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Genty G, Sandoval-Castillo J, Beheregaray LB, Möller LM. Into the Blue: Exploring genetic mechanisms behind the evolution of baleen whales. Gene 2024; 929:148822. [PMID: 39103058 DOI: 10.1016/j.gene.2024.148822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 07/29/2024] [Accepted: 08/02/2024] [Indexed: 08/07/2024]
Abstract
Marine ecosystems are ideal for studying evolutionary adaptations involved in lineage diversification due to few physical barriers and reduced opportunities for strict allopatry compared to terrestrial ecosystems. Cetaceans (whales, dolphins, and porpoises) are a diverse group of mammals that successfully adapted to various habitats within the aquatic environment around 50 million years ago. While the overall adaptive transition from terrestrial to fully aquatic species is relatively well understood, the radiation of modern whales is still unclear. Here high-quality genomes derived from previously published data were used to identify genomic regions that potentially underpinned the diversification of baleen whales (Balaenopteridae). A robust molecular phylogeny was reconstructed based on 10,159 single copy and complete genes for eight mysticetes, seven odontocetes and two cetacean outgroups. Analysis of positive selection across 3,150 genes revealed that balaenopterids have undergone numerous idiosyncratic and convergent genomic variations that may explain their diversification. Genes associated with aging, survival and homeostasis were enriched in all species. Additionally, positive selection on genes involved in the immune system were disclosed for the two largest species, blue and fin whales. Such genes can potentially be ascribed to their morphological evolution, allowing them to attain greater length and increased cell number. Further evidence is presented about gene regions that might have contributed to the extensive anatomical changes shown by cetaceans, including adaptation to distinct environments and diets. This study contributes to our understanding of the genomic basis of diversification in baleen whales and the molecular changes linked to their adaptive radiation, thereby enhancing our understanding of cetacean evolution.
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Affiliation(s)
- Gabrielle Genty
- Cetacean Ecology, Behaviour and Evolution Lab, College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia; Molecular Ecology Lab, College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.
| | - Jonathan Sandoval-Castillo
- Molecular Ecology Lab, College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - Luciano B Beheregaray
- Molecular Ecology Lab, College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - Luciana M Möller
- Cetacean Ecology, Behaviour and Evolution Lab, College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia; Molecular Ecology Lab, College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
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2
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Young FJ, Alcalde Anton A, Melo-Flórez L, Couto A, Foley J, Monllor M, McMillan WO, Montgomery SH. Enhanced long-term memory and increased mushroom body plasticity in Heliconius butterflies. iScience 2024; 27:108949. [PMID: 38357666 PMCID: PMC10864207 DOI: 10.1016/j.isci.2024.108949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 11/27/2023] [Accepted: 01/15/2024] [Indexed: 02/16/2024] Open
Abstract
Heliconius butterflies exhibit expanded mushroom bodies, a key brain region for learning and memory in insects, and a novel foraging strategy unique among Lepidoptera - traplining for pollen. We tested visual long-term memory across six Heliconius and outgroup Heliconiini species. Heliconius species exhibited greater fidelity to learned colors after eight days without reinforcement, with further evidence of recall at 13 days. We also measured the plastic response of the mushroom body calyces over this time period, finding substantial post-eclosion expansion and synaptic pruning in the calyx of Heliconius erato, but not in the outgroup Heliconiini Dryas iulia. In Heliconius erato, visual associative learning experience specifically was associated with a greater retention of synapses and recall accuracy was positively correlated with synapse number. These results suggest that increases in the size of specific brain regions and changes in their plastic response to experience may coevolve to support novel behaviors.
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Affiliation(s)
- Fletcher J. Young
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- Smithsonian Tropical Research Institute, Gamboa, Panama
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Amaia Alcalde Anton
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | | | - Antoine Couto
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Jessica Foley
- Smithsonian Tropical Research Institute, Gamboa, Panama
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | | | | | - Stephen H. Montgomery
- Smithsonian Tropical Research Institute, Gamboa, Panama
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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3
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Hebberecht L, Wainwright JB, Thompson C, Kershenbaum S, McMillan WO, Montgomery SH. Plasticity and genetic effects contribute to different axes of neural divergence in a community of mimetic Heliconius butterflies. J Evol Biol 2023; 36:1116-1132. [PMID: 37341138 DOI: 10.1111/jeb.14188] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 03/12/2023] [Accepted: 04/16/2023] [Indexed: 06/22/2023]
Abstract
Changes in ecological preference, often driven by spatial and temporal variation in resource distribution, can expose populations to environments with divergent information content. This can lead to adaptive changes in the degree to which individuals invest in sensory systems and downstream processes, to optimize behavioural performance in different contexts. At the same time, environmental conditions can produce plastic responses in nervous system development and maturation, providing an alternative route to integrating neural and ecological variation. Here, we explore how these two processes play out across a community of Heliconius butterflies. Heliconius communities exhibit multiple Mullerian mimicry rings, associated with habitat partitioning across environmental gradients. These environmental differences have previously been linked to heritable divergence in brain morphology in parapatric species pairs. They also exhibit a unique dietary adaptation, known as pollen feeding, that relies heavily on learning foraging routes, or trap-lines, between resources, which implies an important environmental influence on behavioural development. By comparing brain morphology across 133 wild-caught and insectary-reared individuals from seven Heliconius species, we find strong evidence for interspecific variation in patterns of neural investment. These largely fall into two distinct patterns of variation; first, we find consistent patterns of divergence in the size of visual brain components across both wild and insectary-reared individuals, suggesting genetically encoded divergence in the visual pathway. Second, we find interspecific differences in mushroom body size, a central component of learning and memory systems, but only among wild caught individuals. The lack of this effect in common-garden individuals suggests an extensive role for developmental plasticity in interspecific variation in the wild. Finally, we illustrate the impact of relatively small-scale spatial effects on mushroom body plasticity by performing experiments altering the cage size and structure experienced by individual H. hecale. Our data provide a comprehensive survey of community level variation in brain structure, and demonstrate that genetic effects and developmental plasticity contribute to different axes of interspecific neural variation.
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Affiliation(s)
- Laura Hebberecht
- School of Biological Sciences, University of Bristol, Bristol, UK
- Department of Zoology, University of Cambridge, Cambridge, UK
- Smithsonian Tropical Research Institute, Gamboa, Panama
| | | | | | | | | | - Stephen H Montgomery
- School of Biological Sciences, University of Bristol, Bristol, UK
- Smithsonian Tropical Research Institute, Gamboa, Panama
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4
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Roston RA, Boessenecker RW, Geisler JH. Evolution and development of the cetacean skull roof: a case study in novelty and homology. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220086. [PMID: 37183892 PMCID: PMC10184229 DOI: 10.1098/rstb.2022.0086] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 11/15/2022] [Indexed: 05/16/2023] Open
Abstract
Skulls of living whales and dolphins (cetaceans) are telescoped-bones of the skull roof are overlapped by expanded facial bones and/or anteriorly extended occipital bones. Evolution of the underlying skull roof (calvarium), which lies between the telescoped regions, is relatively unstudied. We explore the evolution and development of the calvarium of toothed whales (odontocetes) by integrating fetal data with Oligocene odontocete fossils from North America, including eight neonatal and juvenile skulls of Olympicetus†. We identified two potential synapomorphies of crown Cetacea: contact of interparietals with frontals, and a single anterior median interparietal (AMI) element. Within Odontoceti, loss of contact between the parietals diagnoses the clade including Delphinida, Ziphiidae and Platanistidae (=Synrhina). Delphinida is characterized by a greatly enlarged interparietal. New fetal series of delphinoids reveal a consistent developmental pattern with three elements: the AMI and bilateral posterior interparietals (PIs). The PIs most resemble the medial interparietal elements of terrestrial artiodactyls, suggesting that the AMI of cetaceans could be a unique ossification. More broadly, the paucity of conserved anatomical relationships of the interparietals, as well as the fact that the elements often do not coalesce into a single bone, demonstrates that assessing homology of the interparietals across mammals remains challenging. This article is part of the theme issue 'The mammalian skull: development, structure and function'.
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Affiliation(s)
- R. A. Roston
- Department of Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA 98195, USA
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - R. W. Boessenecker
- Department of Geology and Environmental Geosciences, College of Charleston, Charleston, SC 29424, USA
- University of California Museum of Paleontology, University of California, Berkeley, CA 94720, USA
| | - J. H. Geisler
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA
- Department of Paleobiology, National Museum of Natural History, Washington, DC 20560, USA
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5
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Kaplow IM, Lawler AJ, Schäffer DE, Srinivasan C, Sestili HH, Wirthlin ME, Phan BN, Prasad K, Brown AR, Zhang X, Foley K, Genereux DP, Karlsson EK, Lindblad-Toh K, Meyer WK, Pfenning AR. Relating enhancer genetic variation across mammals to complex phenotypes using machine learning. Science 2023; 380:eabm7993. [PMID: 37104615 PMCID: PMC10322212 DOI: 10.1126/science.abm7993] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 02/23/2023] [Indexed: 04/29/2023]
Abstract
Protein-coding differences between species often fail to explain phenotypic diversity, suggesting the involvement of genomic elements that regulate gene expression such as enhancers. Identifying associations between enhancers and phenotypes is challenging because enhancer activity can be tissue-dependent and functionally conserved despite low sequence conservation. We developed the Tissue-Aware Conservation Inference Toolkit (TACIT) to associate candidate enhancers with species' phenotypes using predictions from machine learning models trained on specific tissues. Applying TACIT to associate motor cortex and parvalbumin-positive interneuron enhancers with neurological phenotypes revealed dozens of enhancer-phenotype associations, including brain size-associated enhancers that interact with genes implicated in microcephaly or macrocephaly. TACIT provides a foundation for identifying enhancers associated with the evolution of any convergently evolved phenotype in any large group of species with aligned genomes.
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Affiliation(s)
- Irene M. Kaplow
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Alyssa J. Lawler
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, USA
- Department of Biology, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Daniel E. Schäffer
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Chaitanya Srinivasan
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Heather H. Sestili
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Morgan E. Wirthlin
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, USA
| | - BaDoi N. Phan
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, USA
- Medical Scientist Training Program, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Kavya Prasad
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Ashley R. Brown
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Xiaomeng Zhang
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Kathleen Foley
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, USA
| | - Diane P. Genereux
- Broad Institute, Cambridge, MA, USA
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | | | - Elinor K. Karlsson
- Broad Institute, Cambridge, MA, USA
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Kerstin Lindblad-Toh
- Broad Institute, Cambridge, MA, USA
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Wynn K. Meyer
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, USA
| | - Andreas R. Pfenning
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, USA
- Department of Biology, Carnegie Mellon University, Pittsburgh, PA, USA
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6
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Vacher MC, Durrant CS, Rose J, Hall AJ, Spires‐Jones TL, Gunn‐Moore F, Dagleish MP. Alzheimer's disease-like neuropathology in three species of oceanic dolphin. Eur J Neurosci 2023; 57:1161-1179. [PMID: 36514861 PMCID: PMC10947196 DOI: 10.1111/ejn.15900] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 11/18/2022] [Accepted: 11/25/2022] [Indexed: 12/15/2022]
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disease and the primary cause of disability and dependency among elderly humans worldwide. AD is thought to be a disease unique to humans although several other animals develop some aspects of AD-like pathology. Odontocetes (toothed whales) share traits with humans that suggest they may be susceptible to AD. The brains of 22 stranded odontocetes of five different species were examined using immunohistochemistry to investigate the presence or absence of neuropathological hallmarks of AD: amyloid-beta plaques, phospho-tau accumulation and gliosis. Immunohistochemistry revealed that all aged animals accumulated amyloid plaque pathology. In three animals of three different species of odontocete, there was co-occurrence of amyloid-beta plaques, intraneuronal accumulation of hyperphosphorylated tau, neuropil threads and neuritic plaques. One animal showed well-developed neuropil threads, phospho-tau accumulation and neuritic plaques, but no amyloid plaques. Microglia and astrocytes were present as expected in all brain samples examined, but we observed differences in cell morphology and numbers between individual animals. The simultaneous occurrence of amyloid-beta plaques and hyperphosphorylated tau pathology in the brains of odontocetes shows that these three species develop AD-like neuropathology spontaneously. The significance of this pathology with respect to the health and, ultimately, death of the animals remains to be determined. However, it may contribute to the cause(s) of unexplained live-stranding in some odontocete species and supports the 'sick-leader' theory whereby healthy conspecifics in a pod mass strand due to high social cohesion.
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Affiliation(s)
| | - Claire S. Durrant
- Centre for Discovery Brain Sciences and UK Dementia Research InstituteUniversity of EdinburghEdinburghUK
| | - Jamie Rose
- Centre for Discovery Brain Sciences and UK Dementia Research InstituteUniversity of EdinburghEdinburghUK
| | - Ailsa J. Hall
- Sea Mammal Research Unit, Scottish Oceans InstituteUniversity of St. AndrewsFifeUK
| | - Tara L. Spires‐Jones
- Centre for Discovery Brain Sciences and UK Dementia Research InstituteUniversity of EdinburghEdinburghUK
| | | | - Mark P. Dagleish
- School of Biodiversity, One Health and Veterinary Medicine, Pathology DepartmentUniversity of GlasgowScotlandUK
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7
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Rangan AV, McGrouther CC, Bhadra N, Venn-Watson S, Jensen ED, Schork NJ. A time-series analysis of blood-based biomarkers within a 25-year longitudinal dolphin cohort. PLoS Comput Biol 2023; 19:e1010890. [PMID: 36802395 PMCID: PMC9983899 DOI: 10.1371/journal.pcbi.1010890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 03/03/2023] [Accepted: 01/23/2023] [Indexed: 02/23/2023] Open
Abstract
Causal interactions and correlations between clinically-relevant biomarkers are important to understand, both for informing potential medical interventions as well as predicting the likely health trajectory of any individual as they age. These interactions and correlations can be hard to establish in humans, due to the difficulties of routine sampling and controlling for individual differences (e.g., diet, socio-economic status, medication). Because bottlenose dolphins are long-lived mammals that exhibit several age-related phenomena similar to humans, we analyzed data from a well controlled 25-year longitudinal cohort of 144 dolphins. The data from this study has been reported on earlier, and consists of 44 clinically relevant biomarkers. This time-series data exhibits three starkly different influences: (A) directed interactions between biomarkers, (B) sources of biological variation that can either correlate or decorrelate different biomarkers, and (C) random observation-noise which combines measurement error and very rapid fluctuations in the dolphin's biomarkers. Importantly, the sources of biological variation (type-B) are large in magnitude, often comparable to the observation errors (type-C) and larger than the effect of the directed interactions (type-A). Attempting to recover the type-A interactions without accounting for the type-B and type-C variation can result in an abundance of false-positives and false-negatives. Using a generalized regression which fits the longitudinal data with a linear model accounting for all three influences, we demonstrate that the dolphins exhibit many significant directed interactions (type-A), as well as strong correlated variation (type-B), between several pairs of biomarkers. Moreover, many of these interactions are associated with advanced age, suggesting that these interactions can be monitored and/or targeted to predict and potentially affect aging.
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Affiliation(s)
- Aaditya V. Rangan
- Courant Institute of Mathematical Sciences, New York University, New York, New York, United States of America
| | - Caroline C. McGrouther
- Courant Institute of Mathematical Sciences, New York University, New York, New York, United States of America
| | - Nivedita Bhadra
- Quantitative Medicine and Systems Biology, The Translational Genomics Research Institute, Phoenix, Arizona, United States of America
| | | | - Eric D. Jensen
- US Navy Marine Mammal Program, Naval Information Warfare Center Pacific, San Diego, California, United States of America
| | - Nicholas J. Schork
- Quantitative Medicine and Systems Biology, The Translational Genomics Research Institute, Phoenix, Arizona, United States of America
- Seraphina Therapeutics, Inc., San Diego, California, United States of America
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8
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Ecomorphology of toothed whales (Cetacea, Odontoceti) as revealed by 3D skull geometry. J MAMM EVOL 2023. [DOI: 10.1007/s10914-022-09642-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
AbstractExtant odontocetes (toothed whales) exhibit differences in body size and brain mass, biosonar mode, feeding strategies, and diving and habitat adaptations. Strong selective pressures associated with these factors have likely contributed to the morphological diversification of their skull. Here, we used 3D landmark geometric morphometric data from the skulls of 60 out of ~ 72 extant odontocete species and a well-supported phylogenetic tree to test whether size and shape variation are associated with ecological adaptations at an interspecific scale. Odontocete skull morphology exhibited a significant phylogenetic signal, with skull size showing stronger signal than shape. After accounting for phylogeny, significant associations were detected between skull size and biosonar mode, body length, brain and body mass, maximum and minimum prey size, and maximum peak frequency. Brain mass was also strongly correlated with skull shape together with surface temperature and average and minimum prey size. When asymmetric and symmetric components of shape were analysed separately, a significant correlation was detected between sea surface temperature and both symmetric and asymmetric components of skull shape, and between diving ecology and the asymmetric component. Skull shape variation of odontocetes was strongly influenced by evolutionary allometry but most of the associations with ecological variables were not supported after phylogenetic correction. This suggests that ecomorphological feeding adaptations vary more between, rather than within, odontocete families, and functional anatomical patterns across odontocete clades are canalised by size constraints.
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9
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Martin BS, Bradburd GS, Harmon LJ, Weber MG. Modeling the Evolution of Rates of Continuous Trait Evolution. Syst Biol 2022:6830631. [PMID: 36380474 DOI: 10.1093/sysbio/syac068] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Indexed: 11/17/2022] Open
Abstract
Rates of phenotypic evolution vary markedly across the tree of life, from the accelerated evolution apparent in adaptive radiations to the remarkable evolutionary stasis exhibited by so-called "living fossils". Such rate variation has important consequences for large-scale evolutionary dynamics, generating vast disparities in phenotypic diversity across space, time, and taxa. Despite this, most methods for estimating trait evolution rates assume rates vary deterministically with respect to some variable of interest or change infrequently during a clade's history. These assumptions may cause underfitting of trait evolution models and mislead hypothesis testing. Here, we develop a new trait evolution model that allows rates to vary gradually and stochastically across a clade. Further, we extend this model to accommodate generally decreasing or increasing rates over time, allowing for flexible modeling of "early/late bursts" of trait evolution. We implement a Bayesian method, termed "evolving rates" (evorates for short), to efficiently fit this model to comparative data. Through simulation, we demonstrate that evorates can reliably infer both how and in which lineages trait evolution rates varied during a clade's history. We apply this method to body size evolution in cetaceans, recovering substantial support for an overall slowdown in body size evolution over time with recent bursts among some oceanic dolphins and relative stasis among beaked whales of the genus Mesoplodon. These results unify and expand on previous research, demonstrating the empirical utility of evorates.
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Affiliation(s)
- B S Martin
- Department of Plant Biology, Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI 48824, USA
| | - G S Bradburd
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - L J Harmon
- Department of Biological Sciences, Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho, Moscow, ID 83843, USA
| | - M G Weber
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
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10
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The impact of environmental factors on the evolution of brain size in carnivorans. Commun Biol 2022; 5:998. [PMID: 36130990 PMCID: PMC9492690 DOI: 10.1038/s42003-022-03748-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 07/20/2022] [Indexed: 11/28/2022] Open
Abstract
The reasons why some animals have developed larger brains has long been a subject of debate. Yet, it remains unclear which selective pressures may favour the encephalization and how it may act during evolution at different taxonomic scales. Here we studied the patterns and tempo of brain evolution within the order Carnivora and present large-scale comparative analysis of the effect of ecological, environmental, social, and physiological variables on relative brain size in a sample of 174 extant carnivoran species. We found a complex pattern of brain size change between carnivoran families with differences in both the rate and diversity of encephalization. Our findings suggest that during carnivorans’ evolution, a trade-off have occurred between the cognitive advantages of acquiring a relatively large brain allowing to adapt to specific environments, and the metabolic costs of the brain which may constitute a disadvantage when facing the need to colonize new environments. The brain size of carnivores has evolved to balance a trade-off between increased cognitive function and increased metabolic cost.
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11
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Cooper JA, Hutchinson JR, Bernvi DC, Cliff G, Wilson RP, Dicken ML, Menzel J, Wroe S, Pirlo J, Pimiento C. The extinct shark Otodus megalodon was a transoceanic superpredator: Inferences from 3D modeling. SCIENCE ADVANCES 2022; 8:eabm9424. [PMID: 35977007 PMCID: PMC9385135 DOI: 10.1126/sciadv.abm9424] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 07/06/2022] [Indexed: 06/15/2023]
Abstract
Although shark teeth are abundant in the fossil record, their bodies are rarely preserved. Thus, our understanding of the anatomy of the extinct Otodus megalodon remains rudimentary. We used an exceptionally well-preserved fossil to create the first three-dimensional model of the body of this giant shark and used it to infer its movement and feeding ecology. We estimate that an adult O. megalodon could cruise at faster absolute speeds than any shark species today and fully consume prey the size of modern apex predators. A dietary preference for large prey potentially enabled O. megalodon to minimize competition and provided a constant source of energy to fuel prolonged migrations without further feeding. Together, our results suggest that O. megalodon played an important ecological role as a transoceanic superpredator. Hence, its extinction likely had large impacts on global nutrient transfer and trophic food webs.
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Affiliation(s)
- Jack A. Cooper
- Department of Biosciences, Swansea University, Swansea SA2 8PP, UK
| | - John R. Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK
| | - David C. Bernvi
- KwaZulu-Natal Sharks Board, Umhlanga Rocks 4320, South Africa
| | - Geremy Cliff
- KwaZulu-Natal Sharks Board, Umhlanga Rocks 4320, South Africa
- School of Life Sciences, University of KwaZulu-Natal, Durban, KZN, South Africa
| | - Rory P. Wilson
- Department of Biosciences, Swansea University, Swansea SA2 8PP, UK
| | - Matt L. Dicken
- KwaZulu-Natal Sharks Board, Umhlanga Rocks 4320, South Africa
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, PL4 8AA, UK
| | - Jan Menzel
- JanMenzelArt, Stellenbosch 7600, South Africa
| | - Stephen Wroe
- Function, Evolution, and Anatomy Research Lab, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| | - Jeanette Pirlo
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
- Department of Biological Sciences, California State University Stanislaus, Turlock, CA 95382, USA
| | - Catalina Pimiento
- Department of Biosciences, Swansea University, Swansea SA2 8PP, UK
- Paleontological Institute and Museum, University of Zurich, Zurich CH-8006, Switzerland
- Smithsonian Tropical Research Institution, Balboa, Panama
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12
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Bertrand OC, Shelley SL, Williamson TE, Wible JR, Chester SGB, Flynn JJ, Holbrook LT, Lyson TR, Meng J, Miller IM, Püschel HP, Smith T, Spaulding M, Tseng ZJ, Brusatte SL. Brawn before brains in placental mammals after the end-Cretaceous extinction. Science 2022; 376:80-85. [PMID: 35357913 DOI: 10.1126/science.abl5584] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mammals are the most encephalized vertebrates, with the largest brains relative to body size. Placental mammals have particularly enlarged brains, with expanded neocortices for sensory integration, the origins of which are unclear. We used computed tomography scans of newly discovered Paleocene fossils to show that contrary to the convention that mammal brains have steadily enlarged over time, early placentals initially decreased their relative brain sizes because body mass increased at a faster rate. Later in the Eocene, multiple crown lineages independently acquired highly encephalized brains through marked growth in sensory regions. We argue that the placental radiation initially emphasized increases in body size as extinction survivors filled vacant niches. Brains eventually became larger as ecosystems saturated and competition intensified.
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Affiliation(s)
- Ornella C Bertrand
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland EH9 3FE, UK
| | - Sarah L Shelley
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland EH9 3FE, UK.,Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, PA, USA
| | | | - John R Wible
- Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, PA, USA
| | - Stephen G B Chester
- Department of Anthropology, Brooklyn College, City University of New York, Brooklyn, NY, USA.,Department of Anthropology, The Graduate Center, City University of New York, New York, NY, USA.,New York Consortium in Evolutionary Primatology, New York, NY, USA
| | - John J Flynn
- Division of Paleontology, American Museum of Natural History, New York, NY, USA.,Department of Earth and Environmental Sciences, Columbia University, New York, NY, USA.,Ecology, Evolutionary Biology, and Behavior subprogram, PhD Program in Biology, The Graduate Center, City University of New York, New York, NY, USA.,PhD Program in Earth and Environmental Sciences, The Graduate Center, City University of New York, New York, NY, USA
| | - Luke T Holbrook
- Department of Biological Sciences, Rowan University, Glassboro, NJ, USA
| | | | - Jin Meng
- Division of Paleontology, American Museum of Natural History, New York, NY, USA
| | - Ian M Miller
- Denver Museum of Nature & Science, Denver, CO, USA.,National Geographic Society, Washington, DC, USA
| | - Hans P Püschel
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland EH9 3FE, UK
| | - Thierry Smith
- Directorate Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Michelle Spaulding
- Department of Biological Sciences, Purdue University Northwest, Westville, IN, USA
| | - Z Jack Tseng
- Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, CA, USA
| | - Stephen L Brusatte
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland EH9 3FE, UK.,New Mexico Museum of Natural History and Science, Albuquerque, NM, USA
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13
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Small brains predisposed Late Quaternary mammals to extinction. Sci Rep 2022; 12:3453. [PMID: 35361771 PMCID: PMC8971383 DOI: 10.1038/s41598-022-07327-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 02/11/2022] [Indexed: 11/17/2022] Open
Abstract
The Late Quaternary witnessed a dramatic wave of large mammal extinctions, that are usually attributed to either human hunting or climatic change. We hypothesized that the large mammals that survived the extinctions might have been endowed with larger brain sizes than their relatives, which could have conferred enhanced behavioral plasticity and the ability to cope with the rapidly changing Late Quaternary environmental conditions. We assembled data on brain sizes of 291 extant mammal species plus 50 more that went extinct during the Late Quaternary. Using logistic, and mixed effect models, and controlling for phylogeny and body mass, we found that large brains were associated with higher probability to survive the Late Quaternary extinctions, and that extant species have brains that are, on average, 53% larger when accounting for order as a random effect, and 83% when fitting a single regression line. Moreover, we found that models that used brain size in addition to body size predicted extinction status better than models that used only body size. We propose that possessing a large brain was an important, yet so far neglected characteristic of surviving megafauna species.
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14
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Sun (孙迪) D, Chai (柴思敏) S, Huang (黄鑫) X, Wang (王滢莹) Y, Xiao (肖琳琳) L, Xu (徐士霞) S, Yang (杨光) G. Novel Genomic Insights into Body Size Evolution in Cetaceans and a Resolution of Peto’s Paradox. Am Nat 2022; 199:E28-E42. [DOI: 10.1086/717768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Di Sun (孙迪)
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Simin Chai (柴思敏)
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, Guangdong 511458, China
| | - Xin Huang (黄鑫)
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Yingying Wang (王滢莹)
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Linlin Xiao (肖琳琳)
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Shixia Xu (徐士霞)
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Guang Yang (杨光)
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, Guangdong 511458, China
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15
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Bisconti M, Daniello R, Damarco P, Tartarelli G, Pavia M, Carnevale G. High Encephalization in a Fossil Rorqual Illuminates Baleen Whale Brain Evolution. BRAIN, BEHAVIOR AND EVOLUTION 2021; 96:78-90. [PMID: 34758463 DOI: 10.1159/000519852] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 09/22/2021] [Indexed: 11/19/2022]
Abstract
Baleen whales are considered underencephalized mammals due to their reduced brain size with respect to their body size (encephalization quotient [EQ] << 1). Despite their low EQ, mysticetes exhibit complex behavioral patterns in terms of motor abilities, vocal repertoire, and cultural learning. Very scarce information is available about the morphological evolution of the brain in this group; this makes it difficult to investigate the historical changes in brain shape and size in order to relate the origin of the complex mysticete behavioral repertoire to the evolution of specific neural substrates. Here, the first description of the virtual endocast of a fossil balaenopterid species, Marzanoptera tersillae from the Italian Pliocene, reveals an EQ of around 3, which is exceptional for baleen whales. The endocast showed a morphologically different organization of the brain in this fossil whale as the cerebral hemispheres are anteroposteriorly shortened, the cerebellum lacks the posteromedial expansion of the cerebellar hemispheres, and the cerebellar vermis is unusually reduced. The comparative reductions of the cerebral and cerebellar hemispheres suggest that the motor behavior of M. tersillae probably was less sophisticated than that exhibited by the extant rorqual and humpback species. The presence of an EQ value in this fossil species that is around 10 times higher than that of extant mysticetes opens new questions about brain evolution and provides new, invaluable information about the evolutionary path of morphological and size change in the brain of baleen whales.
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Affiliation(s)
- Michelangelo Bisconti
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy.,Paleontology Department, Natural History Museum of San Diego, San Diego, California, USA
| | - Riccardo Daniello
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy
| | - Piero Damarco
- Museo Paleontologico Territoriale dell'Astigiano, Ente di Gestione del Parco Paleontologico Astigiano, Asti, Italy
| | | | - Marco Pavia
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy
| | - Giorgio Carnevale
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy
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16
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Waugh DA, Thewissen JGM. The pattern of brain-size change in the early evolution of cetaceans. PLoS One 2021; 16:e0257803. [PMID: 34582492 PMCID: PMC8478358 DOI: 10.1371/journal.pone.0257803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 09/10/2021] [Indexed: 11/17/2022] Open
Abstract
Most authors have identified two rapid increases in relative brain size (encephalization quotient, EQ) in cetacean evolution: first at the origin of the modern suborders (odontocetes and mysticetes) around the Eocene-Oligocene transition, and a second at the origin of the delphinoid odontocetes during the middle Miocene. We explore how methods used to estimate brain and body mass alter this perceived timing and rate of cetacean EQ evolution. We provide new data on modern mammals (mysticetes, odontocetes, and terrestrial artiodactyls) and show that brain mass and endocranial volume scale allometrically, and that endocranial volume is not a direct proxy for brain mass. We demonstrate that inconsistencies in the methods used to estimate body size across the Eocene-Oligocene boundary have caused a spurious pattern in earlier relative brain size studies. Instead, we employ a single method, using occipital condyle width as a skeletal proxy for body mass using a new dataset of extant cetaceans, to clarify this pattern. We suggest that cetacean relative brain size is most accurately portrayed using EQs based on the scaling coefficients as observed in the closely related terrestrial artiodactyls. Finally, we include additional data for an Eocene whale, raising the sample size of Eocene archaeocetes to seven. Our analysis of fossil cetacean EQ is different from previous works which had shown that a sudden increase in EQ coincided with the origin of odontocetes at the Eocene-Oligocene boundary. Instead, our data show that brain size increased at the origin of basilosaurids, 5 million years before the Eocene-Oligocene transition, and we do not observe a significant increase in relative brain size at the origin of odontocetes.
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Affiliation(s)
- David A. Waugh
- Department of Anatomy and Neurobiology, Northeast Ohio
Medical University, Rootstown, Ohio, United States of America
| | - J. G. M. Thewissen
- Department of Anatomy and Neurobiology, Northeast Ohio
Medical University, Rootstown, Ohio, United States of America
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17
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Racicot R. Evolution of whale sensory ecology: Frontiers in nondestructive anatomical investigations. Anat Rec (Hoboken) 2021; 305:736-752. [PMID: 34546007 DOI: 10.1002/ar.24761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 06/09/2021] [Accepted: 07/14/2021] [Indexed: 12/18/2022]
Abstract
Studies surrounding the evolution of sensory system anatomy in cetaceans over the last ~100 years have shed light on aspects of the early evolution of hearing sensitivities, the small relative size of the organ of balance (semicircular canals and vestibule), brain (endocast) shape and relative volume changes, and ontogenetic development of sensory-related structures. Here, I review advances in our knowledge of sensory system anatomy as informed by the use of nondestructive imaging techniques, with a focus on applied methods in computed tomography (CT and μCT), and identify the key questions that remain to be addressed. Of these, the most important are: Is lower frequency hearing sensitivity the ancestral condition for whales? Did echolocation evolve more than once in odontocetes; and if so, when and why? How has the structure of the cetacean brain changed, through the evolution of whales, and does this correspond to changes in hearing sensitivities? Finally, what are the general pathways of ontogenetic development of sensory systems in odontocetes and mysticetes? Answering these questions will allow us to understand important macroevolutionary patterns in a fully aquatic mammalian group and provides baseline data on species for which we have limited biological information because of logistical limitations.
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Affiliation(s)
- Rachel Racicot
- Abteilung Messelforschung und Mammalogie, Senckenberg Forschungsinstitut und Naturkundemuseum, Frankfurt am Main, Germany.,Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
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18
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Metabolism: Evolution of dolphin sperm endurance. Curr Biol 2021; 31:R1006-R1008. [PMID: 34428409 DOI: 10.1016/j.cub.2021.06.075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mammalian sperm have long been known to use energy derived from the metabolism of sugars and fatty acids. A new study shows that sperm of dolphins and their relatives lost functionality of the glycolysis pathway and are fueled only by energy-rich fatty acids that are metabolized by extra-large mitochondria, giving them exceptional endurance.
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19
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Pilecky M, Závorka L, Arts MT, Kainz MJ. Omega-3 PUFA profoundly affect neural, physiological, and behavioural competences - implications for systemic changes in trophic interactions. Biol Rev Camb Philos Soc 2021; 96:2127-2145. [PMID: 34018324 DOI: 10.1111/brv.12747] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 05/09/2021] [Accepted: 05/11/2021] [Indexed: 01/01/2023]
Abstract
In recent decades, much conceptual thinking in trophic ecology has been guided by theories of nutrient limitation and the flow of elements, such as carbon and nitrogen, within and among ecosystems. More recently, ecologists have also turned their attention to examining the value of specific dietary nutrients, in particular polyunsaturated fatty acids (PUFA), among which the omega-3 PUFA, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) play a central role as essential components of neuronal cell membranes in many organisms. This review focuses on a new neuro-ecological approach stemming from the biochemical (mechanistic) and physiological (functional) role of DHA in neuronal cell membranes, in particular in conjunction with G-protein coupled receptors (GPCRs). We link the co-evolution of these neurological functions to metabolic dependency on dietary omega-3 PUFA. We outline ways in which deficiencies in dietary DHA supply may affect, cognition, vision, and behaviour, and ultimately, the biological fitness of consumers. We then review emerging evidence that changes in access to dietary omega-3 PUFA may ultimately have profound impacts on trophic interactions leading to potential changes in community structure and ecosystem functioning that, in turn, may affect the supply of DHA within and across ecosystems, including the supply for human consumption.
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Affiliation(s)
- Matthias Pilecky
- WasserCluster Lunz - Biologische Station, Inter-University Center for Aquatic Ecosystem Research, Dr. Carl-Kupelwieser Promenade 5, Lunz am See, 3293, Austria.,Department of Biomedical Research, Donau-Universität Krems, Dr. Karl Dorrek-Straße 30, Krems, 3500, Austria
| | - Libor Závorka
- WasserCluster Lunz - Biologische Station, Inter-University Center for Aquatic Ecosystem Research, Dr. Carl-Kupelwieser Promenade 5, Lunz am See, 3293, Austria
| | - Michael T Arts
- Department of Chemistry and Biology, Ryerson University, 350 Victoria St, Toronto, ON, M5B 2K3, Canada
| | - Martin J Kainz
- WasserCluster Lunz - Biologische Station, Inter-University Center for Aquatic Ecosystem Research, Dr. Carl-Kupelwieser Promenade 5, Lunz am See, 3293, Austria.,Department of Biomedical Research, Donau-Universität Krems, Dr. Karl Dorrek-Straße 30, Krems, 3500, Austria
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20
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Mccurry MR, Marx FG, Evans AR, Park T, Pyenson ND, Kohno N, Castiglione S, Fitzgerald EMG. Brain size evolution in whales and dolphins: new data from fossil mysticetes. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab054] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Cetaceans (whales and dolphins) have some of the largest and most complex brains in the animal kingdom. When and why this trait evolved remains controversial, with proposed drivers ranging from echolocation to foraging complexity and high-level sociality. This uncertainty partially reflects a lack of data on extinct baleen whales (mysticetes), which has obscured deep-time patterns of brain size evolution in non-echolocating cetaceans. Building on new measurements from mysticete fossils, we show that the evolution of large brains preceded that of echolocation, and subsequently followed a complex trajectory involving several independent increases (e.g. in rorquals and oceanic dolphins) and decreases (e.g. in right whales and ‘river dolphins’). Echolocating whales show a greater tendency towards large brain size, thus reaffirming cognitive demands associated with sound processing as a plausible driver of cetacean encephalization. Nevertheless, our results suggest that other factors such as sociality were also important.
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Affiliation(s)
- Matthew R Mccurry
- Australian Museum Research Institute, 1 William Street, Sydney, New South Wales 2010, Australia
- Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, New South Wales 2052, Australia
- Paleobiology, NMNH, Smithsonian Institution, Washington, DC, USA
| | - Felix G Marx
- Museum of New Zealand Te Papa Tongarewa, Wellington, 6011, New Zealand
- Department of Geology, University of Otago, Dunedin, 3054, New Zealand
| | - Alistair R Evans
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Geosciences, Museums Victoria, Melbourne, Victoria, Australia
| | - Travis Park
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, UK
| | - Nicholas D Pyenson
- Paleobiology, NMNH, Smithsonian Institution, Washington, DC, USA
- Department of Paleontology and Geology, Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, USA
| | - Naoki Kohno
- Department of Geology and Palaeontology, National Museum of Nature and Science, Tsukuba, Japan
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Silvia Castiglione
- Department of Earth Sciences, Environment and Resources, University of Naples Federico II, 80138 Napoli,Italy
| | - Erich M G Fitzgerald
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Geosciences, Museums Victoria, Melbourne, Victoria, Australia
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, UK
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21
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Bertrand OC, Püschel HP, Schwab JA, Silcox MT, Brusatte SL. The impact of locomotion on the brain evolution of squirrels and close relatives. Commun Biol 2021; 4:460. [PMID: 33846528 PMCID: PMC8042109 DOI: 10.1038/s42003-021-01887-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 02/22/2021] [Indexed: 02/01/2023] Open
Abstract
How do brain size and proportions relate to ecology and evolutionary history? Here, we use virtual endocasts from 38 extinct and extant rodent species spanning 50+ million years of evolution to assess the impact of locomotion, body mass, and phylogeny on the size of the brain, olfactory bulbs, petrosal lobules, and neocortex. We find that body mass and phylogeny are highly correlated with relative brain and brain component size, and that locomotion strongly influences brain, petrosal lobule, and neocortical sizes. Notably, species living in trees have greater relative overall brain, petrosal lobule, and neocortical sizes compared to other locomotor categories, especially fossorial taxa. Across millions of years of Eocene-Recent environmental change, arboreality played a major role in the early evolution of squirrels and closely related aplodontiids, promoting the expansion of the neocortex and petrosal lobules. Fossoriality in aplodontiids had an opposing effect by reducing the need for large brains.
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Affiliation(s)
- Ornella C Bertrand
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland, UK.
| | - Hans P Püschel
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland, UK
| | - Julia A Schwab
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland, UK
| | - Mary T Silcox
- Department of Anthropology, University of Toronto Scarborough, Toronto, ON, Canada
| | - Stephen L Brusatte
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland, UK
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22
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Smaers JB, Rothman RS, Hudson DR, Balanoff AM, Beatty B, Dechmann DKN, de Vries D, Dunn JC, Fleagle JG, Gilbert CC, Goswami A, Iwaniuk AN, Jungers WL, Kerney M, Ksepka DT, Manger PR, Mongle CS, Rohlf FJ, Smith NA, Soligo C, Weisbecker V, Safi K. The evolution of mammalian brain size. SCIENCE ADVANCES 2021; 7:7/18/eabe2101. [PMID: 33910907 PMCID: PMC8081360 DOI: 10.1126/sciadv.abe2101] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 03/10/2021] [Indexed: 05/08/2023]
Abstract
Relative brain size has long been considered a reflection of cognitive capacities and has played a fundamental role in developing core theories in the life sciences. Yet, the notion that relative brain size validly represents selection on brain size relies on the untested assumptions that brain-body allometry is restrained to a stable scaling relationship across species and that any deviation from this slope is due to selection on brain size. Using the largest fossil and extant dataset yet assembled, we find that shifts in allometric slope underpin major transitions in mammalian evolution and are often primarily characterized by marked changes in body size. Our results reveal that the largest-brained mammals achieved large relative brain sizes by highly divergent paths. These findings prompt a reevaluation of the traditional paradigm of relative brain size and open new opportunities to improve our understanding of the genetic and developmental mechanisms that influence brain size.
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Affiliation(s)
- J B Smaers
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA.
- Division of Anthropology, American Museum of Natural History, New York, NY 10024, USA
| | - R S Rothman
- Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - D R Hudson
- Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - A M Balanoff
- Department of Psychological and Brain Sciences Johns Hopkins University, Baltimore, MD 21218, USA
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
| | - B Beatty
- NYIT College of Osteopathic Medicine, Old Westbury, NY 11568, USA
- United States National Museum, Smithsonian Institution, Washington, DC 20560, USA
| | - D K N Dechmann
- Department of Migration, Max-Planck Institute of Animal Behavior, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, 78464 Konstanz, Germany
| | - D de Vries
- Ecosystems and Environment Research Centre, School of Science, Engineering and Environment, University of Salford, Manchester M5 4WX, UK
| | - J C Dunn
- Division of Biological Anthropology, University of Cambridge, Cambridge CB2 3QG, UK
- Behavioral Ecology Research Group, Anglia Ruskin University, Cambridge CB1 1PT, UK
- Department of Cognitive Biology, University of Vienna, Vienna 1090, Austria
| | - J G Fleagle
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - C C Gilbert
- NYIT College of Osteopathic Medicine, Old Westbury, NY 11568, USA
- Department of Anthropology, Hunter College, New York, NY 10065, USA
- PhD Program in Anthropology, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
- New York Consortium in Evolutionary Primatology, New York, NY 10065, USA
| | - A Goswami
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK
| | - A N Iwaniuk
- Department of Neuroscience, University of Lethbridge, Lethbridge, AB T1K-3M4, Canada
| | - W L Jungers
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794, USA
- Association Vahatra, BP 3972, Antananarivo 101, Madagascar
| | - M Kerney
- Behavioral Ecology Research Group, Anglia Ruskin University, Cambridge CB1 1PT, UK
| | - D T Ksepka
- Bruce Museum, Greenwich, CT 06830, USA
- Department of Ornithology, American Museum of Natural History, New York, NY 10024, USA
- Division of Science and Education, Field Museum of Natural History, Chicago, IL 60605, USA
- Department of Paleobiology, Smithsonian Institution, Washington, DC 20013, USA
| | - P R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - C S Mongle
- Division of Anthropology, American Museum of Natural History, New York, NY 10024, USA
- Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
- Turkana Basin Institute, Stony Brook University, Stony Brook, NY 11794, USA
| | - F J Rohlf
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA
| | - N A Smith
- Division of Science and Education, Field Museum of Natural History, Chicago, IL 60605, USA
- Campbell Geology Museum, Clemson University, Clemson, SC 29634, USA
| | - C Soligo
- Department of Anthropology, University College London, London WC1H 0BW, UK
| | - V Weisbecker
- College of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia
| | - K Safi
- Department of Migration, Max-Planck Institute of Animal Behavior, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, 78464 Konstanz, Germany
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23
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Bisconti M, Damarco P, Tartarelli G, Pavia M, Carnevale G. A natural endocast of an early Miocene odontocete and its implications in cetacean brain evolution. J Comp Neurol 2020; 529:1198-1227. [PMID: 32840887 DOI: 10.1002/cne.25015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 12/18/2022]
Abstract
The natural endocast Museo di Geologia e Paleontologia of the Università degli Studi di Torino (MGPT)-PU 13873 is described and analyzed in order to interpret its taxonomic affinities and its potential significance on our understanding of cetacean brain evolution. The endocast is from the early Miocene of Piedmont (between ca. 19 and 16 million years ago), Northwestern Italy, and shows a number of plesiomorphic characters. These include: scarcely rounded cerebral hemispheres, cerebellum exposed in dorsal view with little superimposition by the cerebral hemispheres, short temporal lobe, and long sylvian fissure. The distance between the hypophysis and the rostral pons is particularly high, as it was determined by the calculus of the hypothalamus quotient, suggesting that the development of a deep interpeduncular fossa was not as advanced as in living odontocetes. The encephalization quotient (EQ) of MGPT-PU 13873 is ~1.81; therefore, this specimen shows an EQ in line with other fossil whales of the same geological age (early Miocene). Comparative analysis shows that there is a critical lack of data from the late Miocene and Pliocene that prevents us to fully understand the recent evolution of the EQ diversity in whales. Moreover, the past diversity of brain size and shape in mysticetes is virtually unknown. All these observations point to the need of additional efforts to uncover evolutionary patterns and processes on cetacean brain evolution.
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Affiliation(s)
- Michelangelo Bisconti
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy.,San Diego Natural History Museum, San Diego, California, USA
| | - Piero Damarco
- Ente di Gestione del Parco Paleontologico Astigiano, Museo Paleontologico Territoriale dell'Astigiano, Asti, Italy
| | | | - Marco Pavia
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy.,Museo di Geologia e Paleontologia, Università degli Studi di Torino, Torino, Italy
| | - Giorgio Carnevale
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy
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24
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A 25-y longitudinal dolphin cohort supports that long-lived individuals in same environment exhibit variation in aging rates. Proc Natl Acad Sci U S A 2020; 117:20950-20958. [PMID: 32778591 PMCID: PMC7456138 DOI: 10.1073/pnas.1918755117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Aging is a degradative process that varies among individuals. Due to limitations in defining and differentiating aging rates in human populations, understanding why some people appear to age slower than others has proven difficult. We analyzed 44 blood-based indices of health as candidate aging rate biomarkers collected over a 25-y period on a relevant, long-lived population of dolphins. Evidence of subsets of dolphins exhibiting slow and accelerated aging rates were detected, despite sharing the same environment, diet, and health care. Furthermore, some dolphin subsets were more likely to develop clinically relevant conditions, including anemia and immunosenescence. Our results support the notion that aging rates in long-lived mammals may be defined and provide insight into novel interventions to delay aging. While it is believed that humans age at different rates, a lack of robust longitudinal human studies using consensus biomarkers meant to capture aging rates has hindered an understanding of the degree to which individuals vary in their rates of aging. Because bottlenose dolphins are long-lived mammals that develop comorbidities of aging similar to humans, we analyzed data from a well-controlled, 25-y longitudinal cohort of 144 US Navy dolphins housed in the same oceanic environment. Our analysis focused on 44 clinically relevant hematologic and clinical chemistry measures recorded during routine blood draws throughout the dolphins’ lifetimes. Using stepwise regression and general linear models that accommodate correlations between measures obtained on individual dolphins, we demonstrate that, in a manner similar to humans, dolphins exhibit independent and linear age-related declines in four of these measures: hemoglobin, alkaline phosphatase, platelets, and lymphocytes. Using linear regressions and analyses of covariance with post hoc Tukey–Kramer tests to compare slopes (i.e., linear age-related rates) of our four aging rate biomarkers among 34 individual dolphins aging from 10 y to up to 40 y old, we could identify slow and accelerated agers and differentiate subgroups that were more or less likely to develop anemia and lymphopenia. This study successfully documents aging rate differences over the lifetime of long-lived individuals in a controlled environment. Our study suggests that nonenvironmental factors influencing aging rate biomarkers, including declining hemoglobin and anemia, may be targeted to delay the effects of aging in a compelling model of human biology.
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Szabo B, Damas-Moreira I, Whiting MJ. Can Cognitive Ability Give Invasive Species the Means to Succeed? A Review of the Evidence. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00187] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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27
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Arold ST. Intrinsic negative feedback as a limiting factor for the evolution of higher forms of intelligence. F1000Res 2020; 9:34. [PMID: 34504689 PMCID: PMC8408545 DOI: 10.12688/f1000research.22039.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/21/2021] [Indexed: 11/20/2022] Open
Abstract
Longstanding scientific efforts have been dedicated to answer why and how our particular intelligence is generated by our brain but not by the brain of other species. However, surprisingly little effort has been made to ask why no other species ever developed an intelligence similar to ours. Here, I explore this question based on genetic and paleontologic evidence. Contrary to the established view, this review suggests that the developmental hurdles alone are not high enough to explain the uniqueness of human intelligence (HI). As an additional explanation I propose that HI is normally not retained by natural selection, because it is, under most conditions, an intrinsically unfavourable trait. This unfavourableness, however, cannot be explained by physical constraints alone; rather, it may also be rooted in the same emotional and social complexity that is necessary for the development of HI. Thus, a major obstacle towards HI may not be solely the development of the required physical assets, but also to cope with harmful individual, social and environmental feedback intrinsically associated with this trait.
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Affiliation(s)
- Stefan T Arold
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, MK, 23955-6900, Saudi Arabia.,Centre de Biologie Structurale, CNRS, INSERM, Université de Montpellier, 34090 Montpellier, France
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Gillet A, Frédérich B, Parmentier E. Divergent evolutionary morphology of the axial skeleton as a potential key innovation in modern cetaceans. Proc Biol Sci 2019; 286:20191771. [PMID: 31771481 PMCID: PMC6939272 DOI: 10.1098/rspb.2019.1771] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/30/2019] [Indexed: 11/12/2022] Open
Abstract
Cetaceans represent the most diverse clade of extant marine tetrapods. Although the restructuring of oceans could have contributed to their diversity, other factors might also be involved. Similar to ichthyosaurs and sharks, variation of morphological traits could have promoted the colonization of new ecological niches and supported their diversification. By combining morphological data describing the axial skeleton of 73 cetacean species with phylogenetic comparative methods, we demonstrate that the vertebral morphology of cetaceans is associated with their habitat. All riverine and coastal species possess a small body size, lengthened vertebrae and a low vertebral count compared with open ocean species. Extant cetaceans have followed two distinct evolutionary pathways relative to their ecology. Whereas most offshore species such as baleen whales evolved towards an increased body size while retaining a low vertebral count, small oceanic dolphins underwent deep modifications of their axial skeleton with an extremely high number of short vertebrae. Our comparative analyses provide evidence these vertebral modifications have potentially operated as key innovations. These novelties contributed to their explosive radiation, resulting in an efficient swimming style that provides energetic advantages to small-sized species.
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Affiliation(s)
- Amandine Gillet
- Laboratory of Functional and Evolutionary Morphology, University of Liège, Liège, Belgium
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Serio C, Castiglione S, Tesone G, Piccolo M, Melchionna M, Mondanaro A, Di Febbraro M, Raia P. Macroevolution of Toothed Whales Exceptional Relative Brain Size. Evol Biol 2019. [DOI: 10.1007/s11692-019-09485-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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30
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Muller AS, Montgomery SH. Co-evolution of cerebral and cerebellar expansion in cetaceans. J Evol Biol 2019; 32:1418-1431. [PMID: 31507000 PMCID: PMC6916408 DOI: 10.1111/jeb.13539] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 08/27/2019] [Indexed: 12/23/2022]
Abstract
Cetaceans possess brains that rank among the largest to have ever evolved, either in terms of absolute mass or relative to body size. Cetaceans have evolved these huge brains under relatively unique environmental conditions, making them a fascinating case study to investigate the constraints and selection pressures that shape how brains evolve. Indeed, cetaceans have some unusual neuroanatomical features, including a thin but highly folded cerebrum with low cortical neuron density, as well as many structural adaptations associated with acoustic communication. Previous reports also suggest that at least some cetaceans have an expanded cerebellum, a brain structure with wide‐ranging functions in adaptive filtering of sensory information, the control of motor actions, and cognition. Here, we report that, relative to the size of the rest of the brain, both the cerebrum and cerebellum are dramatically enlarged in cetaceans and show evidence of co‐evolution, a pattern of brain evolution that is convergent with primates. However, we also highlight several branches where cortico‐cerebellar co‐evolution may be partially decoupled, suggesting these structures can respond to independent selection pressures. Across cetaceans, we find no evidence of a simple linear relationship between either cerebrum and cerebellum size and the complexity of social ecology or acoustic communication, but do find evidence that their expansion may be associated with dietary breadth. In addition, our results suggest that major increases in both cerebrum and cerebellum size occurred early in cetacean evolution, prior to the origin of the major extant clades, and predate the evolution of echolocation.
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Affiliation(s)
| | - Stephen Hugh Montgomery
- Department of Zoology, University of Cambridge, Cambridge, UK.,School of Biological Sciences, University of Bristol, Bristol, UK
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Sun Y, Liu Y, Sun X, Lin Y, Yin D, Xu S, Yang G. Insights into body size variation in cetaceans from the evolution of body-size-related genes. BMC Evol Biol 2019; 19:157. [PMID: 31351448 PMCID: PMC6660953 DOI: 10.1186/s12862-019-1461-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 06/14/2019] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Cetaceans exhibit an exceptionally wide range of body size, yet in this regard, their genetic basis remains poorly explored. In this study, 20 body-size-related genes for which duplication, mutation, or deficiency can cause body size change in mammals were chosen to preliminarily investigate the evolutionary mechanisms underlying the dramatic body size variation in cetaceans. RESULTS We successfully sequenced 20 body-size-related genes in six representative species of cetaceans. A total of 46 codons from 10 genes were detected and determined to be under strong positive selection, 32 (69.6%) of which were further found to be under radical physiochemical changes; moreover, some of these sites were localized in or near important functional regions. Interestingly, positively selected genes were well matched with body size evolution: for small cetaceans, strong evidence of positive selection was detected at ACAN, OBSL1, and GRB10, within which mutations or duplications could cause short stature; positive selection was found in large cetaceans at CBS and EIF2AK3, which could promote growth, and at the PLOD1 gene, within which mutations could cause tall stature. Importantly, relationship analyses revealed that the evolutionary rate of CBS was positively related to body length and body mass with statistical significance. Additionally, we identified 32 cetacean-specific amino acid changes in 10 genes. CONCLUSIONS This is the first study to investigate the molecular basis of dramatic body size variation in cetaceans. Our results provide evidence of the positive selection of several body-size-related genes in cetaceans, as well as divergent selection between large or small cetaceans, which suggest cetacean body size variation possibly associated with these genes. In addition, cetacean-specific amino acid changes might have played key roles in body size evolution after the divergence of cetaceans from their terrestrial relatives. Overall, the evolutionary pattern of these body-size-related genes could provide new insights into genetic mechanisms for the body size variation in cetaceans.
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Affiliation(s)
- Yingying Sun
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 China
| | - Yanzhi Liu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 China
| | - Xiaohui Sun
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 China
| | - Yurui Lin
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 China
| | - Daiqing Yin
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 China
| | - Shixia Xu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 China
| | - Guang Yang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 China
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32
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Benoit J, Legendre LJ, Tabuce R, Obada T, Mararescul V, Manger P. Brain evolution in Proboscidea (Mammalia, Afrotheria) across the Cenozoic. Sci Rep 2019; 9:9323. [PMID: 31249366 PMCID: PMC6597534 DOI: 10.1038/s41598-019-45888-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 06/07/2019] [Indexed: 12/12/2022] Open
Abstract
As the largest and among the most behaviourally complex extant terrestrial mammals, proboscideans (elephants and their extinct relatives) are iconic representatives of the modern megafauna. The timing of the evolution of large brain size and above average encephalization quotient remains poorly understood due to the paucity of described endocranial casts. Here we created the most complete dataset on proboscidean endocranial capacity and analysed it using phylogenetic comparative methods and ancestral character states reconstruction using maximum likelihood. Our analyses support that, in general, brain size and body mass co-evolved in proboscideans across the Cenozoic; however, this pattern appears disrupted by two instances of specific increases in relative brain size in the late Oligocene and early Miocene. These increases in encephalization quotients seem to correspond to intervals of important climatic, environmental and faunal changes in Africa that may have positively selected for larger brain size or body mass.
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Affiliation(s)
- Julien Benoit
- Evolutionary Studies Institute (ESI), University of the Witwatersrand, Braamfontein, 2050, Johannesburg, South Africa.
| | - Lucas J Legendre
- Jackson School of Geosciences, The University of Texas at Austin, 2275 Speedway Stop C9000, Austin, TX, United States
| | - Rodolphe Tabuce
- Institut des Sciences de L'Evolution de Montpellier, Université Montpellier 2, Place Eugène Batillon, F-34095 Montpellier, cedex 05, Montpellier, France
| | - Theodor Obada
- Academy of Sciences of Moldova, Institute of Zoology, Chişinău, Moldova
| | | | - Paul Manger
- School of Anatomical Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, Johannesburg, South Africa
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33
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Affiliation(s)
- Joseph Robert Burger
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
- North Carolina Museum of Natural Sciences, Raleigh, NC, USA
| | | | - Claire Leadbetter
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Farhin Shaikh
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
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Simultaneous detection of macroevolutionary patterns in phenotypic means and rate of change with and within phylogenetic trees including extinct species. PLoS One 2019; 14:e0210101. [PMID: 30682060 PMCID: PMC6347132 DOI: 10.1371/journal.pone.0210101] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 12/17/2018] [Indexed: 11/19/2022] Open
Abstract
Recognizing evolutionary trends in phenotypic means and rates requires the application of phylogenetic comparative methods (PCMs). Most PCMs are unsuited to make full use of fossil information, which is a drawback, given the inclusion of such data improves, and in some cases even corrects, the proper understanding of trait evolution. Here we present a new computer application, written in R, that allows the simultaneous computation of temporal trends in phenotypic mean and evolutionary rate along a phylogeny, and to contrast such patterns among different clades within the tree. By using simulation experiments, we show the new implementation, names search.trend is as powerful as existing PCM tools in discerning macroevolutionary patterns in phenotypic means and rates, but differently from any other PCM allows comparing individual clades to each other, and provides rich information about trait evolution for all lineages in the tree.
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35
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DeCasien AR, Thompson NA, Williams SA, Shattuck MR. Encephalization and longevity evolved in a correlated fashion in Euarchontoglires but not in other mammals. Evolution 2018; 72:2617-2631. [DOI: 10.1111/evo.13633] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 10/18/2018] [Accepted: 10/23/2018] [Indexed: 12/23/2022]
Affiliation(s)
- Alex R. DeCasien
- Department of Anthropology New York University New York New York 10003
- New York Consortium in Evolutionary Primatology New York New York 10024
| | - Nicole A. Thompson
- New York Consortium in Evolutionary Primatology New York New York 10024
- Department of Ecology, Evolution, and Environmental Biology Columbia University New York New York 10027
| | - Scott A. Williams
- Department of Anthropology New York University New York New York 10003
- New York Consortium in Evolutionary Primatology New York New York 10024
| | - Milena R. Shattuck
- Department of Anthropology and Program of Human Biology Hunter College, CUNY New York New York 10065
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36
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Jebb D, Hiller M. Recurrent loss of HMGCS2 shows that ketogenesis is not essential for the evolution of large mammalian brains. eLife 2018; 7:38906. [PMID: 30322448 PMCID: PMC6191284 DOI: 10.7554/elife.38906] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 09/09/2018] [Indexed: 12/04/2022] Open
Abstract
Apart from glucose, fatty acid-derived ketone bodies provide metabolic energy for the brain during fasting and neonatal development. We investigated the evolution of HMGCS2, the key enzyme required for ketone body biosynthesis (ketogenesis). Unexpectedly, we found that three mammalian lineages, comprising cetaceans (dolphins and whales), elephants and mastodons, and Old World fruit bats have lost this gene. Remarkably, many of these species have exceptionally large brains and signs of intelligent behavior. While fruit bats are sensitive to starvation, cetaceans and elephants can still withstand periods of fasting. This suggests that alternative strategies to fuel large brains during fasting evolved repeatedly and reveals flexibility in mammalian energy metabolism. Furthermore, we show that HMGCS2 loss preceded brain size expansion in toothed whales and elephants. Thus, while ketogenesis was likely important for brain size expansion in modern humans, ketogenesis is not a universal precondition for the evolution of large mammalian brains. Our brain requires a lot of energy to work properly. Sugars are usually the main type of fuel for the body, but when they run low – for example during a food shortage – fat, in the form of fatty acids, can be used instead. However, the brain cannot directly process these molecules; instead, fatty acids need to go through ketogenesis, a process that turns fat into ketone bodies, which the organ can then burn. Scientists believe that the ability to create ketone bodies was essential for us to evolve large brains. Yet, it is still unclear if all mammals can transform fatty acids into ketone bodies. One way to look into this question is to track whether other species have HMGCS2, the main enzyme that drives ketogenesis. Jebb and Hiller examined the genomes of 70 different species of mammals for the gene that codes for HMGCS2. The comparisons revealed that cetaceans (whales, dolphins and porpoises), Old World fruit bats and the African savanna elephant have all independently lost their working version of HMGCS2. Yet, many members of these three groups have evolved brains that are large for their body size. The genetic analyses showed that dolphins and elephants developed big brains after the enzyme became inactive, challenging the idea that HMGCS2 – and by extension ketogenesis – is always required for the evolution of large brains. These results may also be useful for conservation efforts. Many fruit bats across the world are severely threatened, and their lack of ketogenesis could explain why these animals are highly sensitive to starvation and quickly die when food becomes scarce.
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Affiliation(s)
- David Jebb
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.,Center for Systems Biology Dresden, Dresden, Germany
| | - Michael Hiller
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.,Center for Systems Biology Dresden, Dresden, Germany
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37
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Breakdown of brain–body allometry and the encephalization of birds and mammals. Nat Ecol Evol 2018; 2:1492-1500. [DOI: 10.1038/s41559-018-0632-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/05/2018] [Indexed: 11/09/2022]
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Abstract
Four extant lineages of mammals have invaded and diversified in the water: Sirenia, Cetacea, Pinnipedia, and Lutrinae. Most of these aquatic clades are larger bodied, on average, than their closest land-dwelling relatives, but the extent to which potential ecological, biomechanical, and physiological controls contributed to this pattern remains untested quantitatively. Here, we use previously published data on the body masses of 3,859 living and 2,999 fossil mammal species to examine the evolutionary trajectories of body size in aquatic mammals through both comparative phylogenetic analysis and examination of the fossil record. Both methods indicate that the evolution of an aquatic lifestyle is driving three of the four extant aquatic mammal clades toward a size attractor at ∼500 kg. The existence of this body size attractor and the relatively rapid selection toward, and limited deviation from, this attractor rule out most hypothesized drivers of size increase. These three independent body size increases and a shared aquatic optimum size are consistent with control by differences in the scaling of energetic intake and cost functions with body size between the terrestrial and aquatic realms. Under this energetic model, thermoregulatory costs constrain minimum size, whereas limitations on feeding efficiency constrain maximum size. The optimum size occurs at an intermediate value where thermoregulatory costs are low but feeding efficiency remains high. Rather than being released from size pressures, water-dwelling mammals are driven and confined to larger body sizes by the strict energetic demands of the aquatic medium.
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Montgomery SH, Mundy NI, Barton RA. Brain evolution and development: adaptation, allometry and constraint. Proc Biol Sci 2017; 283:rspb.2016.0433. [PMID: 27629025 DOI: 10.1098/rspb.2016.0433] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 08/19/2016] [Indexed: 01/08/2023] Open
Abstract
Phenotypic traits are products of two processes: evolution and development. But how do these processes combine to produce integrated phenotypes? Comparative studies identify consistent patterns of covariation, or allometries, between brain and body size, and between brain components, indicating the presence of significant constraints limiting independent evolution of separate parts. These constraints are poorly understood, but in principle could be either developmental or functional. The developmental constraints hypothesis suggests that individual components (brain and body size, or individual brain components) tend to evolve together because natural selection operates on relatively simple developmental mechanisms that affect the growth of all parts in a concerted manner. The functional constraints hypothesis suggests that correlated change reflects the action of selection on distributed functional systems connecting the different sub-components, predicting more complex patterns of mosaic change at the level of the functional systems and more complex genetic and developmental mechanisms. These hypotheses are not mutually exclusive but make different predictions. We review recent genetic and neurodevelopmental evidence, concluding that functional rather than developmental constraints are the main cause of the observed patterns.
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Affiliation(s)
- Stephen H Montgomery
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Nicholas I Mundy
- Department of Zoology, University of Cambridge, St Andrews Street, Cambridge CB2 3EJ, UK
| | - Robert A Barton
- Evolutionary Anthropology Research Group, Durham University, Dawson Building, South Road, Durham DH1 3LE, UK
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40
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Boessenecker RW, Ahmed E, Geisler JH. New records of the dolphin Albertocetus meffordorum (Odontoceti: Xenorophidae) from the lower Oligocene of South Carolina: Encephalization, sensory anatomy, postcranial morphology, and ontogeny of early odontocetes. PLoS One 2017; 12:e0186476. [PMID: 29117197 PMCID: PMC5695589 DOI: 10.1371/journal.pone.0186476] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 10/02/2017] [Indexed: 11/18/2022] Open
Abstract
We report five new specimens of xenorophid dolphins from North and South Carolina. Four of the specimens represent the xenorophid Albertocetus meffordorum, previously only known from the holotype skull. The other is a fragmentary petrosal from the upper Oligocene Belgrade Formation that we refer to Echovenator sp, indicating at least two xenorophids from that unit. Two of the Albertocetus meffordorum specimens are from the lower Oligocene Ashley Formation: 1) a partial skeleton with neurocranium, fragmentary mandible, ribs, vertebrae, and chevrons, and 2) an isolated braincase. The partial vertebral column indicates that Albertocetus retained the ancestral morphology and locomotory capabilities of basilosaurid archaeocetes, toothed mysticetes, and physeteroids, and caudal vertebrae that are as wide as tall suggest that the caudal peduncle, which occurs in all extant Cetacea, was either wide or lacking. CT data from the isolated braincase were used to generate a digital endocast of the cranial cavity. The estimated EQ of this specimen is relatively high for an Oligocene odontocete, and other aspects of the brain, such as its anteroposterior length and relative size of the temporal lobe, are intermediate in morphology between those of extant cetaceans and terrestrial artiodactyls. Ethmoturbinals are also preserved, and are similar in morphology and number to those described for the Miocene odontocete Squalodon. These fossils extend the temporal range of Albertocetus meffordorum into the early Oligocene, its geographic range into South Carolina, and expand our paleobiological understanding of the Xenorophidae.
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Affiliation(s)
- Robert W. Boessenecker
- Department of Geology and Environmental Geosciences, College of Charleston, Charleston, South Carolina, United States of America
- University of California Museum of Paleontology, University of California, Berkeley, California, United States of America
- * E-mail:
| | - Erum Ahmed
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States of America
| | - Jonathan H. Geisler
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States of America
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41
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Fox KCR, Muthukrishna M, Shultz S. The social and cultural roots of whale and dolphin brains. Nat Ecol Evol 2017; 1:1699-1705. [PMID: 29038481 DOI: 10.1038/s41559-017-0336-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 09/01/2017] [Indexed: 02/04/2023]
Abstract
Encephalization, or brain expansion, underpins humans' sophisticated social cognition, including language, joint attention, shared goals, teaching, consensus decision-making and empathy. These abilities promote and stabilize cooperative social interactions, and have allowed us to create a 'cognitive' or 'cultural' niche and colonize almost every terrestrial ecosystem. Cetaceans (whales and dolphins) also have exceptionally large and anatomically sophisticated brains. Here, by evaluating a comprehensive database of brain size, social structures and cultural behaviours across cetacean species, we ask whether cetacean brains are similarly associated with a marine cultural niche. We show that cetacean encephalization is predicted by both social structure and by a quadratic relationship with group size. Moreover, brain size predicts the breadth of social and cultural behaviours, as well as ecological factors (diversity of prey types and to a lesser extent latitudinal range). The apparent coevolution of brains, social structure and behavioural richness of marine mammals provides a unique and striking parallel to the large brains and hyper-sociality of humans and other primates. Our results suggest that cetacean social cognition might similarly have arisen to provide the capacity to learn and use a diverse set of behavioural strategies in response to the challenges of social living.
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Affiliation(s)
- Kieran C R Fox
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, 94305, USA
| | - Michael Muthukrishna
- Department of Psychological and Behavioural Science, London School of Economics and Political Science, London, WC2A 2AE, UK.,Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Susanne Shultz
- School of Earth and Environmental Sciences, University of Manchester, Manchester, M13 9PL, UK.
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Xu S, Sun X, Niu X, Zhang Z, Tian R, Ren W, Zhou K, Yang G. Genetic basis of brain size evolution in cetaceans: insights from adaptive evolution of seven primary microcephaly (MCPH) genes. BMC Evol Biol 2017; 17:206. [PMID: 28851290 PMCID: PMC5576371 DOI: 10.1186/s12862-017-1051-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Accepted: 08/14/2017] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Cetacean brain size expansion is an enigmatic event in mammalian evolution, yet its genetic basis remains poorly explored. Here, all exons of the seven primary microcephaly (MCPH) genes that play key roles in size regulation during brain development were investigated in representative cetacean lineages. RESULTS Sequences of MCPH2-7 genes were intact in cetaceans but frameshift mutations and stop codons was identified in MCPH1. Extensive positive selection was identified in four of six intact MCPH genes: WDR62, CDK5RAP2, CEP152, and ASPM. Specially, positive selection at CDK5RAP2 and ASPM were examined along lineages of odontocetes with increased encephalization quotients (EQ) and mysticetes with reduced EQ but at WDR62 only found along odontocete lineages. Interestingly, a positive association between evolutionary rate (ω) and EQ was identified for CDK5RAP2 and ASPM. Furthermore, we tested the binding affinities between Calmodulin (CaM) and ASPM IQ motif in cetaceans because only CaM combined with IQ, can ASPM perform the function in determining brain size. Preliminary function assay showed binding affinities between CaM and IQ motif of the odontocetes with increased EQ was stronger than for the mysticetes with decreased EQ. In addition, evolution rate of ASPM and CDK5RAP2 were significantly related to mean group size (as one measure of social complexity). CONCLUSIONS Our study investigated the genetic basis of cetacean brain size evolution. Significant positive selection was examined along lineages with both increased and decreased EQ at CDK5RAP2 and ASPM, which is well matched with cetacean complex brain size evolution. Evolutionary rate of CDK5RAP2 and ASPM were significantly related to EQ, suggesting that these two genes may have contributed to EQ expansion in cetaceans. This suggestion was further indicated by our preliminary function test that ASPM might be mainly linked to evolutionary increases in EQ. Most strikingly, our results suggested that cetaceans evolved large brains to manage complex social systems, consisting with the 'social brain hypothesis', as evolutionary rate of ASPM and CDK5RAP2 were significantly related to mean group size.
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Affiliation(s)
- Shixia Xu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023 China
| | - Xiaohui Sun
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023 China
| | - Xu Niu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023 China
| | - Zepeng Zhang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023 China
| | - Ran Tian
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023 China
| | - Wenhua Ren
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023 China
| | - Kaiya Zhou
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023 China
| | - Guang Yang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023 China
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Functional variants of the melanocortin-4 receptor associated with the Odontoceti and Mysticeti suborders of cetaceans. Sci Rep 2017; 7:5684. [PMID: 28720755 PMCID: PMC5515947 DOI: 10.1038/s41598-017-05962-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 06/06/2017] [Indexed: 11/09/2022] Open
Abstract
Cetaceans, a group of mammals adapted to the aquatic environment that descended from terrestrial artiodactyls, exhibit tremendous interspecific differences in a number of phenotypes, including feeding behavior, such as filter feeding in the Mysticeti vs prey-hunting Odontoceti, and size, with the smallest cetacean, the vaquita, at 1.4 meters and the largest, the blue whale, reaching 33 meters. The Melanocortin-4 receptor (MC4R) regulates food intake, energy balance, and somatic growth in both mammals and teleosts. In this study, we examined allelic variants of the MC4R in cetaceans. We sequenced the MC4R from 20 cetaceans, and pharmacologically characterized 17 of these protein products. Results identified a single variation at amino acid 156 in the MC4R from representative species of major cetacean lineages uniquely associated with the toothed whales or Odontoceti (arginine at 156) and baleen whales or Mysticeti (glutamine at 156). The Q156 receptor variant found in the larger baleen whales was functionally less responsive to its endogenous anorexigenic ligand, α-MSH. Furthermore, the R156 receptor variant showed greater constitutive activity and a higher affinity for ligand. These data suggest that the MC4R may be one gene involved in the evolution of feeding ecology, energy balance, and body size in cetaceans.
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Gaudry MJ, Jastroch M, Treberg JR, Hofreiter M, Paijmans JLA, Starrett J, Wales N, Signore AV, Springer MS, Campbell KL. Inactivation of thermogenic UCP1 as a historical contingency in multiple placental mammal clades. SCIENCE ADVANCES 2017; 3:e1602878. [PMID: 28706989 PMCID: PMC5507634 DOI: 10.1126/sciadv.1602878] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 06/21/2017] [Indexed: 05/08/2023]
Abstract
Mitochondrial uncoupling protein 1 (UCP1) is essential for nonshivering thermogenesis in brown adipose tissue and is widely accepted to have played a key thermoregulatory role in small-bodied and neonatal placental mammals that enabled the exploitation of cold environments. We map ucp1 sequences from 133 mammals onto a species tree constructed from a ~51-kb sequence alignment and show that inactivating mutations have occurred in at least 8 of the 18 traditional placental orders, thereby challenging the physiological importance of UCP1 across Placentalia. Selection and timetree analyses further reveal that ucp1 inactivations temporally correspond with strong secondary reductions in metabolic intensity in xenarthrans and pangolins, or in six other lineages coincided with a ~30 million-year episode of global cooling in the Paleogene that promoted sharp increases in body mass and cladogenesis evident in the fossil record. Our findings also demonstrate that members of various lineages (for example, cetaceans, horses, woolly mammoths, Steller's sea cows) evolved extreme cold hardiness in the absence of UCP1-mediated thermogenesis. Finally, we identify ucp1 inactivation as a historical contingency that is linked to the current low species diversity of clades lacking functional UCP1, thus providing the first evidence for species selection related to the presence or absence of a single gene product.
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Affiliation(s)
- Michael J. Gaudry
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Martin Jastroch
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, German Research Center for Environmental Health, Parkring 13, 85748 Garching, Germany
- Department of Animal Physiology, Faculty of Biology, Philipps University of Marburg, D-35032 Marburg, Germany
| | - Jason R. Treberg
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
- Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Michael Hofreiter
- Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | | | - James Starrett
- Department of Biology, University of California, Riverside, CA 92521, USA
| | - Nathan Wales
- Centre for GeoGenetics, Natural History Museum of Denmark, Øster Voldgade 5-7, 1350 Copenhagen, Denmark
| | - Anthony V. Signore
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Mark S. Springer
- Department of Biology, University of California, Riverside, CA 92521, USA
| | - Kevin L. Campbell
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
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The Origin of Filter Feeding in Whales. Curr Biol 2017; 27:2036-2042.e2. [PMID: 28669761 DOI: 10.1016/j.cub.2017.06.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 05/21/2017] [Accepted: 05/31/2017] [Indexed: 11/20/2022]
Abstract
As the largest known vertebrates of all time, mysticetes depend on keratinous sieves called baleen to capture enough small prey to sustain their enormous size [1]. The origins of baleen are controversial: one hypothesis suggests that teeth were lost during a suction-feeding stage of mysticete evolution and that baleen evolved thereafter [2-4], whereas another suggests that baleen evolved before teeth were lost [5]. Here we report a new species of toothed mysticete, Coronodon havensteini, from the Oligocene of South Carolina that is transitional between raptorial archaeocete whales and modern mysticetes. Although the morphology and wear on its anterior teeth indicate that it captured large prey, its broad, imbricated, multi-cusped lower molars frame narrow slots that were likely used for filter feeding. Coronodon havensteini is a basal, if not the most basal, mysticete, and our analysis suggests that it is representative of an initial stage of mysticete evolution in which teeth were functional analogs to baleen. In later lineages, the diastema between teeth increased-in some cases, markedly so [6]-and may mark a stage at which the balance of the oral fissure shifted from mostly teeth to mostly baleen. When placed in a phylogenetic context, our new taxon indicates that filter feeding was preceded by raptorial feeding and that suction feeding evolved separately within a clade removed from modern baleen whales.
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Park T, Fitzgerald EMG, Evans AR. Ultrasonic hearing and echolocation in the earliest toothed whales. Biol Lett 2017; 12:rsbl.2016.0060. [PMID: 27072406 DOI: 10.1098/rsbl.2016.0060] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 03/18/2016] [Indexed: 11/12/2022] Open
Abstract
The evolution of biosonar (production of high-frequency sound and reception of its echo) was a key innovation of toothed whales and dolphins (Odontoceti) that facilitated phylogenetic diversification and rise to ecological predominance. Yet exactly when high-frequency hearing first evolved in odontocete history remains a fundamental question in cetacean biology. Here, we show that archaic odontocetes had a cochlea specialized for sensing high-frequency sound, as exemplified by an Oligocene xenorophid, one of the earliest diverging stem groups. This specialization is not as extreme as that seen in the crown clade. Paired with anatomical correlates for high-frequency signal production in Xenorophidae, this is strong evidence that the most archaic toothed whales possessed a functional biosonar system, and that this signature adaptation of odontocetes was acquired at or soon after their origin.
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Affiliation(s)
- Travis Park
- School of Biological Sciences, Monash University, Melbourne, Australia Geosciences, Museum Victoria, Melbourne, Australia
| | - Erich M G Fitzgerald
- Geosciences, Museum Victoria, Melbourne, Australia National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Alistair R Evans
- School of Biological Sciences, Monash University, Melbourne, Australia Geosciences, Museum Victoria, Melbourne, Australia
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Ridgway SH, Carlin KP, Van Alstyne KR, Hanson AC, Tarpley RJ. Comparison of Dolphins' Body and Brain Measurements with Four Other Groups of Cetaceans Reveals Great Diversity. BRAIN, BEHAVIOR AND EVOLUTION 2017; 88:235-257. [PMID: 28122370 DOI: 10.1159/000454797] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 11/28/2016] [Indexed: 01/06/2023]
Abstract
We compared mature dolphins with 4 other groupings of mature cetaceans. With a large data set, we found great brain diversity among 5 different taxonomic groupings. The dolphins in our data set ranged in body mass from about 40 to 6,750 kg and in brain mass from 0.4 to 9.3 kg. Dolphin body length ranged from 1.3 to 7.6 m. In our combined data set from the 4 other groups of cetaceans, body mass ranged from about 20 to 120,000 kg and brain mass from about 0.2 to 9.2 kg, while body length varied from 1.21 to 26.8 m. Not all cetaceans have large brains relative to their body size. A few dolphins near human body size have human-sized brains. On the other hand, the absolute brain mass of some other cetaceans is only one-sixth as large. We found that brain volume relative to body mass decreases from Delphinidae to a group of Phocoenidae and Monodontidae, to a group of other odontocetes, to Balaenopteroidea, and finally to Balaenidae. We also found the same general trend when we compared brain volume relative to body length, except that the Delphinidae and Phocoenidae-Monodontidae groups do not differ significantly. The Balaenidae have the smallest relative brain mass and the lowest cerebral cortex surface area. Brain parts also vary. Relative to body mass and to body length, dolphins also have the largest cerebellums. Cortex surface area is isometric with brain size when we exclude the Balaenidae. Our data show that the brains of Balaenidae are less convoluted than those of the other cetaceans measured. Large vascular networks inside the cranial vault may help to maintain brain temperature, and these nonbrain tissues increase in volume with body mass and with body length ranging from 8 to 65% of the endocranial volume. Because endocranial vascular networks and other adnexa, such as the tentorium cerebelli, vary so much in different species, brain size measures from endocasts of some extinct cetaceans may be overestimates. Our regression of body length on endocranial adnexa might be used for better estimates of brain volume from endocasts or from endocranial volume of living species or extinct cetaceans.
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Affiliation(s)
- Sam H Ridgway
- National Marine Mammal Foundation, San Diego, CA, USA
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Logan CJ, Kruuk LEB, Stanley R, Thompson AM, Clutton-Brock TH. Endocranial volume is heritable and is associated with longevity and fitness in a wild mammal. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160622. [PMID: 28083105 PMCID: PMC5210687 DOI: 10.1098/rsos.160622] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/17/2016] [Indexed: 05/08/2023]
Abstract
Research on relative brain size in mammals suggests that increases in brain size may generate benefits to survival and costs to fecundity: comparative studies of mammals have shown that interspecific differences in relative brain size are positively correlated with longevity and negatively with fecundity. However, as yet, no studies of mammals have investigated whether similar relationships exist within species, nor whether individual differences in brain size within a wild population are heritable. Here we show that, in a wild population of red deer (Cervus elaphus), relative endocranial volume was heritable (h2 = 63%; 95% credible intervals (CI) = 50-76%). In females, it was positively correlated with longevity and lifetime reproductive success, though there was no evidence that it was associated with fecundity. In males, endocranial volume was not related to longevity, lifetime breeding success or fecundity.
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Affiliation(s)
- C. J. Logan
- Department of Zoology, University of Cambridge, Cambridge, UK
- Author for correspondence: C. J. Logan e-mail:
| | - L. E. B. Kruuk
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
- Division of Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, Australia
| | - R. Stanley
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - A. M. Thompson
- Department of Zoology, University of Cambridge, Cambridge, UK
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Steinhausen C, Zehl L, Haas-Rioth M, Morcinek K, Walkowiak W, Huggenberger S. Multivariate Meta-Analysis of Brain-Mass Correlations in Eutherian Mammals. Front Neuroanat 2016; 10:91. [PMID: 27746724 PMCID: PMC5043137 DOI: 10.3389/fnana.2016.00091] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 09/13/2016] [Indexed: 11/26/2022] Open
Abstract
The general assumption that brain size differences are an adequate proxy for subtler differences in brain organization turned neurobiologists toward the question why some groups of mammals such as primates, elephants, and whales have such remarkably large brains. In this meta-analysis, an extensive sample of eutherian mammals (115 species distributed in 14 orders) provided data about several different biological traits and measures of brain size such as absolute brain mass (AB), relative brain mass (RB; quotient from AB and body mass), and encephalization quotient (EQ). These data were analyzed by established multivariate statistics without taking specific phylogenetic information into account. Species with high AB tend to (1) feed on protein-rich nutrition, (2) have a long lifespan, (3) delayed sexual maturity, and (4) long and rare pregnancies with small litter sizes. Animals with high RB usually have (1) a short life span, (2) reach sexual maturity early, and (3) have short and frequent gestations. Moreover, males of species with high RB also have few potential sexual partners. In contrast, animals with high EQs have (1) a high number of potential sexual partners, (2) delayed sexual maturity, and (3) rare gestations with small litter sizes. Based on these correlations, we conclude that Eutheria with either high AB or high EQ occupy positions at the top of the network of food chains (high trophic levels). Eutheria of low trophic levels can develop a high RB only if they have small body masses.
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Affiliation(s)
- Charlene Steinhausen
- Department II of Anatomy, University of CologneCologne, Germany
- Biocenter, University of CologneCologne, Germany
| | - Lyuba Zehl
- Biocenter, University of CologneCologne, Germany
- Jülich Research Centre, Institute of Neuroscience and Medicine (INM-6) and Institute for Advanced Simulation (IAS-6) and JARA BRAIN Institute IJülich, Germany
| | - Michaela Haas-Rioth
- Department of Anatomy III (Dr. Senckenbergische Anatomie), Goethe University of Frankfurt am MainFrankfurt am Main, Germany
| | | | | | - Stefan Huggenberger
- Department II of Anatomy, University of CologneCologne, Germany
- Biocenter, University of CologneCologne, Germany
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Churchill M, Martinez-Caceres M, de Muizon C, Mnieckowski J, Geisler J. The Origin of High-Frequency Hearing in Whales. Curr Biol 2016; 26:2144-9. [DOI: 10.1016/j.cub.2016.06.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 05/31/2016] [Accepted: 06/01/2016] [Indexed: 10/21/2022]
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