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Morrow A, Smale L, Meek PD, Lundrigan B. Tradeoffs in the sensory brain between diurnal and nocturnal rodents. BRAIN, BEHAVIOR AND EVOLUTION 2024; 99:000538090. [PMID: 38569487 PMCID: PMC11346379 DOI: 10.1159/000538090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 02/20/2024] [Indexed: 04/05/2024]
Abstract
INTRODUCTION Transitions in temporal niche have occurred many times over the course of mammalian evolution. These are associated with changes in sensory stimuli available to animals, particularly with visual cues, because levels of light are so much higher during the day than night. This relationship between temporal niche and available sensory stimuli elicits the expectation that evolutionary transitions between diurnal and nocturnal lifestyles will be accompanied by modifications of sensory systems that optimize the ability of animals to receive, process, and react to important stimuli in the environment. METHODS This study examines the influence of temporal niche on investment in sensory brain tissue of 13 rodent species (five diurnal; eight nocturnal). Animals were euthanized and the brain immediately frozen on dry ice; olfactory bulbs were subsequently dissected and weighed, and the remaining brain was weighed, sectioned, and stained. Stereo Investigator was used to calculate volumes of four sensory regions that function in processing visual (lateral geniculate nucleus, superior colliculus) and auditory (medial geniculate nucleus, inferior colliculus) information. A phylogenetic framework was used to assess the influence of temporal niche on the relative sizes of these brain structures and of olfactory bulb weights. RESULTS Compared to nocturnal species, diurnal species had larger visual regions, whereas nocturnal species had larger olfactory bulbs than their diurnal counterparts. Of the two auditory structures examined, one (medial geniculate nucleus) was larger in diurnal species, while the other (inferior colliculus) did not differ significantly with temporal niche. CONCLUSION Our results indicate a possible indirect association between temporal niche and auditory investment and suggest probable tradeoffs of investment between olfactory and visual areas of the brain, with diurnal species investing more in processing visual information and nocturnal species investing more in processing olfactory information.
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Affiliation(s)
- Andrea Morrow
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA
- Program in Ecology, Evolution, and Behavior, Michigan State University, East Lansing, MI, USA
- BEACON Center for the Study of Evolution, Michigan State University, East Lansing, MI, USA
| | - Laura Smale
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA
- Program in Ecology, Evolution, and Behavior, Michigan State University, East Lansing, MI, USA
- BEACON Center for the Study of Evolution, Michigan State University, East Lansing, MI, USA
- Department of Psychology, Michigan State University, East Lansing, MI, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
| | - Paul Douglas Meek
- Vertebrate Pest Research Unit, New South Wales Department of Primary Industries, Coffs Harbour, NSW, Australia
- School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Barbara Lundrigan
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA
- Program in Ecology, Evolution, and Behavior, Michigan State University, East Lansing, MI, USA
- BEACON Center for the Study of Evolution, Michigan State University, East Lansing, MI, USA
- Michigan State University Museum, East Lansing, MI, USA
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Roese-Miron L, Jones MEH, Ferreira JD, Hsiou AS. Virtual endocasts of Clevosaurus brasiliensis and the tuatara: Rhynchocephalian neuroanatomy and the oldest endocranial record for Lepidosauria. Anat Rec (Hoboken) 2024; 307:1366-1389. [PMID: 36951279 DOI: 10.1002/ar.25212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 03/02/2023] [Accepted: 03/07/2023] [Indexed: 03/24/2023]
Abstract
Understanding the origins of the vertebrate brain is fundamental for uncovering evolutionary patterns in neuroanatomy. Regarding extinct species, the anatomy of the brain and other soft tissues housed in endocranial spaces can be approximated by casts of these cavities (endocasts). The neuroanatomical knowledge of Rhynchocephalia, a reptilian clade exceptionally diverse in the early Mesozoic, is restricted to the brain of its only living relative, Sphenodon punctatus, and unknown for fossil species. Here, we describe the endocast and the reptilian encephalization quotient (REQ) of the Triassic rhynchocephalian Clevosaurus brasiliensis and compare it with an ontogenetic series of S. punctatus. To better understand the informative potential of endocasts in Rhynchocephalia, we also examine the brain-endocast relationship in S. punctatus. We found that the brain occupies 30% of its cavity, but the latter recovers the general shape and length of the brain. The REQ of C. brasiliensis (0.27) is much lower than S. punctatus (0.84-1.16), with the tuatara being close to the mean for non-avian reptiles. The endocast of S. punctatus is dorsoventrally flexed and becomes more elongated throughout ontogeny. The endocast of C. brasiliensis is mostly unflexed and tubular, possibly representing a more plesiomorphic anatomy in relation to S. punctatus. Given the small size of C. brasiliensis, the main differences may result from allometric and heterochronic phenomena, consistent with suggestions that S. punctatus shows peramorphic anatomy compared to Mesozoic rhynchocephalians. Our results highlight a previously undocumented anatomical diversity among rhynchocephalians and provide a framework for future neuroanatomical comparisons among lepidosaurs.
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Affiliation(s)
- Lívia Roese-Miron
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Marc Emyr Huw Jones
- Science Group: Fossil Reptiles, Amphibians and Birds Section, Natural History Museum, London, UK
- Research Department of Cell and Developmental Biology, University College London, London, UK
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - José Darival Ferreira
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Annie Schmaltz Hsiou
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
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3
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The endocast of the insular and extinct Sylviornis neocaledoniae (Aves, Galliformes), reveals insights into its sensory specializations and its twilight ecology. Sci Rep 2022; 12:21185. [PMID: 36477415 PMCID: PMC9729198 DOI: 10.1038/s41598-022-14829-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 06/13/2022] [Indexed: 12/12/2022] Open
Abstract
Sylviornis neocaledoniae (Galliformes, Sylviornithidae), a recently extinct bird of New-Caledonia (Galliformes, Sylviornithidae) is the largest galliform that ever lived and one of the most enigmatic birds in the world. Herein, for the first time, we analyze its neuroanatomy that sheds light on its lifestyle, its brain shape and patterns being correlated to neurological functions. Using morphometric methods, we quantified the endocranial morphology of S. neocaledoniae and compared it with extinct and extant birds in order to obtain ecological and behavioral information about fossil birds. Sylviornis neocaledoniae exhibited reduced optic lobes, a condition also observed in nocturnal taxa endemic to predator-depauperate islands, such as Elephant birds. Functional interpretations suggest that S. neocaledoniae possessed a well-developed somatosensorial system and a good sense of smell in addition to its specialized visual ability for low light conditions, presumably for locating its food. We interpret these results as evidence for a crepuscular lifestyle in S. neocaledoniae.
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4
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Fernández M, Reyes-Pinto R, Norambuena C, Sentis E, Mpodozis J. A canonical interlaminar circuit in the sensory dorsal ventricular ridge of birds: The anatomical organization of the trigeminal pallium. J Comp Neurol 2021; 529:3410-3428. [PMID: 34176123 DOI: 10.1002/cne.25201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 06/08/2021] [Accepted: 06/21/2021] [Indexed: 12/19/2022]
Abstract
The dorsal ventricular ridge (DVR), which is the largest component of the avian pallium, contains discrete partitions receiving tectovisual, auditory, and trigeminal ascending projections. Recent studies have shown that the auditory and the tectovisual regions can be regarded as complexes composed of three highly interconnected layers: an internal senso-recipient one, an intermediate afferent/efferent one, and a more external re-entrant one. Cells located in homotopic positions in each of these layers are reciprocally linked by an interlaminar loop of axonal processes, forming columnar-like local circuits. Whether this type of organization also extends to the trigemino-recipient DVR is, at present, not known. This question is of interest, since afferents forming this sensory pathway, exceptional among amniotes, are not thalamic but rhombencephalic in origin. We investigated this question by placing minute injections of neural tracers into selected locations of vital slices of the chicken telencephalon. We found that neurons of the trigemino-recipient nucleus basorostralis pallii (Bas) establish reciprocal, columnar and homotopical projections with cells located in the overlying ventral mesopallium (MV). "Column-forming" axons originated in B and MV terminate also in the intermediate strip, the fronto-trigeminal nidopallium (NFT), in a restricted manner. We also found that the NFT and an internal partition of B originate substantial, coarse-topographic projections to the underlying portion of the lateral striatum. We conclude that all sensory areas of the DVR are organized according to a common neuroarchitectonic motif, which bears a striking resemblance to that of the radial/laminar intrinsic circuits of the sensory cortices of mammals.
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Affiliation(s)
- Máximo Fernández
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Rosana Reyes-Pinto
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Carolina Norambuena
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Elisa Sentis
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Jorge Mpodozis
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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5
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Endocranial Anatomy of the Giant Extinct Australian Mihirung Birds (Aves, Dromornithidae). DIVERSITY 2021. [DOI: 10.3390/d13030124] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Dromornithids are an extinct group of large flightless birds from the Cenozoic of Australia. Their record extends from the Eocene to the late Pleistocene. Four genera and eight species are currently recognised, with diversity highest in the Miocene. Dromornithids were once considered ratites, but since the discovery of cranial elements, phylogenetic analyses have placed them near the base of the anseriforms or, most recently, resolved them as stem galliforms. In this study, we use morphometric methods to comprehensively describe dromornithid endocranial morphology for the first time, comparing Ilbandornis woodburnei and three species of Dromornis to one another and to four species of extant basal galloanseres. We reveal that major endocranial reconfiguration was associated with cranial foreshortening in a temporal series along the Dromornis lineage. Five key differences are evident between the brain morphology of Ilbandornis and Dromornis, relating to the medial wulst, the ventral eminence of the caudoventral telencephalon, and morphology of the metencephalon (cerebellum + pons). Additionally, dromornithid brains display distinctive dorsal (rostral position of the wulst), and ventral morphology (form of the maxillomandibular [V2+V3], glossopharyngeal [IX], and vagus [X] cranial nerves), supporting hypotheses that dromornithids are more closely related to basal galliforms than anseriforms. Functional interpretations suggest that dromornithids were specialised herbivores that likely possessed well-developed stereoscopic depth perception, were diurnal and targeted a soft browse trophic niche.
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Early CM, Iwaniuk AN, Ridgely RC, Witmer LM. Endocast structures are reliable proxies for the sizes of corresponding regions of the brain in extant birds. J Anat 2020; 237:1162-1176. [PMID: 32892372 DOI: 10.1111/joa.13285] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/01/2020] [Accepted: 07/03/2020] [Indexed: 12/15/2022] Open
Abstract
Endocasts are increasingly relied upon to examine avian brain evolution because they can be used across extant and extinct species. The endocasts of birds appear to be relatively faithful representatives of the external morphology of their brains, but it is unclear how well the size of a surface feature visible on endocasts reflects the volume of the underlying brain region. The optic lobe and the Wulst are two endocast structures that are clearly visible on the external surface of avian endocasts. As they overlie two major visual regions of the brain, the optic tectum and hyperpallium, the surface areas of the optic lobe and Wulst, respectively, are often used to infer visual abilities. To determine whether the surface area of these features reflects the volume of the underlying brain regions, we compared the surface areas of the optic lobes and Wulsts from digital endocasts with the volumes of the optic tecta and hyperpallia from the literature or measured from histological series of brains of the same species. Regression analyses revealed strong, statistically significant correlations between the volumes of the brain regions and the surface areas of the overlying endocast structures. In other words, the size of the hyperpallium and optic tectum can be reliably inferred from the surface areas of the Wulst and optic lobe, respectively. This validation opens the possibility of estimating brain-region volumes for extinct species in order to gain better insights in their visual ecology. It also emphasizes the importance of adopting a quantitative approach to the analysis of endocasts in the study of brain evolution.
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Affiliation(s)
- Catherine M Early
- Biology Department, Science Museum of Minnesota, Saint Paul, MN, USA.,Department of Biological Sciences, Ohio University, Athens, OH, USA.,Florida Museum of Natural History, University of Florida, Gainesville, FL, USA
| | - Andrew N Iwaniuk
- Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada
| | - Ryan C Ridgely
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Lawrence M Witmer
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
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7
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Hogan AVC, Watanabe A, Balanoff AM, Bever GS. Comparative growth in the olfactory system of the developing chick with considerations for evolutionary studies. J Anat 2020; 237:225-240. [PMID: 32314400 PMCID: PMC7369194 DOI: 10.1111/joa.13197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 02/17/2020] [Accepted: 03/10/2020] [Indexed: 12/26/2022] Open
Abstract
Despite the long-held assumption that olfaction plays a relatively minor role in the behavioral ecology of birds, crown-group avians exhibit marked phylogenetic variation in the size and form of the olfactory apparatus. As part of a larger effort to better understand the role of olfaction and olfactory tissues in the evolution and development of the avian skull, we present the first quantitative analysis of ontogenetic scaling between olfactory features [olfactory bulbs (OBs) and olfactory turbinates] and neighboring structures (cerebrum, total brain, respiratory turbinates) based on the model organism Gallus gallus. The OB develops under the predictions of a concerted evolutionary model with rapid early growth that is quickly overcome by the longer, sustained growth of the larger cerebrum. A similar pattern is found in the nasal cavity where the morphologically simple (non-scrolled) olfactory turbinates appear and mature early, with extended growth characterizing the larger and scrolled respiratory turbinates. Pairwise regressions largely recover allometric relationships among the examined structures, with a notable exception being the isometric trajectory of the OB and olfactory turbinate. Their parallel growth suggests a unique regulatory pathway that is likely driven by the morphogenesis of the olfactory nerve, which serves as a structural bridge between the two features. Still, isometry was not necessarily expected given that the olfactory epithelium covers more than just the turbinate. These data illuminate a number of evolutionary hypotheses that, moving forward, should inform tradeoffs and constraints between the olfactory and neighboring systems in the avian head.
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Affiliation(s)
- Aneila V. C. Hogan
- Center for Functional Anatomy and EvolutionJohns Hopkins University School of MedicineBaltimoreMDUSA
| | - Akinobu Watanabe
- Department of AnatomyNew York Institute of Technology College of Osteopathic MedicineNew YorkNYUSA
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNYUSA
- Life Sciences DepartmentVertebrates DivisionNatural History MuseumLondonUK
| | - Amy M. Balanoff
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNYUSA
- Department of Psychological and Brain SciencesJohns Hopkins UniversityBaltimoreMDUSA
| | - Gabriel S. Bever
- Center for Functional Anatomy and EvolutionJohns Hopkins University School of MedicineBaltimoreMDUSA
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNYUSA
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8
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Knoll F, Kawabe S. Avian palaeoneurology: Reflections on the eve of its 200th anniversary. J Anat 2020; 236:965-979. [PMID: 31999834 PMCID: PMC7219626 DOI: 10.1111/joa.13160] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/28/2019] [Accepted: 01/07/2020] [Indexed: 12/13/2022] Open
Abstract
In birds, the brain (especially the telencephalon) is remarkably developed, both in relative volume and complexity. Unlike in most early-branching sauropsids, the adults of birds and other archosaurs have a well-ossified neurocranium. In contrast to the situation in most of their reptilian relatives but similar to what can be seen in mammals, the brains of birds fit closely to the endocranial cavity so that their major external features are reflected in the endocasts. This makes birds a highly suitable group for palaeoneurological investigations. The first observation about the brain in a long-extinct bird was made in the first quarter of the 19th century. However, it was not until the 2000s and the application of modern imaging technologies that avian palaeoneurology really took off. Understanding how the mode of life is reflected in the external morphology of the brains of birds is but one of several future directions in which avian palaeoneurological research may extend. Although the number of fossil specimens suitable for palaeoneurological explorations is considerably smaller in birds than in mammals and will very likely remain so, the coming years will certainly witness a momentous strengthening of this rapidly growing field of research at the overlap between ornithology, palaeontology, evolutionary biology and neurosciences.
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Affiliation(s)
- Fabien Knoll
- ARAID‐Fundación Conjunto Paleontológico de Teruel‐DinópolisTeruelSpain
- Departamento de PaleobiologíaMuseo Nacional de Ciencias Naturales‐CSICMadridSpain
| | - Soichiro Kawabe
- Institute of Dinosaur ResearchFukui Prefectural UniversityFukuiJapan
- Fukui Prefectural Dinosaur MuseumFukuiJapan
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9
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Beyond Endocasts: Using Predicted Brain-Structure Volumes of Extinct Birds to Assess Neuroanatomical and Behavioral Inferences. DIVERSITY-BASEL 2020. [DOI: 10.3390/d12010034] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The shape of the brain influences skull morphology in birds, and both traits are driven by phylogenetic and functional constraints. Studies on avian cranial and neuroanatomical evolution are strengthened by data on extinct birds, but complete, 3D-preserved vertebrate brains are not known from the fossil record, so brain endocasts often serve as proxies. Recent work on extant birds shows that the Wulst and optic lobe faithfully represent the size of their underlying brain structures, both of which are involved in avian visual pathways. The endocasts of seven extinct birds were generated from microCT scans of their skulls to add to an existing sample of endocasts of extant birds, and the surface areas of their Wulsts and optic lobes were measured. A phylogenetic prediction method based on Bayesian inference was used to calculate the volumes of the brain structures of these extinct birds based on the surface areas of their overlying endocast structures. This analysis resulted in hyperpallium volumes of five of these extinct birds and optic tectum volumes of all seven extinct birds. Phylogenetic ANCOVA (phyANCOVA) were performed on regressions of the brain-structure volumes and endocast structure surface areas on various brain size metrics to determine if the relative sizes of these structures in any extinct birds were significantly different from those of the extant birds in the sample. Phylogenetic ANCOVA indicated that no extinct birds studied had relative hyperpallial volumes that were significantly different from the extant sample, nor were any of their optic tecta relatively hypertrophied. The optic tectum of Dinornis robustus was significantly smaller relative to brain size than any of the extant birds in our sample. This study provides an analytical framework for testing the hypotheses of potential functional behavioral capabilities of other extinct birds based on their endocasts.
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10
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Fernández M, Ahumada‐Galleguillos P, Sentis E, Marín G, Mpodozis J. Intratelencephalic projections of the avian visual dorsal ventricular ridge: Laminarly segregated, reciprocally and topographically organized. J Comp Neurol 2019; 528:321-359. [DOI: 10.1002/cne.24757] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/07/2019] [Accepted: 08/08/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Máximo Fernández
- Departamento de Biología, Facultad de Ciencias Universidad de Chile Santiago Chile
| | - Patricio Ahumada‐Galleguillos
- Departamento de Biología, Facultad de Ciencias Universidad de Chile Santiago Chile
- Instituto de Ciencias Biomédicas, Facultad de Medicina Universidad de Chile Santiago Chile
| | - Elisa Sentis
- Departamento de Biología, Facultad de Ciencias Universidad de Chile Santiago Chile
| | - Gonzalo Marín
- Departamento de Biología, Facultad de Ciencias Universidad de Chile Santiago Chile
- Facultad de Medicina Universidad Finis Terrae Santiago Chile
| | - Jorge Mpodozis
- Departamento de Biología, Facultad de Ciencias Universidad de Chile Santiago Chile
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11
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Multiphase progenetic development shaped the brain of flying archosaurs. Sci Rep 2019; 9:10807. [PMID: 31346192 PMCID: PMC6658547 DOI: 10.1038/s41598-019-46959-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 07/05/2019] [Indexed: 11/10/2022] Open
Abstract
The growing availability of virtual cranial endocasts of extinct and extant vertebrates has fueled the quest for endocranial characters that discriminate between phylogenetic groups and resolve their neural significances. We used geometric morphometrics to compare a phylogenetically and ecologically comprehensive data set of archosaurian endocasts along the deep evolutionary history of modern birds and found that this lineage experienced progressive elevation of encephalisation through several chapters of increased endocranial doming that we demonstrate to result from progenetic developments. Elevated encephalisation associated with progressive size reduction within Maniraptoriformes was secondarily exapted for flight by stem avialans. Within Mesozoic Avialae, endocranial doming increased in at least some Ornithurae, yet remained relatively modest in early Neornithes. During the Paleogene, volant non-neoavian birds retained ancestral levels of endocast doming where a broad neoavian niche diversification experienced heterochronic brain shape radiation, as did non-volant Palaeognathae. We infer comparable developments underlying the establishment of pterosaurian brain shapes.
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12
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Allemand R, Boistel R, Daghfous G, Blanchet Z, Cornette R, Bardet N, Vincent P, Houssaye A. Comparative morphology of snake (Squamata) endocasts: evidence of phylogenetic and ecological signals. J Anat 2017; 231:849-868. [PMID: 28960295 DOI: 10.1111/joa.12692] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2017] [Indexed: 12/22/2022] Open
Abstract
Brain endocasts obtained from computed tomography (CT) are now widely used in the field of comparative neuroanatomy. They provide an overview of the morphology of the brain and associated tissues located in the cranial cavity. Through anatomical comparisons between species, insights on the senses, the behavior, and the lifestyle can be gained. Although there are many studies dealing with mammal and bird endocasts, those performed on the brain endocasts of squamates are comparatively rare, thus limiting our understanding of their morphological variability and interpretations. Here, we provide the first comparative study of snake brain endocasts in order to bring new information about the morphology of these structures. Additionally, we test if the snake brain endocast encompasses a phylogenetic and/or an ecological signal. For this purpose, the digital endocasts of 45 snake specimens, including a wide diversity in terms of phylogeny and ecology, were digitized using CT, and compared both qualitatively and quantitatively. Snake endocasts exhibit a great variability. The different methods performed from descriptive characters, linear measurements and the outline curves provided complementary information. All these methods have shown that the shape of the snake brain endocast contains, as in mammals and birds, a phylogenetic signal but also an ecological one. Although phylogenetically related taxa share several similarities between each other, the brain endocast morphology reflects some notable ecological trends: e.g. (i) fossorial species possess both reduced optic tectum and pituitary gland; (ii) both fossorial and marine species have cerebral hemispheres poorly developed laterally; (iii) cerebral hemispheres and optic tectum are more developed in arboreal and terrestrial species.
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Affiliation(s)
- Rémi Allemand
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P - UMR 7207 - CNRS, MNHN, UPMC, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France.,Département Adaptations du Vivant, UMR 7179 - CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | - Renaud Boistel
- IPHEP-UMR CNRS 6046, UFR SFA, Université de Poitiers, Poitiers, France
| | - Gheylen Daghfous
- Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
| | - Zoé Blanchet
- Département Adaptations du Vivant, UMR 7179 - CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | - Raphaël Cornette
- Institut de Systématique, Evolution, Biodiversité, ISYEB - UMR 7205 - CNRS, MNHN, UPMC, EPHE, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France
| | - Nathalie Bardet
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P - UMR 7207 - CNRS, MNHN, UPMC, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France
| | - Peggy Vincent
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P - UMR 7207 - CNRS, MNHN, UPMC, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France
| | - Alexandra Houssaye
- Département Adaptations du Vivant, UMR 7179 - CNRS/Muséum National d'Histoire Naturelle, Paris, France
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13
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Ahmed NI, Thompson C, Bolnick DI, Stuart YE. Brain morphology of the threespine stickleback ( Gasterosteus aculeatus) varies inconsistently with respect to habitat complexity: A test of the Clever Foraging Hypothesis. Ecol Evol 2017; 7:3372-3380. [PMID: 28515873 PMCID: PMC5433989 DOI: 10.1002/ece3.2918] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 02/06/2017] [Accepted: 02/21/2017] [Indexed: 01/06/2023] Open
Abstract
The Clever Foraging Hypothesis asserts that organisms living in a more spatially complex environment will have a greater neurological capacity for cognitive processes related to spatial memory, navigation, and foraging. Because the telencephalon is often associated with spatial memory and navigation tasks, this hypothesis predicts a positive association between telencephalon size and environmental complexity. The association between habitat complexity and brain size has been supported by comparative studies across multiple species but has not been widely studied at the within-species level. We tested for covariation between environmental complexity and neuroanatomy of threespine stickleback (Gasterosteus aculeatus) collected from 15 pairs of lakes and their parapatric streams on Vancouver Island. In most pairs, neuroanatomy differed between the adjoining lake and stream populations. However, the magnitude and direction of this difference were inconsistent between watersheds and did not covary strongly with measures of within-site environmental heterogeneity. Overall, we find weak support for the Clever Foraging Hypothesis in our study.
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Affiliation(s)
- Newaz I Ahmed
- Department of Integrative Biology University of Texas at Austin Austin TX USA.,Department of Internal Medicine University of Texas-Southwestern Dallas TX USA
| | - Cole Thompson
- Department of Integrative Biology University of Texas at Austin Austin TX USA
| | - Daniel I Bolnick
- Department of Integrative Biology University of Texas at Austin Austin TX USA
| | - Yoel E Stuart
- Department of Integrative Biology University of Texas at Austin Austin TX USA
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14
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Griggio M, Fracasso G, Mahr K, Hoi H. Olfactory Assessment of Competitors to the Nest Site: An Experiment on a Passerine Species. PLoS One 2016; 11:e0167905. [PMID: 27936093 PMCID: PMC5148006 DOI: 10.1371/journal.pone.0167905] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 11/22/2016] [Indexed: 11/18/2022] Open
Abstract
Since most avian species have been considered anosmic or microsmatic, olfaction and associated behavioural patterns have hardly been investigated. Most importantly, empirical data on avian olfaction is not equally distributed among species. Initial investigations focused on species with relatively big olfactory bulbs because they were thought to have better olfactory capabilities. Hence, in this study we tested the ability of house sparrows (Passer domesticus) to use chemical cues as parameters to estimate nest features. House sparrows are a commonly used model species, but their olfactory capabilities have not been studied so far. We offered two different odours to males and females, namely the scent of mouse urine (Mus musculus domesticus), representing a possible competitor and a threat to eggs and hatchlings, and the odour of hay, representing a familiar and innocuous odour. The experiment was performed at the sunset to simulate a first inspection to new possible roosting or nesting sites. Interestingly, males but not females preferred to spend significantly more time in front of the hay odour, than in front of the scent of mouse urine. Our results strengthen the hypothesis that oscines can not only perceive odours but also use olfaction to assess the environment and estimate nest site quality.
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Affiliation(s)
- Matteo Griggio
- Dipartimento di Biologia, Università di Padova, Via U. Bassi Padova, Italy
- * E-mail:
| | - Gerardo Fracasso
- Dipartimento di Biologia, Università di Padova, Via U. Bassi Padova, Italy
| | - Katharina Mahr
- Konrad Lorenz Institute of Ethology, Department of Integrative Biology and Evolution, University of Veterinary Medicine of Vienna, Vienna, Austria
| | - Herbert Hoi
- Konrad Lorenz Institute of Ethology, Department of Integrative Biology and Evolution, University of Veterinary Medicine of Vienna, Vienna, Austria
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15
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Balanoff AM, Bever GS, Colbert MW, Clarke JA, Field DJ, Gignac PM, Ksepka DT, Ridgely RC, Smith NA, Torres CR, Walsh S, Witmer LM. Best practices for digitally constructing endocranial casts: examples from birds and their dinosaurian relatives. J Anat 2016; 229:173-90. [PMID: 26403623 PMCID: PMC4948053 DOI: 10.1111/joa.12378] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2015] [Indexed: 11/28/2022] Open
Abstract
The rapidly expanding interest in, and availability of, digital tomography data to visualize casts of the vertebrate endocranial cavity housing the brain (endocasts) presents new opportunities and challenges to the field of comparative neuroanatomy. The opportunities are many, ranging from the relatively rapid acquisition of data to the unprecedented ability to integrate critically important fossil taxa. The challenges consist of navigating the logistical barriers that often separate a researcher from high-quality data and minimizing the amount of non-biological variation expressed in endocasts - variation that may confound meaningful and synthetic results. Our purpose here is to outline preferred approaches for acquiring digital tomographic data, converting those data to an endocast, and making those endocasts as meaningful as possible when considered in a comparative context. This review is intended to benefit those just getting started in the field but also serves to initiate further discussion between active endocast researchers regarding the best practices for advancing the discipline. Congruent with the theme of this volume, we draw our examples from birds and the highly encephalized non-avian dinosaurs that comprise closely related outgroups along their phylogenetic stem lineage.
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Affiliation(s)
- Amy M. Balanoff
- Department of Anatomical SciencesStony Brook UniversityStony BrookNYUSA
| | - G. S. Bever
- Department of AnatomyNew York Institute of TechnologyCollege of Osteopathic MedicineOld WestburyNYUSA
| | - Matthew W. Colbert
- Department of Geological SciencesThe University of Texas at AustinAustinTXUSA
| | - Julia A. Clarke
- Department of Geological SciencesThe University of Texas at AustinAustinTXUSA
| | - Daniel J. Field
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
| | - Paul M. Gignac
- Department of Anatomy and Cell BiologyOklahoma State University Center for Health SciencesTulsaOKUSA
| | | | - Ryan C. Ridgely
- Department of Biomedical SciencesHeritage College of Osteopathic MedicineOhio UniversityAthensOHUSA
| | - N. Adam Smith
- Department of Earth SciencesThe Field Museum of Natural HistoryChicagoILUSA
| | | | - Stig Walsh
- Department of Natural SciencesNational Museums ScotlandEdinburghUK
| | - Lawrence M. Witmer
- Department of Biomedical SciencesHeritage College of Osteopathic MedicineOhio UniversityAthensOHUSA
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16
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Corfield JR, Price K, Iwaniuk AN, Gutierrez-Ibañez C, Birkhead T, Wylie DR. Diversity in olfactory bulb size in birds reflects allometry, ecology, and phylogeny. Front Neuroanat 2015; 9:102. [PMID: 26283931 PMCID: PMC4518324 DOI: 10.3389/fnana.2015.00102] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 07/13/2015] [Indexed: 12/20/2022] Open
Abstract
The relative size of olfactory bulbs (OBs) is correlated with olfactory capabilities across vertebrates and is widely used to assess the relative importance of olfaction to a species’ ecology. In birds, variations in the relative size of OBs are correlated with some behaviors; however, the factors that have led to the high level of diversity seen in OB sizes across birds are still not well understood. In this study, we use the relative size of OBs as a neuroanatomical proxy for olfactory capabilities in 135 species of birds, representing 21 orders. We examine the scaling of OBs with brain size across avian orders, determine likely ancestral states and test for correlations between OB sizes and habitat, ecology, and behavior. The size of avian OBs varied with the size of the brain and this allometric relationship was for the most part isometric, although species did deviate from this trend. Large OBs were characteristic of more basal species and in more recently derived species the OBs were small. Living and foraging in a semi-aquatic environment was the strongest variable driving the evolution of large OBs in birds; olfaction may provide cues for navigation and foraging in this otherwise featureless environment. Some of the diversity in OB sizes was also undoubtedly due to differences in migratory behavior, foraging strategies and social structure. In summary, relative OB size in birds reflect allometry, phylogeny and behavior in ways that parallel that of other vertebrate classes. This provides comparative evidence that supports recent experimental studies into avian olfaction and suggests that olfaction is an important sensory modality for all avian species.
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Affiliation(s)
- Jeremy R Corfield
- Department of Psychology, University of Alberta, Edmonton AB, Canada ; Department of Neuroscience, University of Lethbridge, Lethbridge AB, Canada
| | - Kasandra Price
- Department of Psychology, University of Alberta, Edmonton AB, Canada
| | - Andrew N Iwaniuk
- Department of Neuroscience, University of Lethbridge, Lethbridge AB, Canada
| | | | - Tim Birkhead
- Department of Animal and Plant Sciences, University of Sheffield Sheffield, UK
| | - Douglas R Wylie
- Department of Psychology, University of Alberta, Edmonton AB, Canada
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17
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Carril J, Tambussi CP, Degrange FJ, Benitez Saldivar MJ, Picasso MBJ. Comparative brain morphology of Neotropical parrots (Aves, Psittaciformes) inferred from virtual 3D endocasts. J Anat 2015; 229:239-51. [PMID: 26053196 DOI: 10.1111/joa.12325] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/08/2015] [Indexed: 01/11/2023] Open
Abstract
Psittaciformes are a very diverse group of non-passerine birds, with advanced cognitive abilities and highly developed locomotor and feeding behaviours. Using computed tomography and three-dimensional (3D) visualization software, the endocasts of 14 extant Neotropical parrots were reconstructed, with the aim of analysing, comparing and exploring the morphology of the brain within the clade. A 3D geomorphometric analysis was performed, and the encephalization quotient (EQ) was calculated. Brain morphology character states were traced onto a Psittaciformes tree in order to facilitate interpretation of morphological traits in a phylogenetic context. Our results indicate that: (i) there are two conspicuously distinct brain morphologies, one considered walnut type (quadrangular and wider than long) and the other rounded (narrower and rostrally tapered); (ii) Psittaciformes possess a noticeable notch between hemisphaeria that divides the bulbus olfactorius; (iii) the plesiomorphic and most frequently observed characteristics of Neotropical parrots are a rostrally tapered telencephalon in dorsal view, distinctly enlarged dorsal expansion of the eminentia sagittalis and conspicuous fissura mediana; (iv) there is a positive correlation between body mass and brain volume; (v) psittacids are characterized by high EQ values that suggest high brain volumes in relation to their body masses; and (vi) the endocranial morphology of the Psittaciformes as a whole is distinctive relative to other birds. This new knowledge of brain morphology offers much potential for further insight in paleoneurological, phylogenetic and evolutionary studies.
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Affiliation(s)
- Julieta Carril
- Cátedra de Histología y Embriología Animal, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Claudia Patricia Tambussi
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.,Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), CONICET-UNC, Córdoba, Argentina
| | - Federico Javier Degrange
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.,Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), CONICET-UNC, Córdoba, Argentina.,Centro de Investigaciones Paleobiológicas (CIPAL), Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Juliana Benitez Saldivar
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.,Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Mariana Beatriz Julieta Picasso
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.,División Paleontología Vertebrados, Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Buenos Aires, Argentina
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18
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A unique cellular scaling rule in the avian auditory system. Brain Struct Funct 2015; 221:2675-93. [DOI: 10.1007/s00429-015-1064-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 05/12/2015] [Indexed: 12/31/2022]
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19
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Krilow JM, Iwaniuk AN. Seasonal Variation in Forebrain Region Sizes in Male Ruffed Grouse (Bonasa umbellus). BRAIN, BEHAVIOR AND EVOLUTION 2015; 85:189-202. [PMID: 25997574 DOI: 10.1159/000381277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 02/26/2015] [Indexed: 11/19/2022]
Abstract
The song system of songbirds has provided significant insight into the underlying mechanisms and behavioural consequences of seasonal neuroplasticity. The extent to which seasonal changes in brain region volumes occur in non-songbird species has, however, remained largely untested. Here, we tested whether brain region volumes varied with season in the ruffed grouse (Bonasa umbellus), a gallinaceous bird that produces a unique wing-beating display known as 'drumming' as its primary form of courtship behaviour. Using unbiased stereology, we measured the sizes of the cerebellum, nucleus rotundus, telencephalon, mesopallium, hippocampal formation, striatopallidal complex and arcopallium across spring males, fall males and fall females. The majority of these brain regions did not vary significantly across these three groups. The two exceptions were the striatopallidal complex and arcopallium, both of which were significantly larger in spring males that are actively drumming. These seasonal changes in volume strongly implicate the striatopallidal complex and arcopallium as key structures in the production and/or modulation of the ruffed grouse drumming display and represent the first evidence of seasonal plasticity in the telencephalon underlying a non-vocal courtship behaviour. Our findings also suggest that seasonal plasticity in the striatopallidal complex and arcopallium might be a trait that is shared across many bird species and that both structures are related to the production of multiple forms of courtship and not just learned song.
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Affiliation(s)
- Justin M Krilow
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alta., Canada
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20
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Corfield JR, Eisthen HL, Iwaniuk AN, Parsons S. Anatomical specializations for enhanced olfactory sensitivity in kiwi, Apteryx mantelli. BRAIN, BEHAVIOR AND EVOLUTION 2014; 84:214-26. [PMID: 25376305 DOI: 10.1159/000365564] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 03/25/2014] [Indexed: 11/19/2022]
Abstract
The ability to function in a nocturnal and ground-dwelling niche requires a unique set of sensory specializations. The New Zealand kiwi has shifted away from vision, instead relying on auditory and tactile stimuli to function in its environment and locate prey. Behavioral evidence suggests that kiwi also rely on their sense of smell, using olfactory cues in foraging and possibly also in communication and social interactions. Anatomical studies appear to support these observations: the olfactory bulbs and tubercles have been suggested to be large in the kiwi relative to other birds, although the extent of this enlargement is poorly understood. In this study, we examine the size of the olfactory bulbs in kiwi and compare them with 55 other bird species, including emus, ostriches, rheas, tinamous, and 2 extinct species of moa (Dinornithiformes). We also examine the cytoarchitecture of the olfactory bulbs and olfactory epithelium to determine if any neural specializations beyond size are present that would increase olfactory acuity. Kiwi were a clear outlier in our analysis, with olfactory bulbs that are proportionately larger than those of any other bird in this study. Emus, close relatives of the kiwi, also had a relative enlargement of the olfactory bulbs, possibly supporting a phylogenetic link to well-developed olfaction. The olfactory bulbs in kiwi are almost in direct contact with the olfactory epithelium, which is indeed well developed and complex, with olfactory receptor cells occupying a large percentage of the epithelium. The anatomy of the kiwi olfactory system supports an enhancement for olfactory sensitivities, which is undoubtedly associated with their unique nocturnal niche.
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Affiliation(s)
- Jeremy R Corfield
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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21
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Krabichler Q, Vega-Zuniga T, Morales C, Luksch H, Marín GJ. The visual system of a Palaeognathous bird: Visual field, retinal topography and retino-central connections in the Chilean Tinamou (Nothoprocta perdicaria). J Comp Neurol 2014; 523:226-50. [DOI: 10.1002/cne.23676] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 09/05/2014] [Accepted: 09/09/2014] [Indexed: 02/05/2023]
Affiliation(s)
- Quirin Krabichler
- Chair of Zoology, Technische Universität München; Freising-Weihenstephan Germany
| | - Tomas Vega-Zuniga
- Chair of Zoology, Technische Universität München; Freising-Weihenstephan Germany
| | - Cristian Morales
- Laboratorio de Neurobiología y Biología del Conocer; Departamento de Biología; Facultad de Ciencias; Universidad de Chile; Santiago de Chile Chile
| | - Harald Luksch
- Chair of Zoology, Technische Universität München; Freising-Weihenstephan Germany
| | - Gonzalo J. Marín
- Laboratorio de Neurobiología y Biología del Conocer; Departamento de Biología; Facultad de Ciencias; Universidad de Chile; Santiago de Chile Chile
- Facultad de Medicina; Universidad Finis Terrae; Santiago de Chile Chile
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22
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Comparative quantitative investigations on brains of wild cavies (Cavia aperea) and guinea pigs (Cavia aperea f. porcellus). A contribution to size changes of CNS structures due to domestication. Mamm Biol 2014. [DOI: 10.1016/j.mambio.2013.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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23
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Not all sharks are "swimming noses": variation in olfactory bulb size in cartilaginous fishes. Brain Struct Funct 2014; 220:1127-43. [PMID: 24435575 DOI: 10.1007/s00429-014-0705-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 01/04/2014] [Indexed: 10/25/2022]
Abstract
Olfaction is a universal modality by which all animals sample chemical stimuli from their environment. In cartilaginous fishes, olfaction is critical for various survival tasks including localizing prey, avoiding predators, and chemosensory communication with conspecifics. Little is known, however, about interspecific variation in olfactory capability in these fishes, or whether the relative importance of olfaction in relation to other sensory systems varies with regard to ecological factors, such as habitat and lifestyle. In this study, we have addressed these questions by directly examining interspecific variation in the size of the olfactory bulbs (OB), the region of the brain that receives the primary sensory projections from the olfactory nerve, in 58 species of cartilaginous fishes. Relative OB size was compared among species occupying different ecological niches. Our results show that the OBs maintain a substantial level of allometric independence from the rest of the brain across cartilaginous fishes and that OB size is highly variable among species. These findings are supported by phylogenetic generalized least-squares models, which show that this variability is correlated with ecological niche, particularly habitat. The relatively largest OBs were found in pelagic-coastal/oceanic sharks, especially migratory species such as Carcharodon carcharias and Galeocerdo cuvier. Deep-sea species also possess large OBs, suggesting a greater reliance on olfaction in habitats where vision may be compromised. In contrast, the smallest OBs were found in the majority of reef-associated species, including sharks from the families Carcharhinidae and Hemiscyllidae and dasyatid batoids. These results suggest that there is great variability in the degree to which these fishes rely on olfactory cues. The OBs have been widely used as a neuroanatomical proxy for olfactory capability in vertebrates, and we speculate that differences in olfactory capabilities may be the result of functional rather than phylogenetic adaptations.
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24
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Cunningham SJ, Corfield JR, Iwaniuk AN, Castro I, Alley MR, Birkhead TR, Parsons S. The anatomy of the bill tip of kiwi and associated somatosensory regions of the brain: comparisons with shorebirds. PLoS One 2013; 8:e80036. [PMID: 24244601 PMCID: PMC3828210 DOI: 10.1371/journal.pone.0080036] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 09/27/2013] [Indexed: 11/18/2022] Open
Abstract
Three families of probe-foraging birds, Scolopacidae (sandpipers and snipes), Apterygidae (kiwi), and Threskiornithidae (ibises, including spoonbills) have independently evolved long, narrow bills containing clusters of vibration-sensitive mechanoreceptors (Herbst corpuscles) within pits in the bill-tip. These 'bill-tip organs' allow birds to detect buried or submerged prey via substrate-borne vibrations and/or interstitial pressure gradients. Shorebirds, kiwi and ibises are only distantly related, with the phylogenetic divide between kiwi and the other two taxa being particularly deep. We compared the bill-tip structure and associated somatosensory regions in the brains of kiwi and shorebirds to understand the degree of convergence of these systems between the two taxa. For comparison, we also included data from other taxa including waterfowl (Anatidae) and parrots (Psittaculidae and Cacatuidae), non-apterygid ratites, and other probe-foraging and non probe-foraging birds including non-scolopacid shorebirds (Charadriidae, Haematopodidae, Recurvirostridae and Sternidae). We show that the bill-tip organ structure was broadly similar between the Apterygidae and Scolopacidae, however some inter-specific variation was found in the number, shape and orientation of sensory pits between the two groups. Kiwi, scolopacid shorebirds, waterfowl and parrots all shared hypertrophy or near-hypertrophy of the principal sensory trigeminal nucleus. Hypertrophy of the nucleus basorostralis, however, occurred only in waterfowl, kiwi, three of the scolopacid species examined and a species of oystercatcher (Charadriiformes: Haematopodidae). Hypertrophy of the principal sensory trigeminal nucleus in kiwi, Scolopacidae, and other tactile specialists appears to have co-evolved alongside bill-tip specializations, whereas hypertrophy of nucleus basorostralis may be influenced to a greater extent by other sensory inputs. We suggest that similarities between kiwi and scolopacid bill-tip organs and associated somatosensory brain regions are likely a result of similar ecological selective pressures, with inter-specific variations reflecting finer-scale niche differentiation.
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Affiliation(s)
- Susan J. Cunningham
- Percy FitzPatrick Institute, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch, South Africa
- Institute of Natural Resources, Massey University, Palmerston North, New Zealand
| | - Jeremy R. Corfield
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
- * E-mail:
| | - Andrew N. Iwaniuk
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Isabel Castro
- Institute of Natural Resources, Massey University, Palmerston North, New Zealand
| | - Maurice R. Alley
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| | - Tim R. Birkhead
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, United Kingdom
| | - Stuart Parsons
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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25
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Walsh SA, Iwaniuk AN, Knoll MA, Bourdon E, Barrett PM, Milner AC, Nudds RL, Abel RL, Sterpaio PD. Avian cerebellar floccular fossa size is not a proxy for flying ability in birds. PLoS One 2013; 8:e67176. [PMID: 23825638 PMCID: PMC3692442 DOI: 10.1371/journal.pone.0067176] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 05/15/2013] [Indexed: 12/02/2022] Open
Abstract
Extinct animal behavior has often been inferred from qualitative assessments of relative brain region size in fossil endocranial casts. For instance, flight capability in pterosaurs and early birds has been inferred from the relative size of the cerebellar flocculus, which in life protrudes from the lateral surface of the cerebellum. A primary role of the flocculus is to integrate sensory information about head rotation and translation to stabilize visual gaze via the vestibulo-occular reflex (VOR). Because gaze stabilization is a critical aspect of flight, some authors have suggested that the flocculus is enlarged in flying species. Whether this can be further extended to a floccular expansion in highly maneuverable flying species or floccular reduction in flightless species is unknown. Here, we used micro computed-tomography to reconstruct “virtual” endocranial casts of 60 extant bird species, to extract the same level of anatomical information offered by fossils. Volumes of the floccular fossa and entire brain cavity were measured and these values correlated with four indices of flying behavior. Although a weak positive relationship was found between floccular fossa size and brachial index, no significant relationship was found between floccular fossa size and any other flight mode classification. These findings could be the result of the bony endocranium inaccurately reflecting the size of the neural flocculus, but might also reflect the importance of the flocculus for all modes of locomotion in birds. We therefore conclude that the relative size of the flocculus of endocranial casts is an unreliable predictor of locomotor behavior in extinct birds, and probably also pterosaurs and non-avian dinosaurs.
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Affiliation(s)
- Stig A Walsh
- Department of Natural Sciences, National Museums Scotland, Edinburgh, United Kingdom.
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26
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Corfield JR, Birkhead TR, Spottiswoode CN, Iwaniuk AN, Boogert NJ, Gutiérrez-Ibáñez C, Overington SE, Wylie DR, Lefebvre L. Brain size and morphology of the brood-parasitic and cerophagous honeyguides (Aves: Piciformes). BRAIN, BEHAVIOR AND EVOLUTION 2013; 81:170-86. [PMID: 23615026 DOI: 10.1159/000348834] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 09/09/2012] [Indexed: 11/19/2022]
Abstract
Honeyguides (Indicatoridae, Piciformes) are unique among birds in several respects. All subsist primarily on wax, are obligatory brood parasites and one species engages in 'guiding' behavior in which it leads human honey hunters to bees' nests. This unique life history has likely shaped the evolution of their brain size and morphology. Here, we test that hypothesis using comparative data on relative brain and brain region size of honeyguides and their relatives: woodpeckers, barbets and toucans. Honeyguides have significantly smaller relative brain volumes than all other piciform taxa. Volumetric measurements of the brain indicate that honeyguides have a significantly larger cerebellum and hippocampal formation (HF) than woodpeckers, the sister clade of the honeyguides, although the HF enlargement was not significant across all of our analyses. Cluster analyses also revealed that the overall composition of the brain and telencephalon differs greatly between honeyguides and woodpeckers. The relatively smaller brains of the honeyguides may be a consequence of brood parasitism and cerophagy ('wax eating'), both of which place energetic constraints on brain development and maintenance. The inconclusive results of our analyses of relative HF volume highlight some of the problems associated with comparative studies of the HF that require further study.
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Affiliation(s)
- Jeremy R Corfield
- DST/NRF Center of Excellence, Percy FitzPatrick Institute, University of Cape Town, Cape Town, South Africa
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