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Chen B, Dai W, Li X, Mao T, Liu Y, Pie MR, Yang J, Meegaskumbura M. Wall-following - Phylogenetic context of an enhanced behaviour in stygomorphic Sinocyclocheilus (Cypriniformes: Cyprinidae) cavefishes. Ecol Evol 2024; 14:e11575. [PMID: 38932953 PMCID: PMC11199845 DOI: 10.1002/ece3.11575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 05/26/2024] [Accepted: 05/30/2024] [Indexed: 06/28/2024] Open
Abstract
With 75 known species, the freshwater fish genus Sinocyclocheilus is the largest cavefish radiation in the world and shows multiple adaptations for cave-dwelling (stygomorphic adaptations), which include a range of traits such as eye degeneration (normal-eyed, micro-eyed and eyeless), depigmentation of skin, and in some species, the presence of "horns". Their behavioural adaptations to subterranean environments, however, are poorly understood. Wall-following (WF) behaviour, where an organism remains in close contact with the boundary demarcating its habitat when in the dark, is a peculiar behaviour observed in a wide range of animals and is enhanced in cave dwellers. Hence, we hypothesise that wall-following is also present in Sinocyclocheilus, possibly enhanced in eyeless species compared to eye bearing (normal-/micro-eyed species). Using 13 species representative of Sinocyclocheilus radiation and eye morphs, we designed a series of assays, based on pre-existing methods for Astyanax mexicanus behavioural experiments, to examine wall-following behaviour under three conditions. Our results indicate that eyeless species exhibit significantly enhanced intensities of WF compared to normal-eyed species, with micro-eyed forms demonstrating intermediate intensities in the WF distance. Using a mtDNA based dated phylogeny (chronogram with four clades A-D), we traced the degree of WF of these forms to outline common patterns. We show that the intensity of WF behaviour is higher in the subterranean clades compared to clades dominated by normal-eyed free-living species. We also found that eyeless species are highly sensitive to vibrations, whereas normal-eyed species are the least sensitive. Since WF behaviour is presented to some degree in all Sinocyclocheilus species, and given that these fishes evolved in the late Miocene, we identify this behaviour as being ancestral with WF enhancement related to cave occupation. Results from this diversification-scale study of cavefish behaviour suggest that enhanced wall-following behaviour may be a convergent trait across all stygomorphic lineages.
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Affiliation(s)
- Bing Chen
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of ForestryGuangxi UniversityNanningChina
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Center of Evolutionary Biology, School of Life SciencesFudan UniversityShanghaiChina
| | - Wen‐Zhang Dai
- School of Life Science and Institute of Wetland EcologyNanjing UniversityNanjingChina
| | - Xiang‐Lin Li
- State Key Laboratory of Efficient Production of Forest ResourcesSchool of Ecology and Nature Conservation, Beijing Forestry UniversityBeijingChina
| | - Ting‐Ru Mao
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of ForestryGuangxi UniversityNanningChina
| | - Ye‐Wei Liu
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of ForestryGuangxi UniversityNanningChina
| | - Marcio R. Pie
- Biology DepartmentEdge Hill UniversityOrmskirkLancashireUK
| | - Jian Yang
- Key Laboratory of Environment Change and Resource Use, Beibu GulfNanning Normal UniversityNanningGuangxiChina
| | - Madhava Meegaskumbura
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of ForestryGuangxi UniversityNanningChina
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Ponnimbaduge Perera P, Perez Guerra D, Riddle MR. The Mexican Tetra, Astyanax mexicanus, as a Model System in Cell and Developmental Biology. Annu Rev Cell Dev Biol 2023; 39:23-44. [PMID: 37437210 DOI: 10.1146/annurev-cellbio-012023-014003] [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] [Indexed: 07/14/2023]
Abstract
Our understanding of cell and developmental biology has been greatly aided by a focus on a small number of model organisms. However, we are now in an era where techniques to investigate gene function can be applied across phyla, allowing scientists to explore the diversity and flexibility of developmental mechanisms and gain a deeper understanding of life. Researchers comparing the eyeless cave-adapted Mexican tetra, Astyanax mexicanus, with its river-dwelling counterpart are revealing how the development of the eyes, pigment, brain, cranium, blood, and digestive system evolves as animals adapt to new environments. Breakthroughs in our understanding of the genetic and developmental basis of regressive and constructive trait evolution have come from A. mexicanus research. They include understanding the types of mutations that alter traits, which cellular and developmental processes they affect, and how they lead to pleiotropy. We review recent progress in the field and highlight areas for future investigations that include evolution of sex differentiation, neural crest development, and metabolic regulation of embryogenesis.
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Affiliation(s)
| | | | - Misty R Riddle
- Department of Biology, University of Nevada, Reno, Nevada, USA;
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Gross JB, Berning D, Phelps A, Luc H. An analysis of lateralized neural crest marker expression across development in the Mexican tetra, Astyanax mexicanus. Front Cell Dev Biol 2023; 11:1074616. [PMID: 36875772 PMCID: PMC9975491 DOI: 10.3389/fcell.2023.1074616] [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: 10/19/2022] [Accepted: 02/06/2023] [Indexed: 02/17/2023] Open
Abstract
The biological basis of lateralized cranial aberrations can be rooted in early asymmetric patterning of developmental tissues. However, precisely how development impacts natural cranial asymmetries remains incompletely understood. Here, we examined embryonic patterning of the cranial neural crest at two phases of embryonic development in a natural animal system with two morphotypes: cave-dwelling and surface-dwelling fish. Surface fish are highly symmetric with respect to cranial form at adulthood, however adult cavefish harbor diverse cranial asymmetries. To examine if lateralized aberrations of the developing neural crest underpin these asymmetries, we used an automated technique to quantify the area and expression level of cranial neural crest markers on the left and right sides of the embryonic head. We examined the expression of marker genes encoding both structural proteins and transcription factors at two key stages of development: 36 hpf (∼mid-migration of the neural crest) and 72 hpf (∼early differentiation of neural crest derivatives). Interestingly, our results revealed asymmetric biases at both phases of development in both morphotypes, however consistent lateral biases were less common in surface fish as development progressed. Additionally, this work provides the information on neural crest development, based on whole-mount expression patterns of 19 genes, between stage-matched cave and surface morphs. Further, this study revealed 'asymmetric' noise as a likely normative component of early neural crest development in natural Astyanax fish. Mature cranial asymmetries in cave morphs may arise from persistence of asymmetric processes during development, or as a function of asymmetric processes occurring later in the life history.
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Affiliation(s)
- Joshua B Gross
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
| | - Daniel Berning
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
| | - Ayana Phelps
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
| | - Heidi Luc
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
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Evolution of left-right asymmetry in the sensory system and foraging behavior during adaptation to food-sparse cave environments. BMC Biol 2022; 20:295. [PMID: 36575431 PMCID: PMC9795734 DOI: 10.1186/s12915-022-01501-1] [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: 07/28/2022] [Accepted: 12/12/2022] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Laterality in relation to behavior and sensory systems is found commonly in a variety of animal taxa. Despite the advantages conferred by laterality (e.g., the startle response and complex motor activities), little is known about the evolution of laterality and its plasticity in response to ecological demands. In the present study, a comparative study model, the Mexican tetra (Astyanax mexicanus), composed of two morphotypes, i.e., riverine surface fish and cave-dwelling cavefish, was used to address the relationship between environment and laterality. RESULTS The use of a machine learning-based fish posture detection system and sensory ablation revealed that the left cranial lateral line significantly supports one type of foraging behavior, i.e., vibration attraction behavior, in one cave population. Additionally, left-right asymmetric approaches toward a vibrating rod became symmetrical after fasting in one cave population but not in the other populations. CONCLUSION Based on these findings, we propose a model explaining how the observed sensory laterality and behavioral shift could help adaptation in terms of the tradeoff in energy gain and loss during foraging according to differences in food availability among caves.
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Chen B, Mao T, Liu Y, Dai W, Li X, Rajput AP, Pie MR, Yang J, Gross JB, Meegaskumbura M. Sensory evolution in a cavefish radiation: patterns of neuromast distribution and associated behaviour in Sinocyclocheilus (Cypriniformes: Cyprinidae). Proc Biol Sci 2022; 289:20221641. [PMID: 36476002 PMCID: PMC9554722 DOI: 10.1098/rspb.2022.1641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 09/22/2022] [Indexed: 02/07/2023] Open
Abstract
The genus Sinocyclocheilus, comprising a large radiation of freshwater cavefishes, are well known for their presence of regressive features (e.g. variable eye reduction). Fewer constructive features are known, such as the expansion of the lateral line system (LLS), which is involved in detecting water movements. The precise relationship between LLS expansion and cave adaptation is not well understood. Here, we examine morphology and LLS-mediated behaviour in Sinocyclocheilus species characterized by broad variation in eye size, habitat and geographical distribution. Using live-staining techniques and automated behavioural analyses, we examined 26 Sinocyclocheilus species and quantified neuromast organ number, density and asymmetry within a phylogenetic context. We then examined how these morphological features may relate to wall-following, an established cave-associated behaviour mediated by the lateral line. We show that most species demonstrated laterality (i.e. asymmetry) in neuromast organs on the head, often biased to the right. We also found that wall-following behaviour was distinctive, particularly among eyeless species. Patterns of variation in LLS appear to correlate with the degree of eye loss, as well as geographical distribution. This work reveals that constructive LLS evolution is convergent across distant cavefish taxa and may mediate asymmetric behavioural features that enable survival in stark subterranean microenvironments.
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Affiliation(s)
- Bing Chen
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, People's Republic of China
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Center of Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai 200438, People's Republic of China
| | - Tingru Mao
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, People's Republic of China
| | - Yewei Liu
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, People's Republic of China
| | - Wenzhang Dai
- School of Life Science and Institute of Wetland Ecology, Nanjing University, Nanjing 210000, People's Republic of China
| | - Xianglin Li
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, People's Republic of China
| | - Amrapali P. Rajput
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, People's Republic of China
| | - Marcio R. Pie
- Biology Department, Edge Hill University, Ormskirk, Lancashire L39 4QP, UK
| | - Jian Yang
- Key Laboratory of Environment Change and Resource Use, Beibu Gulf, Nanning Normal University, Nanning, Guangxi, People's Republic of China
| | - Joshua B. Gross
- Department of Biological Sciences, University of Cincinnati, Cincinnati OH 45221, USA
| | - Madhava Meegaskumbura
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, People's Republic of China
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Espinasa L, Diamant R, Mesquita M, Lindquist JM, Powers AM, Helmreich J. Laterality in cavefish: Left or right foraging behavior in Astyanax mexicanus. SUBTERRANEAN BIOLOGY 2022. [DOI: 10.3897/subtbiol.44.86565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The evolution of foraging behaviors is key to colonizing challenging habitats such as a cave’s dark environment. Vibration attraction behavior (VAB) gives fish the ability to swim in the darkness toward a vibration stimulus produced by many prey crustaceans and insects. VAB evolved in the blind Mexican cave tetra, Astyanax mexicanus. VAB is regulated by an increased number of mechanosensory neuromasts, particularly in the eye orbital region. However, VAB in Astyanax is only correlated with the number of neuromasts on the left side. Astyanax also have a bent skull preferentially to the left and a QTL signal for the right-side number of neuromasts. We conducted field studies in five different cave populations for four years. Results support that all cave populations can express behavioral lateralization or preponderance of side to examine a vibrating object. The percentage of individuals favoring one side may change among pools and years. In one cave population (Pachón), for one year, this “handedness” was expressed by preferentially using the right side of their face. On the contrary, in most years and pools, Tinaja, Sabinos, Molino, and Toro cave populations explored preferentially using their left side. This suggests that if there is an adaptative effect, it selects for asymmetry on itself, and not necessarily for which side is the one to be specialized. Results also showed that the laterality varied depending on how responsive an individual fish was, perhaps due to its nutritional, motivational state, or mode of stimuli most relevant at the time for the fish.
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Planidin NP, Reimchen TE. Behavioural responses of threespine stickleback with lateral line asymmetries to experimental mechanosensory stimuli. J Exp Biol 2021; 225:273859. [PMID: 34939652 DOI: 10.1242/jeb.243661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 12/15/2021] [Indexed: 11/20/2022]
Abstract
Behavioural asymmetry, typically referred to as laterality, is widespread among bilaterians and is often associated with asymmetry in brain structure. However, the influence of sensory receptor asymmetry on laterality has undergone limited investigation. Here we use threespine stickleback (Gasterosteus aculeatus) to investigate the influence of lateral line asymmetry on laterality during lab simulations of three mechanosensation-dependent behaviours: predator evasion, prey localization and rheotaxis. We recorded the response of stickleback to impacts at the water surface and water flow in photic conditions and low-frequency oscillations in the dark, across four repeat trials. We then compared individuals' laterality to asymmetry in the number of neuromasts on either side of their body. Stickleback hovered with their right side against the arena wall 57% of the time (P<0.001) in illuminated surface impact trials and 56% of the time in (P=0.085) dark low-frequency stimulation trials. Light regime modulated the effect of neuromast count on laterality, as fish with more neuromasts were more likely to hover with the wall on their right during illumination (P=0.007) but were less likely to do so in darkness (P=0.025). Population level laterality diminished in later trials across multiple behaviours and individuals did not show a consistent side bias in any behaviours. Our results demonstrate a complex relationship between sensory structure asymmetry and laterality, suggesting that laterality is modulated multiple sensory modalities and temporally dynamic.
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Iwashita M, Yoshizawa M. Social-like responses are inducible in asocial Mexican cavefish despite the exhibition of strong repetitive behavior. eLife 2021; 10:72463. [PMID: 34542411 PMCID: PMC8500712 DOI: 10.7554/elife.72463] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 09/17/2021] [Indexed: 12/21/2022] Open
Abstract
Social behavior is a hallmark of complex animal systems; however, some species appear to have secondarily lost this social ability. In these non-social species, whether social abilities are permanently lost or suppressed is unclear. The blind cavefish Astyanax mexicanus is known to be asocial. Here, we reveal that cavefish exhibited social-like interactions in familiar environments but suppressed these interactions in stress-associated unfamiliar environments. Furthermore, the level of suppression in sociality was positively correlated with that of stereotypic repetitive behavior, as seen in mammals. Treatment with a human antipsychotic drug targeting the dopaminergic system induced social-like interactions in cavefish, even in unfamiliar environments, while reducing repetitive behavior. Overall, these results suggest that the antagonistic association between repetitive and social-like behaviors is deeply shared from teleosts through mammals.
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Affiliation(s)
- Motoko Iwashita
- School of Life Sciences, the University of Hawai'i at Manoa, Honolulu, United States
| | - Masato Yoshizawa
- School of Life Sciences, the University of Hawai'i at Manoa, Honolulu, United States
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9
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Ecological predictors of lateral line asymmetry in stickleback (Gasterosteus aculeatus). Evol Ecol 2021. [DOI: 10.1007/s10682-021-10117-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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10
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Switching from mesopredator to apex predator: how do responses vary in amphibians adapted to cave living? Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02909-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Abstract
The effective detection of both prey and predators is pivotal for the survival of mesopredators. However, the condition of being a mesopredator is strongly context dependent. Here we focus on two aquatic caudate species that have colonised caves: the Pyrenean newt (Calotriton asper) and the olm (Proteus anguinus). The former maintains both surface and subterranean populations, while only cave-adapted populations of the latter exist. Both species are apex predators in underground waterbodies, while the Pyrenean newt is a mesopredator in surface waterbodies. Shifting to a higher level of the trophic web through colonising caves may promote the loss of anti-predator response against surface apex predators, and an increase in the ability to detect prey. To test these two non-exclusive hypotheses, we integrated classical behavioural characterisations with a novel approach: the assessment of lateralisation (i.e. preference for one body side exposure). Behavioural experiments were performed using laboratory-reared individuals. We performed 684 trials on 39 Pyrenean newts and eight olms. Under darkness and light conditions, we tested how exposure to different chemical cues (predatory fish, prey and unknown scent) affected individuals’ activity and lateralisation. Both cave and surface Pyrenean newts responded to predator cues, while olms did not. In Pyrenean newts, predator cues reduced the time spent in movement and time spent in lateralisation associated with hunting. Our results show that predator recognition is maintained in a species where recently separated populations inhabit environments lacking of higher predators, while such behaviour tends to be lost in populations with longer history of adaptation.
Significance statement
Predator recognition can be maintained in animals adapted to predator free habitats, but varies with their history of adaptation. Species that are not at the apex of the food web can become top predators if they colonise subterranean environments. We compared the behavioural responses of the olm, a strictly cave species with a long underground evolutionary history, and of the Pyrenean newt, a facultative cave species that also has stream-dwelling populations. Moreover, we integrated a classical behavioural characterisation, such as movement detection, with a novel approach: the assessment of lateralisation. While olms do not respond to external predators scent, cave-dwelling newts still recognise it. This clearly indicates that predator recognition is still maintained in species that have colonised predator-free environments more recently.
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Maldonado E, Rangel-Huerta E, Rodriguez-Salazar E, Pereida-Jaramillo E, Martínez-Torres A. Subterranean life: Behavior, metabolic, and some other adaptations of Astyanax cavefish. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2020; 334:463-473. [PMID: 32346998 DOI: 10.1002/jez.b.22948] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 03/25/2020] [Accepted: 04/04/2020] [Indexed: 12/20/2022]
Abstract
The ability of fishes to adapt to any aquatic environment seems limitless. It is enthralling how new species keep appearing at the deep sea or in subterranean environments. There are close to 230 known species of cavefishes, still today the best-known cavefish is Astyanax mexicanus, a Characid that has become a model organism, and has been studied and scrutinized since 1936. There are two morphotypes for A. mexicanus, a surface fish and a cavefish. The surface fish lives in central and northeastern Mexico and south of the United States, while the cavefish is endemic to the "Sierra del Abra-Tanchipa region" in northeast Mexico. The extensive genetic and genomic analysis depicts a complex origin for Astyanax cavefish, with multiple cave invasions and persistent gene flow among cave populations. The surface founder population prevails in the same region where the caves are. In this review, we focus on both morphotype's main morphological and physiological differences, but mainly in recent discoveries about behavioral and metabolic adaptations for subterranean life. These traits may not be as obvious as the troglomorphic characteristics, but are key to understand how Astyanax cavefish thrives in this environment of perpetual darkness.
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Affiliation(s)
- Ernesto Maldonado
- EvoDevo Research Group, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México
| | - Emma Rangel-Huerta
- EvoDevo Research Group, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México
| | - Elizabeth Rodriguez-Salazar
- EvoDevo Research Group, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México
| | - Elizabeth Pereida-Jaramillo
- Laboratorio de Neurobiología Molecular y Celular, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Santiago de Querétaro, México
| | - Ataulfo Martínez-Torres
- Laboratorio de Neurobiología Molecular y Celular, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Santiago de Querétaro, México
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Powers AK, Berning DJ, Gross JB. Parallel evolution of regressive and constructive craniofacial traits across distinct populations of Astyanax mexicanus cavefish. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2020; 334:450-462. [PMID: 32030873 DOI: 10.1002/jez.b.22932] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/17/2019] [Accepted: 01/21/2020] [Indexed: 01/15/2023]
Abstract
Life in complete darkness has driven the evolution of a suite of troglobitic features in the blind Mexican cavefish Astyanax mexicanus, such as eye and pigmentation loss. While regressive evolution is a hallmark of obligate cave-dwelling organisms, constructive (or augmented) traits commonly arise as well. The cavefish cranium has undergone extensive changes compared with closely-related surface fish. These alterations are rooted in both cranial bones and surrounding sensory tissues such as enhancements in the gustatory and lateral line systems. Cavefish also harbor numerous cranial bone asymmetries: fluctuating asymmetry of individual bones and directional asymmetry in a dorsal bend of the skull. This asymmetry is mirrored by the asymmetrical patterning of mechanosensory neuromasts. We explored the relationship between facial bones and neuromasts using in vivo fluorescent colabeling and microcomputed tomography. We found an increase in neuromast density within dermal bone boundaries across three distinct populations of cavefish compared to surface-dwelling fish. We also show that eye loss disrupts early neuromast patterning, which in turn impacts the development of dermal bones. While cavefish exhibit alterations in cranial bone and neuromast patterning, each population varied in the severity. This variation may reflect observed differences in behavior across populations. For instance, a bend in the dorsal region of the skull may expose neuromasts to water flow on the opposite side of the face, enhancing sensory input and spatial mapping in the dark.
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Affiliation(s)
- Amanda K Powers
- Department of Genetics, Blavatnik Institute at Harvard Medical School, Boston, Massachusetts
| | - Daniel J Berning
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio
| | - Joshua B Gross
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio
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Worsham M, Fernandes VFL, Settle A, Balaan C, Lactaoen K, Tuttle LJ, Iwashita M, Yoshizawa M. Behavioral Tracking and Neuromast Imaging of Mexican Cavefish. J Vis Exp 2019. [PMID: 31009008 DOI: 10.3791/59099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Cave-dwelling animals have evolved a series of morphological and behavioral traits to adapt to their perpetually dark and food-sparse environments. Among these traits, foraging behavior is one of the useful windows into functional advantages of behavioral trait evolution. Presented herein are updated methods for analyzing vibration attraction behavior (VAB: an adaptive foraging behavior) and imaging of associated mechanosensors of cave-adapted tetra, Astyanax mexicanus. In addition, methods are presented for high-throughput tracking of a series of additional cavefish behaviors including hyperactivity and sleep-loss. Cavefish also show asociality, repetitive behavior and higher anxiety. Therefore, cavefish serve as an animal model for evolved behaviors. These methods use free-software and custom-made scripts that can be applied to other types of behavior. These methods provide practical and cost-effective alternatives to commercially available tracking software.
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Affiliation(s)
| | | | | | - Chantell Balaan
- Department of Anatomy, Biochemistry and Physiology, University of Hawai'i at Mānoa
| | - Kimberly Lactaoen
- Department of Anatomy, Biochemistry and Physiology, University of Hawai'i at Mānoa
| | - Lillian J Tuttle
- Department of Biology, University of Hawai'i at Mānoa; Pacific Biosciences Research Center, University of Hawai'i at Mānoa
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