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Zhou D, Deng Y, Wei X, Li T, Li Z, Wang S, Jiang Y, Liu W, Luo B, Feng J. Behavioral responses of cave-roosting bats to artificial light of different spectra and intensities: Implications for lighting management strategy. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 916:170339. [PMID: 38278253 DOI: 10.1016/j.scitotenv.2024.170339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 12/26/2023] [Accepted: 01/19/2024] [Indexed: 01/28/2024]
Abstract
Artificial light at night has become an emerging environmental pollutant, posing a serious threat to biodiversity. Cave-roosting animals are vulnerable to light pollution due to long-term adaptation to nocturnal niches, and the problem is especially severe in the context of cave tourism and limestone mining. Mitigating the adverse impacts of artificial light on cave-dwelling animals presents a challenge. This study aimed to assess the relative contributions of spectral parameters and light intensity to the emergence behavior of nine cave-roosting bat species: Rhinolophus macrotis, Rhinolophus pearsonii, Rhinolophus rex, Rhinolophus pusillus, Rhinolophus siamensis, Rhinolophus sinicus, Hipposideros armiger, Myotis davidii, and Miniopterus fuliginosus. We manipulated light spectra and intensities through light-emitting diode (LED) lighting and gel filters at the entrance of bat roost. We monitored nightly passes per species to quantify bat emergence under the dark control and ten lighting conditions (blue, green, yellow, red, and white light at high and low intensities) using ultrasonic recording. Our analyses showed that the number of bat passes tended to be reduced in the presence of white, green, and yellow light, independent of light intensity. In contrast, the number of bat passes showed no pronounced differences under the dark control, blue light, and red light. The number of bat passes was primarily affected by LED light's blue component, red component, peak wavelength, and half-width instead of light intensity. These results demonstrate that spectral parameters of LED light can significantly affect emergence behavior of cave-dwelling bats. Our findings highlight the importance of manipulating light colors to reduce the negative impacts of light pollution on cave-roosting bats as a function of their spectral sensitivity. We recommend the use of gel filters to manage existing artificial lighting systems at the entrance of bat-inhabited caves.
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Affiliation(s)
- Daying Zhou
- Key Laboratory of Southwest China Wildlife Resources Conservation of Ministry of Education, China West Normal University, 1# Shida Road, Nanchong 637009, China; Liziping Giant Panda's Ecology and Conservation Observation and Research Station of Sichuan Province, Nanchong 637000, China
| | - Yingchun Deng
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, 2555 Jingyue Street, Changchun 130117, China
| | - Xinyi Wei
- Key Laboratory of Southwest China Wildlife Resources Conservation of Ministry of Education, China West Normal University, 1# Shida Road, Nanchong 637009, China
| | - Taohong Li
- Key Laboratory of Southwest China Wildlife Resources Conservation of Ministry of Education, China West Normal University, 1# Shida Road, Nanchong 637009, China
| | - Ziyi Li
- Key Laboratory of Southwest China Wildlife Resources Conservation of Ministry of Education, China West Normal University, 1# Shida Road, Nanchong 637009, China
| | - Sirui Wang
- Key Laboratory of Southwest China Wildlife Resources Conservation of Ministry of Education, China West Normal University, 1# Shida Road, Nanchong 637009, China
| | - Yunke Jiang
- Key Laboratory of Southwest China Wildlife Resources Conservation of Ministry of Education, China West Normal University, 1# Shida Road, Nanchong 637009, China
| | - Wenqin Liu
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, 2555 Jingyue Street, Changchun 130117, China
| | - Bo Luo
- Key Laboratory of Southwest China Wildlife Resources Conservation of Ministry of Education, China West Normal University, 1# Shida Road, Nanchong 637009, China; Liziping Giant Panda's Ecology and Conservation Observation and Research Station of Sichuan Province, Nanchong 637000, China.
| | - Jiang Feng
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, 2555 Jingyue Street, Changchun 130117, China; College of Life Science, Jilin Agricultural University, 2888 Xincheng street, Changchun 130118, China.
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2
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Wainwright JB, Schofield C, Conway M, Phillips D, Martin-Silverstone E, Brodrick EA, Cicconardi F, How MJ, Roberts NW, Montgomery SH. Multiple axes of visual system diversity in Ithomiini, an ecologically diverse tribe of mimetic butterflies. J Exp Biol 2023; 226:jeb246423. [PMID: 37921078 PMCID: PMC10714147 DOI: 10.1242/jeb.246423] [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: 07/18/2023] [Accepted: 10/31/2023] [Indexed: 11/04/2023]
Abstract
The striking structural variation seen in arthropod visual systems can be explained by the overall quantity and spatio-temporal structure of light within habitats coupled with developmental and physiological constraints. However, little is currently known about how fine-scale variation in visual structures arises across shorter evolutionary and ecological scales. In this study, we characterise patterns of interspecific (between species), intraspecific (between sexes) and intraindividual (between eye regions) variation in the visual system of four ithomiine butterfly species. These species are part of a diverse 26-million-year-old Neotropical radiation where changes in mimetic colouration are associated with fine-scale shifts in ecology, such as microhabitat preference. Using a combination of selection analyses on visual opsin sequences, in vivo ophthalmoscopy, micro-computed tomography (micro-CT), immunohistochemistry, confocal microscopy and neural tracing, we quantify and describe physiological, anatomical and molecular traits involved in visual processing. Using these data, we provide evidence of substantial variation within the visual systems of Ithomiini, including: (i) relaxed selection on visual opsins, perhaps mediated by habitat preference, (ii) interspecific shifts in visual system physiology and anatomy, and (iii) extensive sexual dimorphism, including the complete absence of a butterfly-specific optic neuropil in the males of some species. We conclude that considerable visual system variation can exist within diverse insect radiations, hinting at the evolutionary lability of these systems to rapidly develop specialisations to distinct visual ecologies, with selection acting at the perceptual, processing and molecular level.
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Affiliation(s)
- J. Benito Wainwright
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Corin Schofield
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Max Conway
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Daniel Phillips
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Elizabeth Martin-Silverstone
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Emelie A. Brodrick
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Francesco Cicconardi
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Martin J. How
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Nicholas W. Roberts
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Stephen H. Montgomery
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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3
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Katayama N, Koi S, Sassa A, Kurata T, Imaichi R, Kato M, Nishiyama T. Elevated mutation rates underlie the evolution of the aquatic plant family Podostemaceae. Commun Biol 2022; 5:75. [PMID: 35058542 PMCID: PMC8776956 DOI: 10.1038/s42003-022-03003-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 12/23/2021] [Indexed: 12/18/2022] Open
Abstract
Molecular evolutionary rates vary among lineages and influence the evolutionary process. Here, we report elevated genome-wide mutation rates in Podostemaceae, a family of aquatic plants with a unique body plan that allows members to live on submerged rocks in fast-flowing rivers. Molecular evolutionary analyses using 1640 orthologous gene groups revealed two historical increases in evolutionary rates: the first at the emergence of the family and the second at the emergence of Podostemoideae, which is the most diversified subfamily. In both branches, synonymous substitution rates were elevated, indicating higher mutation rates. On early branches, mutations were biased in favour of AT content, which is consistent with a role for ultraviolet light-induced mutation and habitat shift. In ancestors of Podostemoideae, DNA-repair genes were enriched in genes under positive selection, which may have responded to the meristem architectural changes.
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Affiliation(s)
- Natsu Katayama
- Graduate School of Science, Chiba University, Chiba, 263-8522, Japan.
- Research Fellow of Japan Society for the Promotion of Science, Tokyo, 102-0083, Japan.
| | - Satoshi Koi
- Botanical Gardens, Osaka City University, Osaka, 575-0004, Japan
| | - Akira Sassa
- Graduate School of Science, Chiba University, Chiba, 263-8522, Japan
| | - Tetsuya Kurata
- Division of Biological Science, Nara Institute of Science and Technology, Nara, 630-0192, Japan
| | - Ryoko Imaichi
- Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, Tokyo, 112-8681, Japan
| | - Masahiro Kato
- Department of Botany, National Museum of Nature and Science, Tsukuba, 305-0005, Japan
| | - Tomoaki Nishiyama
- Division of Integrated Omics Research, Research Center for Experimental Modeling of Human Disease, Kanazawa University, Kanazawa, 920-0934, Japan.
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4
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Dominy NJ, Melin AD. Liminal Light and Primate Evolution. ANNUAL REVIEW OF ANTHROPOLOGY 2020. [DOI: 10.1146/annurev-anthro-010220-075454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The adaptive origins of primates and anthropoid primates are topics of enduring interest to biological anthropologists. A convention in these discussions is to treat the light environment as binary—night is dark, day is light—and to impute corresponding selective pressure on the visual systems and behaviors of primates. In consequence, debate has tended to focus on whether a given trait can be interpreted as evidence of nocturnal or diurnal behavior in the primate fossil record. Such classification elides the variability in light, or the ways that primates internalize light in their environments. Here, we explore the liminality of light by focusing on what it is, its many sources, and its flux under natural conditions. We conclude by focusing on the intensity and spectral properties of twilight, and we review the mounting evidence of its importance as a cue that determines the onset or offset of primate activities as well as the entrainment of circadian rhythms.
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Affiliation(s)
- Nathaniel J. Dominy
- Department of Anthropology, Dartmouth College, Hanover, New Hampshire 03755, USA
| | - Amanda D. Melin
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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5
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Cho YS, Jun JH, Kim JA, Kim HM, Chung O, Kang SG, Park JY, Kim HJ, Kim S, Kim HJ, Jang JH, Na KJ, Kim J, Park SG, Lee HY, Manica A, Mindell DP, Fuchs J, Edwards JS, Weber JA, Witt CC, Yeo JH, Kim S, Bhak J. Raptor genomes reveal evolutionary signatures of predatory and nocturnal lifestyles. Genome Biol 2019; 20:181. [PMID: 31464627 PMCID: PMC6714440 DOI: 10.1186/s13059-019-1793-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 08/13/2019] [Indexed: 01/11/2023] Open
Abstract
Background Birds of prey (raptors) are dominant apex predators in terrestrial communities, with hawks (Accipitriformes) and falcons (Falconiformes) hunting by day and owls (Strigiformes) hunting by night. Results Here, we report new genomes and transcriptomes for 20 species of birds, including 16 species of birds of prey, and high-quality reference genomes for the Eurasian eagle-owl (Bubo bubo), oriental scops owl (Otus sunia), eastern buzzard (Buteo japonicus), and common kestrel (Falco tinnunculus). Our extensive genomic analysis and comparisons with non-raptor genomes identify common molecular signatures that underpin anatomical structure and sensory, muscle, circulatory, and respiratory systems related to a predatory lifestyle. Compared with diurnal birds, owls exhibit striking adaptations to the nocturnal environment, including functional trade-offs in the sensory systems, such as loss of color vision genes and selection for enhancement of nocturnal vision and other sensory systems that are convergent with other nocturnal avian orders. Additionally, we find that a suite of genes associated with vision and circadian rhythm are differentially expressed in blood tissue between nocturnal and diurnal raptors, possibly indicating adaptive expression change during the transition to nocturnality. Conclusions Overall, raptor genomes show genomic signatures associated with the origin and maintenance of several specialized physiological and morphological features essential to be apex predators. Electronic supplementary material The online version of this article (10.1186/s13059-019-1793-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | - Jung A Kim
- Biological and Genetic Resources Assessment Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Hak-Min Kim
- Korean Genomics Industrialization Center (KOGIC), Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea.,Department of Biomedical Engineering, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | | | - Seung-Gu Kang
- Animal Resources Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Jin-Young Park
- Animal Resources Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Hwa-Jung Kim
- Animal Resources Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Sunghyun Kim
- Strategic Planning Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Hee-Jong Kim
- Chungnam Wild Animal Rescue Center, Kongju National University, Yesan, Republic of Korea
| | - Jin-Ho Jang
- Chungnam Wild Animal Rescue Center, Kongju National University, Yesan, Republic of Korea
| | - Ki-Jeong Na
- College of veterinary medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Jeongho Kim
- Medical care team, Cheongju Zoo, Cheongju, Republic of Korea
| | - Seung Gu Park
- Korean Genomics Industrialization Center (KOGIC), Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | | | - Andrea Manica
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - David P Mindell
- Museum of Vertebrate Zoology, University of California, Berkeley, CA, USA
| | - Jérôme Fuchs
- Institut Systématique Evolution Biodiversité (ISYEB), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, EPHE, Paris, France
| | - Jeremy S Edwards
- Chemistry and Chemical Biology, UNM Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM, USA
| | - Jessica A Weber
- Museum of Southwestern Biology and Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Christopher C Witt
- Museum of Southwestern Biology and Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Joo-Hong Yeo
- Biological and Genetic Resources Assessment Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Soonok Kim
- Biological and Genetic Resources Assessment Division, National Institute of Biological Resources, Incheon, Republic of Korea.
| | - Jong Bhak
- Clinomics Inc, Ulsan, Republic of Korea. .,Korean Genomics Industrialization Center (KOGIC), Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea. .,Department of Biomedical Engineering, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea.
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6
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Gutierrez EDA, Castiglione GM, Morrow JM, Schott RK, Loureiro LO, Lim BK, Chang BSW. Functional Shifts in Bat Dim-Light Visual Pigment Are Associated with Differing Echolocation Abilities and Reveal Molecular Adaptation to Photic-Limited Environments. Mol Biol Evol 2019; 35:2422-2434. [PMID: 30010964 DOI: 10.1093/molbev/msy140] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Bats are excellent models for studying the molecular basis of sensory adaptation. In Chiroptera, a sensory trade-off has been proposed between the visual and auditory systems, though the extent of this association has yet to be fully examined. To investigate whether variation in visual performance is associated with echolocation, we experimentally assayed the dim-light visual pigment rhodopsin from bat species with differing echolocation abilities. While spectral tuning properties were similar among bats, we found that the rate of decay of their light-activated state was significantly slower in a nonecholocating bat relative to species that use distinct echolocation strategies, consistent with a sensory trade-off hypothesis. We also found that these rates of decay were remarkably slower compared with those of other mammals, likely indicating an adaptation to dim light. To examine whether functional changes in rhodopsin are associated with shifts in selection intensity upon bat Rh1 sequences, we implemented selection analyses using codon-based likelihood clade models. While no shifts in selection were identified in response to diverse echolocation abilities of bats, we detected a significant increase in the intensity of evolutionary constraint accompanying the diversification of Chiroptera. Taken together, this suggests that substitutions that modulate the stability of the light-activated rhodopsin state were likely maintained through intensified constraint after bats diversified, being finely tuned in response to novel sensory specializations. Our study demonstrates the power of combining experimental and computational approaches for investigating functional mechanisms underlying the evolution of complex sensory adaptations.
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Affiliation(s)
- Eduardo de A Gutierrez
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Gianni M Castiglione
- Department of Cell and Systems Biology, University of Toronto, ON, Canada.,Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - James M Morrow
- Department of Cell and Systems Biology, University of Toronto, ON, Canada.,Centre of Forensic Sciences, Toronto, ON, Canada
| | - Ryan K Schott
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.,Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Livia O Loureiro
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Burton K Lim
- Department of Natural History, Royal Ontario Museum, Toronto, ON, Canada
| | - Belinda S W Chang
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.,Department of Cell and Systems Biology, University of Toronto, ON, Canada.,Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, ON, Canada
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7
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Abstract
The protein titin plays a key role in vertebrate muscle where it acts like a giant molecular spring. Despite its importance and conservation over vertebrate evolution, a lack of high quality annotations in non-model species makes comparative evolutionary studies of titin challenging. The PEVK region of titin—named for its high proportion of Pro-Glu-Val-Lys amino acids—is particularly difficult to annotate due to its abundance of alternatively spliced isoforms and short, highly repetitive exons. To understand PEVK evolution across mammals, we developed a bioinformatics tool, PEVK_Finder, to annotate PEVK exons from genomic sequences of titin and applied it to a diverse set of mammals. PEVK_Finder consistently outperforms standard annotation tools across a broad range of conditions and improves annotations of the PEVK region in non-model mammalian species. We find that the PEVK region can be divided into two subregions (PEVK-N, PEVK-C) with distinct patterns of evolutionary constraint and divergence. The bipartite nature of the PEVK region has implications for titin diversification. In the PEVK-N region, certain exons are conserved and may be essential, but natural selection also acts on particular codons. In the PEVK-C, exons are more homogenous and length variation of the PEVK region may provide the raw material for evolutionary adaptation in titin function. The PEVK-C region can be further divided into a highly repetitive region (PEVK-CA) and one that is more variable (PEVK-CB). Taken together, we find that the very complexity that makes titin a challenge for annotation tools may also promote evolutionary adaptation.
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8
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Gower DJ, Sampaio FL, Peichl L, Wagner HJ, Loew ER, Mclamb W, Douglas RH, Orlov N, Grace MS, Hart NS, Hunt DM, Partridge JC, Simões BF. Evolution of the eyes of vipers with and without infrared-sensing pit organs. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- David J Gower
- Department of Life Sciences, The Natural History Museum, London, UK
| | - Filipa L Sampaio
- Department of Life Sciences, The Natural History Museum, London, UK
| | - Leo Peichl
- Max Planck Institute for Brain Research, Germany
- Dr. Senckenbergische Anatomie, Goethe University Frankfurt, Germany
| | | | - Ellis R Loew
- Department of Biomedical Sciences, Cornell University, USA
| | - William Mclamb
- Department of Biological Sciences, Florida Institute of Technology, and Center for the Advancement of Science in Space, Melbourne, FL, USA
| | - Ronald H Douglas
- Department of Life Sciences, The Natural History Museum, London, UK
- Department of Optometry and Visual Science, City, University of London, London, UK
| | - Nikolai Orlov
- Department of Herpetology, Zoological Institute, Russian Academy of Sciences, Russia
| | - Michael S Grace
- College of Science, Florida Institute of Technology, Melbourne, FL, USA
| | - Nathan S Hart
- Department of Biological Sciences, Macquarie University, Australia
| | - David M Hunt
- School of Biological Sciences, The University of Western Australia, Australia
- Centre for Ophthalmology and Vision Science, Lions Eye Institute, The University of Western Australia, Perth, Australia
| | - Julian C Partridge
- School of Biological Sciences, The University of Western Australia, Australia
- Oceans Institute, The University of Western Australia, Perth, WA, Australia
| | - Bruno F Simões
- Department of Life Sciences, The Natural History Museum, London, UK
- School of Earth Sciences, University of Bristol, Bristol, UK
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
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9
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Simões BF, Foley NM, Hughes GM, Zhao H, Zhang S, Rossiter SJ, Teeling EC. As Blind as a Bat? Opsin Phylogenetics Illuminates the Evolution of Color Vision in Bats. Mol Biol Evol 2019; 36:54-68. [PMID: 30476197 PMCID: PMC6340466 DOI: 10.1093/molbev/msy192] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Through their unique use of sophisticated laryngeal echolocation bats are considered sensory specialists amongst mammals and represent an excellent model in which to explore sensory perception. Although several studies have shown that the evolution of vision is linked to ecological niche adaptation in other mammalian lineages, this has not yet been fully explored in bats. Recent molecular analysis of the opsin genes, which encode the photosensitive pigments underpinning color vision, have implicated high-duty cycle (HDC) echolocation and the adoption of cave roosting habits in the degeneration of color vision in bats. However, insufficient sampling of relevant taxa has hindered definitive testing of these hypotheses. To address this, novel sequence data was generated for the SWS1 and MWS/LWS opsin genes and combined with existing data to comprehensively sample species representing diverse echolocation types and niches (SWS1 n = 115; MWS/LWS n = 45). A combination of phylogenetic analysis, ancestral state reconstruction, and selective pressure analyses were used to reconstruct the evolution of these visual pigments in bats and revealed that although both genes are evolving under purifying selection in bats, MWS/LWS is highly conserved but SWS1 is highly variable. Spectral tuning analyses revealed that MWS/LWS opsin is tuned to a long wavelength, 555-560 nm in the bat ancestor and the majority of extant taxa. The presence of UV vision in bats is supported by our spectral tuning analysis, but phylogenetic analyses demonstrated that the SWS1 opsin gene has undergone pseudogenization in several lineages. We do not find support for a link between the evolution of HDC echolocation and the pseudogenization of the SWS1 gene in bats, instead we show the SWS1 opsin is functional in the HDC echolocator, Pteronotus parnellii. Pseudogenization of the SWS1 is correlated with cave roosting habits in the majority of pteropodid species. Together these results demonstrate that the loss of UV vision in bats is more widespread than was previously considered and further elucidate the role of ecological niche specialization in the evolution of vision in bats.
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Affiliation(s)
- Bruno F Simões
- UCD School of Biology and Environmental Science, University College Dublin, Dublin 4, Ireland
- School of Earth Science, University of Bristol, Bristol, United Kingdom
- School of Biological Science, The University of Adelaide, South Australia, Australia
| | - Nicole M Foley
- UCD School of Biology and Environmental Science, University College Dublin, Dublin 4, Ireland
| | - Graham M Hughes
- UCD School of Biology and Environmental Science, University College Dublin, Dublin 4, Ireland
| | - Huabin Zhao
- Department of Ecology and Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Shuyi Zhang
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China
| | - Stephen J Rossiter
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Emma C Teeling
- UCD School of Biology and Environmental Science, University College Dublin, Dublin 4, Ireland
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10
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Sadier A, Davies KT, Yohe LR, Yun K, Donat P, Hedrick BP, Dumont ER, Dávalos LM, Rossiter SJ, Sears KE. Multifactorial processes underlie parallel opsin loss in neotropical bats. eLife 2018; 7:37412. [PMID: 30560780 PMCID: PMC6333445 DOI: 10.7554/elife.37412] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 12/04/2018] [Indexed: 12/27/2022] Open
Abstract
The loss of previously adaptive traits is typically linked to relaxation in selection, yet the molecular steps leading to such repeated losses are rarely known. Molecular studies of loss have tended to focus on gene sequences alone, but overlooking other aspects of protein expression might underestimate phenotypic diversity. Insights based almost solely on opsin gene evolution, for instance, have made mammalian color vision a textbook example of phenotypic loss. We address this gap by investigating retention and loss of opsin genes, transcripts, and proteins across ecologically diverse noctilionoid bats. We find multiple, independent losses of short-wave-sensitive opsins. Mismatches between putatively functional DNA sequences, mRNA transcripts, and proteins implicate transcriptional and post-transcriptional processes in the ongoing loss of S-opsins in some noctilionoid bats. Our results provide a snapshot of evolution in progress during phenotypic trait loss, and suggest vertebrate visual phenotypes cannot always be predicted from genotypes alone. Bats are famous for using their hearing to explore their environments, yet fewer people are aware that these flying mammals have both good night and daylight vision. Some bats can even see in color thanks to two light-sensitive proteins at the back of their eyes: S-opsin which detects blue and ultraviolet light and L-opsin which detects green and red light. Many species of bat, however, are missing one of these proteins and cannot distinguish any colors; in other words, they are completely color-blind. Some bat species found in Central and South America have independently lost their ability to see blue-ultraviolet light and have thus also lost their color vision. These bats have diverse diets – ranging from insects to fruits and even blood – and being able to distinguish color may offer an advantage in many of their activities, including hunting or foraging. The vision genes in these bats, therefore, give scientists an opportunity to explore how a seemingly important trait can be lost at the molecular level. Sadier, Davies et al. now report that S-opsin has been lost more than a dozen times during the evolutionary history of these Central and South American bats. The analysis used samples from 55 species, including animals caught from the wild and specimens from museums. As with other proteins, the instructions encoded in the gene sequence for S opsin need to be copied into a molecule of RNA before they can be translated into protein. As expected, S-opsin was lost several times because of changes in the gene sequence that disrupted the formation of the protein. However, at several points in these bats’ evolutionary history, additional changes have taken place that affected the production of the RNA or the protein, without an obvious change to the gene itself. This finding suggests that other studies that rely purely on DNA to understand evolution may underestimate how often traits may be lost. By capturing ‘evolution in action’, these results also provide a more complete picture of the molecular targets of evolution in a diverse set of bats.
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Affiliation(s)
- Alexa Sadier
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, United States
| | - Kalina Tj Davies
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Laurel R Yohe
- Department of Ecology and Evolution, Stony Brook University, New York, United States.,Geology & Geophysics, Yale University, New Haven, United States
| | - Kun Yun
- Department of Animal Biology, University of Illinois, Urbana, United States
| | - Paul Donat
- Department of Ecology and Evolution, Stony Brook University, New York, United States
| | - Brandon P Hedrick
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States
| | - Elizabeth R Dumont
- School of Natural Sciences, University of California, Merced, United States
| | - Liliana M Dávalos
- Department of Ecology and Evolution, Stony Brook University, New York, United States.,Consortium for Inter-Disciplinary Environmental Research, School of Marine and Atmospheric Sciences, Stony Brook University, New York, United States
| | - Stephen J Rossiter
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Karen E Sears
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, United States
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11
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Borges R, Johnson WE, O'Brien SJ, Gomes C, Heesy CP, Antunes A. Adaptive genomic evolution of opsins reveals that early mammals flourished in nocturnal environments. BMC Genomics 2018; 19:121. [PMID: 29402215 PMCID: PMC5800076 DOI: 10.1186/s12864-017-4417-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 12/22/2017] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Based on evolutionary patterns of the vertebrate eye, Walls (1942) hypothesized that early placental mammals evolved primarily in nocturnal habitats. However, not only Eutheria, but all mammals show photic characteristics (i.e. dichromatic vision, rod-dominated retina) suggestive of a scotopic eye design. RESULTS Here, we used integrative comparative genomic and phylogenetic methodologies employing the photoreceptive opsin gene family in 154 mammals to test the likelihood of a nocturnal period in the emergence of all mammals. We showed that mammals possess genomic patterns concordant with a nocturnal ancestry. The loss of the RH2, VA, PARA, PARIE and OPN4x opsins in all mammals led us to advance a probable and most-parsimonious hypothesis of a global nocturnal bottleneck that explains the loss of these genes in the emerging lineage (> > 215.5 million years ago). In addition, ancestral character reconstruction analyses provided strong evidence that ancestral mammals possessed a nocturnal lifestyle, ultra-violet-sensitive vision, low visual acuity and low orbit convergence (i.e. panoramic vision). CONCLUSIONS Overall, this study provides insight into the evolutionary history of the mammalian eye while discussing important ecological aspects of the photic paleo-environments ancestral mammals have occupied.
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Affiliation(s)
- Rui Borges
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, s/n, 4450-208, Porto, Portugal
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
| | - Warren E Johnson
- Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Road, Front Royal, VA, 22630, USA
| | - Stephen J O'Brien
- Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg, Russia, 199004
- Guy Harvey Oceanographic Center, Halmos College of Natural Sciences and Oceanography, Nova Southeastern University, 8000, North Ocean Drive, Ft Lauderdale, 33004, Florida, USA
| | - Cidália Gomes
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, s/n, 4450-208, Porto, Portugal
- ICBAS, Institute of the Biomedical Sciences of Abel Salazar, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal
| | - Christopher P Heesy
- Department of Anatomy, Arizona College of Osteopathic Medicine, Midwestern University, 19555 N. 59th avenue, Glendale, AZ, USA
| | - Agostinho Antunes
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, s/n, 4450-208, Porto, Portugal.
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal.
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12
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Hauzman E, Bonci DMO, Suárez-Villota EY, Neitz M, Ventura DF. Daily activity patterns influence retinal morphology, signatures of selection, and spectral tuning of opsin genes in colubrid snakes. BMC Evol Biol 2017; 17:249. [PMID: 29228925 PMCID: PMC5725783 DOI: 10.1186/s12862-017-1110-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 12/06/2017] [Indexed: 11/10/2022] Open
Abstract
Background Morphological divergences of snake retinal structure point to complex evolutionary processes and adaptations. The Colubridae family has a remarkable variety of retinal structure that can range from all-cone and all-rod to duplex (cone/rod) retinas. To explore whether nocturnal versus diurnal activity is responsible for constraints on molecular evolution and plays a role in visual opsin spectral tuning of colubrids, we carried out molecular evolution analyses of the visual opsin genes LWS, RH1, and SWS1 from 17 species and performed morphological analyses. Results Phylogenetic reconstructions of the RH1 and LWS recovered major clades characterized by primarily diurnal or primarily nocturnal activity patterns, in contrast with the topology for SWS1, which is very similar to the species tree. We found stronger signals of purifying selection along diurnal and nocturnal lineages for RH1 and SWS1, respectively. A blue-shift of the RH1 spectral peak is associated with diurnal habits. Spectral tuning of cone opsins did not differ among diurnal and nocturnal species. Retinas of nocturnal colubrids had many rows of photoreceptor nuclei, with large numbers of rods, labeled by wheat germ agglutinin (WGA), and two types of cones: large cones sensitive to long/medium wavelengths (L/M) and small cones sensitive to ultra-violet/violet wavelengths (UV/VS). In contrast, retinas of diurnal species had only one row of photoreceptor nuclei, with four types of cones: large and double L/M cones, small UV/VS cones, and a second group of small cones, labeled by WGA. Conclusions For LWS gene, selection tests did not confirm different constraints related to activity pattern. For SWS1, stronger purifying selection in nocturnal lineages indicates divergent evolutionary pressures related to the activity pattern, and the importance of the short wavelength sensitivity at low light condition. Activity pattern has a clear influence on the signatures of selection and spectral tuning of RH1, with stronger purifying selection in diurnal lineages, which indicates selective pressure to preserve rhodopsin structure and function in pure-cone retinas. We suggest that the presence of four cone types in primarily diurnal colubrids might be related to the gain of color discrimination capacity. Electronic supplementary material The online version of this article (10.1186/s12862-017-1110-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- E Hauzman
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, Av. Professor Mello Moraes 1721 Bloco A Sala D9 - Butantã, São Paulo, SP, CEP 05508-030, Brazil. .,Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil.
| | - D M O Bonci
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, Av. Professor Mello Moraes 1721 Bloco A Sala D9 - Butantã, São Paulo, SP, CEP 05508-030, Brazil.,Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
| | - E Y Suárez-Villota
- Instituto de Ciencias Marinas y Limnólogicas, Universidad Austral de Chile, Edificio Emilio Pugin, Campus Isla Teja S/N, 5110236, Valdivia, Chile.,Laboratório de Ecologia e Evolução, Instituto Butantan, São Paulo, Brazil
| | - M Neitz
- Department of Opthalmology, University of Washington, 750 Republican Street, Box 358058, Seattle, WA, 98109, USA
| | - D F Ventura
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, Av. Professor Mello Moraes 1721 Bloco A Sala D9 - Butantã, São Paulo, SP, CEP 05508-030, Brazil.,Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
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13
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Insights into visual pigment adaptation and diversity from model ecological and evolutionary systems. Curr Opin Genet Dev 2017; 47:110-120. [PMID: 29102895 DOI: 10.1016/j.gde.2017.09.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 09/18/2017] [Accepted: 09/29/2017] [Indexed: 01/07/2023]
Abstract
Sensory systems provide valuable insight into the evolution of molecular mechanisms underlying organismal anatomy, physiology, and behaviour. Visual pigments, which mediate the first step in visual transduction, offer a unique window into the relationship between molecular variation and visual performance, and enhance our understanding of how ecology, life history, and physiology may shape genetic variation across a variety of organisms. Here we review recent work investigating vertebrate visual pigments from a number of perspectives. Opsin gene duplication, loss, differential expression, structural variation, and the physiological context in which they operate, have profoundly shaped the visual capabilities of vertebrates adapting to novel environments. We note the importance of conceptual frameworks in investigating visual pigment diversity in vertebrates, highlighting key examples including evolutionary transitions between different photic environments, major shifts in life history evolution and ecology, evolutionary innovations in visual system anatomy and physiology, as well as shifts in visually mediated behaviours and behavioural ecology. We emphasize the utility of studying visual pigment evolution in the context of these different perspectives, and demonstrate how the integrative approaches discussed in this review contribute to a better understanding of the underlying molecular processes mediating adaptation in sensory systems, and the contexts in which they occur.
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14
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Maldonado E, Almeida D, Escalona T, Khan I, Vasconcelos V, Antunes A. LMAP: Lightweight Multigene Analyses in PAML. BMC Bioinformatics 2016; 17:354. [PMID: 27597435 PMCID: PMC5011788 DOI: 10.1186/s12859-016-1204-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 08/24/2016] [Indexed: 12/22/2022] Open
Abstract
Background Uncovering how phenotypic diversity arises and is maintained in nature has long been a major interest of evolutionary biologists. Recent advances in genome sequencing technologies have remarkably increased the efficiency to pinpoint genes involved in the adaptive evolution of phenotypes. Reliability of such findings is most often examined with statistical and computational methods using Maximum Likelihood codon-based models (i.e., site, branch, branch-site and clade models), such as those available in codeml from the Phylogenetic Analysis by Maximum Likelihood (PAML) package. While these models represent a well-defined workflow for documenting adaptive evolution, in practice they can be challenging for researchers having a vast amount of data, as multiple types of relevant codon-based datasets are generated, making the overall process hard and tedious to handle, error-prone and time-consuming. Results We introduce LMAP (Lightweight Multigene Analyses in PAML), a user-friendly command-line and interactive package, designed to handle the codeml workflow, namely: directory organization, execution, results gathering and organization for Likelihood Ratio Test estimations with minimal manual user intervention. LMAP was developed for the workstation multi-core environment and provides a unique advantage for processing one, or more, if not all codeml codon-based models for multiple datasets at a time. Our software, proved efficiency throughout the codeml workflow, including, but not limited, to simultaneously handling more than 20 datasets. Conclusions We have developed a simple and versatile LMAP package, with outstanding performance, enabling researchers to analyze multiple different codon-based datasets in a high-throughput fashion. At minimum, two file types are required within a single input directory: one for the multiple sequence alignment and another for the phylogenetic tree. To our knowledge, no other software combines all codeml codon substitution models of adaptive evolution. LMAP has been developed as an open-source package, allowing its integration into more complex open-source bioinformatics pipelines. LMAP package is released under GPLv3 license and is freely available at http://lmapaml.sourceforge.net/. Electronic supplementary material The online version of this article (doi:10.1186/s12859-016-1204-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Emanuel Maldonado
- CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, s/n, 4450-208, Matosinhos, Portugal
| | - Daniela Almeida
- CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, s/n, 4450-208, Matosinhos, Portugal.,Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
| | - Tibisay Escalona
- CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, s/n, 4450-208, Matosinhos, Portugal.,Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
| | - Imran Khan
- CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, s/n, 4450-208, Matosinhos, Portugal.,Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
| | - Vitor Vasconcelos
- CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, s/n, 4450-208, Matosinhos, Portugal.,Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
| | - Agostinho Antunes
- CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, s/n, 4450-208, Matosinhos, Portugal. .,Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal.
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15
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van Hazel I, Dungan SZ, Hauser FE, Morrow JM, Endler JA, Chang BSW. A comparative study of rhodopsin function in the great bowerbird (Ptilonorhynchus nuchalis): Spectral tuning and light-activated kinetics. Protein Sci 2016; 25:1308-18. [PMID: 26889650 DOI: 10.1002/pro.2902] [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: 01/11/2016] [Revised: 02/16/2016] [Accepted: 02/16/2016] [Indexed: 12/18/2022]
Abstract
Rhodopsin is the visual pigment responsible for initiating the phototransduction cascade in vertebrate rod photoreceptors. Although well-characterized in a few model systems, comparative studies of rhodopsin function, particularly for nonmammalian vertebrates are comparatively lacking. Bowerbirds are rare among passerines in possessing a key substitution, D83N, at a site that is otherwise highly conserved among G protein-coupled receptors. While this substitution is present in some dim-light adapted vertebrates, often accompanying another unusual substitution, A292S, its functional relevance in birds is uncertain. To investigate functional effects associated with these two substitutions, we use the rhodopsin gene from the great bowerbird (Ptilonorhynchus nuchalis) as a background for site-directed mutagenesis, in vitro expression and functional characterization. We also mutated these sites in two additional rhodopsins that do not naturally possess N83, chicken and bovine, for comparison. Both sites were found to contribute to spectral blue-shifts, but had opposing effects on kinetic rates. Substitutions at site 83 were found to primarily affect the kinetics of light-activated rhodopsin, while substitutions at site 292 had a larger impact on spectral tuning. The contribution of substitutions at site 83 to spectral tuning in particular depended on genetic background, but overall, the effects of substitutions were otherwise surprisingly additive, and the magnitudes of functional shifts were roughly similar across all three genetic backgrounds. By employing a comparative approach with multiple species, our study provides new insight into the joint impact of sites 83 and 292 on rhodopsin structure-function as well as their evolutionary significance for dim-light vision across vertebrates.
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Affiliation(s)
- Ilke van Hazel
- Department of Ecology and Evolutionary Biology, University of Toronto, Canada
| | - Sarah Z Dungan
- Department of Ecology and Evolutionary Biology, University of Toronto, Canada
| | - Frances E Hauser
- Department of Ecology and Evolutionary Biology, University of Toronto, Canada
| | - James M Morrow
- Department of Cell and Systems Biology, University of Toronto, Canada
| | - John A Endler
- Centre for Integrative Ecology, Deakin University, Australia
| | - Belinda S W Chang
- Department of Ecology and Evolutionary Biology, University of Toronto, Canada.,Department of Cell and Systems Biology, University of Toronto, Canada.,Centre for the Analysis of Genome Evolution and Function, University of Toronto, Canada
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16
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Comparative sequence analyses of rhodopsin and RPE65 reveal patterns of selective constraint across hereditary retinal disease mutations. Vis Neurosci 2016; 33:e002. [DOI: 10.1017/s0952523815000322] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractRetinitis pigmentosa (RP) comprises several heritable diseases that involve photoreceptor, and ultimately retinal, degeneration. Currently, mutations in over 50 genes have known links to RP. Despite advances in clinical characterization, molecular characterization of RP remains challenging due to the heterogeneous nature of causal genes, mutations, and clinical phenotypes. In this study, we compiled large datasets of two important visual genes associated with RP: rhodopsin, which initiates the phototransduction cascade, and the retinoid isomerase RPE65, which regenerates the visual cycle. We used a comparative evolutionary approach to investigate the relationship between interspecific sequence variation and pathogenic mutations that lead to degenerative retinal disease. Using codon-based likelihood methods, we estimated evolutionary rates (dN/dS) across both genes in a phylogenetic context to investigate differences between pathogenic and nonpathogenic amino acid sites. In both genes, disease-associated sites showed significantly lower evolutionary rates compared to nondisease sites, and were more likely to occur in functionally critical areas of the proteins. The nature of the dataset (e.g., vertebrate or mammalian sequences), as well as selection of pathogenic sites, affected the differences observed between pathogenic and nonpathogenic sites. Our results illustrate that these methods can serve as an intermediate step in understanding protein structure and function in a clinical context, particularly in predicting the relative pathogenicity (i.e., functional impact) of point mutations and their downstream phenotypic effects. Extensions of this approach may also contribute to current methods for predicting the deleterious effects of candidate mutations and to the identification of protein regions under strong constraint where we expect pathogenic mutations to occur.
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17
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Teeling EC, Jones G, Rossiter SJ. Phylogeny, Genes, and Hearing: Implications for the Evolution of Echolocation in Bats. BAT BIOACOUSTICS 2016. [DOI: 10.1007/978-1-4939-3527-7_2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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18
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Bickelmann C, Morrow JM, Du J, Schott RK, van Hazel I, Lim S, Müller J, Chang BSW. The molecular origin and evolution of dim-light vision in mammals. Evolution 2015; 69:2995-3003. [PMID: 26536060 DOI: 10.1111/evo.12794] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 09/23/2015] [Accepted: 09/27/2015] [Indexed: 01/19/2023]
Abstract
The nocturnal origin of mammals is a longstanding hypothesis that is considered instrumental for the evolution of endothermy, a potential key innovation in this successful clade. This hypothesis is primarily based on indirect anatomical inference from fossils. Here, we reconstruct the evolutionary history of rhodopsin--the vertebrate visual pigment mediating the first step in phototransduction at low-light levels--via codon-based model tests for selection, combined with gene resurrection methods that allow for the study of ancient proteins. Rhodopsin coding sequences were reconstructed for three key nodes: Amniota, Mammalia, and Theria. When expressed in vitro, all sequences generated stable visual pigments with λMAX values similar to the well-studied bovine rhodopsin. Retinal release rates of mammalian and therian ancestral rhodopsins, measured via fluorescence spectroscopy, were significantly slower than those of the amniote ancestor, indicating altered molecular function possibly related to nocturnality. Positive selection along the therian branch suggests adaptive evolution in rhodopsin concurrent with therian ecological diversification events during the Mesozoic that allowed for an exploration of the environment at varying light levels.
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Affiliation(s)
- Constanze Bickelmann
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, 10115, Berlin, Germany.
| | - James M Morrow
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G5, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Jing Du
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Ryan K Schott
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Ilke van Hazel
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Steve Lim
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G5, Canada
| | - Johannes Müller
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, 10115, Berlin, Germany
| | - Belinda S W Chang
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G5, Canada. .,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada. .,Centre for the Analysis of Genome Evolution and Function, Toronto, ON, M5S 3B2, Canada.
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19
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Dungan SZ, Kosyakov A, Chang BS. Spectral Tuning of Killer Whale (Orcinus orca) Rhodopsin: Evidence for Positive Selection and Functional Adaptation in a Cetacean Visual Pigment. Mol Biol Evol 2015; 33:323-36. [DOI: 10.1093/molbev/msv217] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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20
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Borges R, Khan I, Johnson WE, Gilbert MTP, Zhang G, Jarvis ED, O'Brien SJ, Antunes A. Gene loss, adaptive evolution and the co-evolution of plumage coloration genes with opsins in birds. BMC Genomics 2015; 16:751. [PMID: 26438339 PMCID: PMC4595237 DOI: 10.1186/s12864-015-1924-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 09/11/2015] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND The wide range of complex photic systems observed in birds exemplifies one of their key evolutionary adaptions, a well-developed visual system. However, genomic approaches have yet to be used to disentangle the evolutionary mechanisms that govern evolution of avian visual systems. RESULTS We performed comparative genomic analyses across 48 avian genomes that span extant bird phylogenetic diversity to assess evolutionary changes in the 17 representatives of the opsin gene family and five plumage coloration genes. Our analyses suggest modern birds have maintained a repertoire of up to 15 opsins. Synteny analyses indicate that PARA and PARIE pineal opsins were lost, probably in conjunction with the degeneration of the parietal organ. Eleven of the 15 avian opsins evolved in a non-neutral pattern, confirming the adaptive importance of vision in birds. Visual conopsins sw1, sw2 and lw evolved under negative selection, while the dim-light RH1 photopigment diversified. The evolutionary patterns of sw1 and of violet/ultraviolet sensitivity in birds suggest that avian ancestors had violet-sensitive vision. Additionally, we demonstrate an adaptive association between the RH2 opsin and the MC1R plumage color gene, suggesting that plumage coloration has been photic mediated. At the intra-avian level we observed some unique adaptive patterns. For example, barn owl showed early signs of pseudogenization in RH2, perhaps in response to nocturnal behavior, and penguins had amino acid deletions in RH2 sites responsible for the red shift and retinal binding. These patterns in the barn owl and penguins were convergent with adaptive strategies in nocturnal and aquatic mammals, respectively. CONCLUSIONS We conclude that birds have evolved diverse opsin adaptations through gene loss, adaptive selection and coevolution with plumage coloration, and that differentiated selective patterns at the species level suggest novel photic pressures to influence evolutionary patterns of more-recent lineages.
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Affiliation(s)
- Rui Borges
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas, 177, 4050-123, Porto, Portugal.
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal.
| | - Imran Khan
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas, 177, 4050-123, Porto, Portugal.
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal.
| | - Warren E Johnson
- Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Road, Front Royal, VA, 22630, USA.
| | - M Thomas P Gilbert
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Volgade 5-7, 1350, Copenhagen, Denmark.
| | - Guojie Zhang
- China National GeneBank, BGI-Shenzhen, Shenzen, 518083, China.
- Centre for Social Evolution, Department of Biology, Universitetsparken 15, University of Copenhagen, DK-2100, Copenhagen, Denmark.
| | - Erich D Jarvis
- Department of Neurobiology, Duke University Medical Center Durham, Box 3209, North Carolina, 27710, USA.
- Howard Hughes Medical Institute, Chevy Chase, Maryland, 20815, USA.
| | - Stephen J O'Brien
- Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg, 199004, Russia.
- Oceanographic Center, Nova Southeastern University, 8000 N. Ocean Drive, Ft Lauderdale, Florida, 33004, USA.
| | - Agostinho Antunes
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas, 177, 4050-123, Porto, Portugal.
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal.
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21
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Tsagkogeorga G, McGowen MR, Davies KTJ, Jarman S, Polanowski A, Bertelsen MF, Rossiter SJ. A phylogenomic analysis of the role and timing of molecular adaptation in the aquatic transition of cetartiodactyl mammals. ROYAL SOCIETY OPEN SCIENCE 2015; 2:150156. [PMID: 26473040 PMCID: PMC4593674 DOI: 10.1098/rsos.150156] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 09/02/2015] [Indexed: 05/30/2023]
Abstract
Recent studies have reported multiple cases of molecular adaptation in cetaceans related to their aquatic abilities. However, none of these has included the hippopotamus, precluding an understanding of whether molecular adaptations in cetaceans occurred before or after they split from their semi-aquatic sister taxa. Here, we obtained new transcriptomes from the hippopotamus and humpback whale, and analysed these together with available data from eight other cetaceans. We identified more than 11 000 orthologous genes and compiled a genome-wide dataset of 6845 coding DNA sequences among 23 mammals, to our knowledge the largest phylogenomic dataset to date for cetaceans. We found positive selection in nine genes on the branch leading to the common ancestor of hippopotamus and whales, and 461 genes in cetaceans compared to 64 in hippopotamus. Functional annotation revealed adaptations in diverse processes, including lipid metabolism, hypoxia, muscle and brain function. By combining these findings with data on protein-protein interactions, we found evidence suggesting clustering among gene products relating to nervous and muscular systems in cetaceans. We found little support for shared ancestral adaptations in the two taxa; most molecular adaptations in extant cetaceans occurred after their split with hippopotamids.
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Affiliation(s)
- Georgia Tsagkogeorga
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Michael R. McGowen
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Kalina T. J. Davies
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Simon Jarman
- Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia
| | - Andrea Polanowski
- Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia
| | - Mads F. Bertelsen
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, Frederiksberg 2000, Denmark
| | - Stephen J. Rossiter
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
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Davies KTJ, Bennett NC, Tsagkogeorga G, Rossiter SJ, Faulkes CG. Family Wide Molecular Adaptations to Underground Life in African Mole-Rats Revealed by Phylogenomic Analysis. Mol Biol Evol 2015; 32:3089-107. [PMID: 26318402 PMCID: PMC4652621 DOI: 10.1093/molbev/msv175] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
During their evolutionary radiation, mammals have colonized diverse habitats. Arguably the subterranean niche is the most inhospitable of these, characterized by reduced oxygen, elevated carbon dioxide, absence of light, scarcity of food, and a substrate that is energetically costly to burrow through. Of all lineages to have transitioned to a subterranean niche, African mole-rats are one of the most successful. Much of their ecological success can be attributed to a diet of plant storage organs, which has allowed them to colonize climatically varied habitats across sub-Saharan Africa, and has probably contributed to the evolution of their diverse social systems. Yet despite their many remarkable phenotypic specializations, little is known about molecular adaptations underlying these traits. To address this, we sequenced the transcriptomes of seven mole-rat taxa, including three solitary species, and combined new sequences with existing genomic data sets. Alignments of more than 13,000 protein-coding genes encompassed, for the first time, all six genera and the full spectrum of ecological and social variation in the clade. We detected positive selection within the mole-rat clade and along ancestral branches in approximately 700 genes including loci associated with tumorigenesis, aging, morphological development, and sociality. By combining these results with gene ontology annotation and protein–protein networks, we identified several clusters of functionally related genes. This family wide analysis of molecular evolution in mole-rats has identified a suite of positively selected genes, deepening our understanding of the extreme phenotypic traits exhibited by this group.
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Affiliation(s)
- Kalina T J Davies
- School of Biological & Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Nigel C Bennett
- Department of Zoology & Entomology, University of Pretoria, Pretoria, South Africa
| | - Georgia Tsagkogeorga
- School of Biological & Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Stephen J Rossiter
- School of Biological & Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Christopher G Faulkes
- School of Biological & Chemical Sciences, Queen Mary University of London, London, United Kingdom
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23
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Discovery of a glowing millipede in California and the gradual evolution of bioluminescence in Diplopoda. Proc Natl Acad Sci U S A 2015; 112:6419-24. [PMID: 25941389 DOI: 10.1073/pnas.1500014112] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The rediscovery of the Californian millipede Xystocheir bistipita surprisingly reveals that the species is bioluminescent. Using molecular phylogenetics, we show that X. bistipita is the evolutionary sister group of Motyxia, the only genus of New World bioluminescent millipedes. We demonstrate that bioluminescence originated in the group's most recent common ancestor and evolved by gradual, directional change through diversification. Because bioluminescence in Motyxia has been experimentally demonstrated to be aposematic, forewarning of the animal's cyanide-based toxins, these results are contrary to aposematic theory and empirical evidence that a warning pattern cannot evolve gradually in unpalatable prey. However, gradual evolution of a warning pattern is plausible if faint light emission served another function and was co-opted as an aposematic signal later in the diversification of the genus. Luminescence in Motyxia stem-group taxa may have initially evolved to cope with reactive oxygen stress triggered by a hot, dry environment and was repurposed for aposematism by high-elevation crown-group taxa colonizing new habitats with varying levels of predation. The discovery of bioluminescence in X. bistipita and its pivotal phylogenetic location provides insight into the independent and repeated evolution of bioluminescence across the tree of life.
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24
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Wertheim JO, Murrell B, Smith MD, Kosakovsky Pond SL, Scheffler K. RELAX: detecting relaxed selection in a phylogenetic framework. Mol Biol Evol 2014; 32:820-32. [PMID: 25540451 DOI: 10.1093/molbev/msu400] [Citation(s) in RCA: 405] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Relaxation of selective strength, manifested as a reduction in the efficiency or intensity of natural selection, can drive evolutionary innovation and presage lineage extinction or loss of function. Mechanisms through which selection can be relaxed range from the removal of an existing selective constraint to a reduction in effective population size. Standard methods for estimating the strength and extent of purifying or positive selection from molecular sequence data are not suitable for detecting relaxed selection, because they lack power and can mistake an increase in the intensity of positive selection for relaxation of both purifying and positive selection. Here, we present a general hypothesis testing framework (RELAX) for detecting relaxed selection in a codon-based phylogenetic framework. Given two subsets of branches in a phylogeny, RELAX can determine whether selective strength was relaxed or intensified in one of these subsets relative to the other. We establish the validity of our test via simulations and show that it can distinguish between increased positive selection and a relaxation of selective strength. We also demonstrate the power of RELAX in a variety of biological scenarios where relaxation of selection has been hypothesized or demonstrated previously. We find that obligate and facultative γ-proteobacteria endosymbionts of insects are under relaxed selection compared with their free-living relatives and obligate endosymbionts are under relaxed selection compared with facultative endosymbionts. Selective strength is also relaxed in asexual Daphnia pulex lineages, compared with sexual lineages. Endogenous, nonfunctional, bornavirus-like elements are found to be under relaxed selection compared with exogenous Borna viruses. Finally, selection on the short-wavelength sensitive, SWS1, opsin genes in echolocating and nonecholocating bats is relaxed only in lineages in which this gene underwent pseudogenization; however, selection on the functional medium/long-wavelength sensitive opsin, M/LWS1, is found to be relaxed in all echolocating bats compared with nonecholocating bats.
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Affiliation(s)
| | - Ben Murrell
- Department of Medicine, University of California, San Diego
| | - Martin D Smith
- Bioinformatics and Systems Biology Graduate Program, University of California, San Diego
| | | | - Konrad Scheffler
- Department of Medicine, University of California, San Diego Department of Mathematical Sciences, Stellenbosch University, Stellenbosch, South Africa
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25
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The evolution of pentameric ligand-gated ion-channels and the changing family of anthelmintic drug targets. Parasitology 2014; 142:303-17. [PMID: 25354656 DOI: 10.1017/s003118201400170x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
SUMMARY Pentameric ligand-gated ion-channels rapidly transduce synaptic neurotransmitter signals to an electrical response in post-synaptic neuronal or muscle cells and control the neuromusculature of a majority of multicellular animals. A wide range of pharmaceuticals target these receptors including ethanol, nicotine, anti-depressants and other mood regulating drugs, compounds that control pain and mobility and are targeted by a majority of anthelmintic drugs used to control parasitic infection of humans and livestock. Major advances have been made in recent years to our understanding of the structure, function, activity and the profile of compounds that can activate specific receptors. It is becoming clear that these anthelmintic drug targets are not fixed, but differ in significant details from one nematode species to another. Here we review what is known about the evolution of the pentameric ligand-gated ion-channels, paying particular attention to the nematodes, how we can infer the origins of such receptors and understand the factors that determine how they change both over time and from one species to another. Using this knowledge provides a biological framework in which to understand these important drug targets and avenues to identify new receptors and aid the search for new anthelmintic drugs.
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26
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Fang X, Seim I, Huang Z, Gerashchenko MV, Xiong Z, Turanov AA, Zhu Y, Lobanov AV, Fan D, Yim SH, Yao X, Ma S, Yang L, Lee SG, Kim EB, Bronson RT, Šumbera R, Buffenstein R, Zhou X, Krogh A, Park TJ, Zhang G, Wang J, Gladyshev VN. Adaptations to a subterranean environment and longevity revealed by the analysis of mole rat genomes. Cell Rep 2014; 8:1354-64. [PMID: 25176646 PMCID: PMC4350764 DOI: 10.1016/j.celrep.2014.07.030] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 05/11/2014] [Accepted: 07/17/2014] [Indexed: 02/06/2023] Open
Abstract
Subterranean mammals spend their lives in dark, unventilated environments that are rich in carbon dioxide and ammonia and low in oxygen. Many of these animals are also long-lived and exhibit reduced aging-associated diseases, such as neurodegenerative disorders and cancer. We sequenced the genome of the Damaraland mole rat (DMR, Fukomys damarensis) and improved the genome assembly of the naked mole rat (NMR, Heterocephalus glaber). Comparative genome analyses, along with the transcriptomes of related subterranean rodents, revealed candidate molecular adaptations for subterranean life and longevity, including a divergent insulin peptide, expression of oxygen-carrying globins in the brain, prevention of high CO2-induced pain perception, and enhanced ammonia detoxification. Juxtaposition of the genomes of DMR and other more conventional animals with the genome of NMR revealed several truly exceptional NMR features: unusual thermogenesis, an aberrant melatonin system, pain insensitivity, and unique processing of 28S rRNA. Together, these genomes and transcriptomes extend our understanding of subterranean adaptations, stress resistance, and longevity.
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Affiliation(s)
- Xiaodong Fang
- BGI-Shenzhen, Shenzhen 518083, China; Department of Biology, University of Copenhagen, Copenhagen, 2200 Copenhagen N, Denmark
| | - Inge Seim
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, South Korea
| | | | - Maxim V Gerashchenko
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | - Anton A Turanov
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | - Alexei V Lobanov
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | - Sun Hee Yim
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | - Siming Ma
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Lan Yang
- BGI-Shenzhen, Shenzhen 518083, China
| | - Sang-Goo Lee
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, South Korea
| | - Eun Bae Kim
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, South Korea
| | - Roderick T Bronson
- Rodent Histopathology Laboratory, Harvard Medical School, Boston, MA 02115, USA
| | - Radim Šumbera
- University of South Bohemia, Faculty of Science, Ceske Budejovice 37005, Czech Republic
| | - Rochelle Buffenstein
- Department of Physiology and The Sam and Ann Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center, San Antonio, TX 78245, USA
| | - Xin Zhou
- BGI-Shenzhen, Shenzhen 518083, China
| | - Anders Krogh
- Department of Biology, University of Copenhagen, Copenhagen, 2200 Copenhagen N, Denmark
| | - Thomas J Park
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Guojie Zhang
- BGI-Shenzhen, Shenzhen 518083, China; Department of Biology, University of Copenhagen, Copenhagen, 2200 Copenhagen N, Denmark
| | - Jun Wang
- BGI-Shenzhen, Shenzhen 518083, China; Department of Biology, University of Copenhagen, Copenhagen, 2200 Copenhagen N, Denmark; King Abdulaziz University, Jeddah 21441, Saudi Arabia.
| | - Vadim N Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, South Korea.
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27
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Stathopoulos S, Bishop JM, O’Ryan C. Genetic signatures for enhanced olfaction in the African mole-rats. PLoS One 2014; 9:e93336. [PMID: 24699281 PMCID: PMC3974769 DOI: 10.1371/journal.pone.0093336] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 03/03/2014] [Indexed: 01/06/2023] Open
Abstract
The Olfactory Receptor (OR) superfamily, the largest in the vertebrate genome, is responsible for vertebrate olfaction and is traditionally subdivided into 17 OR families. Recent studies characterising whole-OR subgenomes revealed a 'birth and death' model of evolution for a range of species, however little is known about fine-scale evolutionary dynamics within single-OR families. This study reports the first assessment of fine-scale OR evolution and variation in African mole-rats (Bathyergidae), a family of subterranean rodents endemic to sub-Saharan Africa. Because of the selective pressures of life underground, enhanced olfaction is proposed to be fundamental to the evolutionary success of the Bathyergidae, resulting in a highly diversified OR gene-repertoire. Using a PCR-sequencing approach, we analysed variation in the OR7 family across 14 extant bathyergid species, which revealed enhanced levels of functional polymorphisms concentrated across the receptors' ligand-binding region. We propose that mole-rats are able to recognise a broad range of odorants and that this diversity is reflected throughout their OR7 gene repertoire. Using both classic tests and tree-based methods to test for signals of selection, we investigate evolutionary forces across the mole-rat OR7 gene tree. Four well-supported clades emerged in the OR phylogeny, with varying signals of selection; from neutrality to positive and purifying selection. Bathyergid life-history traits and environmental niche-specialisation are explored as possible drivers of adaptive OR evolution, emerging as non-exclusive contributors to the positive selection observed at OR7 genes. Our results reveal unexpected complexity of evolutionary mechanisms acting within a single OR family, providing insightful perspectives into OR evolutionary dynamics.
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Affiliation(s)
- Sofia Stathopoulos
- Department of Molecular and Cell Biology, University of Cape Town, Cape Town, Western Cape, South Africa
- * E-mail:
| | - Jacqueline M. Bishop
- Department of Biological Sciences, University of Cape Town, Cape Town, Western Cape, South Africa
| | - Colleen O’Ryan
- Department of Molecular and Cell Biology, University of Cape Town, Cape Town, Western Cape, South Africa
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28
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Schott RK, Refvik SP, Hauser FE, López-Fernández H, Chang BSW. Divergent positive selection in rhodopsin from lake and riverine cichlid fishes. Mol Biol Evol 2014; 31:1149-65. [PMID: 24509690 DOI: 10.1093/molbev/msu064] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Studies of cichlid evolution have highlighted the importance of visual pigment genes in the spectacular radiation of the African rift lake cichlids. Recent work, however, has also provided strong evidence for adaptive diversification of riverine cichlids in the Neotropics, which inhabit environments of markedly different spectral properties from the African rift lakes. These ecological and/or biogeographic differences may have imposed divergent selective pressures on the evolution of the cichlid visual system. To test these hypotheses, we investigated the molecular evolution of the dim-light visual pigment, rhodopsin. We sequenced rhodopsin from Neotropical and African riverine cichlids and combined these data with published sequences from African cichlids. We found significant evidence for positive selection using random sites codon models in all cichlid groups, with the highest levels in African lake cichlids. Tests using branch-site and clade models that partitioned the data along ecological (lake, river) and/or biogeographic (African, Neotropical) boundaries found significant evidence of divergent selective pressures among cichlid groups. However, statistical comparisons among these models suggest that ecological, rather than biogeographic, factors may be responsible for divergent selective pressures that have shaped the evolution of the visual system in cichlids. We found that branch-site models did not perform as well as clade models for our data set, in which there was evidence for positive selection in the background. One of our most intriguing results is that the amino acid sites found to be under positive selection in Neotropical and African lake cichlids were largely nonoverlapping, despite falling into the same three functional categories: spectral tuning, retinal uptake/release, and rhodopsin dimerization. Taken together, these results would imply divergent selection across cichlid clades, but targeting similar functions. This study highlights the importance of molecular investigations of ecologically important groups and the flexibility of clade models in explicitly testing ecological hypotheses.
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Affiliation(s)
- Ryan K Schott
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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29
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Shinozaki A, Takagi S, Hosaka YZ, Uehara M. The fibrous tapetum of the horse eye. J Anat 2013; 223:509-18. [PMID: 24102505 DOI: 10.1111/joa.12100] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2013] [Indexed: 11/30/2022] Open
Abstract
The tapetum lucidum is a light-reflective tissue in the eyes of many animals. Many ungulates have a fibrous tapetum. The horse has one of the largest eyes of any living animal and also has excellent vision in low-light environments. This study aimed to clarify the macroscopic tapetal shape, relationship between the tapetal thickness and the degree of pigmentation of the retinal pigment epithelium (RPE), spatial relationship between the visual streak and the tapetum, and wavelength of the light reflected from the tapetum in the horse. Macroscopically, weak light revealed the tapetum as a horizontal band located dorsal to and away from the optic disc. The tapetum expanded dorsally as the illumination increased. The tapetal tissue consisted of lamellae of collagen fibrils running parallel to the retinal surface; these spread over almost the entire ocular fundus and were thicker in the horizontal band dorsal to the disc. Only the horizontal band of the tapetum was covered by unpigmented RPE, suggesting that this band reflects light and is responsible for mesopic and scotopic vision. The visual streak was located in the ventral part of the horizontal band, ventral to the thickest part of the tapetum. The wavelength of the light reflected from the horizontal band of the tapetum was estimated from the diameter and interfibrous distance of the collagen fibrils to be approximately 468 nm. Therefore, the light reflected from the tapetum should be more effectively absorbed by rods than by cones, and should not interfere with photopic vision.
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Affiliation(s)
- Aya Shinozaki
- Department of Veterinary Medicine, Tottori University, Tottori, Japan
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30
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Genome-wide signatures of convergent evolution in echolocating mammals. Nature 2013; 502:228-31. [PMID: 24005325 PMCID: PMC3836225 DOI: 10.1038/nature12511] [Citation(s) in RCA: 237] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 07/30/2013] [Indexed: 11/09/2022]
Abstract
Evolution is typically thought to proceed through divergence of genes, proteins and ultimately phenotypes. However, similar traits might also evolve convergently in unrelated taxa owing to similar selection pressures. Adaptive phenotypic convergence is widespread in nature, and recent results from several genes have suggested that this phenomenon is powerful enough to also drive recurrent evolution at the sequence level. Where homoplasious substitutions do occur these have long been considered the result of neutral processes. However, recent studies have demonstrated that adaptive convergent sequence evolution can be detected in vertebrates using statistical methods that model parallel evolution, although the extent to which sequence convergence between genera occurs across genomes is unknown. Here we analyse genomic sequence data in mammals that have independently evolved echolocation and show that convergence is not a rare process restricted to several loci but is instead widespread, continuously distributed and commonly driven by natural selection acting on a small number of sites per locus. Systematic analyses of convergent sequence evolution in 805,053 amino acids within 2,326 orthologous coding gene sequences compared across 22 mammals (including four newly sequenced bat genomes) revealed signatures consistent with convergence in nearly 200 loci. Strong and significant support for convergence among bats and the bottlenose dolphin was seen in numerous genes linked to hearing or deafness, consistent with an involvement in echolocation. Unexpectedly, we also found convergence in many genes linked to vision: the convergent signal of many sensory genes was robustly correlated with the strength of natural selection. This first attempt to detect genome-wide convergent sequence evolution across divergent taxa reveals the phenomenon to be much more pervasive than previously recognized.
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31
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Shen B, Fang T, Dai M, Jones G, Zhang S. Independent losses of visual perception genes Gja10 and Rbp3 in echolocating bats (Order: Chiroptera). PLoS One 2013; 8:e68867. [PMID: 23874796 PMCID: PMC3715546 DOI: 10.1371/journal.pone.0068867] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 06/04/2013] [Indexed: 11/19/2022] Open
Abstract
A trade-off between the sensory modalities of vision and hearing is likely to have occurred in echolocating bats as the sophisticated mechanism of laryngeal echolocation requires considerable neural processing and has reduced the reliance of echolocating bats on vision for perceiving the environment. If such a trade-off exists, it is reasonable to hypothesize that some genes involved in visual function may have undergone relaxed selection or even functional loss in echolocating bats. The Gap junction protein, alpha 10 (Gja10, encoded by Gja10 gene) is expressed abundantly in mammal retinal horizontal cells and plays an important role in horizontal cell coupling. The interphotoreceptor retinoid-binding protein (Irbp, encoded by the Rbp3 gene) is mainly expressed in interphotoreceptor matrix and is known to be critical for normal functioning of the visual cycle. We sequenced Gja10 and Rbp3 genes in a taxonomically wide range of bats with divergent auditory characteristics (35 and 18 species for Gja10 and Rbp3, respectively). Both genes have became pseudogenes in species from the families Hipposideridae and Rhinolophidae that emit constant frequency echolocation calls with Doppler shift compensation at high-duty-cycles (the most sophisticated form of biosonar known), and in some bat species that emit echolocation calls at low-duty-cycles. Our study thus provides further evidence for the hypothesis that a trade-off occurs at the genetic level between vision and echolocation in bats.
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Affiliation(s)
- Bin Shen
- Institute of Molecular Ecology and Evolution, Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai, China
| | - Tao Fang
- Institute of Molecular Ecology and Evolution, Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai, China
| | - Mengyao Dai
- Institute of Molecular Ecology and Evolution, Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai, China
| | - Gareth Jones
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Shuyi Zhang
- Institute of Molecular Ecology and Evolution, Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai, China
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32
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Nery MF, González DJ, Opazo JC. How to Make a Dolphin: Molecular Signature of Positive Selection in Cetacean Genome. PLoS One 2013; 8:e65491. [PMID: 23840335 PMCID: PMC3686761 DOI: 10.1371/journal.pone.0065491] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 04/25/2013] [Indexed: 01/30/2023] Open
Abstract
Cetaceans are unique in being the only mammals completely adapted to an aquatic environment. This adaptation has required complex changes and sometimes a complete restructuring of physiology, behavior and morphology. Identifying genes that have been subjected to selection pressure during cetacean evolution would greatly enhance our knowledge of the ways in which genetic variation in this mammalian order has been shaped by natural selection. Here, we performed a genome-wide scan for positive selection in the dolphin lineage. We employed models of codon substitution that account for variation of selective pressure over branches on the tree and across sites in a sequence. We analyzed 7,859 nuclear-coding ortholog genes and using a series of likelihood ratio tests (LRTs), we identified 376 genes (4.8%) with molecular signatures of positive selection in the dolphin lineage. We used the cow as the sister group and compared estimates of selection in the cetacean genome to this using the same methods. This allowed us to define which genes have been exclusively under positive selection in the dolphin lineage. The enrichment analysis found that the identified positively selected genes are significantly over-represented for three exclusive functional categories only in the dolphin lineage: segment specification, mesoderm development and system development. Of particular interest for cetacean adaptation to an aquatic life are the following GeneOntology targets under positive selection: genes related to kidney, heart, lung, eye, ear and nervous system development.
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Affiliation(s)
- Mariana F. Nery
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
- Programa de Doctorado en Ciencias mención Ecología y Evolución, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Dimar J. González
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Juan C. Opazo
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
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33
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Jones G, Teeling EC, Rossiter SJ. From the ultrasonic to the infrared: molecular evolution and the sensory biology of bats. Front Physiol 2013; 4:117. [PMID: 23755015 PMCID: PMC3667242 DOI: 10.3389/fphys.2013.00117] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/07/2013] [Indexed: 01/06/2023] Open
Abstract
Great advances have been made recently in understanding the genetic basis of the sensory biology of bats. Research has focused on the molecular evolution of candidate sensory genes, genes with known functions [e.g., olfactory receptor (OR) genes] and genes identified from mutations associated with sensory deficits (e.g., blindness and deafness). For example, the FoxP2 gene, underpinning vocal behavior and sensorimotor coordination, has undergone diversification in bats, while several genes associated with audition show parallel amino acid substitutions in unrelated lineages of echolocating bats and, in some cases, in echolocating dolphins, representing a classic case of convergent molecular evolution. Vision genes encoding the photopigments rhodopsin and the long-wave sensitive opsin are functional in bats, while that encoding the short-wave sensitive opsin has lost functionality in rhinolophoid bats using high-duty cycle laryngeal echolocation, suggesting a sensory trade-off between investment in vision and echolocation. In terms of olfaction, bats appear to have a distinctive OR repertoire compared with other mammals, and a gene involved in signal transduction in the vomeronasal system has become non-functional in most bat species. Bitter taste receptors appear to have undergone a "birth-and death" evolution involving extensive gene duplication and loss, unlike genes coding for sweet and umami tastes that show conservation across most lineages but loss in vampire bats. Common vampire bats have also undergone adaptations for thermoperception, via alternative splicing resulting in the evolution of a novel heat-sensitive channel. The future for understanding the molecular basis of sensory biology is promising, with great potential for comparative genomic analyses, studies on gene regulation and expression, exploration of the role of alternative splicing in the generation of proteomic diversity, and linking genetic mechanisms to behavioral consequences.
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Affiliation(s)
- Gareth Jones
- School of Biological Sciences, University of Bristol Bristol, UK
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34
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Beech RN, Callanan MK, Rao VTS, Dawe GB, Forrester SG. Characterization of cys-loop receptor genes involved in inhibitory amine neurotransmission in parasitic and free living nematodes. Parasitol Int 2013; 62:599-605. [PMID: 23602737 DOI: 10.1016/j.parint.2013.03.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 03/15/2013] [Accepted: 03/22/2013] [Indexed: 01/23/2023]
Abstract
We have isolated two genes, Hco-lgc-53 and Hco-mod-1, from the parasitic nematode Haemonchus contortus, which are orthologs of previously characterized genes that encode dopamine and serotonin-gated chloride channels, respectively, in Caenorhabditis elegans. A search of transcriptome data for the filarial nematode parasites Loa loa, Brugia malayi, and Wucheria bancrofti revealed predicted coding sequences for orthologs of acetylcholine, serotonin and dopamine-gated chloride channels, which correspond to the C. elegans clades acc-1, mod-1 and ggr-3, respectively. Genome data for the more distantly related nematode parasite, Trichinella spiralis, contain genes predicted to encode members of the acc-1 clade only, but all three clades were absent from the trematode Schistosoma mansoni. Analysis of the ratio of non-synonymous to synonymous substitutions (ω) for receptor subunit sequences revealed strong selective constraint over the entire protein, consistent with the known highly conserved 3D structure of cys-loop receptors. This constraint was significantly greater for binding loop residues that are predicted to contact bound ligand and residues of the transmembrane domains. The substitution rate for ligand binding residues was significantly higher for branches leading to the acc-1 and mod-1 clades, where the convergent evolution for binding acetylcholine and serotonin, respectively, is thought to have occurred. Homology models of both Hco-MOD-1 and Hco-LGC-53 channels revealed the presence of binding structures typical of the cys-loop receptor family, including the presence of an aromatic box that is important for the formation of the binding pocket. Both receptors contain a tryptophan in loop C that appears to be a key residue important for the binding of amines to ligand-gated chloride channels. As additional ligand-gated chloride-channel sequences become available for a wider range of species the combination of molecular modeling and analysis of sequence evolution should provide an effective tool to understand the wide diversity of neurotransmitters that bind to this unique group of receptors.
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Affiliation(s)
- Robin N Beech
- Faculty of Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa ON L1H 7K4, Canada
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Meredith RW, Gatesy J, Emerling CA, York VM, Springer MS. Rod monochromacy and the coevolution of cetacean retinal opsins. PLoS Genet 2013; 9:e1003432. [PMID: 23637615 PMCID: PMC3630094 DOI: 10.1371/journal.pgen.1003432] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 02/15/2013] [Indexed: 01/02/2023] Open
Abstract
Cetaceans have a long history of commitment to a fully aquatic lifestyle that extends back to the Eocene. Extant species have evolved a spectacular array of adaptations in conjunction with their deployment into a diverse array of aquatic habitats. Sensory systems are among those that have experienced radical transformations in the evolutionary history of this clade. In the case of vision, previous studies have demonstrated important changes in the genes encoding rod opsin (RH1), short-wavelength sensitive opsin 1 (SWS1), and long-wavelength sensitive opsin (LWS) in selected cetaceans, but have not examined the full complement of opsin genes across the complete range of cetacean families. Here, we report protein-coding sequences for RH1 and both color opsin genes (SWS1, LWS) from representatives of all extant cetacean families. We examine competing hypotheses pertaining to the timing of blue shifts in RH1 relative to SWS1 inactivation in the early history of Cetacea, and we test the hypothesis that some cetaceans are rod monochomats. Molecular evolutionary analyses contradict the "coastal" hypothesis, wherein SWS1 was pseudogenized in the common ancestor of Cetacea, and instead suggest that RH1 was blue-shifted in the common ancestor of Cetacea before SWS1 was independently knocked out in baleen whales (Mysticeti) and in toothed whales (Odontoceti). Further, molecular evidence implies that LWS was inactivated convergently on at least five occasions in Cetacea: (1) Balaenidae (bowhead and right whales), (2) Balaenopteroidea (rorquals plus gray whale), (3) Mesoplodon bidens (Sowerby's beaked whale), (4) Physeter macrocephalus (giant sperm whale), and (5) Kogia breviceps (pygmy sperm whale). All of these cetaceans are known to dive to depths of at least 100 m where the underwater light field is dim and dominated by blue light. The knockout of both SWS1 and LWS in multiple cetacean lineages renders these taxa rod monochromats, a condition previously unknown among mammalian species.
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Affiliation(s)
- Robert W. Meredith
- Department of Biology, University of California Riverside, Riverside, California, United States of America
- Department of Biology and Molecular Biology, Montclair State University, Montclair, New Jersey, United States of America
| | - John Gatesy
- Department of Biology, University of California Riverside, Riverside, California, United States of America
| | - Christopher A. Emerling
- Department of Biology, University of California Riverside, Riverside, California, United States of America
| | - Vincent M. York
- Department of Biology, University of California Riverside, Riverside, California, United States of America
- Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Mark S. Springer
- Department of Biology, University of California Riverside, Riverside, California, United States of America
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A system-level, molecular evolutionary analysis of mammalian phototransduction. BMC Evol Biol 2013; 13:52. [PMID: 23433342 PMCID: PMC3616935 DOI: 10.1186/1471-2148-13-52] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 01/29/2013] [Indexed: 01/12/2023] Open
Abstract
Background Visual perception is initiated in the photoreceptor cells of the retina via the phototransduction system. This system has shown marked evolution during mammalian divergence in such complex attributes as activation time and recovery time. We have performed a molecular evolutionary analysis of proteins involved in mammalian phototransduction in order to unravel how the action of natural selection has been distributed throughout the system to evolve such traits. Results We found selective pressures to be non-randomly distributed according to both a simple protein classification scheme and a protein-interaction network representation of the signaling pathway. Proteins which are topologically central in the signaling pathway, such as the G proteins, as well as retinoid cycle chaperones and proteins involved in photoreceptor cell-type determination, were found to be more constrained in their evolution. Proteins peripheral to the pathway, such as ion channels and exchangers, as well as the retinoid cycle enzymes, have experienced a relaxation of selective pressures. Furthermore, signals of positive selection were detected in two genes: the short-wave (blue) opsin (OPN1SW) in hominids and the rod-specific Na+/ Ca2+, K+ ion exchanger (SLC24A1) in rodents. Conclusions The functions of the proteins involved in phototransduction and the topology of the interactions between them have imposed non-random constraints on their evolution. Thus, in shaping or conserving system-level phototransduction traits, natural selection has targeted the underlying proteins in a concerted manner.
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Niemiller ML, Fitzpatrick BM, Shah P, Schmitz L, Near TJ. Evidence for repeated loss of selective constraint in rhodopsin of amblyopsid cavefishes (Teleostei: Amblyopsidae). Evolution 2012; 67:732-48. [PMID: 23461324 DOI: 10.1111/j.1558-5646.2012.01822.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The genetic mechanisms underlying regressive evolution-the degeneration or loss of a derived trait--are largely unknown, particularly for complex structures such as eyes in cave organisms. In several eyeless animals, the visual photoreceptor rhodopsin appears to have retained functional amino acid sequences. Hypotheses to explain apparent maintenance of function include weak selection for retention of light-sensing abilities and its pleiotropic roles in circadian rhythms and thermotaxis. In contrast, we show that there has been repeated loss of functional constraint of rhodopsin in amblyopsid cavefishes, as at least three cave lineages have independently accumulated unique loss-of-function mutations over the last 10.3 Mya. Although several cave lineages still possess functional rhodopsin, they exhibit increased rates of nonsynonymous mutations that have greater effect on the structure and function of rhodopsin compared to those in surface lineages. These results indicate that functionality of rhodopsin has been repeatedly lost in amblyopsid cavefishes. The presence of a functional copy of rhodopsin in some cave lineages is likely explained by stochastic accumulation of mutations following recent subterranean colonization.
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Affiliation(s)
- Matthew L Niemiller
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996, USA.
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Functional characterization of the rod visual pigment of the echidna (Tachyglossus aculeatus), a basal mammal. Vis Neurosci 2012; 29:211-7. [PMID: 22874131 DOI: 10.1017/s0952523812000223] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Monotremes are the most basal egg-laying mammals comprised of two extant genera, which are largely nocturnal. Visual pigments, the first step in the sensory transduction cascade in photoreceptors of the eye, have been examined in a variety of vertebrates, but little work has been done to study the rhodopsin of monotremes. We isolated the rhodopsin gene of the nocturnal short-beaked echidna (Tachyglossus aculeatus) and expressed and functionally characterized the protein in vitro. Three mutants were also expressed and characterized: N83D, an important site for spectral tuning and metarhodopsin kinetics, and two sites with amino acids unique to the echidna (T158A and F169A). The λ(max) of echidna rhodopsin (497.9 ± 1.1 nm) did not vary significantly in either T158A (498.0 ± 1.3 nm) or F169A (499.4 ± 0.1 nm) but was redshifted in N83D (503.8 ± 1.5 nm). Unlike other mammalian rhodopsins, echidna rhodopsin did react when exposed to hydroxylamine, although not as fast as cone opsins. The retinal release rate of light-activated echidna rhodopsin, as measured by fluorescence spectroscopy, had a half-life of 9.5 ± 2.6 min-1, which is significantly shorter than that of bovine rhodopsin. The half-life of the N83D mutant was 5.1 ± 0.1 min-1, even shorter than wild type. Our results show that with respect to hydroxylamine sensitivity and retinal release, the wild-type echidna rhodopsin displays major differences to all previously characterized mammalian rhodopsins and appears more similar to other nonmammalian vertebrate rhodopsins such as chicken and anole. However, our N83D mutagenesis results suggest that this site may mediate adaptation in the echidna to dim light environments, possibly via increased stability of light-activated intermediates. This study is the first characterization of a rhodopsin from a most basal mammal and indicates that there might be more functional variation in mammalian rhodopsins than previously assumed.
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Weadick CJ, Chang BSW. An improved likelihood ratio test for detecting site-specific functional divergence among clades of protein-coding genes. Mol Biol Evol 2011; 29:1297-300. [PMID: 22319160 DOI: 10.1093/molbev/msr311] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Maximum likelihood codon substitution models have proven useful for studying when and how protein function evolves, but they have recently been criticized on a number of fronts. The strengths and weaknesses of such methods must therefore be identified and improved upon. Here, using simulations, we show that the Clade model C versus M1a test for functional divergence among clades is prone to false positives under simple evolutionary conditions. We then propose a new null model (M2a_rel) that better accounts for among-site variation in selective constraint. We show that the revised test has an improved false-positive rate and good power. Applying this test to previously analyzed data sets of primate ribonucleases and mammalian rhodopsins reveals that some conclusions may have been misled by the original method. The improved test should prove useful for identifying patterns of divergence in selective constraint among paralogous gene families and among orthologs from ecologically divergent species.
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Kott O, Šumbera R, Němec P. Light perception in two strictly subterranean rodents: life in the dark or blue? PLoS One 2010; 5:e11810. [PMID: 20676369 PMCID: PMC2911378 DOI: 10.1371/journal.pone.0011810] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Accepted: 06/23/2010] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND The African mole-rats (Bathyergidae, Rodentia) are strictly subterranean, congenitally microphthalmic rodents that are hardly ever exposed to environmental light. Because of the lack of an overt behavioural reaction to light, they have long been considered to be blind. However, recent anatomical studies have suggested retention of basic visual capabilities. In this study, we employed behavioural tests to find out if two mole-rat species are able to discriminate between light and dark, if they are able to discriminate colours and, finally, if the presence of light in burrows provokes plugging behaviour, which is assumed to have a primarily anti-predatory function. METHODOLOGY/PRINCIPAL FINDING We used a binary choice test to show that the silvery mole-rat Heliophobius argenteocinereus and the giant mole-rat Fukomys mechowii exhibit a clear photoavoidance response to full-spectrum ("white"), blue and green-yellow light, but no significant reaction to ultraviolet or red light during nest building. The mole-rats thus retain dark/light discrimination capabilities and a capacity to perceive short to medium-wavelength light in the photopic range of intensities. These findings further suggest that the mole-rat S opsin has its absorption maximum in the violet/blue part of the spectrum. The assay did not yield conclusive evidence regarding colour discrimination. To test the putative role of vision in bathyergid anti-predatory behaviour, we examined the reaction of mole-rats to the incidence of light in an artificial burrow system. The presence of light in the burrow effectively induced plugging of the illuminated tunnel. CONCLUSION/SIGNIFICANCE Our findings suggest that the photopic vision is conserved and that low acuity residual vision plays an important role in predator avoidance and tunnel maintenance in the African mole-rats.
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Affiliation(s)
- Ondřej Kott
- Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Radim Šumbera
- Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Pavel Němec
- Department of Zoology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
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