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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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2
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De Meester G, Van Linden L, Torfs J, Pafilis P, Šunje E, Steenssens D, Zulčić T, Sassalos A, Van Damme R. Learning with lacertids: Studying the link between ecology and cognition within a comparative framework. Evolution 2022; 76:2531-2552. [PMID: 36111365 DOI: 10.1111/evo.14618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 08/10/2022] [Accepted: 08/21/2022] [Indexed: 01/22/2023]
Abstract
Cognition is an essential tool for animals to deal with environmental challenges. Nonetheless, the ecological forces driving the evolution of cognition throughout the animal kingdom remain enigmatic. Large-scale comparative studies on multiple species and cognitive traits have been advanced as the best way to facilitate our understanding of cognitive evolution, but such studies are rare. Here, we tested 13 species of lacertid lizards (Reptilia: Lacertidae) using a battery of cognitive tests measuring inhibitory control, problem-solving, and spatial and reversal learning. Next, we tested the relationship between species' performance and (a) resource availability (temperature and precipitation), habitat complexity (Normalized Difference Vegetation Index), and habitat variability (seasonality) in their natural habitat and (b) their life history (size at hatching and maturity, clutch size, and frequency). Although species differed markedly in their cognitive abilities, such variation was mostly unrelated to their ecology and life history. Yet, species living in more variable environments exhibited lower behavioral flexibility, likely due to energetic constrains in such habitats. Our standardized protocols provide opportunities for collaborative research, allowing increased sample sizes and replication, essential for moving forward in the field of comparative cognition. Follow-up studies could include more detailed measures of habitat structure and look at other potential selective drivers such as predation.
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Affiliation(s)
- Gilles De Meester
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium.,Section of Zoology and Marine Biology, Department of Biology, National and Kapodistrian University of Athens, Athens, 157 84, Greece
| | - Lisa Van Linden
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium
| | - Jonas Torfs
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium
| | - Panayiotis Pafilis
- Section of Zoology and Marine Biology, Department of Biology, National and Kapodistrian University of Athens, Athens, 157 84, Greece
| | - Emina Šunje
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium.,Department of Biology, Faculty of Natural Sciences, University of Sarajevo, Sarajevo, 71000, Bosnia and Herzegovina.,Herpetological Association in Bosnia and Herzegovina: BHHU: ATRA, Sarajevo, 71000, Bosnia and Herzegovina
| | - Dries Steenssens
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium
| | - Tea Zulčić
- Herpetological Association in Bosnia and Herzegovina: BHHU: ATRA, Sarajevo, 71000, Bosnia and Herzegovina
| | - Athanasios Sassalos
- Section of Zoology and Marine Biology, Department of Biology, National and Kapodistrian University of Athens, Athens, 157 84, Greece
| | - Raoul Van Damme
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium
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3
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Wainwright JB, Montgomery SH. Neuroanatomical shifts mirror patterns of ecological divergence in three diverse clades of mimetic butterflies. Evolution 2022; 76:1806-1820. [PMID: 35767896 PMCID: PMC9540801 DOI: 10.1111/evo.14547] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 05/30/2022] [Accepted: 06/06/2022] [Indexed: 01/22/2023]
Abstract
Microhabitat partitioning in heterogenous environments can support more diverse communities but may expose partitioned species to distinct perceptual challenges. Divergence across microhabitats could therefore lead to local adaptation to contrasting sensory conditions across small spatial scales, but this aspect of community structuring is rarely explored. Diverse communities of ithomiine butterflies provide an example where closely related species partition tropical forests, where shifts in mimetic coloration are tightly associated with shifts in habitat preference. We test the hypothesis that these mimetic and ecological shifts are associated with distinct patterns of sensory neural investment by comparing brain structure across 164 individuals of 16 species from three ithomiine clades. We find distinct brain morphologies between Oleriina and Hypothyris, which are mimetically homogenous and occupy a single microhabitat. Oleriina, which occurs in low-light microhabitats, invests less in visual brain regions than Hypothyris, with one notable exception, Hyposcada anchiala, the only Oleriina sampled to have converged on mimicry rings found in Hypothyris. We also find that Napeogenes, which has diversified into a range of mimicry rings, shows intermediate patterns of sensory investment. We identify flight height as a critical factor shaping neuroanatomical diversity, with species that fly higher in the canopy investing more in visual structures. Our work suggests that the sensory ecology of species may be impacted by, and interact with, the ways in which communities of closely related organisms are adaptively assembled.
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AnimalTraits - a curated animal trait database for body mass, metabolic rate and brain size. Sci Data 2022; 9:265. [PMID: 35654905 PMCID: PMC9163144 DOI: 10.1038/s41597-022-01364-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 04/26/2022] [Indexed: 11/23/2022] Open
Abstract
Trait databases have become important resources for large-scale comparative studies in ecology and evolution. Here we introduce the AnimalTraits database, a curated database of body mass, metabolic rate and brain size, in standardised units, for terrestrial animals. The database has broad taxonomic breadth, including tetrapods, arthropods, molluscs and annelids from almost 2000 species and 1000 genera. All data recorded in the database are sourced from their original empirical publication, and the original metrics and measurements are included with each record. This allows for subsequent data transformations as required. We have included rich metadata to allow users to filter the dataset. The additional R scripts we provide will assist researchers with aggregating standardised observations into species-level trait values. Our goals are to provide this resource without restrictions, to keep the AnimalTraits database current, and to grow the number of relevant traits in the future. Measurement(s) | metabolic rate quantification • body mass • brain size | Technology Type(s) | metabolic rate measurement • body mass quantification • brain mass brain volume |
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Bold and bright: shy and supple? The effect of habitat type on personality-cognition covariance in the Aegean wall lizard (Podarcis erhardii). Anim Cogn 2022; 25:745-767. [PMID: 35037121 DOI: 10.1007/s10071-021-01587-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 11/04/2021] [Accepted: 11/24/2021] [Indexed: 12/27/2022]
Abstract
Animals exhibit considerable and consistent among-individual variation in cognitive abilities, even within a population. Recent studies have attempted to address this variation using insights from the field of animal personality. Generally, it is predicted that animals with "faster" personalities (bolder, explorative, and neophilic) should exhibit faster but less flexible learning. However, the empirical evidence for a link between cognitive style and personality is mixed. One possible reason for such conflicting results may be that personality-cognition covariance changes along ecological conditions, a hypothesis that has rarely been investigated so far. In this study, we tested the effect of habitat complexity on multiple aspects of animal personality and cognition, and how this influenced their relationship, in five populations of the Aegean wall lizard (Podarcis erhardii). Overall, lizards from both habitat types did not differ in average levels of personality or cognition, with the exception that lizards from more complex habitats performed better on a spatial learning task. Nevertheless, we found an intricate interplay between ecology, cognition, and personality, as behavioral associations were often habitat- but also year-dependent. In general, behavioral covariance was either independent of habitat, or found exclusively in the simple, open environments. Our results highlight that valuable insights may be gained by taking ecological variation into account while studying the link between personality and cognition.
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7
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Axelrod CJ, Laberge F, Robinson BW. Interspecific and intraspecific comparisons reveal the importance of evolutionary context in sunfish brain form divergence. J Evol Biol 2021; 34:639-652. [PMID: 33484022 DOI: 10.1111/jeb.13763] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 12/23/2020] [Accepted: 01/11/2021] [Indexed: 01/03/2023]
Abstract
Habitats can select for specialized phenotypic characteristics in animals. However, the consistency of evolutionary responses to particular environmental conditions remains difficult to predict. One trait of great ecological importance is brain form, which is expected to vary between habitats that differ in their cognitive requirements. Here, we compared divergence in brain form and oral jaw size across a common littoral-pelagic ecological axis in two sunfishes at both the intraspecific and interspecific levels. Brain form differed between habitats at every level of comparison; however, divergence was inconsistent, despite consistent differences in oral jaw size. Pumpkinseed and bluegill species differed in cerebellum, optic tectum and olfactory bulb size. These differences are consistent with a historical ecological divergence because they did not manifest between littoral and pelagic ecotypes within either species, suggesting constraints on changes to these regions over short evolutionary time scales. There were also differences in brain form between conspecific ecotypes, but they were inconsistent between species. Littoral pumpkinseed had larger brains than their pelagic counterpart, and littoral bluegill had smaller telencephalons than their pelagic counterpart. Inconsistent brain form divergence between conspecific ecotypes of pumpkinseed and bluegill sharing a common littoral-pelagic habitat axis suggests that contemporary ecological conditions and historic evolutionary context interact to influence evolutionary changes in brain form in fishes.
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Affiliation(s)
- Caleb J Axelrod
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - Frédéric Laberge
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - Beren W Robinson
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
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Storks L, Powell BJ, Leal M. Peeking Inside the Lizard Brain: Neuron Numbers in Anolis and Its Implications for Cognitive Performance and Vertebrate Brain Evolution. Integr Comp Biol 2020; 63:icaa129. [PMID: 33175153 DOI: 10.1093/icb/icaa129] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Studies of vertebrate brain evolution have mainly focused on measures of brain size, particularly relative mass and its allometric scaling across lineages, commonly with the goal of identifying the substrates that underly differences in cognition. However, recent studies on birds and mammals have demonstrated that brain size is an imperfect proxy for neuronal parameters that underly function, such as the number of neurons that make up a given brain region. Here we present estimates of neuron numbers and density in two species of lizard, Anolis cristatellus and A. evermanni, representing the first such data from squamate species, and explore its implications for differences in cognitive performance and vertebrate brain evolution. The isotropic fractionator protocol outlined in this article is optimized for the unique challenges that arise when using this technique with lineages having nucleated erythrocytes and relatively small brains. The number and density of neurons and other cells we find in Anolis for the telencephalon, cerebellum, and the rest of the brain (ROB) follow similar patterns as published data from other vertebrate species. Anolis cristatellus and A. evermanni exhibited differences in their performance in a motor task frequently used to evaluate behavioral flexibility, which was not mirrored by differences in the number, density, or proportion of neurons in either the cerebellum, telencephalon, or ROB. However, the brain of A. evermanni had a significantly higher number of nonneurons and a higher nonneuron to neuron ratio across the whole brain, which could contribute to the observed differences in problem solving between A. cristatellus and A. evermanni. Although limited to two species, our findings suggest that neuron number and density in lizard brains scale similarly to endothermic vertebrates in contrast to the differences observed in brain to body mass relationships. Data from a wider range of species are necessary before we can fully understand vertebrate brain evolution at the neuronal level.
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Affiliation(s)
- Levi Storks
- Division of Biological Sciences, University of Missouri, Columbia, MO, USA
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10
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De Meester G, Huyghe K, Van Damme R. Brain size, ecology and sociality: a reptilian perspective. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/bly206] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Gilles De Meester
- Functional Morphology Group, Department of Biology, University of Antwerp, Wilrijk, Belgium
| | - Katleen Huyghe
- Functional Morphology Group, Department of Biology, University of Antwerp, Wilrijk, Belgium
| | - Raoul Van Damme
- Functional Morphology Group, Department of Biology, University of Antwerp, Wilrijk, Belgium
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11
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Axelrod CJ, Laberge F, Robinson BW. Intraspecific brain size variation between coexisting sunfish ecotypes. Proc Biol Sci 2018; 285:rspb.2018.1971. [PMID: 30404883 DOI: 10.1098/rspb.2018.1971] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 10/12/2018] [Indexed: 01/19/2023] Open
Abstract
Variation in spatial complexity and foraging requirements between habitats can impose different cognitive demands on animals that may influence brain size. However, the relationship between ecologically related cognitive performance and brain size is not well established. We test whether variation in relative brain size and brain region size is associated with habitat use within a population of pumpkinseed sunfish composed of different ecotypes that inhabit either the structurally complex shoreline littoral habitat or simpler open-water pelagic habitat. Sunfish using the littoral habitat have on average 8.3% larger brains than those using the pelagic habitat. We found little difference in the proportional sizes of five brain regions between ecotypes. The results suggest that cognitive demands on sunfish may be reduced in the pelagic habitat given no habitat-specific differences in body condition. They also suggest that either a short divergence time or physiological processes may constrain changes to concerted, global modifications of brain size between sunfish ecotypes.
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Affiliation(s)
- Caleb J Axelrod
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Frédéric Laberge
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Beren W Robinson
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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12
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Hoops D, Desfilis E, Ullmann JFP, Janke AL, Stait-Gardner T, Devenyi GA, Price WS, Medina L, Whiting MJ, Keogh JS. A 3D MRI-based atlas of a lizard brain. J Comp Neurol 2018; 526:2511-2547. [PMID: 29931765 DOI: 10.1002/cne.24480] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 04/01/2018] [Accepted: 04/03/2018] [Indexed: 02/05/2023]
Abstract
Magnetic resonance imaging (MRI) is an established technique for neuroanatomical analysis, being particularly useful in the medical sciences. However, the application of MRI to evolutionary neuroscience is still in its infancy. Few magnetic resonance brain atlases exist outside the standard model organisms in neuroscience and no magnetic resonance atlas has been produced for any reptile brain. A detailed understanding of reptilian brain anatomy is necessary to elucidate the evolutionary origin of enigmatic brain structures such as the cerebral cortex. Here, we present a magnetic resonance atlas for the brain of a representative squamate reptile, the Australian tawny dragon (Agamidae: Ctenophorus decresii), which has been the subject of numerous ecological and behavioral studies. We used a high-field 11.74T magnet, a paramagnetic contrasting-enhancing agent and minimum-deformation modeling of the brains of thirteen adult male individuals. From this, we created a high-resolution three-dimensional model of a lizard brain. The 3D-MRI model can be freely downloaded and allows a better comprehension of brain areas, nuclei, and fiber tracts, facilitating comparison with other species and setting the basis for future comparative evolution imaging studies. The MRI model and atlas of a tawny dragon brain (Ctenophorus decresii) can be viewed online and downloaded using the Wiley Biolucida Server at wiley.biolucida.net.
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Affiliation(s)
- Daniel Hoops
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Ester Desfilis
- Laboratory of Evolutionary and Developmental Neurobiology, Department of Experimental Medicine, Lleida Institute for Biomedical Research Fundació Dr. Pifarré (IRBLleida), University of Lleida, Lleida, Spain
| | - Jeremy F P Ullmann
- Center for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia
| | - Andrew L Janke
- Center for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia
| | - Timothy Stait-Gardner
- Nanoscale Organization and Dynamics Group, Western Sydney University, Penrith, NSW, Australia
| | - Gabriel A Devenyi
- Douglas Hospital Research Centre, Douglas Mental Health University Institute, Montreal, Quebec, Canada.,Department of Psychiatry, McGill University, Montreal, Quebec, Canada
| | - William S Price
- Nanoscale Organization and Dynamics Group, Western Sydney University, Penrith, NSW, Australia
| | - Loreta Medina
- Laboratory of Evolutionary and Developmental Neurobiology, Department of Experimental Medicine, Lleida Institute for Biomedical Research Fundació Dr. Pifarré (IRBLleida), University of Lleida, Lleida, Spain
| | - Martin J Whiting
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - J Scott Keogh
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, Canberra, ACT, Australia
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14
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Winchell KM, Carlen EJ, Puente-Rolón AR, Revell LJ. Divergent habitat use of two urban lizard species. Ecol Evol 2017; 8:25-35. [PMID: 29321848 PMCID: PMC5756862 DOI: 10.1002/ece3.3600] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/01/2017] [Accepted: 10/11/2017] [Indexed: 01/03/2023] Open
Abstract
Faunal responses to anthropogenic habitat modification represent an important aspect of global change. In Puerto Rico, two species of arboreal lizard, Anolis cristatellus and A. stratulus, are commonly encountered in urban areas, yet seem to use the urban habitat in different ways. In this study, we quantified differences in habitat use between these two species in an urban setting. For each species, we measured habitat use and preference, and the niche space of each taxon, with respect to manmade features of the urban environment. To measure niche space of these species in an urban environment, we collected data from a total of six urban sites across four different municipalities on the island of Puerto Rico. We quantified relative abundance of both species, their habitat use, and the available habitat in the environment to measure both microhabitat preference in an urban setting, as well as niche partitioning between the two different lizards. Overall, we found that the two species utilize different portions of the urban habitat. Anolis stratulus tends to use more “natural” portions of the urban environment (i.e., trees and other cultivated vegetation), whereas A. cristatellus more frequently uses anthropogenic structures. We also found that aspects of habitat discrimination in urban areas mirror a pattern measured in prior studies for forested sites in which A. stratulus was found to perch higher than A. cristatellus and preferred lower temperatures and greater canopy cover. In our study, we found that the multivariate niche space occupied by A. stratulus did not differ from the available niche space in natural portions of the urban environment and in turn represented a subset of the niche space occupied by A. cristatellus. The unique niche space occupied by A. cristatellus corresponds to manmade aspects of the urban environment generally not utilized by A. stratulus. Our results demonstrate that some species are merely tolerant of urbanization while others utilize urban habitats in novel ways. This finding has implications for long‐term persistence in urban habitats and suggests that loss of natural habitat elements may lead to nonrandom species extirpations as urbanization intensifies.
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Affiliation(s)
| | | | | | - Liam J Revell
- Department of Biology University of Massachusetts Boston Boston MA USA.,Programa de Biología Universidad del Rosario Bogotá Colombia
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Allemand R, Boistel R, Daghfous G, Blanchet Z, Cornette R, Bardet N, Vincent P, Houssaye A. Comparative morphology of snake (Squamata) endocasts: evidence of phylogenetic and ecological signals. J Anat 2017; 231:849-868. [PMID: 28960295 DOI: 10.1111/joa.12692] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2017] [Indexed: 12/22/2022] Open
Abstract
Brain endocasts obtained from computed tomography (CT) are now widely used in the field of comparative neuroanatomy. They provide an overview of the morphology of the brain and associated tissues located in the cranial cavity. Through anatomical comparisons between species, insights on the senses, the behavior, and the lifestyle can be gained. Although there are many studies dealing with mammal and bird endocasts, those performed on the brain endocasts of squamates are comparatively rare, thus limiting our understanding of their morphological variability and interpretations. Here, we provide the first comparative study of snake brain endocasts in order to bring new information about the morphology of these structures. Additionally, we test if the snake brain endocast encompasses a phylogenetic and/or an ecological signal. For this purpose, the digital endocasts of 45 snake specimens, including a wide diversity in terms of phylogeny and ecology, were digitized using CT, and compared both qualitatively and quantitatively. Snake endocasts exhibit a great variability. The different methods performed from descriptive characters, linear measurements and the outline curves provided complementary information. All these methods have shown that the shape of the snake brain endocast contains, as in mammals and birds, a phylogenetic signal but also an ecological one. Although phylogenetically related taxa share several similarities between each other, the brain endocast morphology reflects some notable ecological trends: e.g. (i) fossorial species possess both reduced optic tectum and pituitary gland; (ii) both fossorial and marine species have cerebral hemispheres poorly developed laterally; (iii) cerebral hemispheres and optic tectum are more developed in arboreal and terrestrial species.
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Affiliation(s)
- Rémi Allemand
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P - UMR 7207 - CNRS, MNHN, UPMC, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France.,Département Adaptations du Vivant, UMR 7179 - CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | - Renaud Boistel
- IPHEP-UMR CNRS 6046, UFR SFA, Université de Poitiers, Poitiers, France
| | - Gheylen Daghfous
- Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
| | - Zoé Blanchet
- Département Adaptations du Vivant, UMR 7179 - CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | - Raphaël Cornette
- Institut de Systématique, Evolution, Biodiversité, ISYEB - UMR 7205 - CNRS, MNHN, UPMC, EPHE, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France
| | - Nathalie Bardet
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P - UMR 7207 - CNRS, MNHN, UPMC, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France
| | - Peggy Vincent
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P - UMR 7207 - CNRS, MNHN, UPMC, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France
| | - Alexandra Houssaye
- Département Adaptations du Vivant, UMR 7179 - CNRS/Muséum National d'Histoire Naturelle, Paris, France
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17
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Hoops D, Ullmann JFP, Janke AL, Vidal-Garcia M, Stait-Gardner T, Dwihapsari Y, Merkling T, Price WS, Endler JA, Whiting MJ, Keogh JS. Sexual selection predicts brain structure in dragon lizards. J Evol Biol 2016; 30:244-256. [PMID: 27696584 DOI: 10.1111/jeb.12984] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 08/30/2016] [Accepted: 09/20/2016] [Indexed: 01/10/2023]
Abstract
Phenotypic traits such as ornaments and armaments are generally shaped by sexual selection, which often favours larger and more elaborate males compared to females. But can sexual selection also influence the brain? Previous studies in vertebrates report contradictory results with no consistent pattern between variation in brain structure and the strength of sexual selection. We hypothesize that sexual selection will act in a consistent way on two vertebrate brain regions that directly regulate sexual behaviour: the medial preoptic nucleus (MPON) and the ventromedial hypothalamic nucleus (VMN). The MPON regulates male reproductive behaviour whereas the VMN regulates female reproductive behaviour and is also involved in male aggression. To test our hypothesis, we used high-resolution magnetic resonance imaging combined with traditional histology of brains in 14 dragon lizard species of the genus Ctenophorus that vary in the strength of precopulatory sexual selection. Males belonging to species that experience greater sexual selection had a larger MPON and a smaller VMN. Conversely, females did not show any patterns of variation in these brain regions. As the volumes of both these regions also correlated with brain volume (BV) in our models, we tested whether they show the same pattern of evolution in response to changes in BV and found that the do. Therefore, we show that the primary brain nuclei underlying reproductive behaviour in vertebrates can evolve in a mosaic fashion, differently between males and females, likely in response to sexual selection, and that these same regions are simultaneously evolving in concert in relation to overall brain size.
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Affiliation(s)
- D Hoops
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - J F P Ullmann
- Center for Advanced Imaging, The University of Queensland, Brisbane, Qld, Australia
| | - A L Janke
- Center for Advanced Imaging, The University of Queensland, Brisbane, Qld, Australia
| | - M Vidal-Garcia
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - T Stait-Gardner
- Nanoscale Organization and Dynamics Group, School of Science and Health, University of Western Sydney, Penrith, NSW, Australia
| | - Y Dwihapsari
- Nanoscale Organization and Dynamics Group, School of Science and Health, University of Western Sydney, Penrith, NSW, Australia
| | - T Merkling
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - W S Price
- Nanoscale Organization and Dynamics Group, School of Science and Health, University of Western Sydney, Penrith, NSW, Australia
| | - J A Endler
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Vic., Australia
| | - M J Whiting
- Department of Biological Sciences, Discipline of Brain, Behavior and Evolution, Macquarie University, Sydney, NSW, Australia
| | - J S Keogh
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Acton, ACT, Australia
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Steinberg DS, Leal M. Visual motion detection and habitat preference in Anolis lizards. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2016; 202:783-790. [PMID: 27558791 DOI: 10.1007/s00359-016-1120-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/10/2016] [Accepted: 08/13/2016] [Indexed: 11/28/2022]
Abstract
The perception of visual stimuli has been a major area of inquiry in sensory ecology, and much of this work has focused on coloration. However, for visually oriented organisms, the process of visual motion detection is often equally crucial to survival and reproduction. Despite the importance of motion detection to many organisms' daily activities, the degree of interspecific variation in the perception of visual motion remains largely unexplored. Furthermore, the factors driving this potential variation (e.g., ecology or evolutionary history) along with the effects of such variation on behavior are unknown. We used a behavioral assay under laboratory conditions to quantify the visual motion detection systems of three species of Puerto Rican Anolis lizard that prefer distinct structural habitat types. We then compared our results to data previously collected for anoles from Cuba, Puerto Rico, and Central America. Our findings indicate that general visual motion detection parameters are similar across species, regardless of habitat preference or evolutionary history. We argue that these conserved sensory properties may drive the evolution of visual communication behavior in this clade.
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Affiliation(s)
- David S Steinberg
- Department of Biology, University of North Carolina, Chapel Hill, NC, 27599, USA.
| | - Manuel Leal
- Division of Biological Sciences, University of Missouri, Columbia, MO, 65211, USA
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