1
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Padilla-Morales B, Acuña-Alonzo AP, Kilili H, Castillo-Morales A, Díaz-Barba K, Maher KH, Fabian L, Mourkas E, Székely T, Serrano-Meneses MA, Cortez D, Ancona S, Urrutia AO. Sexual size dimorphism in mammals is associated with changes in the size of gene families related to brain development. Nat Commun 2024; 15:6257. [PMID: 39048570 PMCID: PMC11269740 DOI: 10.1038/s41467-024-50386-x] [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: 05/05/2023] [Accepted: 07/03/2024] [Indexed: 07/27/2024] Open
Abstract
In mammals, sexual size dimorphism often reflects the intensity of sexual selection, yet its connection to genomic evolution remains unexplored. Gene family size evolution can reflect shifts in the relative importance of different molecular functions. Here, we investigate the associate between brain development gene repertoire to sexual size dimorphism using 124 mammalian species. We reveal significant changes in gene family size associations with sexual size dimorphism. High levels of dimorphism correlate with an expansion of gene families enriched in olfactory sensory perception and a contraction of gene families associated with brain development functions, many of which exhibited particularly high expression in the human adult brain. These findings suggest a relationship between intense sexual selection and alterations in gene family size. These insights illustrate the complex interplay between sexual dimorphism, gene family size evolution, and their roles in mammalian brain development and function, offering a valuable understanding of mammalian genome evolution.
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Affiliation(s)
- Benjamin Padilla-Morales
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, BA2 7AY, UK.
| | | | - Huseyin Kilili
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, BA2 7AY, UK
| | | | - Karina Díaz-Barba
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, BA2 7AY, UK
- Instituto de Ecología, UNAM, Mexico city, 04510, Mexico
- Licenciatura en ciencias genómicas, UNAM, Cuernavaca, 62210, México
| | - Kathryn H Maher
- NERC Environmental Omics Facility, Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Laurie Fabian
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, BA2 7AY, UK
| | - Evangelos Mourkas
- Zoonosis Science Centre, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Tamás Székely
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, BA2 7AY, UK
| | - Martin-Alejandro Serrano-Meneses
- Departamento de Ciencias Químico Biológicas, Universidad de las Américas Puebla, Sta. Catarina Mártir, San Andrés Cholula, Puebla, 72810, México
| | - Diego Cortez
- Centro de Ciencias Genómicas, UNAM, Cuernavaca, 62210, México
| | - Sergio Ancona
- Instituto de Ecología, Departamento de Ecología Evolutiva, UNAM, México City, 04510, México
| | - Araxi O Urrutia
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, BA2 7AY, UK.
- Instituto de Ecología, UNAM, Mexico city, 04510, Mexico.
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2
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Dunbar RIM, Shultz S. Four errors and a fallacy: pitfalls for the unwary in comparative brain analyses. Biol Rev Camb Philos Soc 2023; 98:1278-1309. [PMID: 37001905 DOI: 10.1111/brv.12953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 03/17/2023] [Accepted: 03/17/2023] [Indexed: 04/03/2023]
Abstract
Comparative analyses are the backbone of evolutionary analysis. However, their record in producing a consensus has not always been good. This is especially true of attempts to understand the factors responsible for the evolution of large brains, which have been embroiled in an increasingly polarised debate over the past three decades. We argue that most of these disputes arise from a number of conceptual errors and associated logical fallacies that are the result of a failure to adopt a biological systems-based approach to hypothesis-testing. We identify four principal classes of error: a failure to heed Tinbergen's Four Questions when testing biological hypotheses, misapplying Dobzhansky's Dictum when testing hypotheses of evolutionary adaptation, poorly chosen behavioural proxies for underlying hypotheses, and the use of inappropriate statistical methods. In the interests of progress, we urge a more careful and considered approach to comparative analyses, and the adoption of a broader, rather than a narrower, taxonomic perspective.
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Affiliation(s)
- Robin I M Dunbar
- Department of Experimental Psychology, Anna Watts Building, University of Oxford, Oxford, OX2 6GG, UK
| | - Susanne Shultz
- Department of Earth and Environmental Sciences, Michael Smith Building, University of Manchester, Manchester, M13 9PT, UK
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3
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Heldstab SA, Isler K, Graber SM, Schuppli C, van Schaik CP. The economics of brain size evolution in vertebrates. Curr Biol 2022; 32:R697-R708. [PMID: 35728555 DOI: 10.1016/j.cub.2022.04.096] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Across the animal kingdom, we see remarkable variation in brain size. This variation has even increased over evolutionary time. Traditionally, studies aiming to explain brain size evolution have looked at the fitness benefits of increased brain size in relation to its increased cognitive performance in the social and/or ecological domain. However, brains are among the most energetically expensive tissues in the body and also require an uninterrupted energy supply. If not compensated, these energetic demands inevitably lead to a reduction in energy allocation to other vital functions. In this review, we summarize how an increasing number of studies show that to fully comprehend brain size evolution and the large variation in brain size across lineages, it is important to look at the economics of brains, including the different pathways through which the high energetic costs of brains can be offset. We further show how numerous studies converge on the conclusion that cognitive abilities can only drive brain size evolution in vertebrate lineages where they result in an improved energy balance through favourable ecological preconditions. Cognitive benefits that do not directly improve the organism's energy balance can only be selectively favoured when they produce such large improvements in reproduction or survival that they outweigh the negative energetic effects of the large brain.
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Affiliation(s)
- Sandra A Heldstab
- Department of Anthropology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Development and Evolution of Cognition Research Group, Max Planck Institute of Animal Behavior, Bücklestrasse 5a, 78467 Konstanz, Germany.
| | - Karin Isler
- Department of Anthropology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Sereina M Graber
- Department of Anthropology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Caroline Schuppli
- Department of Anthropology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Development and Evolution of Cognition Research Group, Max Planck Institute of Animal Behavior, Bücklestrasse 5a, 78467 Konstanz, Germany
| | - Carel P van Schaik
- Department of Anthropology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Comparative Socioecology Group, Max Planck Institute of Animal Behavior, Bücklestrasse 5a, 78467 Konstanz, Germany; Department of Evolutionary Biology and Environmental Science, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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4
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Anderson AP, Jones AG. The relationship between sexual dimorphism and androgen response element proliferation in primate genomes. Evolution 2022; 76:1331-1346. [PMID: 35420699 PMCID: PMC9321733 DOI: 10.1111/evo.14483] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 03/04/2022] [Accepted: 03/13/2022] [Indexed: 01/22/2023]
Abstract
In the males of many vertebrate species, sexual selection has led to the evolution of sexually dimorphic traits, which often are developmentally controlled by androgen signaling involving androgen response elements (AREs). Evolutionary changes in the number and genomic locations of AREs can modify patterns of receptor regulation and potentially alter gene expression. Here, we use recently sequenced primate genomes to evaluate the hypothesis that the strength of sexual selection is related to the genome-wide number of AREs in a diversifying lineage. In humans, we find a higher incidence of AREs near male-biased genes and androgen-responsive genes when compared to randomly selected genes from the genome. In a set of primates, we find that gains or losses of AREs proximal to genes are correlated with changes in male expression levels and the degree of sex-biased expression of those genes. In a larger set of primates, we find that increases in indicators of sexual selection are correlated with genome-wide ARE counts. Our results suggest that the responsiveness of the genome to androgens in humans and their close relatives has been shaped by sexual selection that arises from competition among males for mating access to females.
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Affiliation(s)
| | - Adam G. Jones
- Department of BiologyUniversity of IdahoMoscowIdaho83844
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5
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Godfrey RK, Swartzlander M, Gronenberg W. Allometric analysis of brain cell number in Hymenoptera suggests ant brains diverge from general trends. Proc Biol Sci 2021; 288:20210199. [PMID: 33757353 PMCID: PMC8059961 DOI: 10.1098/rspb.2021.0199] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 02/26/2021] [Indexed: 12/12/2022] Open
Abstract
Many comparative neurobiological studies seek to connect sensory or behavioural attributes across taxa with differences in their brain composition. Recent studies in vertebrates suggest cell number and density may be better correlated with behavioural ability than brain mass or volume, but few estimates of such figures exist for insects. Here, we use the isotropic fractionator (IF) method to estimate total brain cell numbers for 32 species of Hymenoptera spanning seven subfamilies. We find estimates from using this method are comparable to traditional, whole-brain cell counts of two species and to published estimates from established stereological methods. We present allometric scaling relationships between body and brain mass, brain mass and nuclei number, and body mass and cell density and find that ants stand out from bees and wasps as having particularly small brains by measures of mass and cell number. We find that Hymenoptera follow the general trend of smaller animals having proportionally larger brains. Smaller Hymenoptera also feature higher brain cell densities than the larger ones, as is the case in most vertebrates, but in contrast with primates, in which neuron density remains rather constant across changes in brain mass. Overall, our findings establish the IF as a useful method for comparative studies of brain size evolution in insects.
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Affiliation(s)
- R. Keating Godfrey
- Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
| | | | - Wulfila Gronenberg
- Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA
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6
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Szabo B, Damas-Moreira I, Whiting MJ. Can Cognitive Ability Give Invasive Species the Means to Succeed? A Review of the Evidence. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00187] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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7
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Mai 麦春兰 CL, Liao 廖文波 WB, Lüpold S, Kotrschal A. Relative Brain Size Is Predicted by the Intensity of Intrasexual Competition in Frogs. Am Nat 2020; 196:169-179. [PMID: 32673088 DOI: 10.1086/709465] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Competition over mates is a powerful force shaping trait evolution. For instance, better cognitive abilities may be beneficial in male-male competition and thus be selected for by intrasexual selection. Alternatively, investment in physical attributes favoring male performance in competition for mates may lower the resources available for brain development, and more intense male mate competition would coincide with smaller brains. To date, only indirect evidence for such relationships exists, and most studies are heavily biased toward primates and other homoeothermic vertebrates. We tested the association between male brain size (relative to body size) and male-male competition across N=30 species of Chinese anurans. Three indicators of the intensity of male mate competition-operational sex ratio (OSR), spawning-site density, and male forelimb muscle mass-were positively associated with relative brain size, whereas the absolute spawning group size was not. The relationship with the OSR and male forelimb muscle mass was stronger for the male than for the female brains. Taken together, our findings suggest that the increased cognitive abilities of larger brains are beneficial in male-male competition. This study adds taxonomic breadth to the mounting evidence for a prominent role of sexual selection in vertebrate brain evolution.
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8
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Fernandes HB, Peñaherrera-Aguirre M, Woodley of Menie MA, Figueredo AJ. Macroevolutionary patterns and selection modes for general intelligence (G) and for commonly used neuroanatomical volume measures in primates. INTELLIGENCE 2020. [DOI: 10.1016/j.intell.2020.101456] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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9
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Culumber ZW, Engel N, Travis J, Hughes KA. Larger female brains do not reduce male sexual coercion. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2019.11.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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10
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Rogell B, Dowling DK, Husby A. Controlling for body size leads to inferential biases in the biological sciences. Evol Lett 2019; 4:73-82. [PMID: 32055413 PMCID: PMC7006466 DOI: 10.1002/evl3.151] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 10/14/2019] [Accepted: 10/20/2019] [Indexed: 01/15/2023] Open
Abstract
Many traits correlate with body size. Studies that seek to uncover the ecological factors that drive evolutionary responses in traits typically examine these responses relative to associated changes in body size using multiple regression analysis. However, it is not well appreciated that in the presence of strongly correlated variables, the partial (i.e., relative) regression coefficients often change sign compared to the original coefficients. Such sign reversals are difficult to interpret in a biologically meaningful way, and could lead to erroneous evolutionary inferences if the true mechanism underlying the sign reversal differed from the proposed mechanism. Here, we use simulations to demonstrate that sign reversal occurs over a wide range of parameter values common in the biological sciences. Further, as a case‐in‐point, we review the literature on brain size evolution; a field that explores how ecological traits relate to the evolution of relative brain size (brain size relative to body size). We find that most studies show sign reversals and thus that the inferences of many studies in this field may be inconclusive. Finally, we propose some approaches to mitigating this issue.
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Affiliation(s)
- Björn Rogell
- Department of Zoology Stockholm University Svante Arrhenius väg 18 Stockholm Sweden.,Department of Aquatic Resources, Institute of Freshwater Research Swedish University of Agricultural Sciences Drottningholm 17893 Sweden
| | - Damian K Dowling
- School of Biological Sciences Monash University Clayton Victoria 3800 Australia
| | - Arild Husby
- Centre for Biodiversity Dynamics Norwegian University of Science and Technology 7491 Trondheim Norway.,Evolutionary Biology, Department of Ecology and Genetics Uppsala University 75236 Uppsala Sweden
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11
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Cassini MH. A mixed model of the evolution of polygyny and sexual size dimorphism in mammals. Mamm Rev 2019. [DOI: 10.1111/mam.12171] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marcelo H. Cassini
- Laboratorio de Biología del Comportamiento IBYME CONICET Obligado 2490, 1429 Buenos Aires Argentina
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12
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Kalberer S, DeRango E, Trillmich F, Krüger O. Evolution of age at primiparity in pinnipeds in the absence of the quality-quantity trade-off in reproduction. Ecol Evol 2019; 9:5450-5456. [PMID: 31110693 PMCID: PMC6509388 DOI: 10.1002/ece3.5138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 03/01/2019] [Accepted: 03/13/2019] [Indexed: 12/05/2022] Open
Abstract
Age at primiparity (AP) is a key life history trait which is crucial to the evolution of life history strategies. This trait is particularly interesting in pinnipeds (walrus, eared seals, and true seals), which are monotocous animals. Thus, the commonly observed trade-off between offspring quality and quantity does not apply to this taxon. Therefore, comparative studies on the evolution of AP might shed light on other important evolutionary correlates when litter size is fixed. Using phylogenetic generalized least squares analyses, we found a strong negative and robust correlation between relative birth mass (mean pup birth mass as a proportion of mean adult female mass) and AP. Rather than trading-off an early start of reproduction with light relative offspring mass, this result suggests that pinnipeds exhibit either faster (i.e., higher relative offspring mass leading to shorter lactation length, and thus shorter interbirth interval) or slower life histories and that an early AP and a heavy relative offspring mass co-evolved into a comparatively fast life history strategy. On the other hand, AP was positively related to lactation length: A later start of reproduction was associated with a longer lactation length. Consequently, variation in AP in pinnipeds seems to be affected by an interplay between costs and benefits of early reproduction mediated by relative investment into the single offspring via relative birth mass and lactation length.
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Affiliation(s)
| | - Eugene DeRango
- Department of Animal BehaviourBielefeld UniversityBielefeldGermany
| | - Fritz Trillmich
- Department of Animal BehaviourBielefeld UniversityBielefeldGermany
| | - Oliver Krüger
- Department of Animal BehaviourBielefeld UniversityBielefeldGermany
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13
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Miller IF, Barton RA, Nunn CL. Quantitative uniqueness of human brain evolution revealed through phylogenetic comparative analysis. eLife 2019; 8:e41250. [PMID: 30702428 PMCID: PMC6379089 DOI: 10.7554/elife.41250] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 01/29/2019] [Indexed: 12/26/2022] Open
Abstract
While the human brain is clearly large relative to body size, less is known about the timing of brain and brain component expansion within primates and the relative magnitude of volumetric increases. Using Bayesian phylogenetic comparative methods and data for both extant and fossil species, we identified that a distinct shift in brain-body scaling occurred as hominins diverged from other primates, and again as humans and Neanderthals diverged from other hominins. Within hominins, we detected a pattern of directional and accelerating evolution towards larger brains, consistent with a positive feedback process in the evolution of the human brain. Contrary to widespread assumptions, we found that the human neocortex is not exceptionally large relative to other brain structures. Instead, our analyses revealed a single increase in relative neocortex volume at the origin of haplorrhines, and an increase in relative cerebellar volume in apes.
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Affiliation(s)
- Ian F Miller
- Ecology and Evolutionary BiologyPrinceton UniversityPrincetonUnited States
- Department of Evolutionary AnthropologyDuke UniversityDurhamUnited States
| | - Robert A Barton
- Evolutionary Anthropology Research Group, Department of AnthropologyUniversity of DurhamDurhamUnited Kingdom
| | - Charles L Nunn
- Department of Evolutionary AnthropologyDuke UniversityDurhamUnited States
- Duke Global Health InstituteDuke UniversityDurhamUnited States
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14
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DeCasien AR, Thompson NA, Williams SA, Shattuck MR. Encephalization and longevity evolved in a correlated fashion in Euarchontoglires but not in other mammals. Evolution 2018; 72:2617-2631. [DOI: 10.1111/evo.13633] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 10/18/2018] [Accepted: 10/23/2018] [Indexed: 12/23/2022]
Affiliation(s)
- Alex R. DeCasien
- Department of Anthropology New York University New York New York 10003
- New York Consortium in Evolutionary Primatology New York New York 10024
| | - Nicole A. Thompson
- New York Consortium in Evolutionary Primatology New York New York 10024
- Department of Ecology, Evolution, and Environmental Biology Columbia University New York New York 10027
| | - Scott A. Williams
- Department of Anthropology New York University New York New York 10003
- New York Consortium in Evolutionary Primatology New York New York 10024
| | - Milena R. Shattuck
- Department of Anthropology and Program of Human Biology Hunter College, CUNY New York New York 10065
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15
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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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16
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Beston SM, Broyles W, Walsh MR. Increased juvenile predation is not associated with evolved differences in adult brain size in Trinidadian killifish ( Rivulus hartii). Ecol Evol 2017; 7:884-894. [PMID: 28168025 PMCID: PMC5288286 DOI: 10.1002/ece3.2668] [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: 09/28/2016] [Revised: 11/02/2016] [Accepted: 11/05/2016] [Indexed: 11/12/2022] Open
Abstract
Vertebrates exhibit extensive variation in brain size. The long-standing assumption is that this variation is driven by ecologically mediated selection. Recent work has shown that an increase in predator-induced mortality is associated with evolved increases and decreases in brain size. Thus, the manner in which predators induce shifts in brain size remains unclear. Increased predation early in life is a key driver of many adult traits, including life-history and behavioral traits. Such results foreshadow a connection between age-specific mortality and selection on adult brain size. Trinidadian killifish, Rivulus hartii, are found in sites with and without guppies, Poecilia reticulata. The densities of Rivulus drop dramatically in sites with guppies because guppies prey upon juvenile Rivulus. Previous work has shown that guppy predation is associated with the evolution of adult life-history traits in Rivulus. In this study, we compared second-generation laboratory-born Rivulus from sites with and without guppies for differences in brain size and associated trade-offs between brain size and other components of fitness. Despite the large amount of existing research on the importance of early-life events on the evolution of adult traits, and the role of predation on both behavior and brain size, we did not find an association between the presence of guppies and evolutionary shifts in Rivulus brain size. Such results argue that increased rates of juvenile mortality may not alter selection on adult brain size.
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Affiliation(s)
| | - Whitnee Broyles
- Department of BiologyUniversity of Texas at ArlingtonArlingtonTXUSA
| | - Matthew R. Walsh
- Department of BiologyUniversity of Texas at ArlingtonArlingtonTXUSA
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17
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Tsuboi M, Lim ACO, Ooi BL, Yip MY, Chong VC, Ahnesjö I, Kolm N. Brain size evolution in pipefishes and seahorses: the role of feeding ecology, life history and sexual selection. J Evol Biol 2016; 30:150-160. [PMID: 27748990 DOI: 10.1111/jeb.12995] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 09/15/2016] [Accepted: 10/14/2016] [Indexed: 01/25/2023]
Abstract
Brain size varies greatly at all taxonomic levels. Feeding ecology, life history and sexual selection have been proposed as key components in generating contemporary diversity in brain size across vertebrates. Analyses of brain size evolution have, however, been limited to lineages where males predominantly compete for mating and females choose mates. Here, we present the first original data set of brain sizes in pipefishes and seahorses (Syngnathidae) a group in which intense female mating competition occurs in many species. After controlling for the effect of shared ancestry and overall body size, brain size was positively correlated with relative snout length. Moreover, we found that females, on average, had 4.3% heavier brains than males and that polyandrous species demonstrated more pronounced (11.7%) female-biased brain size dimorphism. Our results suggest that adaptations for feeding on mobile prey items and sexual selection in females are important factors in brain size evolution of pipefishes and seahorses. Most importantly, our study supports the idea that sexual selection plays a major role in brain size evolution, regardless of on which sex sexual selection acts stronger.
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Affiliation(s)
- M Tsuboi
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - A C O Lim
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.,Save Our Seahorses Malaysia, Petaling Jaya, Selangor, Malaysia
| | - B L Ooi
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.,Save Our Seahorses Malaysia, Petaling Jaya, Selangor, Malaysia
| | - M Y Yip
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.,Save Our Seahorses Malaysia, Petaling Jaya, Selangor, Malaysia
| | - V C Chong
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.,Institute of Ocean and Earth Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - I Ahnesjö
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - N Kolm
- Department of Zoology/Ethology, Stockholm University, Stockholm, Sweden
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18
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Hoops D, Ullmann JFP, Janke AL, Vidal-Garcia M, Stait-Gardner T, Dwihapsari Y, Merkling T, Price WS, Endler JA, Whiting MJ, Keogh JS. Sexual selection predicts brain structure in dragon lizards. J Evol Biol 2016; 30:244-256. [PMID: 27696584 DOI: 10.1111/jeb.12984] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 08/30/2016] [Accepted: 09/20/2016] [Indexed: 01/10/2023]
Abstract
Phenotypic traits such as ornaments and armaments are generally shaped by sexual selection, which often favours larger and more elaborate males compared to females. But can sexual selection also influence the brain? Previous studies in vertebrates report contradictory results with no consistent pattern between variation in brain structure and the strength of sexual selection. We hypothesize that sexual selection will act in a consistent way on two vertebrate brain regions that directly regulate sexual behaviour: the medial preoptic nucleus (MPON) and the ventromedial hypothalamic nucleus (VMN). The MPON regulates male reproductive behaviour whereas the VMN regulates female reproductive behaviour and is also involved in male aggression. To test our hypothesis, we used high-resolution magnetic resonance imaging combined with traditional histology of brains in 14 dragon lizard species of the genus Ctenophorus that vary in the strength of precopulatory sexual selection. Males belonging to species that experience greater sexual selection had a larger MPON and a smaller VMN. Conversely, females did not show any patterns of variation in these brain regions. As the volumes of both these regions also correlated with brain volume (BV) in our models, we tested whether they show the same pattern of evolution in response to changes in BV and found that the do. Therefore, we show that the primary brain nuclei underlying reproductive behaviour in vertebrates can evolve in a mosaic fashion, differently between males and females, likely in response to sexual selection, and that these same regions are simultaneously evolving in concert in relation to overall brain size.
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Affiliation(s)
- D Hoops
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - J F P Ullmann
- Center for Advanced Imaging, The University of Queensland, Brisbane, Qld, Australia
| | - A L Janke
- Center for Advanced Imaging, The University of Queensland, Brisbane, Qld, Australia
| | - M Vidal-Garcia
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - T Stait-Gardner
- Nanoscale Organization and Dynamics Group, School of Science and Health, University of Western Sydney, Penrith, NSW, Australia
| | - Y Dwihapsari
- Nanoscale Organization and Dynamics Group, School of Science and Health, University of Western Sydney, Penrith, NSW, Australia
| | - T Merkling
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - W S Price
- Nanoscale Organization and Dynamics Group, School of Science and Health, University of Western Sydney, Penrith, NSW, Australia
| | - J A Endler
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Vic., Australia
| | - M J Whiting
- Department of Biological Sciences, Discipline of Brain, Behavior and Evolution, Macquarie University, Sydney, NSW, Australia
| | - J S Keogh
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Acton, ACT, Australia
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19
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Henriksen R, Johnsson M, Andersson L, Jensen P, Wright D. The domesticated brain: genetics of brain mass and brain structure in an avian species. Sci Rep 2016; 6:34031. [PMID: 27687864 PMCID: PMC5043184 DOI: 10.1038/srep34031] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/05/2016] [Indexed: 11/08/2022] Open
Abstract
As brain size usually increases with body size it has been assumed that the two are tightly constrained and evolutionary studies have therefore often been based on relative brain size (i.e. brain size proportional to body size) rather than absolute brain size. The process of domestication offers an excellent opportunity to disentangle the linkage between body and brain mass due to the extreme selection for increased body mass that has occurred. By breeding an intercross between domestic chicken and their wild progenitor, we address this relationship by simultaneously mapping the genes that control inter-population variation in brain mass and body mass. Loci controlling variation in brain mass and body mass have separate genetic architectures and are therefore not directly constrained. Genetic mapping of brain regions indicates that domestication has led to a larger body mass and to a lesser extent a larger absolute brain mass in chickens, mainly due to enlargement of the cerebellum. Domestication has traditionally been linked to brain mass regression, based on measurements of relative brain mass, which confounds the large body mass augmentation due to domestication. Our results refute this concept in the chicken.
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Affiliation(s)
- R. Henriksen
- AVIAN Behavioural Genomics and Physiology Group, IFM Biology, Linköping University, Linköping 58183, Sweden
| | - M. Johnsson
- AVIAN Behavioural Genomics and Physiology Group, IFM Biology, Linköping University, Linköping 58183, Sweden
| | - L. Andersson
- Dept of Medical Biochemistry and Microbiology, Uppsala University, BMC, Husargatan 3, Uppsala 75123, Sweden
| | - P. Jensen
- AVIAN Behavioural Genomics and Physiology Group, IFM Biology, Linköping University, Linköping 58183, Sweden
| | - D. Wright
- AVIAN Behavioural Genomics and Physiology Group, IFM Biology, Linköping University, Linköping 58183, Sweden
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20
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Steinhausen C, Zehl L, Haas-Rioth M, Morcinek K, Walkowiak W, Huggenberger S. Multivariate Meta-Analysis of Brain-Mass Correlations in Eutherian Mammals. Front Neuroanat 2016; 10:91. [PMID: 27746724 PMCID: PMC5043137 DOI: 10.3389/fnana.2016.00091] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 09/13/2016] [Indexed: 11/26/2022] Open
Abstract
The general assumption that brain size differences are an adequate proxy for subtler differences in brain organization turned neurobiologists toward the question why some groups of mammals such as primates, elephants, and whales have such remarkably large brains. In this meta-analysis, an extensive sample of eutherian mammals (115 species distributed in 14 orders) provided data about several different biological traits and measures of brain size such as absolute brain mass (AB), relative brain mass (RB; quotient from AB and body mass), and encephalization quotient (EQ). These data were analyzed by established multivariate statistics without taking specific phylogenetic information into account. Species with high AB tend to (1) feed on protein-rich nutrition, (2) have a long lifespan, (3) delayed sexual maturity, and (4) long and rare pregnancies with small litter sizes. Animals with high RB usually have (1) a short life span, (2) reach sexual maturity early, and (3) have short and frequent gestations. Moreover, males of species with high RB also have few potential sexual partners. In contrast, animals with high EQs have (1) a high number of potential sexual partners, (2) delayed sexual maturity, and (3) rare gestations with small litter sizes. Based on these correlations, we conclude that Eutheria with either high AB or high EQ occupy positions at the top of the network of food chains (high trophic levels). Eutheria of low trophic levels can develop a high RB only if they have small body masses.
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Affiliation(s)
- Charlene Steinhausen
- Department II of Anatomy, University of CologneCologne, Germany
- Biocenter, University of CologneCologne, Germany
| | - Lyuba Zehl
- Biocenter, University of CologneCologne, Germany
- Jülich Research Centre, Institute of Neuroscience and Medicine (INM-6) and Institute for Advanced Simulation (IAS-6) and JARA BRAIN Institute IJülich, Germany
| | - Michaela Haas-Rioth
- Department of Anatomy III (Dr. Senckenbergische Anatomie), Goethe University of Frankfurt am MainFrankfurt am Main, Germany
| | | | | | - Stefan Huggenberger
- Department II of Anatomy, University of CologneCologne, Germany
- Biocenter, University of CologneCologne, Germany
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21
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Zeng Y, Lou SL, Liao WB, Jehle R, Kotrschal A. Sexual selection impacts brain anatomy in frogs and toads. Ecol Evol 2016; 6:7070-7079. [PMID: 28725383 PMCID: PMC5513231 DOI: 10.1002/ece3.2459] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 07/20/2016] [Accepted: 08/18/2016] [Indexed: 11/10/2022] Open
Abstract
Natural selection is a major force in the evolution of vertebrate brain size, but the role of sexual selection in brain size evolution remains enigmatic. At least two opposing schools of thought predict a relationship between sexual selection and brain size. Sexual selection should facilitate the evolution of larger brains because better cognitive abilities may aid the competition for mates. However, it may also restrict brain size evolution due to energetic trade‐offs between brain tissue and sexually selected traits. Here, we examined the patterns of selection on brain size and brain anatomy in male anurans (frogs and toads), a group where the strength of sexual selection differs markedly among species, using a phylogenetically controlled generalized least‐squared (PGLS) regression analyses. The analysis revealed that in 43 Chinese anuran species, neither mating system, nor type of courtship, or testes mass was significantly associated with relative brain size. While none of those factors related to the relative size of olfactory nerves, optic tecta, telencephalon, and cerebellum, the olfactory bulbs were relatively larger in monogamous species and those using calls during courtship. Our findings support the mosaic model of brain evolution and suggest that while the investigated aspects of sexual selection do not seem to play a prominent role in the evolution of brain size of anurans, they do impact their brain anatomy.
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Affiliation(s)
- Yu Zeng
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education) China West Normal University Nanchong Sichuan China
| | - Shang Ling Lou
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education) China West Normal University Nanchong Sichuan China
| | - Wen Bo Liao
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education) China West Normal University Nanchong Sichuan China
| | - Robert Jehle
- School of Environment & Life Sciences University of Salford Salford UK
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22
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Tsuboi M, Kotrschal A, Hayward A, Buechel SD, Zidar J, Løvlie H, Kolm N. Evolution of brain-body allometry in Lake Tanganyika cichlids. Evolution 2016; 70:1559-68. [DOI: 10.1111/evo.12965] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 05/12/2016] [Accepted: 05/18/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Masahito Tsuboi
- Evolutionary Biology Centre; Department of Ecology and Genetics/Animal Ecology; Uppsala University; Norbyvägen 18D SE-75236 Uppsala Sweden
| | - Alexander Kotrschal
- Department of Zoology/Ethology; Stockholm University; Svante Arrhenius väg 18B SE-10691 Stockholm Sweden
| | - Alexander Hayward
- Department of Zoology/Ethology; Stockholm University; Svante Arrhenius väg 18B SE-10691 Stockholm Sweden
| | - Severine Denise Buechel
- Department of Zoology/Ethology; Stockholm University; Svante Arrhenius väg 18B SE-10691 Stockholm Sweden
| | - Josefina Zidar
- IFM Biology; Linköping University; Campus Valla SE-58183 Linköping Sweden
| | - Hanne Løvlie
- IFM Biology; Linköping University; Campus Valla SE-58183 Linköping Sweden
| | - Niclas Kolm
- Department of Zoology/Ethology; Stockholm University; Svante Arrhenius väg 18B SE-10691 Stockholm Sweden
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23
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Liao WB, Lou SL, Zeng Y, Merilä J. Evolution of anuran brains: disentangling ecological and phylogenetic sources of variation. J Evol Biol 2015; 28:1986-96. [PMID: 26248891 DOI: 10.1111/jeb.12714] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 07/12/2015] [Accepted: 08/01/2015] [Indexed: 02/06/2023]
Abstract
Variation in ecological selection pressures has been implicated to explain variation in brain size and architecture in fishes, birds and mammals, but little is known in this respect about amphibians. Likewise, the relative importance of constraint vs. mosaic hypotheses of brain evolution in explaining variation in brain size and architecture remains contentious. Using phylogenetic comparative methods, we studied interspecific variation in brain size and size of different brain parts among 43 Chinese anuran frogs and explored how much of this variation was explainable by variation in ecological factors (viz. habitat type, diet and predation risk). We also evaluated which of the two above-mentioned hypotheses best explains the observed patterns. Although variation in brain size explained on average 80.5% of the variation in size of different brain parts (supporting the constraint hypothesis), none of the three ecological factors were found to explain variation in overall brain size. However, habitat and diet type explained a significant amount of variation in telencephalon size, as well in three composite measures of brain architecture. Likewise, predation risk explained a significant amount of variation in bulbus olfactorius and optic tecta size. Our results show that evolution of anuran brain accommodates features compatible with both constraint (viz. strong allometry among brain parts) and mosaic (viz. independent size changes in response to ecological factors in certain brain parts) models of brain size evolution.
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Affiliation(s)
- W B Liao
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China.,Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - S L Lou
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
| | - Y Zeng
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
| | - J Merilä
- Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki, Finland
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24
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Weisbecker V, Blomberg S, Goldizen AW, Brown M, Fisher D. The evolution of relative brain size in marsupials is energetically constrained but not driven by behavioral complexity. BRAIN, BEHAVIOR AND EVOLUTION 2015; 85:125-35. [PMID: 25966967 DOI: 10.1159/000377666] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 02/02/2015] [Indexed: 11/19/2022]
Abstract
Evolutionary increases in mammalian brain size relative to body size are energetically costly but are also thought to confer selective advantages by permitting the evolution of cognitively complex behaviors. However, many suggested associations between brain size and specific behaviors - particularly related to social complexity - are possibly confounded by the reproductive diversity of placental mammals, whose brain size evolution is the most frequently studied. Based on a phylogenetic generalized least squares analysis of a data set on the reproductively homogenous clade of marsupials, we provide the first quantitative comparison of two hypotheses based on energetic constraints (maternal investment and seasonality) with two hypotheses that posit behavioral selection on relative brain size (social complexity and environmental interactions). We show that the two behavioral hypotheses have far less support than the constraint hypotheses. The only unambiguous associates of brain size are the constraint variables of litter size and seasonality. We also found no association between brain size and specific behavioral complexity categories within kangaroos, dasyurids, and possums. The largest-brained marsupials after phylogenetic correction are from low-seasonality New Guinea, supporting the notion that low seasonality represents greater nutrition safety for brain maintenance. Alternatively, low seasonality might improve the maternal support of offspring brain growth. The lack of behavioral brain size associates, found here and elsewhere, supports the general 'cognitive buffer hypothesis' as the best explanatory framework of mammalian brain size evolution. However, it is possible that brain size alone simply does not provide sufficient resolution on the question of how brain morphology and cognitive capacities coevolve.
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Affiliation(s)
- Vera Weisbecker
- School of Biological Sciences, University of Queensland, St. Lucia, Qld., Australia
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25
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Churchill M, Clementz MT, Kohno N. Predictive equations for the estimation of body size in seals and sea lions (Carnivora: Pinnipedia). J Anat 2014; 225:232-45. [PMID: 24916814 DOI: 10.1111/joa.12199] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2014] [Indexed: 11/29/2022] Open
Abstract
Body size plays an important role in pinniped ecology and life history. However, body size data is often absent for historical, archaeological, and fossil specimens. To estimate the body size of pinnipeds (seals, sea lions, and walruses) for today and the past, we used 14 commonly preserved cranial measurements to develop sets of single variable and multivariate predictive equations for pinniped body mass and total length. Principal components analysis (PCA) was used to test whether separate family specific regressions were more appropriate than single predictive equations for Pinnipedia. The influence of phylogeny was tested with phylogenetic independent contrasts (PIC). The accuracy of these regressions was then assessed using a combination of coefficient of determination, percent prediction error, and standard error of estimation. Three different methods of multivariate analysis were examined: bidirectional stepwise model selection using Akaike information criteria; all-subsets model selection using Bayesian information criteria (BIC); and partial least squares regression. The PCA showed clear discrimination between Otariidae (fur seals and sea lions) and Phocidae (earless seals) for the 14 measurements, indicating the need for family-specific regression equations. The PIC analysis found that phylogeny had a minor influence on relationship between morphological variables and body size. The regressions for total length were more accurate than those for body mass, and equations specific to Otariidae were more accurate than those for Phocidae. Of the three multivariate methods, the all-subsets approach required the fewest number of variables to estimate body size accurately. We then used the single variable predictive equations and the all-subsets approach to estimate the body size of two recently extinct pinniped taxa, the Caribbean monk seal (Monachus tropicalis) and the Japanese sea lion (Zalophus japonicus). Body size estimates using single variable regressions generally under or over-estimated body size; however, the all-subset regression produced body size estimates that were close to historically recorded body length for these two species. This indicates that the all-subset regression equations developed in this study can estimate body size accurately.
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Affiliation(s)
- Morgan Churchill
- Department of Geology and Geophysics, University of Wyoming, Laramie, WY, USA; Program in Ecology, University of Wyoming, Laramie, WY, USA
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26
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Herczeg G, Välimäki K, Gonda A, Merilä J. Evidence for sex-specific selection in brain: a case study of the nine-spined stickleback. J Evol Biol 2014; 27:1604-12. [DOI: 10.1111/jeb.12409] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 04/04/2014] [Accepted: 04/13/2014] [Indexed: 11/30/2022]
Affiliation(s)
- G. Herczeg
- Behavioural Ecology Group; Department of Systematic Zoology and Ecology; Eötvös Loránd University; Budapest Hungary
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; Helsinki Finland
| | - K. Välimäki
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; Helsinki Finland
- Monitoring Team; Finnish Museum of Natural History; University of Helsinki; Helsinki Finland
| | - A. Gonda
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; Helsinki Finland
| | - J. Merilä
- Ecological Genetics Research Unit; Department of Biosciences; University of Helsinki; Helsinki Finland
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27
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Krüger O, Wolf JBW, Jonker RM, Hoffman JI, Trillmich F. DISENTANGLING THE CONTRIBUTION OF SEXUAL SELECTION AND ECOLOGY TO THE EVOLUTION OF SIZE DIMORPHISM IN PINNIPEDS. Evolution 2014; 68:1485-96. [DOI: 10.1111/evo.12370] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 01/17/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Oliver Krüger
- Department of Animal Behaviour; Bielefeld University; PO Box 10 01 31 33501 Bielefeld Germany
| | - Jochen B. W. Wolf
- Department of Evolutionary Biology; Evolutionary Biology Centre; Uppsala University; Norbyvägen 18D 75236 Uppsala Sweden
| | - Rudy M. Jonker
- Department of Animal Behaviour; Bielefeld University; PO Box 10 01 31 33501 Bielefeld Germany
| | - Joseph I. Hoffman
- Department of Animal Behaviour; Bielefeld University; PO Box 10 01 31 33501 Bielefeld Germany
| | - Fritz Trillmich
- Department of Animal Behaviour; Bielefeld University; PO Box 10 01 31 33501 Bielefeld Germany
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28
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Gonda A, Herczeg G, Merilä J. Evolutionary ecology of intraspecific brain size variation: a review. Ecol Evol 2013; 3:2751-64. [PMID: 24567837 PMCID: PMC3930043 DOI: 10.1002/ece3.627] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 12/24/2022] Open
Abstract
The brain is a trait of central importance for organismal performance and fitness. To date, evolutionary studies of brain size variation have mainly utilized comparative methods applied at the level of species or higher taxa. However, these studies suffer from the difficulty of separating causality from correlation. In the other extreme, studies of brain plasticity have focused mainly on within-population patterns. Between these extremes lie interpopulational studies, focusing on brain size variation among populations of the same species that occupy different habitats or selective regimes. These studies form a rapidly growing field of investigations which can help us to understand brain evolution by providing a test bed for ideas born out of interspecific studies, as well as aid in uncovering the relative importance of genetic and environmental factors shaping variation in brain size and architecture. Aside from providing the first in depth review of published intraspecific studies of brain size variation, we discuss the prospects embedded with interpopulational studies of brain size variation. In particular, the following topics are identified as deserving further attention: (i) studies focusing on disentangling the contributions of genes, environment, and their interactions on brain variation within and among populations, (ii) studies applying quantitative genetic tools to evaluate the relative importance of genetic and environmental factors on brain features at different ontogenetic stages, (iii) apart from utilizing simple gross estimates of brain size, future studies could benefit from use of neuroanatomical, neurohistological, and/or molecular methods in characterizing variation in brain size and architecture. Evolution of brain size and architecture is a widely studied topic. However, the majority of studies are interspecific and comparative. Here we summarize the recently growing body of intraspecific studies based on population comparisons and outline the future potential in this approach.
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Affiliation(s)
- Abigél Gonda
- Ecological Genetics Research UnitDepartment of Biosciences, University of HelsinkiP.O. Box 65, FI-00014, Helsinki, Finland
| | - Gábor Herczeg
- Ecological Genetics Research UnitDepartment of Biosciences, University of HelsinkiP.O. Box 65, FI-00014, Helsinki, Finland
- Behavioural Ecology GroupDepartment of Systematic Zoology and Ecology, Eötvös Loránd UniversityPázmány Péter sétány 1/C, H-1117, Budapest, Hungary
| | - Juha Merilä
- Ecological Genetics Research UnitDepartment of Biosciences, University of HelsinkiP.O. Box 65, FI-00014, Helsinki, Finland
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29
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González-Suárez M, Cassini MH. Variance in male reproductive success and sexual size dimorphism in pinnipeds: testing an assumption of sexual selection theory. Mamm Rev 2013. [DOI: 10.1111/mam.12012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Manuela González-Suárez
- Department of Conservation Biology; Estación Biológica de Doñana CSIC; Calle Américo Vespucio s/n 41092 Sevilla Spain
| | - Marcelo H. Cassini
- Behavioural Biology Lab; IBYME-CONICET; Obligado 2490 1428 Buenos Aires Argentina
- Group of Studies in Ecology of Mammals; DCB; Universidad de Luján; Rutas 5 y 7 6700 Buenos Aires Argentina
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30
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Willemet R. Reconsidering the evolution of brain, cognition, and behavior in birds and mammals. Front Psychol 2013; 4:396. [PMID: 23847570 PMCID: PMC3696912 DOI: 10.3389/fpsyg.2013.00396] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 06/12/2013] [Indexed: 01/23/2023] Open
Abstract
Despite decades of research, some of the most basic issues concerning the extraordinarily complex brains and behavior of birds and mammals, such as the factors responsible for the diversity of brain size and composition, are still unclear. This is partly due to a number of conceptual and methodological issues. Determining species and group differences in brain composition requires accounting for the presence of taxon-cerebrotypes and the use of precise statistical methods. The role of allometry in determining brain variables should be revised. In particular, bird and mammalian brains appear to have evolved in response to a variety of selective pressures influencing both brain size and composition. “Brain” and “cognition” are indeed meta-variables, made up of the variables that are ecologically relevant and evolutionarily selected. External indicators of species differences in cognition and behavior are limited by the complexity of these differences. Indeed, behavioral differences between species and individuals are caused by cognitive and affective components. Although intra-species variability forms the basis of species evolution, some of the mechanisms underlying individual differences in brain and behavior appear to differ from those between species. While many issues have persisted over the years because of a lack of appropriate data or methods to test them; several fallacies, particularly those related to the human brain, reflect scientists' preconceptions. The theoretical framework on the evolution of brain, cognition, and behavior in birds and mammals should be reconsidered with these biases in mind.
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31
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García-Peña GE, Sol D, Iwaniuk AN, Székely T. Sexual selection on brain size in shorebirds (Charadriiformes). J Evol Biol 2013; 26:878-88. [DOI: 10.1111/jeb.12104] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 10/21/2012] [Accepted: 12/10/2012] [Indexed: 11/30/2022]
Affiliation(s)
| | - D. Sol
- CREAF; Cerdanyola del Vallès Spain
- CSIC; Cerdanyola del Vallès Spain
| | - A. N. Iwaniuk
- National Museum of Natural History; Smithsonian Institution; Washington DC USA
- Department of Neuroscience; Canadian Centre for Behavioural Neuroscience; University of Lethbridge; Lethbridge AB Canada
| | - T. Székely
- Department of Biology and Biochemistry; University of Bath; Bath UK
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32
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Smaers JB, Dechmann DKN, Goswami A, Soligo C, Safi K. Comparative analyses of evolutionary rates reveal different pathways to encephalization in bats, carnivorans, and primates. Proc Natl Acad Sci U S A 2012; 109:18006-11. [PMID: 23071335 PMCID: PMC3497830 DOI: 10.1073/pnas.1212181109] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Variation in relative brain size is commonly interpreted as the result of selection on neuronal capacity. However, this approach ignores that relative brain size is also linked to another highly adaptive variable: body size. Considering that one-way tradeoff mechanisms are unlikely to provide satisfactory evolutionary explanations, we introduce an analytical framework that describes and quantifies all possible evolutionary scenarios between two traits. To investigate the effects of body mass changes on the interpretation of relative brain size evolution, we analyze three mammalian orders that are expected to be subject to different selective pressures on body size due to differences in locomotor adaptation: bats (powered flight), primates (primarily arboreal), and carnivorans (primarily terrestrial). We quantify rates of brain and body mass changes along individual branches of phylogenetic trees using an adaptive peak model of evolution. We find that the magnitude and variance of the level of integration of brain and body mass rates, and the subsequent relative influence of either brain or body size evolution on the brain-body relationship, differ significantly between orders and subgroups within orders. Importantly, we find that variation in brain-body relationships was driven primarily by variability in body mass. Our approach allows a more detailed interpretation of correlated trait evolution and variation in the underlying evolutionary pathways. Results demonstrate that a principal focus on interpreting relative brain size evolution as selection on neuronal capacity confounds the effects of body mass changes, thereby hiding important aspects that may contribute to explaining animal diversity.
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Affiliation(s)
- Jeroen B. Smaers
- Department of Anthropology, University College London, London WC1H 0BW, United Kingdom
- Department of Genetics, Evolution, and Environment, University College London, London WC1E 6BT, United Kingdom
| | - Dina K. N. Dechmann
- Department of Biology, University of Konstanz, 78464 Konstanz, Germany
- Department of Migration and Immunoecology, Max Planck Institute for Ornithology, 78315 Radolfzell, Germany; and
| | - Anjali Goswami
- Department of Genetics, Evolution, and Environment, University College London, London WC1E 6BT, United Kingdom
- Department of Earth Sciences, University College London, London WC1E 6BT, United Kingdom
| | - Christophe Soligo
- Department of Anthropology, University College London, London WC1H 0BW, United Kingdom
| | - Kamran Safi
- Department of Biology, University of Konstanz, 78464 Konstanz, Germany
- Department of Migration and Immunoecology, Max Planck Institute for Ornithology, 78315 Radolfzell, Germany; and
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Abstract
Females frequently mate with several males, whose sperm then compete to fertilize available ova. Sperm competition represents a potent selective force that is expected to shape male expenditure on the ejaculate. Here, we review empirical data that illustrate the evolutionary consequences of sperm competition. Sperm competition favors the evolution of increased testes size and sperm production. In some species, males appear capable of adjusting the number of sperm ejaculated, depending on the perceived levels of sperm competition. Selection is also expected to act on sperm form and function, although the evidence for this remains equivocal. Comparative studies suggest that sperm length and swimming speed may increase in response to selection from sperm competition. However, the mechanisms driving this pattern remain unclear. Evidence that sperm length influences sperm swimming speed is mixed and fertilization trials performed across a broad range of species demonstrate inconsistent relationships between sperm form and function. This ambiguity may in part reflect the important role that seminal fluid proteins (sfps) play in affecting sperm function. There is good evidence that sfps are subject to selection from sperm competition, and recent work is pointing to an ability of males to adjust their seminal fluid chemistry in response to sperm competition from rival males. We argue that future research must consider sperm and seminal fluid components of the ejaculate as a functional unity. Research at the genomic level will identify the genes that ultimately control male fertility.
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Affiliation(s)
- Leigh W Simmons
- Centre for Evolutionary Biology, , School of Animal Biology (M092), The University of Western Australia, Crawley, Western Australia 6009, Australia.
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Fitzpatrick JL, Almbro M, Gonzalez-Voyer A, Kolm N, Simmons LW. MALE CONTEST COMPETITION AND THE COEVOLUTION OF WEAPONRY AND TESTES IN PINNIPEDS. Evolution 2012; 66:3595-604. [DOI: 10.1111/j.1558-5646.2012.01713.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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