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Bialas JT, Dylewski Ł, Tobolka M. Brain size mediates the choice of breeding strategy in the red-backed shrike Lanius collurio. Integr Zool 2024; 19:683-693. [PMID: 38196090 DOI: 10.1111/1749-4877.12803] [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] [Indexed: 01/11/2024]
Abstract
The brain size of vertebrates represents a trade-off between natural selection for enhanced cognitive abilities and the energetic constraints of brain tissue production. Processing information efficiently can confer benefits, but it also entails time costs. Breeding strategies, encompassing timing of breeding onset and nest-site selection, may be related to brain size. In this study, we aim to elucidate the relationship between brain size, breeding timing, nest-site choice, and breeding success in the red-backed shrike Lanius collurio. Our findings revealed that the timing of the first egg-laying date was associated with female head size, with larger-headed females tending to lay eggs later in the breeding season. Additionally, we observed that breeding success was positively correlated with increased nest concealment. However, this relationship was stronger in males with smaller heads. In turn, nest concealment was not related to head size but primarily influenced breeding onset. These results suggest that the choice of breeding strategy may be moderated by brain size, with differences between sexes. Larger-headed females may invest more time in selecting nesting sites, leading to delayed breeding onset, while larger-headed males may compensate for suboptimal nest concealment. Our study sheds light on the intricate interplay between brain size, breeding timing, nest-site preferences, and breeding success in passerine birds, underscoring the potential role of cognitive capacity in shaping individual decision-making processes.
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Affiliation(s)
- Joanna T Bialas
- Department of Zoology, Poznań University of Life Sciences, Poznań, Poland
| | - Łukasz Dylewski
- Department of Zoology, Poznań University of Life Sciences, Poznań, Poland
| | - Marcin Tobolka
- Department of Zoology, Poznań University of Life Sciences, Poznań, Poland
- Konrad Lorenz Institute of Ethology, University of Veterinary Medicine Vienna, Wien, Austria
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2
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Corral-Lopez A, Kotrschal A, Szorkovszky A, Garate-Olaizola M, Herbert-Read J, van der Bijl W, Romenskyy M, Zeng HL, Buechel SD, Fontrodona-Eslava A, Pelckmans K, Mank JE, Kolm N. Evolution of schooling drives changes in neuroanatomy and motion characteristics across predation contexts in guppies. Nat Commun 2023; 14:6027. [PMID: 37758730 PMCID: PMC10533906 DOI: 10.1038/s41467-023-41635-6] [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: 09/11/2022] [Accepted: 09/12/2023] [Indexed: 09/29/2023] Open
Abstract
One of the most spectacular displays of social behavior is the synchronized movements that many animal groups perform to travel, forage and escape from predators. However, elucidating the neural mechanisms underlying the evolution of collective behaviors, as well as their fitness effects, remains challenging. Here, we study collective motion patterns with and without predation threat and predator inspection behavior in guppies experimentally selected for divergence in polarization, an important ecological driver of coordinated movement in fish. We find that groups from artificially selected lines remain more polarized than control groups in the presence of a threat. Neuroanatomical measurements of polarization-selected individuals indicate changes in brain regions previously suggested to be important regulators of perception, fear and attention, and motor response. Additional visual acuity and temporal resolution tests performed in polarization-selected and control individuals indicate that observed differences in predator inspection and schooling behavior should not be attributable to changes in visual perception, but rather are more likely the result of the more efficient relay of sensory input in the brain of polarization-selected fish. Our findings highlight that brain morphology may play a fundamental role in the evolution of coordinated movement and anti-predator behavior.
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Affiliation(s)
- Alberto Corral-Lopez
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, Canada.
- Department of Zoology/Ethology, Stockholm University, Stockholm, Sweden.
- Division of Biosciences, University College London, London, UK.
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden.
| | - Alexander Kotrschal
- Department of Zoology/Ethology, Stockholm University, Stockholm, Sweden
- Behavioural Ecology, Wageningen University & Research, Wageningen, Netherlands
| | - Alexander Szorkovszky
- RITMO Centre for Interdisciplinary Studies in Rhythm, Time and Motion, University of Oslo, Oslo, Norway
| | - Maddi Garate-Olaizola
- Department of Zoology/Ethology, Stockholm University, Stockholm, Sweden
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - James Herbert-Read
- Department of Zoology, University of Cambridge, Cambridge, UK
- Aquatic Ecology, Lund University, Lund, Sweden
| | - Wouter van der Bijl
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
| | - Maksym Romenskyy
- Department of Zoology/Ethology, Stockholm University, Stockholm, Sweden
- Department of Life Sciences, Imperial College London, London, UK
| | - Hong-Li Zeng
- School of Science, Nanjing University of Posts and Telecommunications, Nanjing, China
| | - Severine Denise Buechel
- Department of Zoology/Ethology, Stockholm University, Stockholm, Sweden
- Behavioural Ecology, Wageningen University & Research, Wageningen, Netherlands
| | - Ada Fontrodona-Eslava
- Department of Zoology/Ethology, Stockholm University, Stockholm, Sweden
- Centre for Biological Diversity, School of Biology, University of St Andrews, St Andrews, UK
| | | | - Judith E Mank
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
| | - Niclas Kolm
- Department of Zoology/Ethology, Stockholm University, Stockholm, Sweden
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3
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Pohle AK, Zalewski A, Muturi M, Dullin C, Farková L, Keicher L, Dechmann DKN. Domestication effect of reduced brain size is reverted when mink become feral. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230463. [PMID: 37416828 PMCID: PMC10320332 DOI: 10.1098/rsos.230463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 06/12/2023] [Indexed: 07/08/2023]
Abstract
A typical consequence of breeding animal species for domestication is a reduction in relative brain size. When domesticated animals escape from captivity and establish feral populations, the larger brain of the wild phenotype is usually not regained. In the American mink (Neovison vison), we found an exception to this rule. We confirmed the previously described reduction in relative braincase size and volume compared to their wild North American ancestors in mink bred for their fur in Poland, in a dataset of 292 skulls. We then also found a significant regrowth of these measures in well-established feral populations in Poland. Closely related, small mustelids are known for seasonal reversible changes in skull and brain size. It seems that these small mustelids are able to regain the brain size, which is adaptive for living in the wild, and flexibly respond to selection accordingly.
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Affiliation(s)
- Ann-Kathrin Pohle
- Department of Migration, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany
- Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Bücklestraße 5a, 78467 Konstanz, Germany
- University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Andrzej Zalewski
- Mammal Research Institute, Polish Academy of Sciences, 17-230 Białowieża, Poland
| | - Marion Muturi
- Department of Migration, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany
| | - Christian Dullin
- Department for Diagnostic and Interventional Radiology, University Medical Center Goettingen, Robert-Koch-Straße 40, 37075 Goettingen, Germany
- Department Translational Molecular Imaging, Max Planck Institute for Multidisciplinary Sciences, Herman-Rein-Straße 3, 37075 Goettingen, Germany
- Department for Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 420, 69120 Heidelberg, Germany
| | - Lucie Farková
- Department of Migration, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany
- Department of Zoology, Charles University, Viničná 7, 128 00 Prague, Czech Republic
| | - Lara Keicher
- Department of Migration, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany
- University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Dina K. N. Dechmann
- Department of Migration, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany
- University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
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4
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Howell KJ, Walsh MR. Transplant experiments demonstrate that larger brains are favoured in high-competition environments in Trinidadian killifish. Ecol Lett 2023; 26:53-62. [PMID: 36262097 DOI: 10.1111/ele.14133] [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: 05/25/2022] [Revised: 09/19/2022] [Accepted: 09/22/2022] [Indexed: 12/27/2022]
Abstract
The extent to which the evolution of a larger brain is adaptive remains controversial. Trinidadian killifish (Anablepsoides hartii) are found in sites that differ in predation intensity; fish that experience decreased predation and increased intraspecific competition exhibit larger brains. We evaluated the connection between brain size and fitness (survival and growth) when killifish are found in their native habitats and when fish are transplanted from sites with predators to high-competition sites that lack predators. Selection for a larger brain was absent within locally adapted populations. Conversely, there was a strong positive relationship between brain size and growth in transplanted but not resident fish in high-competition environments. We also observed significantly larger brain sizes in the transplanted fish that were recaptured at the end of the experiment versus those that were not. Our results provide experimental support that larger brains increase fitness and are favoured in high-competition environments.
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Affiliation(s)
- Kaitlyn J Howell
- Department of Biology, University of Texas at Arlington, Arlington, Texas, USA
| | - Matthew R Walsh
- Department of Biology, University of Texas at Arlington, Arlington, Texas, USA
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5
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Fu Y, Song Y, Yang C, Liu X, Liu Y, Huang Y. Relationship between brain size and digestive tract length support the expensive-tissue hypothesis in Feirana quadranus. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.982590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The brain is among the most energetically costly organs in the vertebrate body, while the size of the brain varies within species. The expensive-tissue hypothesis (ETH) predicts that increasing the size of another costly organ, such as the gut, should compensate for the cost of a small brain. Here, the ETH was tested by analyzing the relationship between brain size variation and digestive tract length in a Swelled-vented frog (Feirana quadranus). A total of 125 individuals across 10 populations ranging from 586 to 1,702 m a.s.l. from the Qinling-Daba Mountains were sampled. With the increase in altitude, the brain size decreases and the digestive tract length increases. Different brain regions do not change their relative size in a consistent manner. The sizes of telencephalon and cerebellum decrease with the increase in altitude, while the olfactory nerve increases its size at high altitudes. However, the olfactory bulb and optic tectum have no significant relationship with altitude. After controlling for snout-vent length (SVL), a significant negative correlation could be found between brain size and digestive tract length in F. quadranus. Therefore, the intraspecific variation of brain size follows the general patterns of ETH in this species. The results suggest that annual mean temperature and annual precipitation are environmental factors influencing the adaptive evolution of brain size and digestive tract length. This study also suggests that food composition, activity times, and habitat complexity are the potential reasons driving the adaptive evolution of brain size and digestive tract length.
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6
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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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7
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Liao WB, Jiang Y, Li DY, Jin L, Zhong MJ, Qi Y, Lüpold S, Kotrschal A. Cognition contra camouflage: How the brain mediates predator-driven crypsis evolution. SCIENCE ADVANCES 2022; 8:eabq1878. [PMID: 35977010 PMCID: PMC9385145 DOI: 10.1126/sciadv.abq1878] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 07/01/2022] [Indexed: 06/01/2023]
Abstract
While crypsis is a prominent antipredator adaptation, the role of the brain in predator-driven evolution remains controversial. Resolving this controversy requires contextualizing the brain with established antipredator traits and predation pressure. We hypothesize that the reduced predation risk through crypsis relaxes predation-driven selection on the brain and provide comparative evidence across 102 Chinese frog species for our hypothesis. Specifically, our phylogenetic path analysis reveals an indirect relationship between predation risk and crypsis that is mediated by brain size. This result suggests that at a low predation risk, frogs can afford to be conspicuous and use their large brain for cognitive predator evasion. This strategy may become less efficient or energetically costlier under higher predation pressure, favoring smaller brains and instead increasing crypsis.
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Affiliation(s)
- Wen Bo Liao
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
- Key Laboratory of Artificial Propagation and Utilization in Anurans of Nanchong City, China West Normal University, Nanchong, Sichuan, China
| | - Ying Jiang
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
| | - Da Yong Li
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
| | - Long Jin
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
| | - Mao Jun Zhong
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
| | - Yin Qi
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Alexander Kotrschal
- Behavioral Ecology, Department of Animal Sciences, Wageningen University, Wageningen, Netherlands
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8
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Závorka L, Wallerius ML, Kainz MJ, Höjesjö J. Linking omega-3 polyunsaturated fatty acids in natural diet with brain size of wild consumers. Oecologia 2022; 199:797-807. [PMID: 35960390 DOI: 10.1007/s00442-022-05229-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 07/20/2022] [Indexed: 01/27/2023]
Abstract
Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are key structural lipids and their dietary intake is essential for brain development of virtually all vertebrates. The importance of n-3 LC-PUFA has been demonstrated in clinical and laboratory studies, but little is known about how differences in the availability of n-3 LC-PUFA in natural prey influence brain development of wild consumers. Consumers foraging at the interface of aquatic and terrestrial food webs can differ substantially in their intake of n-3 LC-PUFA, which may lead to differences in brain development, yet this hypothesis remains to be tested. Here we use the previously demonstrated shift towards higher reliance on n-3 LC-PUFA deprived terrestrial prey of native brown trout Salmo trutta living in sympatry with invasive brook trout Salvelinus fontinalis to explore this hypothesis. We found that the content of n-3 LC-PUFA in muscle tissues of brown trout decreased with increasing consumption of n-3 LC-PUFA deprived terrestrial prey. Brain volume was positively related to the content of the n-3 LC-PUFA, docosahexaenoic acid, in muscle tissues of brown trout. Our study thus suggests that increased reliance on diets low in n-3 LC-PUFA, such as terrestrial subsidies, can have a significant negative impact on brain development of wild trout. Our findings provide the first evidence of how brains of wild vertebrate consumers response to scarcity of n-3 LC-PUFA content in natural prey.
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Affiliation(s)
- Libor Závorka
- WasserCluster Lunz, Inter-university Centre for Aquatic Ecosystem Research, 3293, Lunz am See, Austria.
| | - Magnus Lovén Wallerius
- Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, 405 30, Gothenburg, Sweden
| | - Martin J Kainz
- WasserCluster Lunz, Inter-university Centre for Aquatic Ecosystem Research, 3293, Lunz am See, Austria.,Department of Biomedical Research, Danube University Krems, 3500, Krems, Austria
| | - Johan Höjesjö
- Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, 405 30, Gothenburg, Sweden
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9
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Predation impacts brain allometry in female guppies (Poecilia reticulata). Evol Ecol 2022; 36:1045-1059. [DOI: 10.1007/s10682-022-10191-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 05/16/2022] [Accepted: 05/16/2022] [Indexed: 11/30/2022]
Abstract
AbstractCognitive and sensory abilities are vital in affecting survival under predation risk, leading to selection on brain anatomy. However, how exactly predation and brain evolution are linked has not yet been resolved, as current empirical evidence is inconclusive. This may be due to predation pressure having different effects across life stages and/or due to confounding factors in ecological comparisons of predation pressure. Here, we used adult guppies (Poecilia reticulata) to experimentally test how direct predation during adulthood would impact the relative brain size and brain anatomy of surviving individuals to examine if predators selectively remove individuals with specific brain morphology. To this end, we compared fish surviving predation to control fish, which were exposed to visual and olfactory predator cues but could not be predated on. We found that predation impacted the relative size of female brains. However, this effect was dependent on body size, as larger female survivors showed relatively larger brains, while smaller survivors showed relatively smaller brains when compared to control females. We found no differences in male relative brain size between survivors and controls, nor for any specific relative brain region sizes for either sex. Our results corroborate the important, yet complex, role of predation as an important driver of variation in brain size.
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10
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Liu M, Liu Y, Wang H, Jia J, Liu K. Color Discrimination Provides Insight into the Relationship between Personality Cognition and Brain Morphology in the Western Mosquitofish (Gambusia affinis). BRAIN, BEHAVIOR AND EVOLUTION 2022; 97:274-283. [PMID: 35189620 DOI: 10.1159/000522483] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 02/06/2022] [Indexed: 06/14/2023]
Abstract
Recent studies on the differences in cognitive ability between individuals focused on two aspects: one is whether the individual differences in cognitive ability are related to brain size, the other is whether they pertain to certain personality traits. To explore these two hypotheses, we tested the personality traits, cognitive abilities, and brain volumes of western mosquitofish (Gambusia affinis). First, a color preference test was conducted to select two unbiased colors for G. affinis for subsequent cognitive tests. The results showed that G. affinis had a great preference for red and green to yellow and blue; therefore, the red-green combination was selected for the study of cognitive abilities. Then, we explored the relationship among cognition, personality, and brain morphology through cognitive abilities tests, personality traits, and brain volume measurements. We found that there was a trade-off among cognition, personality, and brain morphology. For example, more active individuals found food faster, but had also poor memory; Those individuals with larger corpus cerebelli were bolder while they were less likely to find food; The individuals that found food faster were more active and had a smaller inferior lobe. The color preference test provides a reliable way for selecting unbiased colors for behavioral studies in G. affinis. Meanwhile, our study indicates that there exists a balance mechanism among cognition, personality, and brain morphology.
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Affiliation(s)
- Mengyu Liu
- College of Animal Science and Technology, Northwest A&F University, Yangling, China,
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China,
| | - Yanqiu Liu
- 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
| | - Jia Jia
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Kai Liu
- Fujian Provincial Key Laboratory of Marine Fishery Resources and Eco-Environment, Fisheries College, Jimei University, Xiamen, China
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11
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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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12
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McNeil RM, Devigili A, Kolm N, Fitzpatrick JL. Does brain size affect mate choice? An experimental examination in pygmy halfbeaks. Behav Ecol 2021; 32:1103-1113. [PMID: 34949959 PMCID: PMC8691582 DOI: 10.1093/beheco/arab046] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/26/2021] [Accepted: 04/22/2021] [Indexed: 11/16/2022] Open
Abstract
Choosing a mate is one of the most important decisions in an animal's lifetime. Female mate choice is often guided by the presence or intensity of male sexual ornaments, which must be integrated and compared among potential mates. Individuals with greater cognitive abilities may be better at evaluating and comparing sexual ornaments, even when the difference in ornaments is small. While brain size is often used as a proxy for cognitive ability, its effect on mate choice has rarely been investigated. Here, we investigate the effect of brain size on mate preferences in the pygmy halfbeak Dermogenys collettei, a small freshwater fish that forms mixed-sex shoals where mating takes place. Pygmy halfbeaks are ideal models as their semi-transparent heads allow for external brain measurements. After validating the use of external measurements as a proxy for internal brain size, we presented females with large or small brains (relative to body length) with two males that had either a large or small difference in sexual ornamentation (measured by the total area of red coloration). Unexpectedly, neither total relative brain size nor relative telencephalon size affected any measured aspect of mate preference. However, the difference in male sexual ornamentation did affect preference, with females preferring males with a smaller area of red coloration when the difference in ornaments was large. This study highlights the complexities of mate choice and the importance of considering a range of stimuli when examining mate preferences.
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Affiliation(s)
- Rebecca M McNeil
- Department of Zoology: Ethology, Stockholm University, Svante Arrhenius väg 18b, 106 91 Stockholm, Sweden
| | - Alessandro Devigili
- Department of Zoology: Ethology, Stockholm University, Svante Arrhenius väg 18b, 106 91 Stockholm, Sweden
| | - Niclas Kolm
- Department of Zoology: Ethology, Stockholm University, Svante Arrhenius väg 18b, 106 91 Stockholm, Sweden
| | - John L Fitzpatrick
- Department of Zoology: Ethology, Stockholm University, Svante Arrhenius väg 18b, 106 91 Stockholm, Sweden
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13
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Chen M, Li G, Liu J, Li S. Large brain size is associated with low extra-pair paternity across bird species. Ecol Evol 2021; 11:13601-13608. [PMID: 34646493 PMCID: PMC8495782 DOI: 10.1002/ece3.8087] [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: 07/29/2021] [Revised: 08/17/2021] [Accepted: 08/20/2021] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Gaining extrapair copulations (EPCs) is a complicated behavior process. The interaction between males and females to procure EPCs may be involved in brain function evolution and lead to a larger brain. Thus, we hypothesized that extrapair paternity (EPP) rate can be predicted by relative brain size in birds. Past work has implied that the EPP rate is associated with brain size, but empirical evidence is rare. METHODS We collated data from published references on EPP levels and brain size of 215 bird species to examine whether the evolution of EPP rate can be predicted by brain size using phylogenetically generalized least square (PGLS) models and phylogenetic path analyses. RESULTS We found that EPP rates (both the percentage EP offspring and percentage of broods with EP offspring) are negatively associated with relative brain size. We applied phylogenetic path analysis to test the causal relationship between relative brain size and EPP rate. Best-supported models (ΔCICc < 2) suggested that large brain lead to reduced EPP rate, which failed to support the hypothesis that high rates of EPP cause the evolution of larger brains. CONCLUSION This study indicates that pursuing EPCs may be a natural instinct in birds and the interaction between males and females for EPCs may lead to large brains, which in turn may restrict their EPC level for both sexes across bird species.
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Affiliation(s)
- Min Chen
- College of Life ScienceYangtze UniversityJingzhouChina
| | - Guopan Li
- College of Life ScienceYangtze UniversityJingzhouChina
| | - Jinlong Liu
- College of Life ScienceYangtze UniversityJingzhouChina
| | - Shaobin Li
- College of Life ScienceYangtze UniversityJingzhouChina
- MOE Key Laboratory of Biodiversity and Ecology EngineeringBeijing Normal UniversityBeijingChina
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14
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Monnet G, Rosenfeld JS, Richards JG. Behavioural variation between piscivore and insectivore rainbow trout Oncorhynchus mykiss. JOURNAL OF FISH BIOLOGY 2021; 99:955-963. [PMID: 33969488 DOI: 10.1111/jfb.14781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 05/03/2021] [Accepted: 05/06/2021] [Indexed: 06/12/2023]
Abstract
A proactive-reactive continuum integrating multiple (i.e., 3+) dimensions of animal behaviour has been reported as a major axis of behavioural differentiation, but its stability along a biological hierarchy from individuals to populations remains speculative. Piscivore and insectivore rainbow trout (Oncorhynchus mykiss) represent closely related ecotypes with strong ecological divergence driven by selection for a large-bodied piscivorous lifestyle with fast juvenile growth vs. selection for smaller adult body size and lower growth associated with an insectivorous diet. To evaluate whether differences in behaviour between ecotypes are consistent with a proactive-reactive axis and consistent along a biological hierarchy, the authors examined variation in emergence time from a shelter, exploration, activity and predator inspection among individuals, populations and ecotypes of juvenile piscivore and insectivore rainbow trout O. mykiss. As expected, the faster-growing piscivore ecotype was more proactive (i.e., shorter emergence time, exploration and predator inspection) than the more reactive insectivore ecotype. This behavioural contrast was partly maintained across populations, although activity differences were most pronounced among populations, rather than emergence time. Insectivore fry showed substantial variation in behavioural expression among individuals within populations; by contrast, piscivores showed highly similar proactive behaviours with significantly lower inter-individual variation in behavioural expression, suggesting intense selection on behaviour supporting their faster growth. This work suggests that piscivore and insectivore O. mykiss broadly differ in behaviour along a proactive vs. reactive continuum, and highlights the greater multidimensionality of behavioural expression within the insectivore ecotype. Contrasting behaviours between ecotypes may result from differential selection for slow vs. fast juvenile growth and associated metabolism, and may contribute to adult trophic specialization.
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Affiliation(s)
- Gauthier Monnet
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Jordan S Rosenfeld
- British Columbia Ministry of the Environment, Vancouver, British Columbia, Canada
- Institute for the Oceans and Fisheries, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Jeffrey G Richards
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
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15
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Sowersby W, Eckerström-Liedholm S, Kotrschal A, Näslund J, Rowiński P, Gonzalez-Voyer A, Rogell B. Fast life-histories are associated with larger brain size in killifishes. Evolution 2021; 75:2286-2298. [PMID: 34270088 DOI: 10.1111/evo.14310] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 06/11/2021] [Accepted: 06/25/2021] [Indexed: 11/27/2022]
Abstract
The high energetic demands associated with the vertebrate brain are proposed to result in a trade-off between the pace of life-history and relative brain size. However, because both life-history and brain size also have a strong relationship with body size, any associations between the pace of life-history and relative brain size may be confounded by coevolution with body size. Studies on systems where contrasts in the pace of life-history occur without concordant contrasts in body size could therefore add to our understanding of the potential coevolution between relative brain size and life-history. Using one such system - 21 species of killifish - we employed a common garden design across two ontogenetic stages to investigate the association between relative brain size and the pace of life-history. Contrary to predictions, we found that relative brain size was larger in adult fast-living killifishes, compared to slow-living species. Although we found no differences in relative brain size between juvenile killifishes. Our results suggest that fast- and slow-living killifishes do not exhibit the predicted trade-off between brain size and life-history. Instead, fast and slow-living killifishes could differ in the ontogenetic timing of somatic versus neural growth or inhabit environments that differ considerably in cognitive demands.
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Affiliation(s)
- Will Sowersby
- Department of Zoology, Stockholm University, Stockholm, Sweden.,Department of Biology, Osaka City University, Osaka, Japan
| | - Simon Eckerström-Liedholm
- Department of Zoology, Stockholm University, Stockholm, Sweden.,Wild Animal Initiative, Farmington, Minnesota, USA
| | - Alexander Kotrschal
- Department of Zoology, Stockholm University, Stockholm, Sweden.,Department of Animal Sciences: Behavioural Ecology, Wageningen University, Wageningen, Netherlands
| | - Joacim Näslund
- Department of Zoology, Stockholm University, Stockholm, Sweden.,Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Drottningholm, Sweden
| | - Piotr Rowiński
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Alejandro Gonzalez-Voyer
- Department of Zoology, Stockholm University, Stockholm, Sweden.,Instituto de Ecología, Universidad Nacional Autónoma de México, México, Mexico
| | - Björn Rogell
- Department of Zoology, Stockholm University, Stockholm, Sweden.,Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Drottningholm, Sweden
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16
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Howell KJ, Beston SM, Stearns S, Walsh MR. Coordinated evolution of brain size, structure, and eye size in Trinidadian killifish. Ecol Evol 2021; 11:365-375. [PMID: 33437435 PMCID: PMC7790632 DOI: 10.1002/ece3.7051] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/29/2020] [Accepted: 11/01/2020] [Indexed: 12/19/2022] Open
Abstract
Brain size, brain architecture, and eye size vary extensively in vertebrates. However, the extent to which the evolution of these components is intricately connected remains unclear. Trinidadian killifish, Anablepsoides hartii, are found in sites that differ in the presence and absence of large predatory fish. Decreased rates of predation are associated with evolutionary shifts in brain size; males from sites without predators have evolved a relatively larger brain and eye size than males from sites with predators. Here, we evaluated the extent to which the evolution of brain size, brain structure, and eye size covary in male killifish. We utilized wild-caught and common garden-reared specimens to determine whether specific components of the brain have evolved in response to differences in predation and to determine if there is covariation between the evolution of brain size, brain structure, and eye size. We observed consistent shifts in brain architecture in second generation common garden reared, but not wild caught preserved fish. Male killifish from sites that lack predators exhibited a significantly larger telencephalon, optic tectum, cerebellum, and dorsal medulla when compared with fish from sites with predators. We also found positive connections between the evolution of brain structure and eye size but not between overall brain size and eye size. These results provide evidence for evolutionary covariation between the components of the brain and eye size. Such results suggest that selection, directly or indirectly, acts upon specific regions of the brain, rather than overall brain size, to enhance visual capabilities.
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Affiliation(s)
| | | | - Sara Stearns
- 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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Boussard A, Amcoff M, Buechel SD, Kotrschal A, Kolm N. The link between relative brain size and cognitive ageing in female guppies (Poecilia reticulata) artificially selected for variation in brain size. Exp Gerontol 2020; 146:111218. [PMID: 33373711 DOI: 10.1016/j.exger.2020.111218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/10/2020] [Accepted: 12/16/2020] [Indexed: 11/29/2022]
Abstract
Cognitive ageing is the general process when certain mental skills gradually deteriorate with age. Across species, there is a pattern of a slower brain structure degradation rate in large-brained species. Hence, having a larger brain might buffer the impact of cognitive ageing and positively affect survival at older age. However, few studies have investigated the link between relative brain size and cognitive ageing at the intraspecific level. In particular, experimental data on how brain size affects brain function also into higher age is largely missing. We used 288 female guppies (Poecilia reticulata), artificially selected for large and small relative brain size, to investigate variation in colour discrimination and behavioural flexibility, at 4-6, 12 and 24 months of age. These ages are particularly interesting since they cover the life span from sexual maturation until maximal life length under natural conditions. We found no evidence for a slower cognitive ageing rate in large-brained females in neither initial colour discrimination nor reversal learning. Behavioural flexibility was predicted by large relative brain size in the youngest group, but the effect of brain size disappeared with increasing age. This result suggests that cognitive ageing rate is faster in large-brained female guppies, potentially due to the faster ageing and shorter lifespan in the large-brained selection lines. It also means that cognition levels align across different brain sizes with older age. We conclude that there are cognitive consequences of ageing that vary with relative brain size in advanced learning abilities, whereas fundamental aspects of learning can be maintained throughout the ecologically relevant life span.
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Affiliation(s)
- Annika Boussard
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden.
| | - Mirjam Amcoff
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden.
| | - Severine D Buechel
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden; Department of Animal Sciences: Behavioural Ecology, Wageningen University & Research, 6708 WD Wageningen, Netherlands.
| | - Alexander Kotrschal
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden; Department of Animal Sciences: Behavioural Ecology, Wageningen University & Research, 6708 WD Wageningen, Netherlands.
| | - Niclas Kolm
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden.
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18
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Boussard A, Buechel SD, Amcoff M, Kotrschal A, Kolm N. Brain size does not predict learning strategies in a serial reversal learning test. J Exp Biol 2020; 223:jeb224741. [PMID: 32561630 PMCID: PMC7413604 DOI: 10.1242/jeb.224741] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 06/10/2020] [Indexed: 11/20/2022]
Abstract
Reversal learning assays are commonly used across a wide range of taxa to investigate associative learning and behavioural flexibility. In serial reversal learning, the reward contingency in a binary discrimination is reversed multiple times. Performance during serial reversal learning varies greatly at the interspecific level, as some animals adopt a rule-based strategy that enables them to switch quickly between reward contingencies. A larger relative brain size, generating enhanced learning ability and increased behavioural flexibility, has been proposed to be an important factor underlying this variation. Here, we experimentally tested this hypothesis at the intraspecific level. We used guppies (Poecilia reticulata) artificially selected for small and large relative brain size, with matching differences in neuron number, in a serial reversal learning assay. We tested 96 individuals over 10 serial reversals and found that learning performance and memory were predicted by brain size, whereas differences in efficient learning strategies were not. We conclude that variation in brain size and neuron number is important for variation in learning performance and memory, but these differences are not great enough to cause the larger differences in efficient learning strategies observed at higher taxonomic levels.
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Affiliation(s)
- Annika Boussard
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden
| | - Séverine D Buechel
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden
| | - Mirjam Amcoff
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden
| | - Alexander Kotrschal
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden
- Behaviour Ecology, Wageningen University, De Elst 1, 6708wd Wageningen, The Netherlands
| | - Niclas Kolm
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden
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19
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Axelrod CJ, Laberge F, Robinson BW. Isolating the effects of ontogenetic niche shift on brain size development using pumpkinseed sunfish ecotypes. Evol Dev 2020; 22:312-322. [DOI: 10.1111/ede.12333] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Caleb J. Axelrod
- Department of Integrative BiologyUniversity of Guelph Guelph Ontario Canada
| | - Frédéric Laberge
- Department of Integrative BiologyUniversity of Guelph Guelph Ontario Canada
| | - Beren W. Robinson
- Department of Integrative BiologyUniversity of Guelph Guelph Ontario Canada
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20
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21
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Mitchell DJ, Vega-Trejo R, Kotrschal A. Experimental translocations to low predation lead to non-parallel increases in relative brain size. Biol Lett 2020; 16:20190654. [PMID: 31964256 PMCID: PMC7013489 DOI: 10.1098/rsbl.2019.0654] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 12/06/2019] [Indexed: 12/03/2022] Open
Abstract
Predation is a near ubiquitous factor of nature and a powerful selective force on prey. Moreover, it has recently emerged as an important driver in the evolution of brain anatomy, though population comparisons show ambiguous results with considerable unexplained variation. Here, we test the reproducibility of reduced predation on evolutionary trajectories of brain evolution. We make use of an introduction experiment, whereby guppies (Poecilia reticulata) from a single high predation stream were introduced to four low predation streams. After 8-9 years of natural selection in the wild and two generations of common garden conditions in the laboratory, we quantified brain anatomy. Relative brain region sizes did not differ between populations. However, we found a general increase and striking variation in relative brain size of introduced populations, which varied from no change to a 12.5% increase in relative brain weight, relative to the ancestral high predation population. We interpret this as evidence for non-parallel evolution, which implies a weak or inconsistent association of relative brain size with fitness in low predation sites. The evolution of brain anatomy appears sensitive to unknown environmental factors, or contingent on either chance events or historical legacies of environmental change.
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Affiliation(s)
- David J. Mitchell
- Department of Zoology/Ethology, Stockholm University, Svante Arrheniusväg 18B, 10691 Stockholm, Sweden
| | - Regina Vega-Trejo
- Department of Zoology/Ethology, Stockholm University, Svante Arrheniusväg 18B, 10691 Stockholm, Sweden
| | - Alexander Kotrschal
- Department of Zoology/Ethology, Stockholm University, Svante Arrheniusväg 18B, 10691 Stockholm, Sweden
- Department of Animal Sciences, Behavioural Ecology group, Wageningen University, 6708 Wageningen, The Netherlands
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22
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Abelson ES. Big brains reduce extinction risk in Carnivora. Oecologia 2019; 191:721-729. [PMID: 31650235 DOI: 10.1007/s00442-019-04527-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 10/03/2019] [Indexed: 11/28/2022]
Abstract
Why are some mammals more vulnerable to extinction than others? Past studies have explored many life history traits as correlates of extinction, but have not been successful at developing a unified understanding of why some species become extinct while other species persist despite living at the same time, under similar conditions, and facing equivalent challenges. I propose that the lens of wildlife behavior may bring into focus a more comprehensive view of why some species have gone extinct while others persist. The fossil record has recorded extinction events over carnivoran history; unfortunately, behavior is not well recorded in the fossil record. As a proxy for behavior, I examine relative encephalization (RE), brain size after controlling for body mass and phylogeny, as it has been found to be biologically relevant in understanding a wide variety of animal behavioral traits. I focus on the data-rich order Carnivora for which there are comprehensive data on brain size and extinction between 40 and 0.012 million years ago. I use Cox proportional-hazards models to assess the role that RE and body size have played on extinction risk for 224 species in the order Carnivora that existed between 40 and 0.012 million years ago. I show generally that carnivoran species with reduced RE had higher relative risks of extinction. Additionally, I find an interaction between RE and body size such that RE had the largest effects on relative extinction risk in the smallest-bodied species. These results suggest that RE is important for understanding extinction risk in Carnivora over geologic time frames.
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Affiliation(s)
- Eric S Abelson
- Department of Biology, Stanford University, Stanford, USA. .,USDA Forest Service, Pacific Southwest Research Station, Albany, USA.
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23
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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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24
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Marhounová L, Kotrschal A, Kverková K, Kolm N, Němec P. Artificial selection on brain size leads to matching changes in overall number of neurons. Evolution 2019; 73:2003-2012. [PMID: 31339177 PMCID: PMC6772110 DOI: 10.1111/evo.13805] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/13/2019] [Accepted: 06/19/2019] [Indexed: 12/16/2022]
Abstract
Neurons are the basic computational units of the brain, but brain size is the predominant surrogate measure of brain functional capacity in comparative and cognitive neuroscience. This approach is based on the assumption that larger brains harbor higher numbers of neurons and their connections, and therefore have a higher information-processing capacity. However, recent studies have shown that brain mass may be less strongly correlated with neuron counts than previously thought. Till now, no experimental test has been conducted to examine the relationship between evolutionary changes in brain size and the number of brain neurons. Here, we provide such a test by comparing neuron number in artificial selection lines of female guppies (Poecilia reticulata) with >15% difference in relative brain mass and numerous previously demonstrated cognitive differences. Using the isotropic fractionator, we demonstrate that large-brained females have a higher overall number of neurons than small-brained females, but similar neuronal densities. Importantly, this difference holds also for the telencephalon, a key region for cognition. Our study provides the first direct experimental evidence that selection for brain mass leads to matching changes in number of neurons and shows that brain size evolution is intimately linked to the evolution of neuron number and cognition.
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Affiliation(s)
- Lucie Marhounová
- Department of Zoology, Faculty of ScienceCharles University12844PragueCzech Republic
| | - Alexander Kotrschal
- Behavioural Ecology GroupDepartment of Animal Sciences6708wdWageningenNetherlands
- Department of Zoology/EthologyStockholm University10691StockholmSweden
| | - Kristina Kverková
- Department of Zoology, Faculty of ScienceCharles University12844PragueCzech Republic
| | - Niclas Kolm
- Department of Zoology/EthologyStockholm University10691StockholmSweden
| | - Pavel Němec
- Department of Zoology, Faculty of ScienceCharles University12844PragueCzech Republic
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25
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Swain A, Fagan WF. Group size and decision making: experimental evidence for minority games in fish behaviour. Anim Behav 2019. [DOI: 10.1016/j.anbehav.2019.05.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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26
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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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27
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Fong S, Buechel SD, Boussard A, Kotrschal A, Kolm N. Plastic changes in brain morphology in relation to learning and environmental enrichment in the guppy ( Poecilia reticulata). ACTA ACUST UNITED AC 2019; 222:jeb.200402. [PMID: 31053644 DOI: 10.1242/jeb.200402] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 04/26/2019] [Indexed: 12/19/2022]
Abstract
Despite the common assumption that the brain is malleable to surrounding conditions mainly during ontogeny, plastic neural changes can occur also in adulthood. One of the driving forces responsible for alterations in brain morphology is increasing environmental complexity that may demand enhanced cognitive abilities (e.g. attention, memory and learning). However, studies looking at the relationship between brain morphology and learning are scarce. Here, we tested the effects of both learning and environmental enrichment on neural plasticity in guppies (Poecilia reticulata), by means of either a reversal-learning test or a spatial-learning test. Given considerable evidence supporting environmentally induced plastic alterations, two separate control groups that were not subjected to any cognitive test were included to account for potential changes induced by the experimental setup alone. We did not find any effect of learning on any of our brain measurements. However, we found strong evidence for an environmental effect, where fish given access to the spatial-learning environment had larger relative brain size and optic tectum size in relation to those exposed to the reversal-learning environment. Our results demonstrate the plasticity of the adult brain to respond adaptively mainly to environmental conditions, providing support for the environmental enhancement theory.
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Affiliation(s)
- Stephanie Fong
- Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Séverine D Buechel
- Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Annika Boussard
- Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden
| | | | - Niclas Kolm
- Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden
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28
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Herczeg G, Urszán TJ, Orf S, Nagy G, Kotrschal A, Kolm N. Brain size predicts behavioural plasticity in guppies (Poecilia reticulata): An experiment. J Evol Biol 2018; 32:218-226. [PMID: 30474900 DOI: 10.1111/jeb.13405] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 11/12/2018] [Accepted: 11/18/2018] [Indexed: 11/28/2022]
Abstract
Understanding how animal personality (consistent between-individual behavioural differences) arises has become a central topic in behavioural sciences. This endeavour is complicated by the fact that not only the mean behaviour of individuals (behavioural type) but also the strength of their reaction to environmental change (behavioural plasticity) varies consistently. Personality and cognitive abilities are linked, and we suggest that behavioural plasticity could also be explained by differences in brain size (a proxy for cognitive abilities), since accurate decisions are likely essential to make behavioural plasticity beneficial. We test this idea in guppies (Poecilia reticulata), artificially selected for large and small brain size, which show clear cognitive differences between selection lines. To test whether those lines differed in behavioural plasticity, we reared them in groups in structurally enriched environments and then placed adults individually into empty tanks, where we presented them daily with visual predator cues and monitored their behaviour for 20 days with video-aided motion tracking. We found that individuals differed consistently in activity and risk-taking, as well as in behavioural plasticity. In activity, only the large-brained lines demonstrated habituation (increased activity) to the new environment, whereas in risk-taking, we found sensitization (decreased risk-taking) in both brain size lines. We conclude that brain size, potentially via increasing cognitive abilities, may increase behavioural plasticity, which in turn can improve habituation to novel environments. However, the effects seem to be behaviour-specific. Our results suggest that brain size likely explains some of the variation in behavioural plasticity found at the intraspecific level.
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Affiliation(s)
- Gábor Herczeg
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, EötvösLoránd University, Budapest, Hungary
| | - Tamás J Urszán
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, EötvösLoránd University, Budapest, Hungary
| | - Stephanie Orf
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, EötvösLoránd University, Budapest, Hungary
| | - Gergely Nagy
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, EötvösLoránd University, Budapest, Hungary
| | | | - Niclas Kolm
- Department of Zoology, Stockholm University, Stockholm, Sweden
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Amodio P, Boeckle M, Schnell AK, Ostojíc L, Fiorito G, Clayton NS. Grow Smart and Die Young: Why Did Cephalopods Evolve Intelligence? Trends Ecol Evol 2018; 34:45-56. [PMID: 30446408 DOI: 10.1016/j.tree.2018.10.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/16/2018] [Accepted: 10/18/2018] [Indexed: 11/16/2022]
Abstract
Intelligence in large-brained vertebrates might have evolved through independent, yet similar processes based on comparable socioecological pressures and slow life histories. This convergent evolutionary route, however, cannot explain why cephalopods developed large brains and flexible behavioural repertoires: cephalopods have fast life histories and live in simple social environments. Here, we suggest that the loss of the external shell in cephalopods (i) caused a dramatic increase in predatory pressure, which in turn prevented the emergence of slow life histories, and (ii) allowed the exploitation of novel challenging niches, thus favouring the emergence of intelligence. By highlighting convergent and divergent aspects between cephalopods and large-brained vertebrates we illustrate how the evolution of intelligence might not be constrained to a single evolutionary route.
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Affiliation(s)
- Piero Amodio
- Department of Psychology, University of Cambridge, Cambridge, UK.
| | - Markus Boeckle
- Department of Psychology, University of Cambridge, Cambridge, UK
| | | | - Ljerka Ostojíc
- Department of Psychology, University of Cambridge, Cambridge, UK
| | - Graziano Fiorito
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Nicola S Clayton
- Department of Psychology, University of Cambridge, Cambridge, UK
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30
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Reynoso MMN, Lucia A, Zerba EN, Alzogaray RA. Eugenol-hyperactivated nymphs of Triatoma infestans become intoxicated faster than non-hyperactivated nymphs when exposed to a permethrin-treated surface. Parasit Vectors 2018; 11:573. [PMID: 30390682 PMCID: PMC6215654 DOI: 10.1186/s13071-018-3146-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 10/10/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Eugenol is a botanical monoterpene that hyperactivates the blood-sucking bug Triatoma infestans, and permethrin is a pyrethroid with a strong triatomicide effect. In the present work, we tested the hypothesis that eugenol-hyperactivated nymphs of T. infestans pick up more insecticide, and then become intoxicated faster, than non-hyperactivated nymphs when exposed to a permethrin-treated surface. RESULTS Values of knockdown time 50% (KT50) for third-instar T. infestans exposed to a paper impregnated with permethrin were obtained under the following situations: (a.i.) immediately after topical application of eugenol (KT50: 66.75 min for acetone pre-treated controls, and 46.27 min for eugenol pre-treated nymphs); (a.ii.) 30 min after topical application of eugenol (KT50: 66.79 min for controls, and 66.79 min for eugenol pre-treated nymphs); (b) simultaneously with exposure to eugenol vapors (KT50: 51.90 min for controls, and 39.5 min for nymphs exposed to an eugenol-treated filter paper); and (c) immediately after an injection of eugenol (on average, controls were knocked down after 63.00 min, whereas nymphs injected with eugenol were knocked down after 65.30 min). In other experimental series, the distance traveled (DT) by nymphs exposed to eugenol was quantified in the same situations previously described, but without exposure to permethrin. In (a.i.), the DT in interval 0-30 min after topical application of eugenol was 487.00 (control) and 1127.50 (eugenol) cm; in (a.ii.), the DT in the interval 31-60 min after topical application was 336.75 (control) and 256.75 (eugenol) cm; in (b), DT was 939.08 (control) and 1048.53 (eugenol) cm; and in (c), it was 589.20 (control) and 700.00 (eugenol) cm. The KT50 values for permethrin decreased significantly in situations (a.i.) and (b), and eugenol only produced a significant hyperactivity in the same situations. Finally, the amount of permethrin picked up by non-hyperactivated and hyperactivated nymphs exposed to a film of permethrin was quantified by gas chromatography. Non-hyperactivated nymphs picked up 0.34 μg/insect of permethrin, while hyperactivated nymphs picked up 0.65 μg/insect. CONCLUSION Results support the hypothesis that eugenol-hyperactivated nymphs of T. infestans pick up more insecticide, and then become intoxicated faster, than non-hyperactivated nymphs when exposed to a permethrin-treated surface.
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Affiliation(s)
| | - Alejandro Lucia
- UNIDEF-CITEDEF-CONICET- CIPEIN, Juan B. de La Salle 4397, (1603) Villa Martelli, Buenos Aires, Argentina
| | - Eduardo Nicolás Zerba
- UNIDEF-CITEDEF-CONICET- CIPEIN, Juan B. de La Salle 4397, (1603) Villa Martelli, Buenos Aires, Argentina
| | - Raúl Adolfo Alzogaray
- UNIDEF-CITEDEF-CONICET- CIPEIN, Juan B. de La Salle 4397, (1603) Villa Martelli, Buenos Aires, Argentina.
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31
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Bloch NI, Corral-López A, Buechel SD, Kotrschal A, Kolm N, Mank JE. Early neurogenomic response associated with variation in guppy female mate preference. Nat Ecol Evol 2018; 2:1772-1781. [PMID: 30297748 PMCID: PMC6349141 DOI: 10.1038/s41559-018-0682-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 08/29/2018] [Indexed: 12/20/2022]
Abstract
Understanding the evolution of mate choice requires dissecting the mechanisms of female preference, particularly how these differ among social contexts and preference phenotypes. Here we study the female neurogenomic response after only 10 minutes of mate exposure in both a sensory component (optic tectum) and a decision-making component (telencephalon) of the brain. By comparing the transcriptional response between females with and without preferences for colorful males, we identified unique neurogenomic elements associated with the female preference phenotype that are not present in females without preference. Network analysis revealed different properties for this response at the sensory-processing and the decision-making levels, and showed that this response is highly centralized in the telencephalon. Furthermore, we identified an additional set of genes that vary in expression across social contexts, beyond mate evaluation. We show that transcription factors among those loci are predicted to regulate the transcriptional response of the genes we found to be associated with female preference.
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Affiliation(s)
- Natasha I Bloch
- Department of Genetics, Evolution and Environment, University College London, London, UK.
| | | | | | | | - Niclas Kolm
- Department of Zoology/Ethology, Stockholm University, Stockholm, Sweden
| | - Judith E Mank
- Department of Genetics, Evolution and Environment, University College London, London, UK.,Department of Organismal Biology, Uppsala University, Uppsala, Sweden
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32
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Szorkovszky A, Kotrschal A, Herbert-Read JE, Buechel SD, Romenskyy M, Rosén E, van der Bijl W, Pelckmans K, Kolm N, Sumpter DJ. Assortative interactions revealed by sorting of animal groups. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2018.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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33
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Reddon AR, Chouinard‐Thuly L, Leris I, Reader SM. Wild and laboratory exposure to cues of predation risk increases relative brain mass in male guppies. Funct Ecol 2018. [DOI: 10.1111/1365-2435.13128] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Adam R. Reddon
- Department of BiologyMcGill University Montreal Quebec Canada
| | | | - Ioannis Leris
- Department of BiologyMcGill University Montreal Quebec Canada
- Department of Biology and Helmholtz InstituteUtrecht University Utrecht The Netherlands
| | - Simon M. Reader
- Department of BiologyMcGill University Montreal Quebec Canada
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34
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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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35
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Buechel SD, Boussard A, Kotrschal A, van der Bijl W, Kolm N. Brain size affects performance in a reversal-learning test. Proc Biol Sci 2018; 285:20172031. [PMID: 29367391 PMCID: PMC5805926 DOI: 10.1098/rspb.2017.2031] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 12/13/2017] [Indexed: 02/06/2023] Open
Abstract
It has become increasingly clear that a larger brain can confer cognitive benefits. Yet not all of the numerous aspects of cognition seem to be affected by brain size. Recent evidence suggests that some more basic forms of cognition, for instance colour vision, are not influenced by brain size. We therefore hypothesize that a larger brain is especially beneficial for distinct and gradually more complex aspects of cognition. To test this hypothesis, we assessed the performance of brain size selected female guppies (Poecilia reticulata) in two distinct aspects of cognition that differ in cognitive complexity. In a standard reversal-learning test we first investigated basic learning ability with a colour discrimination test, then reversed the reward contingency to specifically test for cognitive flexibility. We found that large-brained females outperformed small-brained females in the reversed-learning part of the test but not in the colour discrimination part of the test. Large-brained individuals are hence cognitively more flexible, which probably yields fitness benefits, as they may adapt more quickly to social and/or ecological cognitive challenges. Our results also suggest that a larger brain becomes especially advantageous with increasing cognitive complexity. These findings corroborate the significance of brain size for cognitive evolution.
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Affiliation(s)
- Séverine D Buechel
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691, Stockholm, Sweden
| | - Annika Boussard
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691, Stockholm, Sweden
| | - Alexander Kotrschal
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691, Stockholm, Sweden
| | - Wouter van der Bijl
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691, Stockholm, Sweden
| | - Niclas Kolm
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691, Stockholm, Sweden
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36
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Corral-López A, Kotrschal A, Kolm N. Selection for relative brain size affects context-dependent male preferences, but not discrimination, of female body size in guppies. J Exp Biol 2018; 221:jeb.175240. [DOI: 10.1242/jeb.175240] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 05/01/2018] [Indexed: 12/26/2022]
Abstract
Understanding what drives animal decisions is fundamental in evolutionary biology, and mate choice decisions are arguably some of the most important decisions in any individual's life. As cognitive ability can impact decision-making, elucidating the link between mate choice and cognitive ability is necessary to fully understand mate choice. To experimentally study this link, we used guppies (Poecilia reticulata) artificially selected for divergence in relative brain size and with previously demonstrated differences in cognitive ability. A previous test in our female guppy selection lines demonstrated the impact of brain size and cognitive ability on information processing during female mate choice decisions. Here we evaluated the effect of brain size and cognitive ability on male mate choice decisions. Specifically, we investigated the preferences of large-brained, small-brained, and non-selected guppy males for female body size, a key indicator of female fecundity in this species. For this, male preferences were quantified in dichotomous choice tests when presented to dyads of females with small, medium and large body size differences. All types of males showed preference for larger females but no effect of brain size was found in the ability to discriminate between differently sized females. However, we found that non-selected and large-brained males, but not small-brained males, showed context-dependent preferences for larger females depending on the difference in female size. Our results have two important implications. First, they provide further evidence that male mate choice occurs also in a species in which secondary sexual ornamentation occurs only in males. Second, they show that brain size and cognitive ability have important effects on individual variation in mating preferences and sexually selected traits.
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Affiliation(s)
- Alberto Corral-López
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B. SE-10691, Stockholm, Sweden
| | - Alexander Kotrschal
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B. SE-10691, Stockholm, Sweden
| | - Niclas Kolm
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B. SE-10691, Stockholm, Sweden
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37
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Kotrschal A, Szorkovszky A, Romenskyy M, Perna A, Buechel SD, Zeng HL, Pelckmans K, Sumpter D, Kolm N. Brain size does not impact shoaling dynamics in unfamiliar groups of guppies (Poecilia reticulata). Behav Processes 2017; 147:13-20. [PMID: 29248747 DOI: 10.1016/j.beproc.2017.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 12/13/2017] [Accepted: 12/13/2017] [Indexed: 11/26/2022]
Abstract
Collective movement is achieved when individuals adopt local rules to interact with their neighbours. How the brain processes information about neighbours' positions and movements may affect how individuals interact in groups. As brain size can determine such information processing it should impact collective animal movement. Here we investigate whether brain size affects the structure and organisation of newly forming fish shoals by quantifying the collective movement of guppies (Poecilia reticulata) from large- and small-brained selection lines, with known differences in learning and memory. We used automated tracking software to determine shoaling behaviour of single-sex groups of eight or two fish and found no evidence that brain size affected the speed, group size, or spatial and directional organisation of fish shoals. Our results suggest that brain size does not play an important role in how fish interact with each other in these types of moving groups of unfamiliar individuals. Based on these results, we propose that shoal dynamics are likely to be governed by relatively basic cognitive processes that do not differ in these brain size selected lines of guppies.
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Affiliation(s)
| | | | - Maksym Romenskyy
- Department of Mathematics, Uppsala University, 75106, Uppsala, Sweden
| | - Andrea Perna
- Department of Life Sciences, University of Roehampton, London, United Kingdom
| | - Severine D Buechel
- Department of Zoology, Stockholm University, SE-10691, Stockholm, Sweden
| | - Hong-Li Zeng
- Department of Mathematics, Uppsala University, 75106, Uppsala, Sweden
| | | | - David Sumpter
- Department of Mathematics, Uppsala University, 75106, Uppsala, Sweden
| | - Niclas Kolm
- Department of Zoology, Stockholm University, SE-10691, Stockholm, Sweden
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38
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Luo Y, Zhong MJ, Huang Y, Li F, Liao WB, Kotrschal A. Seasonality and brain size are negatively associated in frogs: evidence for the expensive brain framework. Sci Rep 2017; 7:16629. [PMID: 29192284 PMCID: PMC5709389 DOI: 10.1038/s41598-017-16921-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 11/20/2017] [Indexed: 12/22/2022] Open
Abstract
The challenges of seasonal environments are thought to contribute to brain evolution, but in which way is debated. According to the Cognitive Buffer Hypothesis (CBH) brain size should increase with seasonality, as the cognitive benefits of a larger brain should help overcoming periods of food scarcity via, for instance, increased behavioral flexibility. However, in line with the Expensive Brain Framework (EBF) brain size should decrease with seasonality because a smaller brain confers energetic benefits in periods of food scarcity. Empirical evidence is inconclusive and mostly limited to homoeothermic animals. Here we used phylogenetic comparative analyses to test the impact of seasonality on brain evolution across 30 species of anurans (frogs) experiencing a wide range of temperature and precipitation. Our results support the EBF because relative brain size and the size of the optic tectum were negatively correlated with variability in temperature. In contrast, we found no association between the variability in precipitation and the length of the dry season with either brain size or the sizes of other major brain regions. We suggest that seasonality-induced food scarcity resulting from higher variability in temperature constrains brain size evolution in anurans. Less seasonal environments may therefore facilitate the evolution of larger brains in poikilothermic animals.
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Affiliation(s)
- Yi Luo
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, Sichuan, China
- Institute of Eco-adaptation in Amphibians and Reptiles, China West Normal University, Nanchong, 637009, Sichuan, China
| | - Mao Jun Zhong
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, Sichuan, China
- Institute of Eco-adaptation in Amphibians and Reptiles, China West Normal University, Nanchong, 637009, Sichuan, China
| | - Yan Huang
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, Sichuan, China
- Institute of Eco-adaptation in Amphibians and Reptiles, China West Normal University, Nanchong, 637009, Sichuan, China
| | - Feng Li
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, Sichuan, China
- Institute of Eco-adaptation in Amphibians and Reptiles, China West Normal University, Nanchong, 637009, Sichuan, China
| | - Wen Bo Liao
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, Sichuan, China.
- Institute of Eco-adaptation in Amphibians and Reptiles, China West Normal University, Nanchong, 637009, Sichuan, China.
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39
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Corral-López A, Garate-Olaizola M, Buechel SD, Kolm N, Kotrschal A. On the role of body size, brain size, and eye size in visual acuity. Behav Ecol Sociobiol 2017; 71:179. [PMID: 29213179 PMCID: PMC5705735 DOI: 10.1007/s00265-017-2408-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 11/11/2017] [Accepted: 11/16/2017] [Indexed: 10/25/2022]
Abstract
Abstract The visual system is highly variable across species, and such variability is a key factor influencing animal behavior. Variation in the visual system, for instance, can influence the outcome of learning tasks when visual stimuli are used. We illustrate this issue in guppies (Poecilia reticulata) artificially selected for large and small relative brain size with pronounced behavioral differences in learning experiments and mate choice tests. We performed a study of the visual system by quantifying eye size and optomotor response of large-brained and small-brained guppies. This represents the first experimental test of the link between brain size evolution and visual acuity. We found that female guppies have larger eyes than male guppies, both in absolute terms and in relation to their body size. Likewise, individuals selected for larger brains had slightly larger eyes but not better visual acuity than small-brained guppies. However, body size was positively associated with visual acuity. We discuss our findings in relation to previous macroevolutionary studies on the evolution of brain morphology, eye morphology, visual acuity, and ecological variables, while stressing the importance of accounting for sensory abilities in behavioral studies. Significance statement Pre-existing perceptual biases can be keys for the development of specific behavioral patterns. Hence, potential differences in sensory systems need to be taken into account in the study of animal behavior. We highlight this necessity concentrating on the visual domain and using experimental data on brain size-selected guppies in which we assessed eye size and visual acuity. Behavioral differences between large-brained and small-brained guppies in learning and mate choice predominantly relied on tests using visual cues. Analyses of visual capabilities in this system are therefore necessary. Furthermore, this system offers the unprecedented opportunity to experimentally test the relationship between brain size, eye morphology, and visual capabilities. Our results show similar visual acuities between large-brained and small-brained guppies. However, the differences observed in eye area between the sexes, together with the observed positive relationship between body size and visual acuity, highlight the need to incorporate perceptive differences in the study of animal behavior.
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Affiliation(s)
- Alberto Corral-López
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
| | - Maddi Garate-Olaizola
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
| | - Severine D Buechel
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
| | - Niclas Kolm
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
| | - Alexander Kotrschal
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
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40
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Kotrschal A, Zeng HL, van der Bijl W, Öhman-Mägi C, Kotrschal K, Pelckmans K, Kolm N. Evolution of brain region volumes during artificial selection for relative brain size. Evolution 2017; 71:2942-2951. [PMID: 28986929 DOI: 10.1111/evo.13373] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 09/14/2017] [Accepted: 09/24/2017] [Indexed: 12/28/2022]
Abstract
The vertebrate brain shows an extremely conserved layout across taxa. Still, the relative sizes of separate brain regions vary markedly between species. One interesting pattern is that larger brains seem associated with increased relative sizes only of certain brain regions, for instance telencephalon and cerebellum. Till now, the evolutionary association between separate brain regions and overall brain size is based on comparative evidence and remains experimentally untested. Here, we test the evolutionary response of brain regions to directional selection on brain size in guppies (Poecilia reticulata) selected for large and small relative brain size. In these animals, artificial selection led to a fast response in relative brain size, while body size remained unchanged. We use microcomputer tomography to investigate how the volumes of 11 main brain regions respond to selection for larger versus smaller brains. We found no differences in relative brain region volumes between large- and small-brained animals and only minor sex-specific variation. Also, selection did not change allometric scaling between brain and brain region sizes. Our results suggest that brain regions respond similarly to strong directional selection on relative brain size, which indicates that brain anatomy variation in contemporary species most likely stem from direct selection on key regions.
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Affiliation(s)
| | - Hong-Li Zeng
- Department of Mathematics, Uppsala University, Uppsala, Sweden
| | | | | | - Kurt Kotrschal
- Department of Behavioural Biology, University of Vienna, Vienna, Austria.,Konrad Lorenz Forschungsstelle, University of Vienna, Vienna, Austria.,Wolf Science Center, University of Veterinary Medicine Vienna, Ernstbrunn, Austria
| | | | - Niclas Kolm
- Department of Zoology, Stockholm University, Stockholm, Sweden
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41
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Ebneter C, Pick JL, Tschirren B. A trade-off between reproductive investment and maternal cerebellum size in a precocial bird. Biol Lett 2017; 12:rsbl.2016.0659. [PMID: 28003519 DOI: 10.1098/rsbl.2016.0659] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/01/2016] [Indexed: 11/12/2022] Open
Abstract
Natural selection favours increased investment in reproduction, yet considerable variation in parental investment is observed in natural populations. Life-history theory predicts that this variation is maintained by a trade-off between the benefits of increased reproductive investment and its associated costs for the parents. The nature of these costs of reproduction, however, remains poorly understood. The brain is an energetically highly expensive organ and increased reproductive investment may, therefore, negatively affect brain maintenance. Using artificial selection lines for high and low prenatal maternal investment in a precocial bird, the Japanese quail (Coturnix japonica), we provide experimental evidence for this hypothesis by showing that increased prenatal provisioning negatively affects the size of a particular brain region of the mother, the cerebellum. Our finding suggests that cognitive demands may constrain the evolution of parental investment, and vice versa, contributing to the maintenance of variation in reproductive behaviour in animal populations.
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Affiliation(s)
- Christina Ebneter
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Joel L Pick
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Barbara Tschirren
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland .,Centre for Ecology and Conservation, University of Exeter, Penryn TR10 9FE, UK
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42
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Sex composition modulates the effects of familiarity in new environment. Behav Processes 2017; 140:133-138. [DOI: 10.1016/j.beproc.2017.05.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 04/06/2017] [Accepted: 05/02/2017] [Indexed: 12/29/2022]
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43
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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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44
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Abstract
There is a tension between the conception of cognition as a central nervous system (CNS) process and a view of cognition as extending towards the body or the contiguous environment. The centralised conception requires large or complex nervous systems to cope with complex environments. Conversely, the extended conception involves the outsourcing of information processing to the body or environment, thus making fewer demands on the processing power of the CNS. The evolution of extended cognition should be particularly favoured among small, generalist predators such as spiders, and here, we review the literature to evaluate the fit of empirical data with these contrasting models of cognition. Spiders do not seem to be cognitively limited, displaying a large diversity of learning processes, from habituation to contextual learning, including a sense of numerosity. To tease apart the central from the extended cognition, we apply the mutual manipulability criterion, testing the existence of reciprocal causal links between the putative elements of the system. We conclude that the web threads and configurations are integral parts of the cognitive systems. The extension of cognition to the web helps to explain some puzzling features of spider behaviour and seems to promote evolvability within the group, enhancing innovation through cognitive connectivity to variable habitat features. Graded changes in relative brain size could also be explained by outsourcing information processing to environmental features. More generally, niche-constructed structures emerge as prime candidates for extending animal cognition, generating the selective pressures that help to shape the evolving cognitive system.
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Affiliation(s)
- Hilton F Japyassú
- Biology Institute, Federal University of Bahia, Rua Barão de Jeremoabo s/n, Campus de Ondina, Salvador, Bahia, 40170-115, Brazil.
- Centre for Biodiversity, School of Biology, University of St Andrews, Harold Mitchell Building, St Andrews, Fife, UK, KY16 9TH.
| | - Kevin N Laland
- Centre for Biodiversity, School of Biology, University of St Andrews, Harold Mitchell Building, St Andrews, Fife, UK, KY16 9TH
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45
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Näslund J, Pettersson L, Johnsson JI. Behavioural reactions of three-spined sticklebacks to simulated risk of predation—Effects of predator distance and movement. Facets (Ott) 2017. [DOI: 10.1139/facets-2015-0015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The behavioural response of animals to predation risk commonly depends on the behaviour of potential predators. Here, we report an experiment investigating effects of predator model (a life-like wooden trout model) distance and movement on the behaviour of three-spined sticklebacks Gasterosteus aculeatus L. in a standardized experimental setting. When the predator model was immobile, the behaviour of the sticklebacks could, in general, not be clearly distinguished from a no-predator control treatment. When moving the predator 41 cm towards the stickleback, clear anti-predator behaviours were observed. However, behavioural expression depended on the distance to the predator. At the two farthest distances (approaching from 129 to 88 cm and from 170 to 129 cm), the sticklebacks approached the predator and spent little time freezing. At the two closest distances (approaching from 88 to 47 cm and from 47 to 6 cm), the sticklebacks increased the distance to the predator model and froze their movements. These results suggest that the closest-distance groups showed avoidance behaviour, whereas the farthest-distance groups instead appeared to start inspecting the potential predator. This provides evidence for conditional anti-predator behaviour and highlights the importance of considering distance to, and movement of predator models when interpreting data from standardized behavioural trials.
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Affiliation(s)
- Joacim Näslund
- University of Gothenburg, Department of Biological and Environmental Sciences, Box 463, SE-405 30 Gothenburg, Sweden
| | - Leo Pettersson
- University of Gothenburg, Department of Biological and Environmental Sciences, Box 463, SE-405 30 Gothenburg, Sweden
| | - Jörgen I Johnsson
- University of Gothenburg, Department of Biological and Environmental Sciences, Box 463, SE-405 30 Gothenburg, Sweden
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46
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Corral-López A, Bloch NI, Kotrschal A, van der Bijl W, Buechel SD, Mank JE, Kolm N. Female brain size affects the assessment of male attractiveness during mate choice. SCIENCE ADVANCES 2017; 3:e1601990. [PMID: 28345039 PMCID: PMC5362185 DOI: 10.1126/sciadv.1601990] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 02/09/2017] [Indexed: 05/23/2023]
Abstract
Mate choice decisions are central in sexual selection theory aimed to understand how sexual traits evolve and their role in evolutionary diversification. We test the hypothesis that brain size and cognitive ability are important for accurate assessment of partner quality and that variation in brain size and cognitive ability underlies variation in mate choice. We compared sexual preference in guppy female lines selected for divergence in relative brain size, which we have previously shown to have substantial differences in cognitive ability. In a dichotomous choice test, large-brained and wild-type females showed strong preference for males with color traits that predict attractiveness in this species. In contrast, small-brained females showed no preference for males with these traits. In-depth analysis of optomotor response to color cues and gene expression of key opsins in the eye revealed that the observed differences were not due to differences in visual perception of color, indicating that differences in the ability to process indicators of attractiveness are responsible. We thus provide the first experimental support that individual variation in brain size affects mate choice decisions and conclude that differences in cognitive ability may be an important underlying mechanism behind variation in female mate choice.
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Affiliation(s)
- Alberto Corral-López
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
| | - Natasha I. Bloch
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, U.K
| | - Alexander Kotrschal
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
| | - Wouter van der Bijl
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
| | - Severine D. Buechel
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
| | - Judith E. Mank
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, U.K
| | - Niclas Kolm
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
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47
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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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48
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Stankowich T, Romero AN. The correlated evolution of antipredator defences and brain size in mammals. Proc Biol Sci 2017; 284:20161857. [PMID: 28077771 PMCID: PMC5247489 DOI: 10.1098/rspb.2016.1857] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 11/21/2016] [Indexed: 11/12/2022] Open
Abstract
Mammals that possess elaborate antipredator defences such as body armour, spines and quills are usually well protected, intermediate in size, primarily insectivorous and live in simple open environments. The benefits of such defences seem clear and may relax selection on maintaining cognitive abilities that aid in vigilance and predator recognition, and their bearers may accrue extensive production and maintenance costs. Here, in this comparative phylogenetic analysis of measurements of encephalization quotient and morphological defence scores of 647 mammal species representing nearly every order, we found that as lineages evolve stronger defences, they suffer a correlated reduction in encephalization. The only exceptions were those that live in trees-a complex three-dimensional world probably requiring greater cognitive abilities. At the proximate level, because brain tissue is extremely energetically expensive to build, mammals may be trading off spending more on elaborate defences and saving by building less powerful brains. At the ultimate level, having greater defences may also reduce the need for advanced cognitive abilities for constant assessment of environmental predation risk, especially in simple open environments.
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Affiliation(s)
- Theodore Stankowich
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840, USA
| | - Ashly N Romero
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840, USA
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49
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Sayol F, Maspons J, Lapiedra O, Iwaniuk AN, Székely T, Sol D. Environmental variation and the evolution of large brains in birds. Nat Commun 2016; 7:13971. [PMID: 28004733 PMCID: PMC5192215 DOI: 10.1038/ncomms13971] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 11/17/2016] [Indexed: 11/27/2022] Open
Abstract
Environmental variability has long been postulated as a major selective force in the evolution of large brains. However, assembling evidence for this hypothesis has proved difficult. Here, by combining brain size information for over 1,200 bird species with remote-sensing analyses to estimate temporal variation in ecosystem productivity, we show that larger brains (relative to body size) are more likely to occur in species exposed to larger environmental variation throughout their geographic range. Our reconstructions of evolutionary trajectories are consistent with the hypothesis that larger brains (relative to body size) evolved when the species invaded more seasonal regions. However, the alternative—that the species already possessed larger brains when they invaded more seasonal regions—cannot be completely ruled out. Regardless of the exact mechanism, our findings provide strong empirical support for the association between large brains and environmental variability. Environmental variation has been hypothesized to favour the evolution of large brains capable of adjusting behaviour to changing circumstances. Here, Sayol et al. find that across more than 1200 bird species, species with relatively large brains are indeed associated with more variable habitats.
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Affiliation(s)
- Ferran Sayol
- CREAF, Cerdanyola del Vallès, 08193 Catalonia, Spain
| | - Joan Maspons
- CREAF, Cerdanyola del Vallès, 08193 Catalonia, Spain
| | - Oriol Lapiedra
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 01238, USA
| | - Andrew N Iwaniuk
- Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Tamás Székely
- Milner Centre of Evolution, Department of Biology &Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Daniel Sol
- CREAF, Cerdanyola del Vallès, 08193 Catalonia, Spain.,CSIC, Cerdanyola del Vallès, 08193 Catalonia, Spain
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50
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Buechel SD, Booksmythe I, Kotrschal A, Jennions MD, Kolm N. Artificial selection on male genitalia length alters female brain size. Proc Biol Sci 2016; 283:20161796. [PMID: 27881751 PMCID: PMC5136585 DOI: 10.1098/rspb.2016.1796] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 10/17/2016] [Indexed: 01/03/2023] Open
Abstract
Male harassment is a classic example of how sexual conflict over mating leads to sex-specific behavioural adaptations. Females often suffer significant costs from males attempting forced copulations, and the sexes can be in an arms race over male coercion. Yet, despite recent recognition that divergent sex-specific interests in reproduction can affect brain evolution, sexual conflict has not been addressed in this context. Here, we investigate whether artificial selection on a correlate of male success at coercion, genital length, affects brain anatomy in males and females. We analysed the brains of eastern mosquitofish (Gambusia holbrooki), which had been artificially selected for long or short gonopodium, thereby mimicking selection arising from differing levels of male harassment. By analogy to how prey species often have relatively larger brains than their predators, we found that female, but not male, brain size was greater following selection for a longer gonopodium. Brain subregion volumes remained unchanged. These results suggest that there is a positive genetic correlation between male gonopodium length and female brain size, which is possibly linked to increased female cognitive ability to avoid male coercion. We propose that sexual conflict is an important factor in the evolution of brain anatomy and cognitive ability.
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Affiliation(s)
- Séverine D Buechel
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden
| | - Isobel Booksmythe
- Division of Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Alexander Kotrschal
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden
| | - Michael D Jennions
- Division of Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Niclas Kolm
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, 10691 Stockholm, Sweden
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