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White HE, Tucker AS, Fernandez V, Portela Miguez R, Hautier L, Herrel A, Urban DJ, Sears KE, Goswami A. Pedomorphosis in the ancestry of marsupial mammals. Curr Biol 2023:S0960-9822(23)00457-8. [PMID: 37119816 DOI: 10.1016/j.cub.2023.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 02/27/2023] [Accepted: 04/05/2023] [Indexed: 05/01/2023]
Abstract
Within mammals, different reproductive strategies (e.g., egg laying, live birth of extremely underdeveloped young, and live birth of well-developed young) have been linked to divergent evolutionary histories. How and when developmental variation across mammals arose is unclear. While egg laying is unquestionably considered the ancestral state for all mammals, many long-standing biases treat the extreme underdeveloped state of marsupial young as the ancestral state for therian mammals (clade including both marsupials and placentals), with the well-developed young of placentals often considered the derived mode of development. Here, we quantify mammalian cranial morphological development and estimate ancestral patterns of cranial shape development using geometric morphometric analysis of the largest comparative ontogenetic dataset of mammals to date (165 specimens, 22 species). We identify a conserved region of cranial morphospace for fetal specimens, after which cranial morphology diversified through ontogeny in a cone-shaped pattern. This cone-shaped pattern of development distinctively reflected the upper half of the developmental hourglass model. Moreover, cranial morphological variation was found to be significantly associated with the level of development (position on the altricial-precocial spectrum) exhibited at birth. Estimation of ancestral state allometry (size-related shape change) reconstructs marsupials as pedomorphic relative to the ancestral therian mammal. In contrast, the estimated allometries for the ancestral placental and ancestral therian were indistinguishable. Thus, from our results, we hypothesize that placental mammal cranial development most closely reflects that of the ancestral therian mammal, while marsupial cranial development represents a more derived mode of mammalian development, in stark contrast to many interpretations of mammalian evolution.
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Affiliation(s)
- Heather E White
- Science Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK; Centre for Craniofacial and Regenerative Biology, King's College London, Great Maze Pond, London SE1 9RT, UK; Division of Biosciences, University College London, Gower Street, London WC1E 6DE, UK.
| | - Abigail S Tucker
- Centre for Craniofacial and Regenerative Biology, King's College London, Great Maze Pond, London SE1 9RT, UK
| | - Vincent Fernandez
- European Synchrotron Radiation Facility, 71 rue des Martyrs, 38000 Grenoble, France
| | | | - Lionel Hautier
- Science Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK; Institut des Sciences de l'Evolution, Université de Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
| | - Anthony Herrel
- UMR 7179, Centre National de la Recherche Scientifique/Muséum National d'Histoire Naturelle, Département Adaptations du Vivant, 55 rue Buffon, 75005 Paris, France
| | - Daniel J Urban
- Institute of Genomic Biology, University of Illinois, Urbana, IL 61801, USA
| | - Karen E Sears
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Anjali Goswami
- Science Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK; Division of Biosciences, University College London, Gower Street, London WC1E 6DE, UK
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Anatomical Correlates of Cursoriality are Compromised by Body Size and Propensity to Burrow in a Group of Small Mammals (Lagomorpha). Evol Biol 2022. [DOI: 10.1007/s11692-022-09584-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AbstractHighly cursorial animals are specialised for fast, sustained running via specific morphological adaptations, notably including changes in limb segment length and mechanical advantage. Members of the order Lagomorpha (hares, rabbits and pikas) vary in cursorial ability; hares are generally highly cursorial, rabbits more frequently saltate, and pikas predominantly trot. Previous investigations of lagomorphs have identified anatomical trends correlated with this ‘cursoriality gradient’, however, the phylogenetic sampling of such investigations has been limited to three American species, namely the American pika (Ochotona princeps), brush rabbit (Sylvilagus bachmani), and black-tailed jackrabbit (Lepus californicus). Here, we expand the phylogenetic sample and body size range by including novel data from Australian samples of the European rabbit (Oryctolagus cuniculus) and European hare (L. europaeus), alongside unpublished data on the Eastern cottontail (S. floridanus). X-ray Computed Tomography and digital landmarking were used to capture proportions within the appendicular skeleton of ~ 40 specimens of each European species. In doubling the number of species studied, we find the previously-identified morphological gradients associated with cursorial behaviour are complicated when evaluated in the larger sample. The relative length and joint velocity of limbs was found to be lower than predicted in European rabbits and hares. Furthermore, we present a novel assessment of morphological integration in the lagomorph appendicular skeleton, finding between-limb covariation patterns that are generally similar to those of other mammals. Broadly, these results suggest cursoriality is only one of many selective forces driving lagomorph skeletal evolution, with variations in body size and fossoriality potentially having measurable impacts.
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Pevsner SK, Grossnickle DM, Luo ZX. The functional diversity of marsupial limbs is influenced by both ecology and developmental constraint. Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blab168] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Extant marsupials are less ecologically diverse than placentals, and this is reflected by placentals exhibiting a greater diversity of locomotor modes, including powered flight and fully aquatic swimming. One proposed explanation for this discrepancy is that the development of more disparate marsupial forelimbs is prevented by the neonate’s crawl to the pouch, which requires precocious forelimb development for climbing adaptations. To test predictions of this Developmental Constraint Hypothesis (DCH), we pursue a comparative morphometric study on osteological traits of mammalian limbs, with an emphasis on functional differentiation of marsupial limbs among locomotor modes. We apply multivariate analyses to a large dataset of limb metrics and a diverse sample of mammals, with the placental sample limited to taxa whose locomotor modes are exhibited in marsupials. Overall, we do not find consistent evidence in support of the DCH. Diprotodontia serves as an exception, with comparisons of their forelimbs to hind limbs supporting the DCH. Our results suggest that developmental constraints on marsupial forelimbs may have limited marsupial diversity to some degree. Despite this, the marsupial locomotor groups show unexpectedly high levels of morphological differentiation relative to placentals of the same locomotor modes, indicating that ecological functions may overcome developmental constraints on a macroevolutionary scale.
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Affiliation(s)
- Spencer K Pevsner
- School of Earth Sciences, University of Bristol, Bristol, UK
- Department of Organismal Biology & Anatomy, University of Chicago, Chicago, IL, USA
| | | | - Zhe-Xi Luo
- Department of Organismal Biology & Anatomy, University of Chicago, Chicago, IL, USA
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Fabre AC, Dowling C, Portela Miguez R, Fernandez V, Noirault E, Goswami A. Functional constraints during development limit jaw shape evolution in marsupials. Proc Biol Sci 2021; 288:20210319. [PMID: 33906406 PMCID: PMC8079998 DOI: 10.1098/rspb.2021.0319] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 03/29/2021] [Indexed: 01/17/2023] Open
Abstract
Differences in jaw function experienced through ontogeny can have striking consequences for evolutionary outcomes, as has been suggested for the major clades of mammals. By contrast to placentals, marsupial newborns have an accelerated development of the head and forelimbs, allowing them to crawl to the mother's teats to suckle within just a few weeks of conception. The different functional requirements that marsupial newborns experience in early postnatal development have been hypothesized to have constrained their morphological diversification relative to placentals. Here, we test whether marsupials have a lower ecomorphological diversity and rate of evolution in comparison with placentals, focusing specifically on their jaws. To do so, a geometric morphometric approach was used to characterize jaw shape for 151 living and extinct species of mammals spanning a wide phylogenetic, developmental and functional diversity. Our results demonstrate that jaw shape is significantly influenced by both reproductive mode and diet, with substantial ecomorphological convergence between metatherians and eutherians. However, metatherians have markedly lower disparity and rate of mandible shape evolution than observed for eutherians. Thus, despite their ecomorphological diversity and numerous convergences with eutherians, the evolution of the jaw in metatherians appears to be strongly constrained by their specialized reproductive biology.
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Affiliation(s)
- Anne-Claire Fabre
- Department of Life Sciences, The Natural History Museum, London SW7 5DB, UK
- Palaeontological Institute and Museum, University of Zurich, Zurich, Switzerland
| | - Carys Dowling
- Department of Life Sciences, The Natural History Museum, London SW7 5DB, UK
| | | | - Vincent Fernandez
- Imaging and Analysis Centre, The Natural History Museum, London SW7 5DB, UK
| | - Eve Noirault
- Department of Life Sciences, The Natural History Museum, London SW7 5DB, UK
| | - Anjali Goswami
- Department of Life Sciences, The Natural History Museum, London SW7 5DB, UK
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Ontogenetic origins of cranial convergence between the extinct marsupial thylacine and placental gray wolf. Commun Biol 2021; 4:51. [PMID: 33420327 PMCID: PMC7794302 DOI: 10.1038/s42003-020-01569-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 12/01/2020] [Indexed: 01/29/2023] Open
Abstract
Phenotypic convergence, describing the independent evolution of similar characteristics, offers unique insights into how natural selection influences developmental and molecular processes to generate shared adaptations. The extinct marsupial thylacine and placental gray wolf represent one of the most extraordinary cases of convergent evolution in mammals, sharing striking cranial similarities despite 160 million years of independent evolution. We digitally reconstructed their cranial ontogeny from birth to adulthood to examine how and when convergence arises through patterns of allometry, mosaicism, modularity, and integration. We find the thylacine and wolf crania develop along nearly parallel growth trajectories, despite lineage-specific constraints and heterochrony in timing of ossification. These constraints were found to enforce distinct cranial modularity and integration patterns during development, which were unable to explain their adult convergence. Instead, we identify a developmental origin for their convergent cranial morphologies through patterns of mosaic evolution, occurring within bone groups sharing conserved embryonic tissue origins. Interestingly, these patterns are accompanied by homoplasy in gene regulatory networks associated with neural crest cells, critical for skull patterning. Together, our findings establish empirical links between adaptive phenotypic and genotypic convergence and provides a digital resource for further investigations into the developmental basis of mammalian evolution.
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Petrović TG, Vukov T, Tomašević Kolarov N. Patterns of correlations and locomotor specialization in anuran limbs: association with phylogeny and ecology. ZOOLOGY 2020; 144:125864. [PMID: 33220626 DOI: 10.1016/j.zool.2020.125864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 10/26/2020] [Accepted: 11/01/2020] [Indexed: 11/30/2022]
Abstract
As anuran saltatory locomotion has specific functional requirements achieved through certain intra- and inter-limb proportions, we analyzed pattern and degree of morphological integration in limbs of ten anuran species to reveal the relationship of shared developmental programs of serially homologous structures and locomotor specialization. Our main objectives were (1) to examine if morphological and functional differences in forelimb and hindlimb were associated with reduced covariation between limbs, (2) and to reveal patterns of correlation between species and the roles played by evolutionary history (phylogeny) and ecology (lifestyle and habitat use). Species with different locomotor behaviours (walking, jumping, hopping, running, climbing, swimming and burrowing) were used. Partial correlations showed that species shared similar patterns of functionally based morphological integration, with increased correlations in elements within limbs and reduced correlations between limbs. This was mainly based on strong correlations between proximal elements, humerus-radioulna and femur-tibiofibula. To test the influence of phylogenetic relationships and ecological demands we used different matrices (correlation similarity matrix, ecological similarity matrix, matrices of phylogenetic distance and morphological distance). The changes in correlation patterns are shown to be dissociated from phylogeny. On the other hand, they are to some extent shaped by habitat use and locomotion, as the species with similar locomotor behaviour also tend to have stronger similarity in integration patterns. The results from this study provide insight into the processes underlying the evolutionary change of anuran limbs, highlighting function as the main factor that shaped morphological integration of the examined species.
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Affiliation(s)
- Tamara G Petrović
- Department of Physiology, Institute for Biological Research "Siniša Stanković", National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Tanja Vukov
- Department of Evolutionary biology, Institute for Biological Research "Siniša Stanković", National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia
| | - Nataša Tomašević Kolarov
- Department of Evolutionary biology, Institute for Biological Research "Siniša Stanković", National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia
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Denyer AL, Regnault S, Hutchinson JR. Evolution of the patella and patelloid in marsupial mammals. PeerJ 2020; 8:e9760. [PMID: 32879804 PMCID: PMC7443095 DOI: 10.7717/peerj.9760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 07/28/2020] [Indexed: 12/24/2022] Open
Abstract
The musculoskeletal system of marsupial mammals has numerous unusual features beyond the pouch and epipubic bones. One example is the widespread absence or reduction (to a fibrous “patelloid”) of the patella (“kneecap”) sesamoid bone, but prior studies with coarse sampling indicated complex patterns of evolution of this absence or reduction. Here, we conducted an in-depth investigation into the form of the patella of extant marsupial species and used the assembled dataset to reconstruct the likely pattern of evolution of the marsupial patella. Critical assessment of the available literature was followed by examination and imaging of museum specimens, as well as CT scanning and histological examination of dissected wet specimens. Our results, from sampling about 19% of extant marsupial species-level diversity, include new images and descriptions of the fibrocartilaginous patelloid in Thylacinus cynocephalus (the thylacine or “marsupial wolf”) and other marsupials as well as the ossified patella in Notoryctes ‘marsupial moles’, Caenolestes shrew opossums, bandicoots and bilbies. We found novel evidence of an ossified patella in one specimen of Macropus rufogriseus (Bennett’s wallaby), with hints of similar variation in other species. It remains uncertain whether such ossifications are ontogenetic variation, unusual individual variation, pathological or otherwise, but future studies must continue to be conscious of variation in metatherian patellar sesamoid morphology. Our evolutionary reconstructions using our assembled data vary, too, depending on the reconstruction algorithm used. A maximum likelihood algorithm favours ancestral fibrocartilaginous “patelloid” for crown clade Marsupialia and independent origins of ossified patellae in extinct sparassodonts, peramelids, notoryctids and caenolestids. A maximum parsimony algorithm favours ancestral ossified patella for the clade [Marsupialia + sparassodonts] and subsequent reductions into fibrocartilage in didelphids, dasyuromorphs and diprotodonts; but this result changed to agree more with the maximum likelihood results if the character state reconstructions were ordered. Thus, there is substantial homoplasy in marsupial patellae regardless of the evolutionary algorithm adopted. We contend that the most plausible inference, however, is that metatherians independently ossified their patellae at least three times in their evolution. Furthermore, the variability of the patellar state we observed, even within single species (e.g. M. rufogriseus), is fascinating and warrants further investigation, especially as it hints at developmental plasticity that might have been harnessed in marsupial evolution to drive the complex patterns inferred here.
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Affiliation(s)
- Alice L Denyer
- Structure & Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, North Mymms, Hertfordshire, United Kingdom
| | - Sophie Regnault
- Structure & Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, North Mymms, Hertfordshire, United Kingdom.,Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, United States of America
| | - John R Hutchinson
- Structure & Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, North Mymms, Hertfordshire, United Kingdom
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8
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Martín-Serra A, Benson RBJ. Developmental Constraints Do Not Influence Long-Term Phenotypic Evolution of Marsupial Forelimbs as Revealed by Interspecific Disparity and Integration Patterns. Am Nat 2020; 195:547-560. [DOI: 10.1086/707194] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Weisbecker V, Guillerme T, Speck C, Sherratt E, Abraha HM, Sharp AC, Terhune CE, Collins S, Johnston S, Panagiotopoulou O. Individual variation of the masticatory system dominates 3D skull shape in the herbivory-adapted marsupial wombats. Front Zool 2019; 16:41. [PMID: 31695725 PMCID: PMC6824091 DOI: 10.1186/s12983-019-0338-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 10/04/2019] [Indexed: 12/19/2022] Open
Abstract
Background Within-species skull shape variation of marsupial mammals is widely considered low and strongly size-dependent (allometric), possibly due to developmental constraints arising from the altricial birth of marsupials. However, species whose skulls are impacted by strong muscular stresses – particularly those produced through mastication of tough food items – may not display such intrinsic patterns very clearly because of the known plastic response of bone to muscle activity of the individual. In such cases, allometry may not dominate within-species shape variation, even if it is a driver of evolutionary shape divergence; ordination of shape in a geometric morphometric context through principal component analysis (PCA) should reveal main variation in areas under masticatory stress (incisor region/zygomatic arches/mandibular ramus); but this main variation should emerge from high individual variability and thus have low eigenvalues. Results We assessed the evidence for high individual variation through 3D geometric morphometric shape analysis of crania and mandibles of three species of grazing-specialized wombats, whose diet of tough grasses puts considerable strain on their masticatory system. As expected, we found little allometry and low Principal Component 1 (PC1) eigenvalues within crania and mandibles of all three species. Also as expected, the main variation was in the muzzle, zygomatic arches, and masticatory muscle attachments of the mandibular ramus. We then implemented a new test to ask if the landmark variation reflected on PC1 was reflected in individuals with opposite PC1 scores and with opposite shapes in Procrustes space. This showed that correspondence between individual and ordinated shape variation was limited, indicating high levels of individual variability in the masticatory apparatus. Discussion Our results are inconsistent with hypotheses that skull shape variation within marsupial species reflects a constraint pattern. Rather, they support suggestions that individual plasticity can be an important determinant of within-species shape variation in marsupials (and possibly other mammals) with high masticatory stresses, making it difficult to understand the degree to which intrinsic constraints act on shape variation at the within-species level. We conclude that studies that link micro- and macroevolutionary patterns of shape variation might benefit from a focus on species with low-impact mastication, such as carnivorous or frugivorous species.
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Affiliation(s)
- Vera Weisbecker
- 1School of Biological Sciences, The University of Queensland, Brisbane, Australia
| | - Thomas Guillerme
- 1School of Biological Sciences, The University of Queensland, Brisbane, Australia
| | - Cruise Speck
- 1School of Biological Sciences, The University of Queensland, Brisbane, Australia
| | - Emma Sherratt
- 2School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Hyab Mehari Abraha
- 3Monash Biomedicine Discovery Institute, Department of Anatomy & Developmental Biology, Monash University, Melbourne, Australia
| | - Alana C Sharp
- 4Department of Cell & Developmental Biology, University College London, London, UK.,5Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - Claire E Terhune
- 6Department of Anthropology, University of Arkansas, Fayetteville, USA
| | - Simon Collins
- 7School of Agricultural and Food Sciences, The University of Queensland, Brisbane, Australia
| | - Stephen Johnston
- 7School of Agricultural and Food Sciences, The University of Queensland, Brisbane, Australia
| | - Olga Panagiotopoulou
- 3Monash Biomedicine Discovery Institute, Department of Anatomy & Developmental Biology, Monash University, Melbourne, Australia
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10
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Sherratt E, Coutts FJ, Rasmussen AR, Sanders KL. Vertebral evolution and ontogenetic allometry: The developmental basis of extreme body shape divergence in microcephalic sea snakes. Evol Dev 2019; 21:135-144. [DOI: 10.1111/ede.12284] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 02/04/2019] [Accepted: 02/05/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Emma Sherratt
- Department of Ecology and Evolutionary Biology School of Biological Sciences, The University of Adelaide Adelaide South Australia Australia
| | - Felicity J. Coutts
- Department of Ecology and Evolutionary Biology School of Biological Sciences, The University of Adelaide Adelaide South Australia Australia
- Earth Sciences Section, South Australian Museum Adelaide South Australia Australia
| | - Arne R. Rasmussen
- The Royal Danish Academy of Fine Arts, Schools of Architecture, Design and Conservation Copenhagen Denmark
| | - Kate L. Sanders
- Department of Ecology and Evolutionary Biology School of Biological Sciences, The University of Adelaide Adelaide South Australia Australia
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11
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Kelly EM, Marcot JD, Selwood L, Sears KE. The Development of Integration in Marsupial and Placental Limbs. Integr Org Biol 2019; 1:oby013. [PMID: 33791518 PMCID: PMC7671123 DOI: 10.1093/iob/oby013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The morphological interdependence of traits, or their integration, is commonly thought to influence their evolution. As such, study of morphological integration and the factors responsible for its generation form an important branch of the field of morphological evolution. However, most research to date on post-cranial morphological integration has focused on adult patterns of integration. This study investigates patterns of correlation (i.e., morphological integration) among skeletal elements of the fore- and hind limbs of developing marsupial and placental mammals. The goals of this study are to establish how patterns of limb integration vary over development in marsupials and placentals, and identify factors that are likely responsible for their generation. Our results indicate that although the overall pattern of correlation among limb elements is consistent with adult integration throughout mammalian development, correlations vary at the level of the individual element and stage. As a result, the relative integration among fore- and hind limb elements varies dynamically between stages during development in both marsupial and placental mammals. Therefore, adult integration studies of the limbs may not be indicative of developmental integration. Results are also consistent with integration during early limb development being more heavily influenced by genetic and developmental factors, and later by function. Additionally, results are generally consistent with a constraint on marsupial forelimb evolution caused by the functional requirements of the crawl to the teat that operates by limiting morphological variation before and at the time of birth, and not after.
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Affiliation(s)
- E M Kelly
- School of Integrative Biology, University of Illinois, Urbana, IL61801, USA
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - J D Marcot
- Department of Ecology and Evolutionary Biology, University of California at Los Angeles, Los Angeles, CA90095, USA
| | - L Selwood
- Department of Zoology, University of Melbourne, Melbourne, Australia
| | - K E Sears
- Department of Ecology and Evolutionary Biology, University of California at Los Angeles, Los Angeles, CA90095, USA
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12
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Watanabe J. Clade-specific evolutionary diversification along ontogenetic major axes in avian limb skeleton. Evolution 2018; 72:2632-2652. [PMID: 30328113 DOI: 10.1111/evo.13627] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 10/02/2018] [Accepted: 10/07/2018] [Indexed: 12/16/2022]
Abstract
The evolutionary diversification of birds has been facilitated by specializations for various locomotor modes, with which the proportion of the limb skeleton is closely associated. However, recent studies have identified phylogenetic signals in this system, suggesting the presence of historical factors that have affected its evolutionary variability. In this study, to explore potential roles of ontogenetic integration in biasing the evolution in the avian limb skeleton, evolutionary diversification patterns in six avian families (Anatidae, Procellariidae, Ardeidae, Phalacrocoracidae, Laridae, and Alcidae) were examined and compared to the postnatal ontogenetic trajectories in those taxa, based on measurement of 2641 specimens and recently collected ontogenetic series, supplemented by published data. Morphometric analyses of lengths of six limb bones (humerus, ulna, carpometacarpus, femur, tibiotarsus, and tarsometatarsus) demonstrated that: (1) ontogenetic trajectories are diverse among families; (2) evolutionary diversification is significantly anisotropic; and, most importantly, (3) major axes of evolutionary diversification are correlated with clade-specific ontogenetic major axes in the shape space. These results imply that the evolutionary variability of the avian limbs has been biased along the clade-specific ontogenetic trajectories. It may explain peculiar diversification patterns characteristic to some avian groups, including the long-leggedness in Ardeidae and tendency for flightlessness in Anatidae.
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Affiliation(s)
- Junya Watanabe
- Department of Geology and Mineralogy, Kyoto University, Kyoto, Japan
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13
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Rates of morphological evolution, asymmetry and morphological integration of shell shape in scallops. BMC Evol Biol 2017; 17:248. [PMID: 29216839 PMCID: PMC5721563 DOI: 10.1186/s12862-017-1098-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 11/27/2017] [Indexed: 12/20/2022] Open
Abstract
Background Rates of morphological evolution vary across different taxonomic groups, and this has been proposed as one of the main drivers for the great diversity of organisms on Earth. Of the extrinsic factors pertaining to this variation, ecological hypotheses feature prominently in observed differences in phenotypic evolutionary rates across lineages. But complex organisms are inherently modular, comprising distinct body parts that can be differentially affected by external selective pressures. Thus, the evolution of trait covariation and integration in modular systems may also play a prominent role in shaping patterns of phenotypic diversity. Here we investigate the role ecological diversity plays in morphological integration, and the tempo of shell shape evolution and of directional asymmetry in bivalved scallops. Results Overall, the shape of both valves and the magnitude of asymmetry of the whole shell (difference in shape between valves) are traits that are evolving fast in ecomorphs under strong selective pressures (gliders, recessers and nestling), compared to low rates observed in other ecomorphs (byssal-attaching, free-living and cementing). Given that different parts of an organism can be under different selective pressures from the environment, we also examined the degree of evolutionary integration between the valves as it relates to ecological shifts. We find that evolutionary morphological integration is consistent and surprisingly high across species, indicating that while the left and right valves of a scallop shell are diversifying in accordance with ecomorphology, they are doing so in a concerted fashion. Conclusions Our study on scallops adds another strong piece of evidence that ecological shifts play an important role in the tempo and mode of morphological evolution. Strong selective pressures from the environment, inferred from the repeated evolution of distinct ecomorphs, have influenced the rate of morphological evolution in valve shape and the magnitude of asymmetry between valves. Our observation that morphological integration of the valves making up the shell is consistently strong suggests tight developmental pathways are responsible for the concerted evolution of these structures while environmental pressures are driving whole shell shape. Finally, our study shows that directional asymmetry in shell shape among species is an important aspect of scallop macroevolution. Electronic supplementary material The online version of this article (10.1186/s12862-017-1098-5) contains supplementary material, which is available to authorized users.
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