dorsally deflected pygostyle. Convergent evolution of a common pygostyle phenotype in diving birds suggests that this morphology is related to the mechanical demands of using the tail as a rudder during underwater foraging. Thus, distinct locomotor behaviors influence not only feather attributes but also the underlying caudal skeleton, reinforcing the importance of the entire caudal locomotor module in avian ecological diversification.
Collapse
Affiliation(s)
- Ryan N. Felice
- Department of Biological Sciences, Ohio University, Athens, Ohio, United States of America
- Ohio Center for Ecology and Evolutionary Studies, Ohio University, Athens, Ohio, United States of America
| | - Patrick M. O’Connor
- Ohio Center for Ecology and Evolutionary Studies, Ohio University, Athens, Ohio, United States of America
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio, United States of America
| |
Collapse
|
19
|
Abstract
Morphological integration describes the degree to which sets of organismal traits covary with one another. Morphological covariation may be evaluated at various levels of biological organization, but when characterizing such patterns across species at the macroevolutionary level, phylogeny must be taken into account. We outline an analytical procedure based on the evolutionary covariance matrix that allows species-level patterns of morphological integration among structures defined by sets of traits to be evaluated while accounting for the phylogenetic relationships among taxa, providing a flexible and robust complement to related phylogenetic independent contrasts based approaches. Using computer simulations under a Brownian motion model we show that statistical tests based on the approach display appropriate Type I error rates and high statistical power for detecting known levels of integration, and these trends remain consistent for simulations using different numbers of species, and for simulations that differ in the number of trait dimensions. Thus, our procedure provides a useful means of testing hypotheses of morphological integration in a phylogenetic context. We illustrate the utility of this approach by evaluating evolutionary patterns of morphological integration in head shape for a lineage of Plethodon salamanders, and find significant integration between cranial shape and mandible shape. Finally, computer code written in R for implementing the procedure is provided.
Collapse
Affiliation(s)
- Dean C Adams
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, United States of America
| | - Ryan N Felice
- Department of Biological Sciences, Ohio University, Athens, Ohio, United States of America
| |
Collapse
|
20
|
|