1
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Farnworth MS, Montgomery SH. Evolution of neural circuitry and cognition. Biol Lett 2024; 20:20230576. [PMID: 38747685 DOI: 10.1098/rsbl.2023.0576] [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: 12/10/2023] [Accepted: 03/26/2024] [Indexed: 05/25/2024] Open
Abstract
Neural circuits govern the interface between the external environment, internal cues and outwardly directed behaviours. To process multiple environmental stimuli and integrate these with internal state requires considerable neural computation. Expansion in neural network size, most readily represented by whole brain size, has historically been linked to behavioural complexity, or the predominance of cognitive behaviours. Yet, it is largely unclear which aspects of circuit variation impact variation in performance. A key question in the field of evolutionary neurobiology is therefore how neural circuits evolve to allow improved behavioural performance or innovation. We discuss this question by first exploring how volumetric changes in brain areas reflect actual neural circuit change. We explore three major axes of neural circuit evolution-replication, restructuring and reconditioning of cells and circuits-and discuss how these could relate to broader phenotypes and behavioural variation. This discussion touches on the relevant uses and limitations of volumetrics, while advocating a more circuit-based view of cognition. We then use this framework to showcase an example from the insect brain, the multi-sensory integration and internal processing that is shared between the mushroom bodies and central complex. We end by identifying future trends in this research area, which promise to advance the field of evolutionary neurobiology.
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Affiliation(s)
- Max S Farnworth
- School of Biological Sciences, University of Bristol , Bristol, UK
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2
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Reyes AS, Bittar A, Ávila LC, Botia C, Esmeral NP, Bloch NI. Divergence in brain size and brain region volumes across wild guppy populations. Proc Biol Sci 2022; 289:20212784. [PMID: 36000235 PMCID: PMC9399710 DOI: 10.1098/rspb.2021.2784] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Complex evolutionary dynamics have produced extensive variation in brain anatomy in the animal world. In guppies, Poecilia reticulata, brain size and anatomy have been extensively studied in the laboratory contributing to our understanding of brain evolution and the cognitive advantages that arise with brain anatomical variation. However, it is unclear whether these laboratory results can be translated to natural populations. Here, we study brain neuroanatomy and its relationship with sexual traits across 18 wild guppy populations in diverse environments. We found extensive variation in female and male relative brain size and brain region volumes across populations in different environment types and with varying degrees of predation risk. In contrast with laboratory studies, we found differences in allometric scaling of brain regions, leading to variation in brain region proportions across populations. Finally, we found an association between sexual traits, mainly the area of black patches and tail length, and brain size. Our results suggest differences in ecological conditions and sexual traits are associated with differences in brain size and brain regions volumes in the wild, as well as sexual dimorphisms in the brain's neuroanatomy.
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Affiliation(s)
- Angie S. Reyes
- Department of Biomedical Engineering, University of Los Andes, Bogota, Colombia
| | - Amaury Bittar
- Department of Biomedical Engineering, University of Los Andes, Bogota, Colombia
| | - Laura C. Ávila
- Department of Biomedical Engineering, University of Los Andes, Bogota, Colombia
| | - Catalina Botia
- Department of Biomedical Engineering, University of Los Andes, Bogota, Colombia
| | - Natalia P. Esmeral
- Department of Biomedical Engineering, University of Los Andes, Bogota, Colombia
| | - Natasha I. Bloch
- Department of Biomedical Engineering, University of Los Andes, Bogota, Colombia
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3
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Fasano G, Compagnucci C, Dallapiccola B, Tartaglia M, Lauri A. Teleost Fish and Organoids: Alternative Windows Into the Development of Healthy and Diseased Brains. Front Mol Neurosci 2022; 15:855786. [PMID: 36034498 PMCID: PMC9403253 DOI: 10.3389/fnmol.2022.855786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
The variety in the display of animals’ cognition, emotions, and behaviors, typical of humans, has its roots within the anterior-most part of the brain: the forebrain, giving rise to the neocortex in mammals. Our understanding of cellular and molecular events instructing the development of this domain and its multiple adaptations within the vertebrate lineage has progressed in the last decade. Expanding and detailing the available knowledge on regionalization, progenitors’ behavior and functional sophistication of the forebrain derivatives is also key to generating informative models to improve our characterization of heterogeneous and mechanistically unexplored cortical malformations. Classical and emerging mammalian models are irreplaceable to accurately elucidate mechanisms of stem cells expansion and impairments of cortex development. Nevertheless, alternative systems, allowing a considerable reduction of the burden associated with animal experimentation, are gaining popularity to dissect basic strategies of neural stem cells biology and morphogenesis in health and disease and to speed up preclinical drug testing. Teleost vertebrates such as zebrafish, showing conserved core programs of forebrain development, together with patients-derived in vitro 2D and 3D models, recapitulating more accurately human neurogenesis, are now accepted within translational workflows spanning from genetic analysis to functional investigation. Here, we review the current knowledge of common and divergent mechanisms shaping the forebrain in vertebrates, and causing cortical malformations in humans. We next address the utility, benefits and limitations of whole-brain/organism-based fish models or neuronal ensembles in vitro for translational research to unravel key genes and pathological mechanisms involved in neurodevelopmental diseases.
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4
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Liu M, Jia J, Wang H, Wang L. Allometric model of brain morphology of Hemiculter leucisculus and its variation along climatic gradients. J Anat 2022; 241:259-271. [PMID: 35383914 DOI: 10.1111/joa.13664] [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: 08/03/2021] [Revised: 03/24/2022] [Accepted: 03/24/2022] [Indexed: 11/27/2022] Open
Abstract
Prior studies on Hemiculter leucisculus, which is a widespread native fish in China, mainly focused on its growth, feeding habits, and individual fecundity, but few have investigated the brain. In this research, we explored the developmental patterns of the Hemiculter leucisculus brain and found the brain showed allometry through sample time points and three age groups. At the same time, we found that the brain varied along climatic gradients. The volumes of the olfactory bulbs, telencephalic lobes, optic tectum, corpus cerebelli, and total brain in the south were larger than those in the north, while the volume of the hypothalamus in the north was larger than in the south. This study provides a view for the in-depth study of the acclimatized mechanism of the teleost brain, lays a foundation for the further study of evolutionary ecology, and provides a reference for the phenotypic plasticity of the teleost brain.
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Affiliation(s)
- Mengyu Liu
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China.,Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Jia Jia
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - He Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Lihong Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
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5
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Závorka L, Koene JP, Armstrong TA, Fehlinger L, Adams CE. Differences in brain morphology of brown trout across stream, lake, and hatchery environments. Ecol Evol 2022; 12:e8684. [PMID: 35309753 PMCID: PMC8902666 DOI: 10.1002/ece3.8684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 11/11/2022] Open
Abstract
It has been suggested that a trade‐off between cognitive capacity and developmental costs may drive brain size and morphology across fish species, but this pattern is less well explored at the intraspecific level. Physical habitat complexity has been proposed as a key selection pressure on cognitive capacity that shapes brain morphology of fishes. In this study, we compared brain morphology of brown trout, Salmo trutta, from stream, lake, and hatchery environments, which generally differ in physical complexity ranging from low habitat complexity in the hatchery to high habitat complexity in streams and intermediate complexity in lakes. We found that brain size, and the size of optic tectum and telencephalon differed across the three habitats, both being largest in lake fish with a tendency to be smaller in the stream compared to hatchery fish. Therefore, our findings do not support the hypothesis that in brown trout the volume of brain and its regions important for navigation and decision‐making increases in physically complex habitats. We suggest that the observed differences in brain size might be associated with diet quality and habitat‐specific behavioral adaptations rather than physical habitat complexity.
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Affiliation(s)
- Libor Závorka
- WasserCluster Lunz - Inter-University Centre for Aquatic Ecosystem Research Lunz am See Austria.,Institute of Biodiversity, Animal Health and Comparative Medicine College of Medical, Veterinary and Life Sciences University of Glasgow Glasgow UK
| | - J Peter Koene
- Institute of Biodiversity, Animal Health and Comparative Medicine College of Medical, Veterinary and Life Sciences University of Glasgow Glasgow UK.,Scottish Centre for Ecology and the Natural Environment (SCENE) University of Glasgow Glasgow UK
| | - Tiffany A Armstrong
- Institute of Biodiversity, Animal Health and Comparative Medicine College of Medical, Veterinary and Life Sciences University of Glasgow Glasgow UK
| | - Lena Fehlinger
- WasserCluster Lunz - Inter-University Centre for Aquatic Ecosystem Research Lunz am See Austria
| | - Colin E Adams
- Scottish Centre for Ecology and the Natural Environment (SCENE) University of Glasgow Glasgow UK
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6
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Fong S, Rogell B, Amcoff M, Kotrschal A, van der Bijl W, Buechel SD, Kolm N. Rapid mosaic brain evolution under artificial selection for relative telencephalon size in the guppy ( Poecilia reticulata). SCIENCE ADVANCES 2021; 7:eabj4314. [PMID: 34757792 PMCID: PMC8580313 DOI: 10.1126/sciadv.abj4314] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The mosaic brain evolution hypothesis, stating that brain regions can evolve relatively independently during cognitive evolution, is an important idea to understand how brains evolve with potential implications even for human brain evolution. Here, we provide the first experimental evidence for this hypothesis through an artificial selection experiment in the guppy (Poecilia reticulata). After four generations of selection on relative telencephalon volume (relative to brain size), we found substantial changes in telencephalon size but no changes in other regions. Further comparisons revealed that up-selected lines had larger telencephalon, while down-selected lines had smaller telencephalon than wild Trinidadian populations. Our results support that independent evolutionary changes in specific brain regions through mosaic brain evolution can be important facilitators of cognitive evolution.
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Affiliation(s)
- Stephanie Fong
- Department of Zoology, Stockholm University, Stockholm, Sweden
- Corresponding author. (S.F.); (N.K.)
| | - Björn Rogell
- Department of Zoology, Stockholm University, Stockholm, Sweden
- Department of Aquatic Resources, Swedish University of Agricultural Sciences, Drottningholm, Sweden
| | - Mirjam Amcoff
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Alexander Kotrschal
- Department of Zoology, Stockholm University, Stockholm, Sweden
- Department of Behavioural Ecology, Wageningen University, Wageningen, Netherlands
| | - Wouter van der Bijl
- Department of Zoology, Stockholm University, Stockholm, Sweden
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | | | - Niclas Kolm
- Department of Zoology, Stockholm University, Stockholm, Sweden
- Corresponding author. (S.F.); (N.K.)
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7
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Liu M, Liu Y, Wang X, Wang H. Brain morphological adaptations of
Gambusia affinis
along climatic gradients in China. J ZOOL SYST EVOL RES 2021. [DOI: 10.1111/jzs.12544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Mengyu Liu
- College of Animal Science and Technology Northwest A&F University Yangling China
| | - Yanqiu Liu
- College of Animal Science and Technology Northwest A&F University Yangling China
| | - Xiaoqin Wang
- College of Animal Science and Technology Northwest A&F University Yangling China
| | - He Wang
- College of Animal Science and Technology Northwest A&F University Yangling China
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8
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Avin S, Currie A, Montgomery SH. An agent-based model clarifies the importance of functional and developmental integration in shaping brain evolution. BMC Biol 2021; 19:97. [PMID: 33971877 PMCID: PMC8111752 DOI: 10.1186/s12915-021-01024-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 04/13/2021] [Indexed: 01/01/2023] Open
Abstract
Background Vertebrate brain structure is characterised not only by relative consistency in scaling between components, but also by many examples of divergence from these general trends.. Alternative hypotheses explain these patterns by emphasising either ‘external’ processes, such as coordinated or divergent selection, or ‘internal’ processes, like developmental coupling among brain regions. Although these hypotheses are not mutually exclusive, there is little agreement over their relative importance across time or how that importance may vary across evolutionary contexts. Results We introduce an agent-based model to simulate brain evolution in a ‘bare-bones’ system and examine dependencies between variables shaping brain evolution. We show that ‘concerted’ patterns of brain evolution do not, in themselves, provide evidence for developmental coupling, despite these terms often being treated as synonymous in the literature. Instead, concerted evolution can reflect either functional or developmental integration. Our model further allows us to clarify conditions under which such developmental coupling, or uncoupling, is potentially adaptive, revealing support for the maintenance of both mechanisms in neural evolution. Critically, we illustrate how the probability of deviation from concerted evolution depends on the cost/benefit ratio of neural tissue, which increases when overall brain size is itself under constraint. Conclusions We conclude that both developmentally coupled and uncoupled brain architectures can provide adaptive mechanisms, depending on the distribution of selection across brain structures, life history and costs of neural tissue. However, when constraints also act on overall brain size, heterogeneity in selection across brain structures will favour region specific, or mosaic, evolution. Regardless, the respective advantages of developmentally coupled and uncoupled brain architectures mean that both may persist in fluctuating environments. This implies that developmental coupling is unlikely to be a persistent constraint, but could evolve as an adaptive outcome to selection to maintain functional integration.
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Affiliation(s)
- Shahar Avin
- Centre for the Study of Existential Risk, University of Cambridge, Cambridge, UK
| | - Adrian Currie
- Department of Sociology, Philosophy and Anthropology, University of Exeter, Exeter, UK
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9
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Colby AE, Kimock CM, Higham JP. Endocranial volume is variable and heritable, but not related to fitness, in a free-ranging primate. Sci Rep 2021; 11:4235. [PMID: 33608572 PMCID: PMC7895985 DOI: 10.1038/s41598-021-81265-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 12/24/2020] [Indexed: 01/31/2023] Open
Abstract
Large relative brain size is a defining characteristic of the order Primates. Arguably, this can be attributed to selection for behavioral aptitudes linked to a larger brain size. In order for selection of a trait to occur, the trait must vary, that variation must be heritable, and enhance fitness. In this study, we use a quantitative genetic approach to investigate the production and maintenance of variation in endocranial volume in a population of free-ranging rhesus macaques. We measured the endocranial volume and body mass proxies of 542 rhesus macaques from Cayo Santiago. We investigated variation in endocranial volume within and between sexes. Using a genetic pedigree, we estimated heritability of absolute and relative endocranial volume, and selection gradients of both traits as well as estimated body mass in the sample. Within this population, both absolute and relative endocranial volume display variation and sexual dimorphism. Both absolute and relative endocranial volume are highly heritable, but we found no evidence of selection on absolute or relative endocranial volume. These findings suggest that endocranial volume is not undergoing selection, or that we did not detect it because selection is neither linear nor quadratic, or that we lacked sufficient sample sizes to detect it.
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Affiliation(s)
- Abigail E Colby
- Department of Anthropology, New York University, New York, NY, 10003, USA
| | - Clare M Kimock
- Department of Anthropology, New York University, New York, NY, 10003, USA
| | - James P Higham
- Department of Anthropology, New York University, New York, NY, 10003, USA.
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10
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Axelrod CJ, Laberge F, Robinson BW. Interspecific and intraspecific comparisons reveal the importance of evolutionary context in sunfish brain form divergence. J Evol Biol 2021; 34:639-652. [PMID: 33484022 DOI: 10.1111/jeb.13763] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 12/23/2020] [Accepted: 01/11/2021] [Indexed: 01/03/2023]
Abstract
Habitats can select for specialized phenotypic characteristics in animals. However, the consistency of evolutionary responses to particular environmental conditions remains difficult to predict. One trait of great ecological importance is brain form, which is expected to vary between habitats that differ in their cognitive requirements. Here, we compared divergence in brain form and oral jaw size across a common littoral-pelagic ecological axis in two sunfishes at both the intraspecific and interspecific levels. Brain form differed between habitats at every level of comparison; however, divergence was inconsistent, despite consistent differences in oral jaw size. Pumpkinseed and bluegill species differed in cerebellum, optic tectum and olfactory bulb size. These differences are consistent with a historical ecological divergence because they did not manifest between littoral and pelagic ecotypes within either species, suggesting constraints on changes to these regions over short evolutionary time scales. There were also differences in brain form between conspecific ecotypes, but they were inconsistent between species. Littoral pumpkinseed had larger brains than their pelagic counterpart, and littoral bluegill had smaller telencephalons than their pelagic counterpart. Inconsistent brain form divergence between conspecific ecotypes of pumpkinseed and bluegill sharing a common littoral-pelagic habitat axis suggests that contemporary ecological conditions and historic evolutionary context interact to influence evolutionary changes in brain form in fishes.
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Affiliation(s)
- Caleb J Axelrod
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - Frédéric Laberge
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - Beren W Robinson
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
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11
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Herczeg G, Urszán TJ, Orf S, Nagy G, Kotrschal A, Kolm N. Yes, correct context is indeed the key: An answer to Haave-Audet et al. 2019. J Evol Biol 2019; 32:1450-1455. [PMID: 31604005 DOI: 10.1111/jeb.13548] [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: 10/04/2019] [Accepted: 10/07/2019] [Indexed: 11/26/2022]
Abstract
We published a study recently testing the link between brain size and behavioural plasticity using brain size selected guppy (Poecilia reticulata) lines (2019, Journal of Evolutionary Biology, 32, 218-226). Only large-brained fish showed habituation to a new, but actually harmless environment perceived as risky, by increasing movement activity over the 20-day observation period. We concluded that "Our results suggest that brain size likely explains some of the variation in behavioural plasticity found at the intraspecific level". In a commentary published in the same journal, Haave-Audet et al. challenged the main message of our study, stating that (a) relative brain size is not a suitable proxy for cognitive ability and (b) habituation measured by us is likely not adaptive and costly. In our response, we first show that a decade's work has proven repeatedly that relative brain size is indeed positively linked to cognitive performance in our model system. Second, we discuss how switching from stressed to unstressed behaviour in stressful situations without real risk is likely adaptive. Finally, we point out that the main cost of behavioural plasticity in our case is the development and maintenance of the neural system needed for information processing, and not the expression of plasticity. We hope that our discussion with Haave-Audet et al. helps clarifying some central issues in this emerging research field.
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Affiliation(s)
- Gábor Herczeg
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest, Hungary
| | - Tamás János Urszán
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest, Hungary
| | - Stephanie Orf
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest, Hungary
| | - Gergely Nagy
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest, Hungary
| | | | - Niclas Kolm
- Department of Zoology, Stockholm University, Stockholm, Sweden
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12
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D'Aniello B, Di Cosmo A, Scandurra A, Pinelli C. Mosaic and Concerted Brain Evolution: The Contribution of Microscopic Comparative Neuroanatomy in Lower Vertebrates. Front Neuroanat 2019; 13:86. [PMID: 31607870 PMCID: PMC6773805 DOI: 10.3389/fnana.2019.00086] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 09/09/2019] [Indexed: 01/05/2023] Open
Affiliation(s)
- Biagio D'Aniello
- Department of Biology, University of Naples “Federico II”, MSA Campus, Naples, Italy
| | - Anna Di Cosmo
- Department of Biology, University of Naples “Federico II”, MSA Campus, Naples, Italy
| | - Anna Scandurra
- Department of Biology, University of Naples “Federico II”, MSA Campus, Naples, Italy
| | - Claudia Pinelli
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania “L. Vanvitelli”, Caserta, Italy
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13
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Muller AS, Montgomery SH. Co-evolution of cerebral and cerebellar expansion in cetaceans. J Evol Biol 2019; 32:1418-1431. [PMID: 31507000 PMCID: PMC6916408 DOI: 10.1111/jeb.13539] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 08/27/2019] [Indexed: 12/23/2022]
Abstract
Cetaceans possess brains that rank among the largest to have ever evolved, either in terms of absolute mass or relative to body size. Cetaceans have evolved these huge brains under relatively unique environmental conditions, making them a fascinating case study to investigate the constraints and selection pressures that shape how brains evolve. Indeed, cetaceans have some unusual neuroanatomical features, including a thin but highly folded cerebrum with low cortical neuron density, as well as many structural adaptations associated with acoustic communication. Previous reports also suggest that at least some cetaceans have an expanded cerebellum, a brain structure with wide‐ranging functions in adaptive filtering of sensory information, the control of motor actions, and cognition. Here, we report that, relative to the size of the rest of the brain, both the cerebrum and cerebellum are dramatically enlarged in cetaceans and show evidence of co‐evolution, a pattern of brain evolution that is convergent with primates. However, we also highlight several branches where cortico‐cerebellar co‐evolution may be partially decoupled, suggesting these structures can respond to independent selection pressures. Across cetaceans, we find no evidence of a simple linear relationship between either cerebrum and cerebellum size and the complexity of social ecology or acoustic communication, but do find evidence that their expansion may be associated with dietary breadth. In addition, our results suggest that major increases in both cerebrum and cerebellum size occurred early in cetacean evolution, prior to the origin of the major extant clades, and predate the evolution of echolocation.
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Affiliation(s)
| | - Stephen Hugh Montgomery
- Department of Zoology, University of Cambridge, Cambridge, UK.,School of Biological Sciences, University of Bristol, Bristol, UK
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14
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Absolute and relative estimates of genetic and environmental variance in brain structure volumes. Brain Struct Funct 2019; 224:2805-2821. [PMID: 31428865 DOI: 10.1007/s00429-019-01931-8] [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: 10/30/2018] [Accepted: 07/30/2019] [Indexed: 10/26/2022]
Abstract
Comparing estimates of the amount of genetic and environmental variance for different brain structures may elucidate differences in the genetic architecture or developmental constraints of individual brain structures. However, most studies compare estimates of relative genetic (heritability) and environmental variance in brain structure, which do not reflect differences in absolute variance between brain regions. Here we used a population sample of young adult twins and singleton siblings of twins (n = 791; M = 23 years, Queensland Twin IMaging study) to estimate the absolute genetic and environmental variance, standardised by the phenotypic mean, in the size of cortical, subcortical, and ventricular brain structures. Mean-standardised genetic variance differed widely across structures [23.5-fold range 0.52% (hippocampus) to 12.28% (lateral ventricles)], but the range of estimates within cortical, subcortical, or ventricular structures was more moderate (two to fivefold range). There was no association between mean-standardised and relative measures of genetic variance (i.e., heritability) in brain structure volumes. We found similar results in an independent sample (n = 1075, M = 29 years, Human Connectome Project). These findings open important new lines of enquiry: namely, understanding the bases of these variance patterns, and their implications regarding the genetic architecture, evolution, and development of the human brain.
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15
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Pike TW, Ramsey M, Wilkinson A. Environmentally induced changes to brain morphology predict cognitive performance. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0287. [PMID: 30104432 DOI: 10.1098/rstb.2017.0287] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2018] [Indexed: 11/12/2022] Open
Abstract
The relationship between the size and structure of a species' brain and its cognitive capacity has long interested scientists. Generally, this work relates interspecific variation in brain anatomy with performance on a variety of cognitive tasks. However, brains are known to show considerable short-term plasticity in response to a range of social, ecological and environmental factors. Despite this, we have a remarkably poor understanding of how this impacts on an animal's cognitive performance. Here, we non-invasively manipulated the relative size of brain regions associated with processing visual and chemical information in fish (the optic tectum and olfactory bulbs, respectively). We then tested performance in a cognitive task in which information from the two sensory modalities was in conflict. Although the fish could effectively use both visual and chemical information if presented in isolation, when they received cues from both modalities simultaneously, those with a relatively better developed optic tectum showed a greater reliance on visual information, while individuals with relatively better developed olfactory bulbs showed a greater reliance on chemical information. These results suggest that short-term changes in brain structure, possibly resulting from an attempt to minimize the costs of developing unnecessary but energetically expensive brain regions, may have marked effects on cognitive performance.This article is part of the theme issue 'Causes and consequences of individual differences in cognitive abilities'.
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Affiliation(s)
- Thomas W Pike
- School of Life Sciences, University of Lincoln, Lincoln LN6 7TS, UK
| | - Michael Ramsey
- School of Life Sciences, University of Lincoln, Lincoln LN6 7TS, UK.,School of Science and Technology, Nottingham Trent University, Nottingham NG1 4FQ, UK
| | - Anna Wilkinson
- School of Life Sciences, University of Lincoln, Lincoln LN6 7TS, UK.,Wildlife Research Center, Kyoto University, Kyoto 606-8203, Japan
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16
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Halley AC, Krubitzer L. Not all cortical expansions are the same: the coevolution of the neocortex and the dorsal thalamus in mammals. Curr Opin Neurobiol 2019; 56:78-86. [PMID: 30658218 DOI: 10.1016/j.conb.2018.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/18/2018] [Accepted: 12/09/2018] [Indexed: 02/06/2023]
Abstract
A central question in comparative neurobiology concerns how evolution has produced brains with expanded neocortices, composed of more areas with unique connectivity and functional properties. Some mammalian lineages, such as primates, exhibit exceptionally large cortices relative to the amount of sensory inputs from the dorsal thalamus, and this expansion is associated with a larger number of distinct cortical areas, composing a larger proportion of the cortical sheet. We propose a link between the organization of the neocortex and its expansion relative to the size of the dorsal thalamus, based on a combination of work in comparative neuroanatomy and experimental research.
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Affiliation(s)
- Andrew C Halley
- Center for Neuroscience, University of California, Davis, CA, United States
| | - Leah Krubitzer
- Center for Neuroscience, University of California, Davis, CA, United States; Department of Psychology, University of California, Davis, CA, United States.
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17
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Axelrod CJ, Laberge F, Robinson BW. Intraspecific brain size variation between coexisting sunfish ecotypes. Proc Biol Sci 2018; 285:rspb.2018.1971. [PMID: 30404883 DOI: 10.1098/rspb.2018.1971] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 10/12/2018] [Indexed: 01/19/2023] Open
Abstract
Variation in spatial complexity and foraging requirements between habitats can impose different cognitive demands on animals that may influence brain size. However, the relationship between ecologically related cognitive performance and brain size is not well established. We test whether variation in relative brain size and brain region size is associated with habitat use within a population of pumpkinseed sunfish composed of different ecotypes that inhabit either the structurally complex shoreline littoral habitat or simpler open-water pelagic habitat. Sunfish using the littoral habitat have on average 8.3% larger brains than those using the pelagic habitat. We found little difference in the proportional sizes of five brain regions between ecotypes. The results suggest that cognitive demands on sunfish may be reduced in the pelagic habitat given no habitat-specific differences in body condition. They also suggest that either a short divergence time or physiological processes may constrain changes to concerted, global modifications of brain size between sunfish ecotypes.
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Affiliation(s)
- Caleb J Axelrod
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Frédéric Laberge
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Beren W Robinson
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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18
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Breakdown of brain–body allometry and the encephalization of birds and mammals. Nat Ecol Evol 2018; 2:1492-1500. [DOI: 10.1038/s41559-018-0632-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/05/2018] [Indexed: 11/09/2022]
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19
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Angyal D, Balázs G, Krízsik V, Herczeg G, Fehér Z. Molecular and morphological divergence in a stygobiont gastropod lineage (Truncatelloidea, Moitessieriidae, Paladilhiopsis
) within an isolated karstic area in the Mecsek Mountains (Hungary). J ZOOL SYST EVOL RES 2018. [DOI: 10.1111/jzs.12220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dorottya Angyal
- Department of Zoology; Hungarian Natural History Museum; Budapest Hungary
| | - Gergely Balázs
- Department of Systematic Zoology and Ecology; Eötvös Loránd University; Budapest Hungary
| | - Virág Krízsik
- Laboratory of Molecular Taxonomy; Hungarian Natural History Museum; Budapest Hungary
| | - Gábor Herczeg
- Department of Systematic Zoology and Ecology; Eötvös Loránd University; Budapest Hungary
| | - Zoltán Fehér
- Department of Zoology; Hungarian Natural History Museum; Budapest Hungary
- Central Research Laboratories; Zoology Department; Natural History Museum; Vienna Austria
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20
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Samuk K, Xue J, Rennision DJ. Exposure to predators does not lead to the evolution of larger brains in experimental populations of threespine stickleback. Evolution 2018; 72:916-929. [PMID: 29392719 DOI: 10.1111/evo.13444] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Revised: 01/18/2018] [Accepted: 01/21/2018] [Indexed: 01/22/2023]
Abstract
Natural selection is often invoked to explain differences in brain size among vertebrates. However, the particular agents of selection that shape brain size variation remain obscure. Recent studies suggest that predators may select for larger brains because increased cognitive and sensory abilities allow prey to better elude predators. Yet, there is little direct evidence that exposure to predators causes the evolution of larger brains in prey species. We experimentally tested this prediction by exposing families of 1000-2000 F2 hybrid benthic-limnetic threespine stickleback to predators under naturalistic conditions, along with matched controls. After two generations of selection, we found that fish from the predator addition treatment had significantly smaller brains (specifically smaller telencephalons and optic lobes) than fish from the control treatment. After an additional generation of selection, we reared experimental fish in a common environment and found that this difference in brain size was maintained in the offspring of fish from the predator addition treatment. Our results provide direct experimental evidence that (a) predators can indeed drive the evolution of brain size--but not in the fashion commonly expected and (b) that the tools of experimental evolution can be used to the study the evolution of the vertebrate brain.
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Affiliation(s)
- Kieran Samuk
- Department of Biology, Duke University, Durham, North Carolina 27708
| | - Jan Xue
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Diana J Rennision
- Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
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21
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Duckworth RA, Potticary AL, Badyaev AV. On the Origins of Adaptive Behavioral Complexity: Developmental Channeling of Structural Trade-offs. ADVANCES IN THE STUDY OF BEHAVIOR 2018. [DOI: 10.1016/bs.asb.2017.10.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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22
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Montgomery SH, Mundy NI, Barton RA. Brain evolution and development: adaptation, allometry and constraint. Proc Biol Sci 2017; 283:rspb.2016.0433. [PMID: 27629025 DOI: 10.1098/rspb.2016.0433] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 08/19/2016] [Indexed: 01/08/2023] Open
Abstract
Phenotypic traits are products of two processes: evolution and development. But how do these processes combine to produce integrated phenotypes? Comparative studies identify consistent patterns of covariation, or allometries, between brain and body size, and between brain components, indicating the presence of significant constraints limiting independent evolution of separate parts. These constraints are poorly understood, but in principle could be either developmental or functional. The developmental constraints hypothesis suggests that individual components (brain and body size, or individual brain components) tend to evolve together because natural selection operates on relatively simple developmental mechanisms that affect the growth of all parts in a concerted manner. The functional constraints hypothesis suggests that correlated change reflects the action of selection on distributed functional systems connecting the different sub-components, predicting more complex patterns of mosaic change at the level of the functional systems and more complex genetic and developmental mechanisms. These hypotheses are not mutually exclusive but make different predictions. We review recent genetic and neurodevelopmental evidence, concluding that functional rather than developmental constraints are the main cause of the observed patterns.
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Affiliation(s)
- Stephen H Montgomery
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Nicholas I Mundy
- Department of Zoology, University of Cambridge, St Andrews Street, Cambridge CB2 3EJ, UK
| | - Robert A Barton
- Evolutionary Anthropology Research Group, Durham University, Dawson Building, South Road, Durham DH1 3LE, UK
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23
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Keagy J, Braithwaite VA, Boughman JW. Brain differences in ecologically differentiated sticklebacks. Curr Zool 2017; 64:243-250. [PMID: 30402065 PMCID: PMC5905471 DOI: 10.1093/cz/zox074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/20/2017] [Indexed: 11/12/2022] Open
Abstract
Populations that have recently diverged offer a powerful model for studying evolution. Ecological differences are expected to generate divergent selection on multiple traits, including neurobiological ones. Animals must detect, process, and act on information from their surroundings and the form of this information can be highly dependent on the environment. We might expect different environments to generate divergent selection not only on the sensory organs, but also on the brain regions responsible for processing sensory information. Here, we test this hypothesis using recently evolved reproductively isolated species pairs of threespine stickleback fish Gasterosteus aculeatus that have well-described differences in many morphological and behavioral traits correlating with ecological differences. We use a state-of-the-art method, magnetic resonance imaging, to get accurate volumetric data for 2 sensory processing regions, the olfactory bulbs and optic tecta. We found a tight correlation between ecology and the size of these brain regions relative to total brain size in 2 lakes with intact species pairs. Limnetic fish, which rely heavily on vision, had relatively larger optic tecta and smaller olfactory bulbs compared with benthic fish, which utilize olfaction to a greater extent. Benthic fish also had larger total brain volumes relative to their body size compared with limnetic fish. These differences were erased in a collapsed species pair in Enos Lake where anthropogenic disturbance has led to intense hybridization. Together these data indicate that evolution of sensory processing regions can occur rapidly and independently.
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Affiliation(s)
- Jason Keagy
- Department of Animal Biology, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA.,Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48824, USA
| | - Victoria A Braithwaite
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA 16802, USA.,Department of Biology, Pennsylvania State University, University Park, PA 16802, USA.,Center for Brain, Behavior and Cognition, Pennsylvania State University, University Park, PA 16802, USA
| | - Janette W Boughman
- Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48824, USA.,Program in Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI 48824, USA
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24
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Harrison PW, Montgomery SH. Genetics of Cerebellar and Neocortical Expansion in Anthropoid Primates: A Comparative Approach. BRAIN, BEHAVIOR AND EVOLUTION 2017; 89:274-285. [PMID: 28683440 PMCID: PMC5637284 DOI: 10.1159/000477432] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 05/10/2017] [Accepted: 05/10/2017] [Indexed: 12/15/2022]
Abstract
What adaptive changes in brain structure and function underpin the evolution of increased cognitive performance in humans and our close relatives? Identifying the genetic basis of brain evolution has become a major tool in answering this question. Numerous cases of positive selection, altered gene expression or gene duplication have been identified that may contribute to the evolution of the neocortex, which is widely assumed to play a predominant role in cognitive evolution. However, the components of the neocortex co-evolve with other functionally interdependent regions of the brain, most notably in the cerebellum. The cerebellum is linked to a range of cognitive tasks and expanded rapidly during hominoid evolution. Here we present data that suggest that, across anthropoid primates, protein-coding genes with known roles in cerebellum development were just as likely to be targeted by selection as genes linked to cortical development. Indeed, based on currently available gene ontology data, protein-coding genes with known roles in cerebellum development are more likely to have evolved adaptively during hominoid evolution. This is consistent with phenotypic data suggesting an accelerated rate of cerebellar expansion in apes that is beyond that predicted from scaling with the neocortex in other primates. Finally, we present evidence that the strength of selection on specific genes is associated with variation in the volume of either the neocortex or the cerebellum, but not both. This result provides preliminary evidence that co-variation between these brain components during anthropoid evolution may be at least partly regulated by selection on independent loci, a conclusion that is consistent with recent intraspecific genetic analyses and a mosaic model of brain evolution that predicts adaptive evolution of brain structure.
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Affiliation(s)
- Peter W. Harrison
- Department of Genetics, Evolution and Environment, University College London, London, UK
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, UK
| | - Stephen H. Montgomery
- Department of Genetics, Evolution and Environment, University College London, London, UK
- Department of Zoology, University of Cambridge, Cambridge, UK
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25
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Kotrschal A, Deacon AE, Magurran AE, Kolm N. Predation pressure shapes brain anatomy in the wild. Evol Ecol 2017; 31:619-633. [PMID: 32009719 PMCID: PMC6961500 DOI: 10.1007/s10682-017-9901-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 05/08/2017] [Indexed: 11/30/2022]
Abstract
There is remarkable diversity in brain anatomy among vertebrates and evidence is accumulating that predatory interactions are crucially important for this diversity. To test this hypothesis, we collected female guppies (Poecilia reticulata) from 16 wild populations and related their brain anatomy to several aspects of predation pressure in this ecosystem, such as the biomass of the four major predators of guppies (one prawn and three fish species), and predator diversity (number of predatory fish species in each site). We found that populations from localities with higher prawn biomass had relatively larger telencephalon size as well as larger brains. Optic tectum size was positively associated with one of the fish predator’s biomass and with overall predator diversity. However, both olfactory bulb and hypothalamus size were negatively associated with the biomass of another of the fish predators. Hence, while fish predator occurrence is associated with variation in brain anatomy, prawn occurrence is associated with variation in brain size. Our results suggest that cognitive challenges posed by local differences in predator communities may lead to changes in prey brain anatomy in the wild.
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Affiliation(s)
- Alexander Kotrschal
- 1Department of Ethology/Zoology, Stockholm University, Svante Arheniusväg 18B, 10691 Stockholm, Sweden
| | - Amy E Deacon
- 2Department of Life Sciences, The University of the West Indies, St Augustine, Trinidad and Tobago
| | - Anne E Magurran
- 3School of Biology, University of St Andrews, St Andrews, Scotland, UK
| | - Niclas Kolm
- 1Department of Ethology/Zoology, Stockholm University, Svante Arheniusväg 18B, 10691 Stockholm, Sweden
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26
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Toli EA, Noreikiene K, DeFaveri J, Merilä J. Environmental enrichment, sexual dimorphism, and brain size in sticklebacks. Ecol Evol 2017; 7:1691-1698. [PMID: 28331580 PMCID: PMC5355184 DOI: 10.1002/ece3.2717] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 11/21/2016] [Accepted: 12/17/2016] [Indexed: 01/29/2023] Open
Abstract
Evidence for phenotypic plasticity in brain size and the size of different brain parts is widespread, but experimental investigations into this effect remain scarce and are usually conducted using individuals from a single population. As the costs and benefits of plasticity may differ among populations, the extent of brain plasticity may also differ from one population to another. In a common garden experiment conducted with three-spined sticklebacks (Gasterosteus aculeatus) originating from four different populations, we investigated whether environmental enrichment (aquaria provided with structural complexity) caused an increase in the brain size or size of different brain parts compared to controls (bare aquaria). We found no evidence for a positive effect of environmental enrichment on brain size or size of different brain parts in either of the sexes in any of the populations. However, in all populations, males had larger brains than females, and the degree of sexual size dimorphism (SSD) in relative brain size ranged from 5.1 to 11.6% across the populations. Evidence was also found for genetically based differences in relative brain size among populations, as well as for plasticity in the size of different brain parts, as evidenced by consistent size differences among replicate blocks that differed in their temperature.
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Affiliation(s)
- Elisavet A Toli
- Molecular Ecology & Conservation Genetics Lab Department of Biological Applications & Technology University of Ioannina Ioannina Greece; Ecological Genetics Research Unit Department of Biosciences University of Helsinki Helsinki Finland
| | - Kristina Noreikiene
- Ecological Genetics Research Unit Department of Biosciences University of Helsinki Helsinki Finland
| | - Jacquelin DeFaveri
- Ecological Genetics Research Unit Department of Biosciences University of Helsinki Helsinki Finland
| | - Juha Merilä
- Ecological Genetics Research Unit Department of Biosciences University of Helsinki Helsinki Finland
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27
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Li Z, Guo B, Yang J, Herczeg G, Gonda A, Balázs G, Shikano T, Calboli FCF, Merilä J. Deciphering the genomic architecture of the stickleback brain with a novel multilocus gene-mapping approach. Mol Ecol 2017; 26:1557-1575. [DOI: 10.1111/mec.14005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 11/11/2016] [Accepted: 11/14/2016] [Indexed: 12/24/2022]
Affiliation(s)
- Zitong Li
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; P.O. Box 65 FI-00014 Helsinki Finland
| | - Baocheng Guo
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; P.O. Box 65 FI-00014 Helsinki Finland
| | - Jing Yang
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; P.O. Box 65 FI-00014 Helsinki Finland
| | - Gábor Herczeg
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; P.O. Box 65 FI-00014 Helsinki Finland
- Behavioural Ecology Group; Department of Systematic Zoology and Ecology; Eötvös Loránd University; Pázmány Péter sétány1/C 1117 Budapest Hungary
| | - Abigél Gonda
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; P.O. Box 65 FI-00014 Helsinki Finland
| | - Gergely Balázs
- Behavioural Ecology Group; Department of Systematic Zoology and Ecology; Eötvös Loránd University; Pázmány Péter sétány1/C 1117 Budapest Hungary
| | - Takahito Shikano
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; P.O. Box 65 FI-00014 Helsinki Finland
| | - Federico C. F. Calboli
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; P.O. Box 65 FI-00014 Helsinki Finland
| | - Juha Merilä
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; P.O. Box 65 FI-00014 Helsinki Finland
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28
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Logan CJ, Kruuk LEB, Stanley R, Thompson AM, Clutton-Brock TH. Endocranial volume is heritable and is associated with longevity and fitness in a wild mammal. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160622. [PMID: 28083105 PMCID: PMC5210687 DOI: 10.1098/rsos.160622] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/17/2016] [Indexed: 05/08/2023]
Abstract
Research on relative brain size in mammals suggests that increases in brain size may generate benefits to survival and costs to fecundity: comparative studies of mammals have shown that interspecific differences in relative brain size are positively correlated with longevity and negatively with fecundity. However, as yet, no studies of mammals have investigated whether similar relationships exist within species, nor whether individual differences in brain size within a wild population are heritable. Here we show that, in a wild population of red deer (Cervus elaphus), relative endocranial volume was heritable (h2 = 63%; 95% credible intervals (CI) = 50-76%). In females, it was positively correlated with longevity and lifetime reproductive success, though there was no evidence that it was associated with fecundity. In males, endocranial volume was not related to longevity, lifetime breeding success or fecundity.
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Affiliation(s)
- C. J. Logan
- Department of Zoology, University of Cambridge, Cambridge, UK
- Author for correspondence: C. J. Logan e-mail:
| | - L. E. B. Kruuk
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
- Division of Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, Australia
| | - R. Stanley
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - A. M. Thompson
- Department of Zoology, University of Cambridge, Cambridge, UK
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29
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Metzger DCH, Schulte PM. Maternal stress has divergent effects on gene expression patterns in the brains of male and female threespine stickleback. Proc Biol Sci 2016; 283:rspb.2016.1734. [PMID: 27683372 DOI: 10.1098/rspb.2016.1734] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 09/05/2016] [Indexed: 11/12/2022] Open
Abstract
Maternal stress can have long-term effects on neurodevelopment that can influence offspring performance and population evolutionary trajectories. To examine the mechanistic basis for these neurodevelopmental effects of maternal stress, we used RNA-seq to assess differential gene expression across the brain transcriptome of adult male and female threespine stickleback (Gasterosteus aculeatus) from stressed and unstressed mothers. We identified sexually divergent effects of maternal stress on the brain transcriptome. In males, genes that were upregulated by maternal stress were enriched for processes involved in synaptic function and organization and steroid hormone-mediated signalling pathways, whereas in females genes that were upregulated by maternal stress were enriched for processes involved in protein translation and metabolic functions. The expression of several genes involved in the hypothalamic-pituitary-interrenal response to stress and epigenetic processes such as the regulation of DNA methylation patterns and miRNAs increased in males and not in females. These data suggest that maternal stress has markedly different effects on cellular pathways in the brains of male and female offspring of mothers that are exposed to stress, which could have important implications when assessing the long-term ecological and evolutionary impacts of stress across generations.
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Affiliation(s)
- David C H Metzger
- Department of Zoology, 6270 University Boulevard, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - Patricia M Schulte
- Department of Zoology, 6270 University Boulevard, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
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30
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Näslund J, Larsen MH, Thomassen ST, Aarestrup K, Johnsson JI. Environment‐dependent plasticity and ontogenetic changes in the brain of hatchery‐reared Atlantic salmon. J Zool (1987) 2016. [DOI: 10.1111/jzo.12392] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. Näslund
- Department of Biological and Environmental Sciences University of Gothenburg Gothenburg Sweden
| | - M. H. Larsen
- National Institute of Aquatic Resources Section for Freshwater Fisheries and Ecology Technical University of Denmark Silkeborg Denmark
- Danish Centre for Wild Salmon Randers Denmark
| | | | - K. Aarestrup
- National Institute of Aquatic Resources Section for Freshwater Fisheries and Ecology Technical University of Denmark Silkeborg Denmark
| | - J. I. Johnsson
- Department of Biological and Environmental Sciences University of Gothenburg Gothenburg Sweden
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31
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Toli EA, Calboli FCF, Shikano T, Merilä J. A universal and reliable assay for molecular sex identification of three-spined sticklebacks (Gasterosteus aculeatus). Mol Ecol Resour 2016; 16:1389-1400. [PMID: 27238091 DOI: 10.1111/1755-0998.12543] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 05/20/2016] [Accepted: 05/20/2016] [Indexed: 11/27/2022]
Abstract
In heterogametic species, biological differences between the two sexes are ubiquitous, and hence, errors in sex identification can be a significant source of noise and bias in studies where sex-related sources of variation are of interest or need to be controlled for. We developed and validated a universal multimarker assay for reliable sex identification of three-spined sticklebacks (Gasterosteus aculeatus). The assay makes use of genotype scores from three sex-linked loci and utilizes Bayesian probabilistic inference to identify sex of the genotyped individuals. The results, validated with 286 phenotypically sexed individuals from six populations of sticklebacks representing all major genetic lineages (cf. Pacific, Atlantic and Japan Sea), indicate that in contrast to commonly used single-marker-based sex identification assays, the developed multimarker assay should be 100% accurate. As the markers in the assay can be scored from agarose gels, it provides a quick and cost-efficient tool for universal sex identification of three-spined sticklebacks. The general principle of combining information from multiple markers to improve the reliability of sex identification is transferable and can be utilized to develop and validate similar assays for other species.
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Affiliation(s)
- E-A Toli
- Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, P.O. Box 65, Helsinki, FI-00014, Finland.,Molecular Ecology & Conservation Genetics Lab, Department of Biological Applications & Technology, University of Ioannina, Ioannina, GR-45110, Greece
| | - F C F Calboli
- Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, P.O. Box 65, Helsinki, FI-00014, Finland
| | - T Shikano
- Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, P.O. Box 65, Helsinki, FI-00014, Finland
| | - J Merilä
- Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, P.O. Box 65, Helsinki, FI-00014, Finland.
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32
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Schulz‐Mirbach T, Eifert C, Riesch R, Farnworth MS, Zimmer C, Bierbach D, Klaus S, Tobler M, Streit B, Indy JR, Arias‐Rodriguez L, Plath M. Toxic hydrogen sulphide shapes brain anatomy: a comparative study of sulphide‐adapted ecotypes in the
Poecilia mexicana
complex. J Zool (1987) 2016. [DOI: 10.1111/jzo.12366] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- T. Schulz‐Mirbach
- Department Biology II Ludwig‐Maximilians‐University Munich Planegg‐Martinsried Germany
| | - C. Eifert
- Ecology and Evolution J. W. Goethe University Frankfurt Frankfurt am Main Germany
| | - R. Riesch
- School of Biological Sciences Royal Holloway University of London Egham UK
| | - M. S. Farnworth
- Göttingen Center for Molecular Biosciences Georg‐August‐University Göttingen Göttingen Germany
| | - C. Zimmer
- Ecology and Evolution J. W. Goethe University Frankfurt Frankfurt am Main Germany
| | - D. Bierbach
- Department of Biology and Ecology of Fishes Leibniz‐Institute of Freshwater Ecology and Inland Fisheries Berlin Germany
| | - S. Klaus
- Ecology and Evolution J. W. Goethe University Frankfurt Frankfurt am Main Germany
| | - M. Tobler
- Division of Biology Kansas State University Manhattan KS USA
| | - B. Streit
- Ecology and Evolution J. W. Goethe University Frankfurt Frankfurt am Main Germany
| | - J. R. Indy
- División Académica de Ciencias Biológicas Universidad Juárez Autónoma de Tabasco (UJAT) Villahermosa Tabasco México
| | - L. Arias‐Rodriguez
- División Académica de Ciencias Biológicas Universidad Juárez Autónoma de Tabasco (UJAT) Villahermosa Tabasco México
| | - M. Plath
- College of Animal Science and Technology Northwest A&F University Yangling China
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33
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Thompson RRJ, Paul ES, Radford AN, Purser J, Mendl M. Routine handling methods affect behaviour of three-spined sticklebacks in a novel test of anxiety. Behav Brain Res 2016; 306:26-35. [PMID: 26965568 PMCID: PMC4850245 DOI: 10.1016/j.bbr.2016.03.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 02/29/2016] [Accepted: 03/05/2016] [Indexed: 11/30/2022]
Abstract
Fish are increasingly popular subjects in behavioural and neurobiological research. It is therefore important that they are housed and handled appropriately to ensure good welfare and reliable scientific findings, and that species-appropriate behavioural tests (e.g. of cognitive/affective states) are developed. Routine handling of captive animals may cause physiological stress responses that lead to anxiety-like states (e.g. increased perception of danger). In fish, these may be particularly pronounced when handling during tank-to-tank transfer involves removal from water into air. Here we develop and use a new combined scototaxis (preference for dark over light areas) and novel-tank-diving test, alongside conventional open-field and novel-object tests, to measure the effects of transferring three-spined sticklebacks (Gasterosteus aculeatus) between tanks using a box or net (in and out of water respectively). Preference tests for dark over light areas confirmed the presence of scototaxis in this species. Open-field and novel-object tests failed to detect any significant differences between net and box-handled fish. However, the combined diving and scototaxis detected consistent differences between the treatments. Net-handled fish spent less time on the dark side of the tank, less time in the bottom third, and kept a greater distance from the 'safe' bottom dark area than box-handled fish. Possible explanations for this reduction in anxiety-like behaviour in net-handled fish are discussed. The combined diving and scototaxis test may be a sensitive and taxon-appropriate method for measuring anxiety-like states in fish.
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Affiliation(s)
- Ralph R J Thompson
- Centre for Behavioural Biology, School of Veterinary Science, University of Bristol, UK
| | - Elizabeth S Paul
- Centre for Behavioural Biology, School of Veterinary Science, University of Bristol, UK
| | | | - Julia Purser
- School of Biological Sciences, University of Bristol, UK
| | - Michael Mendl
- Centre for Behavioural Biology, School of Veterinary Science, University of Bristol, UK.
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Edmunds NB, McCann KS, Laberge F. Food Web Structure Shapes the Morphology of Teleost Fish Brains. BRAIN, BEHAVIOR AND EVOLUTION 2016; 87:128-38. [PMID: 27216606 DOI: 10.1159/000445973] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 04/05/2016] [Indexed: 11/19/2022]
Abstract
Previous work showed that teleost fish brain size correlates with the flexible exploitation of habitats and predation abilities in an aquatic food web. Since it is unclear how regional brain changes contribute to these relationships, we quantitatively examined the effects of common food web attributes on the size of five brain regions in teleost fish at both within-species (plasticity or natural variation) and between-species (evolution) scales. Our results indicate that brain morphology is influenced by habitat use and trophic position, but not by the degree of littoral-pelagic habitat coupling, despite the fact that the total brain size was previously shown to increase with habitat coupling in Lake Huron. Intriguingly, the results revealed two potential evolutionary trade-offs: (i) relative olfactory bulb size increased, while relative optic tectum size decreased, across a trophic position gradient, and (ii) the telencephalon was relatively larger in fish using more littoral-based carbon, while the cerebellum was relatively larger in fish using more pelagic-based carbon. Additionally, evidence for a within-species effect on the telencephalon was found, where it increased in size with trophic position. Collectively, these results suggest that food web structure has fundamentally contributed to the shaping of teleost brain morphology.
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Herczeg G, Gonda A, Balázs G, Noreikiene K, Merilä J. Experimental evidence for sex-specific plasticity in adult brain. Front Zool 2015; 12:38. [PMID: 26705404 PMCID: PMC4690261 DOI: 10.1186/s12983-015-0130-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 12/15/2015] [Indexed: 01/22/2023] Open
Abstract
Background Plasticity in brain size and the size of different brain regions during early ontogeny is known from many vertebrate taxa, but less is known about plasticity in the brains of adults. In contrast to mammals and birds, most parts of a fish’s brain continue to undergo neurogenesis throughout adulthood, making lifelong plasticity in brain size possible. We tested whether maturing adult three-spined sticklebacks (Gasterosteus aculeatus) reared in a stimulus-poor environment exhibited brain plasticity in response to environmental enrichment, and whether these responses were sex-specific, thus altering the degree of sexual size dimorphism in the brain. Results Relative sizes of total brain and bulbus olfactorius showed sex-specific responses to treatment: males developed larger brains but smaller bulbi olfactorii than females in the enriched treatment. Hence, the degree of sexual size dimorphism (SSD) in relative brain size and the relative size of the bulbus olfactorius was found to be environment-dependent. Furthermore, the enriched treatment induced development of smaller tecta optica in both sexes. Conclusions These results demonstrate that adult fish can alter the size of their brain (or brain regions) in response to environmental stimuli, and these responses can be sex-specific. Hence, the degree of SSD in brain size can be environment-dependent, and our results hint at the possibility of a large plastic component to SSD in stickleback brains. Apart from contributing to our understanding of the processes shaping and explaining variation in brain size and the size of different brain regions in the wild, the results show that provision of structural complexity in captive environments can influence brain development. Assuming that the observed plasticity influences fish behaviour, these findings may also have relevance for fish stocking, both for economical and conservational purposes. Electronic supplementary material The online version of this article (doi:10.1186/s12983-015-0130-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gábor Herczeg
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány1/C, 1117 Budapest, Hungary ; Ecological Genetics Research Unit, Department of Biosciences, FI-00014 University of Helsinki, Helsinki, Finland
| | - Abigél Gonda
- Ecological Genetics Research Unit, Department of Biosciences, FI-00014 University of Helsinki, Helsinki, Finland
| | - Gergely Balázs
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány1/C, 1117 Budapest, Hungary
| | - Kristina Noreikiene
- Ecological Genetics Research Unit, Department of Biosciences, FI-00014 University of Helsinki, Helsinki, Finland
| | - Juha Merilä
- Ecological Genetics Research Unit, Department of Biosciences, FI-00014 University of Helsinki, Helsinki, Finland
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