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Martinez Q, Amson E, Laska M. Does the number of functional olfactory receptor genes predict olfactory sensitivity and discrimination performance in mammals? J Evol Biol 2024; 37:238-247. [PMID: 38297391 DOI: 10.1093/jeb/voae006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 12/05/2023] [Accepted: 01/04/2024] [Indexed: 02/02/2024]
Abstract
The number of functional genes coding for olfactory receptors differs markedly between species and has repeatedly been suggested to be predictive of a species' olfactory capabilities. To test this assumption, we compiled a database of all published olfactory detection threshold values in mammals and used three sets of data on olfactory discrimination performance that employed the same structurally related monomolecular odour pairs with different mammal species. We extracted the number of functional olfactory receptor genes of the 20 mammal species for which we found data on olfactory sensitivity and/or olfactory discrimination performance from the Chordata Olfactory Receptor Database. We found that the overall olfactory detection thresholds significantly correlate with the number of functional olfactory receptor genes. Similarly, the overall proportion of successfully discriminated monomolecular odour pairs significantly correlates with the number of functional olfactory receptor genes. These results provide the first statistically robust evidence for the relationship between olfactory capabilities and their genomics correlates. However, when analysed individually, of the 44 monomolecular odourants for which data on olfactory sensitivity from at least five mammal species are available, only five yielded a significant correlation between olfactory detection thresholds and the number of functional olfactory receptors genes. Also, for the olfactory discrimination performance, no significant correlation was found for any of the 74 relationships between the proportion of successfully discriminated monomolecular odour pairs and the number of functional olfactory receptor genes. While only a rather limited amount of data on olfactory detection thresholds and olfactory discrimination scores in a rather limited number of mammal species is available so far, we conclude that the number of functional olfactory receptor genes may be a predictor of olfactory sensitivity and discrimination performance in mammals.
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Affiliation(s)
| | - Eli Amson
- Staatliches Museum für Naturkunde Stuttgart, Stuttgart, Germany
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2
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LaDue CA, Snyder RJ. Asian elephants distinguish sexual status and identity of unfamiliar elephants using urinary odours. Biol Lett 2023; 19:20230491. [PMID: 38115746 PMCID: PMC10731322 DOI: 10.1098/rsbl.2023.0491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 11/30/2023] [Indexed: 12/21/2023] Open
Abstract
Despite the ubiquity of odours in mammals, few studies have documented the natural olfactory abilities of many 'non-model' species such as the Asian elephant. As Asian elephants are endangered, we may apply odours to more effectively manage threatened populations. We implemented a habituation-discrimination paradigm for the first time in Asian elephants to test the ability of elephants to discriminate between unfamiliar male elephant urine, hypothesizing that elephants would successfully distinguish non-musth from musth urine and also distinguish identity between two closely related individuals. We conducted two bioassay series, exposing three female and three male zoo-housed elephants to the same urine sample (non-musth urine in the first series, and urine from an unfamiliar individual in the second) over 5 days. On the sixth day, we simultaneously presented each elephant with a novel sample (either musth urine or urine from a second unfamiliar individual) alongside the habituated urine sample, comparing rates of chemosensory response to each sample to indicate discrimination. All elephants successfully discriminated non-musth from musth urine, and also urine from two unfamiliar half-brothers. Our results further demonstrate the remarkable olfactory abilities of elephants with promising implications for conservation and management.
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Affiliation(s)
- Chase A. LaDue
- Oklahoma City Zoo and Botanical Garden, Oklahoma City, Oklahoma, USA
| | - Rebecca J. Snyder
- Oklahoma City Zoo and Botanical Garden, Oklahoma City, Oklahoma, USA
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3
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Eiting TP, Smith TD, Forger NG, Dumont ER. Neuronal scaling in the olfactory system of bats. Anat Rec (Hoboken) 2023; 306:2781-2790. [PMID: 37658819 DOI: 10.1002/ar.25311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 07/18/2023] [Accepted: 08/11/2023] [Indexed: 09/05/2023]
Abstract
Comparative studies are a common way to address large-scale questions in sensory biology. For studies that investigate olfactory abilities, the most commonly used metric is olfactory bulb size. However, recent work has called into question the broad-scale use of olfactory bulb size. In this paper, we use three neuroanatomical measures with a more mechanistic link to olfactory function (number of olfactory sensory neurons (OSNs), number of mitral cells (MCs), and number of glomeruli) to ask how species with different diets may differ with respect to olfactory ability. We use phyllostomid bats as our study system because behavioral and physiological work has shown that fruit- and nectar-feeding phyllostomids rely on odors for detecting, localizing, and assessing potential foods, while insect-eating species do not. Therefore, we predicted that fruit- and nectar-feeding bats would have larger numbers of these three neuroanatomical measures than insect-eating species. In general, our results supported the predictions. We found that fruit-eaters had greater numbers of OSNs and glomeruli than insect-eaters, but we found no difference between groups in number of MCs. We also examined the allometric relationship between the three neuroanatomical variables and olfactory bulb volume, and we found isometry in all cases. These findings lend support to the notion that neuroanatomical measures can offer valuable insights into comparative olfactory abilities, and suggest that the size of the olfactory bulb may be an informative parameter to use at the whole-organism level.
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Affiliation(s)
- Thomas P Eiting
- Graduate Program in Organismic and Evolutionary Biology, 221 Morrill Science Center, University of Massachusetts, Amherst, Massachusetts, USA
| | - Timothy D Smith
- School of Physical Therapy, 108 Central Loop, Slippery Rock University, Slippery Rock, Pennsylvania, USA
| | - Nancy G Forger
- Department of Psychology and Center for Neuroendocrine Studies, Tobin Hall, 135 Hicks Way, University of Massachusetts, Amherst, Massachusetts, USA
| | - Elizabeth R Dumont
- Graduate Program in Organismic and Evolutionary Biology, 221 Morrill Science Center, University of Massachusetts, Amherst, Massachusetts, USA
- Department of Biology, 221 Morrill Science Center, University of Massachusetts, Amherst, Massachusetts, USA
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Hoerner F, Lawrenz A, Oerke AK, Müller DWH, Azogu-Sepe I, Roller M, Damerau K, Preisfeld A. Long-Term Olfactory Memory in African Elephants. Animals (Basel) 2023; 13:ani13040679. [PMID: 36830466 PMCID: PMC9951961 DOI: 10.3390/ani13040679] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/18/2023] Open
Abstract
African elephants are capable of discriminating scents up to a single changed molecule and show the largest reported repertoire of olfactory receptor genes. Olfaction plays an important role in family bonding. However, to the best of our knowledge, no empirical data exist on their ability to remember familiar scents long-term. In an ethological experiment, two mother-daughter pairs were presented with feces of absent kin, absent non-kin, and present non-kin. Video recordings showed reactions of elephants recognizing kin after long-term separation but only minor reactions to non-kin. Results give the empirical implication that elephants have an olfactory memory longer than 1 year and up to 12 years and can distinguish between kin and non-kin just by scent. These findings confirm the significance of scent for family bonds in African elephants.
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Affiliation(s)
- Franziska Hoerner
- Department of Zoology, University of Wuppertal, 42119 Wuppertal, Germany
- Correspondence:
| | | | - Ann-Kathrin Oerke
- Endocrinology Laboratory, German Primate Centre, 37077 Goettingen, Germany
| | | | - Idu Azogu-Sepe
- Serengeti-Park Department of Research, Serengeti-Park Hodenhagen, 29693 Hodenhagen, Germany
| | | | - Karsten Damerau
- Department of Ecology, Europa-Universität Flensburg, 24943 Flensburg, Germany
| | - Angelika Preisfeld
- Department of Zoology, University of Wuppertal, 42119 Wuppertal, Germany
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5
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Thüs P, Lunau K, Wester P. Associative colour learning and discrimination in the South African Cape rock sengi Elephantulus edwardii (Macroscelidea, Afrotheria, Mammalia). MAMMALIA 2022. [DOI: 10.1515/mammalia-2022-0034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abstract
Beside insects, sengis also consume plant material such as leaves, fruits, seeds and floral nectar. It is known that they use olfaction for foraging, but little is known about their vision and visual learning capabilities. Colour vision has been tested in two species, showing that they are likely dichromats (green- and blue-sensitive retinal cone-photoreceptors, meaning red-green colour blind). Our aim was to examine the learning and colour discrimination abilities of another species, Elephantulus edwardii. Using training procedures and choice experiments, we tested the hypotheses that the animals can associate a reward with trained colours and that they can discriminate between different colour hues. The sengis preferred the trained colours over the others, indicating associative learning. They could discriminate between all tested colours (blue, red, green, yellow). The sengis’ colour choice behaviour indicates that the animals can use also colour features to find food plant material. Additionally, learning abilities most likely are essential for the sengis’ foraging activities, for instance by associating floral or fruit shape, colour or scent with nectar or ripe fruit, to increase the efficiency to locate food sources.
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Affiliation(s)
- Patricia Thüs
- Institute of Sensory Ecology , Heinrich-Heine-University , Düsseldorf , Germany
| | - Klaus Lunau
- Institute of Sensory Ecology , Heinrich-Heine-University , Düsseldorf , Germany
| | - Petra Wester
- Institute of Sensory Ecology , Heinrich-Heine-University , Düsseldorf , Germany
- School of Life Sciences , University of KwaZulu-Natal , PB X01 , Pietermaritzburg 3209 , South Africa
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Quesada-Moreno MM, Fatima M, Medel R, Pérez C, Schnell M. Sniffing out camphor: the fine balance between hydrogen bonding and London dispersion in the chirality recognition with α-fenchol. Phys Chem Chem Phys 2022; 24:12849-12859. [PMID: 35532923 DOI: 10.1039/d2cp00308b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Binary complexes between the chiral monoterpenoids camphor and α-fenchol were explored with vibrational and rotational jet spectroscopy as well as density functional theory in order to explore how chirality can influence the binding preferences in gas-phase complexes. The global minimum structures of the two diastereomers were assigned. It is found that chirality recognition leads to different compromises in the fine balance between intermolecular interactions. While one isomer features a stronger hydrogen bond, the other one is more tightly arranged and stabilized by larger London dispersion interactions. These new spectroscopic results help understand the influence of chirality in molecular aggregation and unveil the kind of interactions involved between a chiral alcohol and a chiral ketone with large dispersion contributions.
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Affiliation(s)
- María Mar Quesada-Moreno
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany. .,Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, 18071, Granada, Spain
| | - Mariyam Fatima
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany. .,I. Institute of Physics, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
| | - Robert Medel
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstr. 6, D-37077 Göttingen, Germany.
| | - Cristóbal Pérez
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany. .,Departamento de Química Física y Química Inorgánica, Facultad de Ciencias & I.U. CINQUIMA, Universidad de Valladolid, E-47011 Valladolid, Spain
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany. .,Christian-Albrechts-Universität zu Kiel, Institut für Physikalische Chemie, Max-Eyth-Straße 1, 24118 Kiel, Germany.
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Acknowledging the Relevance of Elephant Sensory Perception to Human–Elephant Conflict Mitigation. Animals (Basel) 2022; 12:ani12081018. [PMID: 35454264 PMCID: PMC9031250 DOI: 10.3390/ani12081018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 04/11/2022] [Accepted: 04/12/2022] [Indexed: 02/05/2023] Open
Abstract
Simple Summary Elephants have a unique sensory perspective of the world, using their complex olfactory and auditory systems to make foraging and social decisions. All three species of elephants are endangered and inhabit environments, which are being affected rapidly by human development. Anthropogenic disturbances can have significant effects on elephants’ abilities to perceive sensory information and communicate with one another, potentially further endangering their survival. Conflicts over high-quality resources also arise from the overlapping habitation of humans and elephants. While many different methods have been employed to reduce this conflict, we propose that elephants’ unique olfactory and acoustic sensory strengths be considered in future mitigation strategies to achieve coexistence. Abstract Elephants are well known for their socio-cognitive abilities and capacity for multi-modal sensory perception and communication. Their highly developed olfactory and acoustic senses provide them with a unique non-visual perspective of their physical and social worlds. The use of these complex sensory signals is important not only for communication between conspecifics, but also for decisions about foraging and navigation. These decisions have grown increasingly risky given the exponential increase in unpredictable anthropogenic change in elephants’ natural habitats. Risk taking often develops from the overlap of human and elephant habitat in Asian and African range countries, where elephants forage for food in human habitat and crop fields, leading to conflict over high-quality resources. To mitigate this conflict, a better understanding of the elephants’ sensory world and its impact on their decision-making process should be considered seriously in the development of long-term strategies for promoting coexistence between humans and elephants. In this review, we explore the elephants’ sensory systems for audition and olfaction, their multi-modal capacities for communication, and the anthropogenic changes that are affecting their behavior, as well as the need for greater consideration of elephant behavior in elephant conservation efforts.
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Schulte BA, LaDue CA. The Chemical Ecology of Elephants: 21st Century Additions to Our Understanding and Future Outlooks. Animals (Basel) 2021; 11:2860. [PMID: 34679881 PMCID: PMC8532676 DOI: 10.3390/ani11102860] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/24/2021] [Accepted: 09/28/2021] [Indexed: 01/19/2023] Open
Abstract
Chemical signals are the oldest and most ubiquitous means of mediating intra- and interspecific interactions. The three extant species of elephants, the Asian elephant and the two African species, savanna and forest share sociobiological patterns in which chemical signals play a vital role. Elephants emit secretions and excretions and display behaviors that reveal the importance of odors in their interactions. In this review, we begin with a brief introduction of research in elephant chemical ecology leading up to the 21st century, and then we summarize the body of work that has built upon it and occurred in the last c. 20 years. The 21st century has expanded our understanding on elephant chemical ecology, revealing their use of odors to detect potential threats and make dietary choices. Furthermore, complementary in situ and ex situ studies have allowed the careful observations of captive elephants to be extended to fieldwork involving their wild counterparts. While important advances have been made in the 21st century, further work should investigate the roles of chemical signaling in elephants and how these signals interact with other sensory modalities. All three elephant species are threatened with extinction, and we suggest that chemical ecology can be applied for targeted conservation efforts.
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Affiliation(s)
- Bruce A. Schulte
- Department of Biology, Western Kentucky University, Bowling Green, KY 42101, USA
| | - Chase A. LaDue
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA 22030, USA;
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9
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Wood M, Chamaillé-Jammes S, Hammerbacher A, Shrader AM. African elephants can detect water from natural and artificial sources via olfactory cues. Anim Cogn 2021; 25:53-61. [PMID: 34292432 DOI: 10.1007/s10071-021-01531-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/01/2021] [Accepted: 07/06/2021] [Indexed: 11/28/2022]
Abstract
Water is vital for mammals. Yet, as ephemeral sources can be difficult to find, it raises the question, how do mammals locate water? Elephants (Loxodonta africana) are water-dependent herbivores that possess exceptional olfactory capabilities, and it has been suggested that they may locate water via smell. However, there is no evidence to support this claim. To explore this, we performed two olfactory choice experiments with semi-tame elephants. In the first, we tested whether elephants could locate water using olfactory cues alone. For this, we used water from two natural dams and a drinking trough utilised by the elephants. Distilled water acted as a control. In the second, we explored whether elephants could detect three key volatile organic compounds (VOCs) commonly associated with water (geosmin, 2-methylisoborneol, and dimethyl sulphide). We found that the elephants could locate water olfactorily, but not the distilled water. Moreover, they were also able to detect the three VOCs associated with water. However, these VOCs were not in the odour profiles of the water sources in our experiments. This suggests that the elephants were either able to detect the unique odour profiles of the different water sources or used other VOCs that they associate with water. Ultimately, our findings indicate that elephants can locate water olfactorily at small spatial scales, but the extent to which they, and other mammals, can detect water over larger scales (e.g. km) remains unclear.
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Affiliation(s)
- Matthew Wood
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Pretoria, South Africa
| | - Simon Chamaillé-Jammes
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Pretoria, South Africa.,CEFE, Univ Montpellier, CNRS, EPHE, IRD, Univ Paul Valéry Montpellier 3, Montpellier, France
| | - Almuth Hammerbacher
- Forestry and Agricultural Biotechnology Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Adrian M Shrader
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Pretoria, South Africa.
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Tan WH, Hii A, Solana‐Mena A, Wong EP, Loke VPW, Tan ASL, Kromann‐Clausen A, Hii N, bin Pura P, bin Tunil MT, A/L Din S, Chin CF, Campos‐Arceiz A. Long‐term monitoring of seed dispersal by Asian elephants in a Sundaland rainforest. Biotropica 2021. [DOI: 10.1111/btp.12889] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Wei Harn Tan
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
| | - Adeline Hii
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
| | - Alicia Solana‐Mena
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
| | - Ee Phin Wong
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
- Management & Ecology of Malaysian Elephants University of Nottingham Malaysia Semenyih Malaysia
| | - Vivienne P. W. Loke
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
| | - Ange S. L. Tan
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
| | - Anders Kromann‐Clausen
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
| | - Ning Hii
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
| | - Param bin Pura
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
| | - Muhamad Tauhid bin Tunil
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
| | - Sudin A/L Din
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
| | - Chiew Foan Chin
- School of Biosciences The University of Nottingham Malaysia Kajang Malaysia
| | - Ahimsa Campos‐Arceiz
- School of Environmental and Geographical Sciences The University of Nottingham Malaysia Kajang Malaysia
- Southeast Asia Biodiversity Research Institute Chinese Academy of Sciences Nay Pyi Taw Myanmar
- Center for Integrative Conservation Xishuangbanna Tropical Botanical GardenChinese Academy of Sciences Mengla China
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Bird DJ, Jacquemetton C, Buelow SA, Evans AW, Van Valkenburgh B. Domesticating olfaction: Dog breeds, including scent hounds, have reduced cribriform plate morphology relative to wolves. Anat Rec (Hoboken) 2020; 304:139-153. [PMID: 33205623 DOI: 10.1002/ar.24518] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 05/26/2020] [Accepted: 06/12/2020] [Indexed: 11/08/2022]
Abstract
The domestic dog is assumed by nearly everyone to be the consummate smeller. Within the species Canis familiaris individual breeds, such as the bloodhound or beagle, are known as olfactory stars. These are "scent breeds," a grouping variably defined as a genetic clade or breed class commonly used for scent detection tasks. Previous work suggests that the dog has a more robust olfactory anatomy than many mammal species. Now we undertake a closer investigation of the dog's olfactory system, both in relationship to its closest wild relatives, the wolf and coyote, and across individual breeds. First, we seek to resolve whether the dog has lost olfactory capacity through its domestication from the wolf lineage. Second, we test the inertial lore that among dogs, "scent breeds," have a superior olfactory facility. As a measure of relative olfactory capacity, we look to the cribriform plate (CP), a bony cup in the posterior nasal cavity perforated by passageways for all olfactory nerve bundles streaming from the periphery to the brain. Using high-resolution computed tomography (CT) scans and digital quantification, we compare relative CP size in 46 dog breeds, the coyote and gray wolf. Results show the dog has a reduced CP surface area relative to the wolf and coyote. Moreover, we found no significant differences between CP size of "scent" and "non-scent" breeds. Our study suggests that the dog lost olfactory capacity as a result of domestication and this loss was not recovered in particular breed groupings through directed artificial selection for increased olfactory facility.
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Affiliation(s)
- Deborah J Bird
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, California, USA
| | - Christiane Jacquemetton
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, California, USA
| | - Sophie A Buelow
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, California, USA
| | - Andrew W Evans
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, California, USA
| | - Blaire Van Valkenburgh
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, California, USA
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12
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Nevo O, Schmitt MH, Ayasse M, Valenta K. Sweet tooth: Elephants detect fruit sugar levels based on scent alone. Ecol Evol 2020; 10:11399-11407. [PMID: 33144973 PMCID: PMC7593167 DOI: 10.1002/ece3.6777] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 08/07/2020] [Accepted: 08/18/2020] [Indexed: 11/10/2022] Open
Abstract
The ability to assess food quality is crucial to all organisms. Fleshy fruits are a major source of nutrients to various animals, and unlike most food sources, have evolved to be attractive and to be consumed by animals to promote seed dispersal. It has recently been established that fruit scent-the bouquet of volatile chemicals emitted by ripe fruit-is an evolved communication system between plants and animals. Further, it has been argued that chemicals that are synthesized from sugar and its products may be an honest signal for sugar content and fruit quality. Elephants are important seed dispersers for numerous species and possess an olfactory system that is likely to outperform most other animals. We tested the hypothesis that fruit scent signifies sugar content and that elephants are capable of assessing fruit sugar levels based on scent alone. Using a paired-choice test of marula fruits (Sclerocarya birrea) by semitame African elephants, we show that elephants are capable of identifying more sugar-rich fruits based on scent alone and that this is likely based on two chemical compounds: ethanol and ethyl acetate, both downstream products of sugar fermentation. These results shed light on the mechanisms driving elephant feeding ecology, plant signaling, and the coevolutionary process between angiosperms and animal seed dispersers.
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Affiliation(s)
- Omer Nevo
- Institute of Evolutionary Ecology and Conservation GenomicsUlm UniversityUlmGermany
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
- Institute of BiodiversityFriedrich Schiller University JenaJenaGermany
| | - Melissa H. Schmitt
- Department of Ecology, Evolution, and Marine BiologyUniversity of California Santa BarbaraSanta BarbaraCAUSA
- South African Environmental Observation NetworkNdlovu NodePhalaborwaSouth Africa
| | - Manfred Ayasse
- Institute of Evolutionary Ecology and Conservation GenomicsUlm UniversityUlmGermany
| | - Kim Valenta
- Department of AnthropologyUniversity of FloridaGainesvilleFLUSA
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13
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DeGreeff LE, Simon AG, Peranich K, Holness HK, Frank K, Furton KG. Generalization and Discrimination of Molecularly Similar Odorants in Detection Canines and the Influence of Training. Behav Processes 2020; 177:104148. [PMID: 32464153 DOI: 10.1016/j.beproc.2020.104148] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 05/19/2020] [Accepted: 05/22/2020] [Indexed: 11/16/2022]
Abstract
Operationally-deployed canine detectors are often trained on one or a limited number of materials representing a single target odor, and training frequently occurs using materials of a high purity grade in controlled scenarios with minimal other background odors. Conversely, in the field, canine detectors are expected to generalize and identify variations of the target odor, while discriminating from similar extraneous or background odors. This exemplifies the balance between generalization and discrimination required for effective canine detectors. This research explored the tendency for detection canines to generalize or discriminate between similar odorants. Two groups of related odorants were used in two separate studies; (1) odorants of similar functional groups with differing carbon chains, and (2) odorants of similar carbon chain length but differing functional groups. Within each odorant set, the effect of training was addressed by incrementally increasing the number of odorants each canine was trained to detect. Initially, discrimination increased with increasing molecular dissimilarity in both odorant groups. After further training on additional related odorants, generalization increased across the set of odorants of the same carbon chain length, but there were no significant changes in either generalization or discrimination across the set of odorants of the same functional group. The results suggest that the canines in this study were more likely to generalize across compounds of the same chain length with differing functional group than across compounds of the same functional group, but differing chain lengths. Furthermore, some variation in performance between individual canines indicated that the tendency to generalize differed with experience, breed, and other factors affecting olfaction.
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Affiliation(s)
- Lauryn E DeGreeff
- U.S. Naval Research Laboratory, Code 6181, 4555 Overlook Ave. SW, Washington DC, 20375, USA; Florida International University, International Forensic Research Institute, Chemistry Department, 11200 SW 8(th)St., Miami, FL, 33199, USA.
| | - Alison G Simon
- former National Research Council post-doctoral fellow at U.S. Naval Research Laboratory, 4555 Overlook Ave. SW, Washington DC, 20375, USA
| | - Kimberly Peranich
- Naval Surface Warfare Center Indian Head EOD Technology Division, 3767 Strauss Ave., Indian Head MD, 20640, USA
| | - Howard K Holness
- Florida International University, International Forensic Research Institute, Chemistry Department, 11200 SW 8(th)St., Miami, FL, 33199, USA
| | - Kelvin Frank
- Florida International University, International Forensic Research Institute, Chemistry Department, 11200 SW 8(th)St., Miami, FL, 33199, USA
| | - Kenneth G Furton
- Florida International University, International Forensic Research Institute, Chemistry Department, 11200 SW 8(th)St., Miami, FL, 33199, USA
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15
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McArthur C, Finnerty PB, Schmitt MH, Shuttleworth A, Shrader AM. Plant volatiles are a salient cue for foraging mammals: elephants target preferred plants despite background plant odour. Anim Behav 2019. [DOI: 10.1016/j.anbehav.2019.07.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Niimura Y, Matsui A, Touhara K. Acceleration of Olfactory Receptor Gene Loss in Primate Evolution: Possible Link to Anatomical Change in Sensory Systems and Dietary Transition. Mol Biol Evol 2019; 35:1437-1450. [PMID: 29659972 DOI: 10.1093/molbev/msy042] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Primates have traditionally been regarded as vision-oriented animals with low olfactory ability, though this "microsmatic primates" view has been challenged recently. To clarify when and how degeneration of the olfactory system occurred and to specify the relevant factors during primate evolution, we here examined the olfactory receptor (OR) genes from 24 phylogenetically and ecologically diverse primate species. The results revealed that strepsirrhines with curved noses had functional OR gene repertoires that were nearly twice as large as those for haplorhines with simple noses. Neither activity pattern (nocturnal/diurnal) nor color vision system showed significant correlation with the number of functional OR genes while phylogeny and nose structure (haplorhine/strepsirrhine) are statistically controlled, but extent of folivory did. We traced the evolutionary fates of individual OR genes by identifying orthologous gene groups, demonstrating that the rates of OR gene losses were accelerated at the ancestral branch of haplorhines, which coincided with the acquisition of acute vision. The highest rate of OR gene loss was observed at the ancestral branch of leaf-eating colobines; this reduction is possibly linked with the dietary transition from frugivory to folivory because odor information is essential for fruit foraging but less so for leaf foraging. Intriguingly, we found accelerations of OR gene losses in an external branch to every hominoid species examined. These findings suggest that the current OR gene repertoire in each species has been shaped by a complex interplay of phylogeny, anatomy, and habitat; therefore, multiple factors may contribute to the olfactory degeneration in primates.
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Affiliation(s)
- Yoshihito Niimura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo, Japan.,Lead Contact
| | - Atsushi Matsui
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo, Japan
| | - Kazushige Touhara
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo, Japan
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17
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Ferrando S, Amaroli A, Gallus L, Aicardi S, Di Blasi D, Christiansen JS, Vacchi M, Ghigliotti L. Secondary Folds Contribute Significantly to the Total Surface Area in the Olfactory Organ of Chondrichthyes. Front Physiol 2019; 10:245. [PMID: 30930795 PMCID: PMC6424019 DOI: 10.3389/fphys.2019.00245] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 02/25/2019] [Indexed: 12/05/2022] Open
Abstract
The olfactory organ of Chondrichthyes is characterized by a central support with several lamellae covered by a sensory olfactory epithelium. Although secondary folds are present on the lamellae in all the chondrichthyan species analyzed to date, their shape and size have not been described. We here analyze the olfactory organ of 13 elasmobranch and 1 holocephalan species, describe the shape of the secondary folds and evaluate how they contribute to the epithelial surface area. The secondary folds vary in shape and size, and they should always be considered when comparing the epithelial surface area among species; in fact, the increase of the area, due to the presence of the secondary folds, spans from 70 to 495% in the considered species. Because of the complexity of the shapes, we approach the description of the secondary folds by analyzing histological sections of the olfactory lamellae to obtain illustrative silhouettes. We introduce two indexes in order to describe a 2D-sectioned shape of the secondary folds. Considering the different numerical parameters which describe the morphology of the olfactory organ (secondary folds included), a principal component analysis elucidates the possible ecological role and phylogenetic relationship of the chondrichthyan olfactory organ.
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Affiliation(s)
- Sara Ferrando
- Department of Earth, Environmental, and Life Sciences, University of Genoa, Genoa, Italy
| | - Andrea Amaroli
- Department of Earth, Environmental, and Life Sciences, University of Genoa, Genoa, Italy.,Department of Surgical Sciences and Integrates Diagnostics, University of Genoa, Genoa, Italy
| | - Lorenzo Gallus
- Department of Earth, Environmental, and Life Sciences, University of Genoa, Genoa, Italy
| | - Stefano Aicardi
- Department of Earth, Environmental, and Life Sciences, University of Genoa, Genoa, Italy
| | | | - Jørgen S Christiansen
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway.,Environmental and Marine Biology, Åbo Akademi University, Turku, Finland
| | - Marino Vacchi
- National Research Council of Italy, IAS, Genoa, Italy
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18
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Bird DJ, Murphy WJ, Fox-Rosales L, Hamid I, Eagle RA, Van Valkenburgh B. Olfaction written in bone: cribriform plate size parallels olfactory receptor gene repertoires in Mammalia. Proc Biol Sci 2019. [PMID: 29540522 DOI: 10.1098/rspb.2018.0100] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The evolution of mammalian olfaction is manifested in a remarkable diversity of gene repertoires, neuroanatomy and skull morphology across living species. Olfactory receptor genes (ORGs), which initiate the conversion of odorant molecules into odour perceptions and help an animal resolve the olfactory world, range in number from a mere handful to several thousand genes across species. Within the snout, each of these ORGs is exclusively expressed by a discrete population of olfactory sensory neurons (OSNs), suggesting that newly evolved ORGs may be coupled with new OSN populations in the nasal epithelium. Because OSN axon bundles leave high-fidelity perforations (foramina) in the bone as they traverse the cribriform plate (CP) to reach the brain, we predicted that taxa with larger ORG repertoires would have proportionately expanded footprints in the CP foramina. Previous work found a correlation between ORG number and absolute CP size that disappeared after accounting for body size. Using updated, digital measurement data from high-resolution CT scans and re-examining the relationship between CP and body size, we report a striking linear correlation between relative CP area and number of functional ORGs across species from all mammalian superorders. This correlation suggests strong developmental links in the olfactory pathway between genes, neurons and skull morphology. Furthermore, because ORG number is linked to olfactory discriminatory function, this correlation supports relative CP size as a viable metric for inferring olfactory capacity across modern and extinct species. By quantifying CP area from a fossil sabertooth cat (Smilodon fatalis), we predicted a likely ORG repertoire for this extinct felid.
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Affiliation(s)
- Deborah J Bird
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 610 Charles E. Young Drive South, Los Angeles, CA 90095-8347, USA
| | - William J Murphy
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA
| | - Lester Fox-Rosales
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 610 Charles E. Young Drive South, Los Angeles, CA 90095-8347, USA
| | - Iman Hamid
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 610 Charles E. Young Drive South, Los Angeles, CA 90095-8347, USA
| | - Robert A Eagle
- Department of Atmospheric and Oceanic Sciences, Institute of the Environment and Sustainability, University of California Los Angeles, 520 Portola Plaza, Math Sciences Building 7127, Los Angeles, CA 90095, USA
| | - Blaire Van Valkenburgh
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 610 Charles E. Young Drive South, Los Angeles, CA 90095-8347, USA
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19
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20
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Hughes GM, Boston ESM, Finarelli JA, Murphy WJ, Higgins DG, Teeling EC. The Birth and Death of Olfactory Receptor Gene Families in Mammalian Niche Adaptation. Mol Biol Evol 2018; 35:1390-1406. [PMID: 29562344 PMCID: PMC5967467 DOI: 10.1093/molbev/msy028] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [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
The olfactory receptor (OR) gene families, which govern mammalian olfaction, have undergone extensive expansion and contraction through duplication and pseudogenization. Previous studies have shown that broadly defined environmental adaptations (e.g., terrestrial vs. aquatic) are correlated with the number of functional and non-functional OR genes retained. However, to date, no study has examined species-specific gene duplications in multiple phylogenetically divergent mammals to elucidate OR evolution and adaptation. Here, we identify the OR gene families driving adaptation to different ecological niches by mapping the fate of species-specific gene duplications in the OR repertoire of 94 diverse mammalian taxa, using molecular phylogenomic methods. We analyze >70,000 OR gene sequences mined from whole genomes, generated from novel amplicon sequencing data, and collated with data from previous studies, comprising one of the largest OR studies to date. For the first time, we demonstrate statistically significant patterns of OR species-specific gene duplications associated with the presence of a functioning vomeronasal organ. With respect to dietary niche, we uncover a novel link between a large number of duplications in OR family 5/8/9 and herbivory. Our results also highlight differences between social and solitary niches, indicating that a greater OR repertoire expansion may be associated with a solitary lifestyle. This study demonstrates the utility of species-specific duplications in elucidating gene family evolution, revealing how the OR repertoire has undergone expansion and contraction with respect to a number of ecological adaptations in mammals.
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Affiliation(s)
- Graham M Hughes
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | - Emma S M Boston
- AECOM, 9th Floor Clarence West Building, Clarence Street West, Belfast, BT2 7GP, United Kingdom
| | - John A Finarelli
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | - William J Murphy
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX
| | - Desmond G Higgins
- UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Emma C Teeling
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
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21
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LaDue CA, Goodwin TE, Schulte BA. Concentration-dependent chemosensory responses towards pheromones are influenced by receiver attributes in Asian elephants. Ethology 2018. [DOI: 10.1111/eth.12741] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chase A. LaDue
- Department of Biology; Western Kentucky University; Bowling Green KY USA
| | | | - Bruce A. Schulte
- Department of Biology; Western Kentucky University; Bowling Green KY USA
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22
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African elephants (Loxodonta africana) display remarkable olfactory acuity in human scent matching to sample performance. Appl Anim Behav Sci 2018. [DOI: 10.1016/j.applanim.2017.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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23
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Finnerty PB, Stutz RS, Price CJ, Banks PB, McArthur C. Leaf odour cues enable non‐random foraging by mammalian herbivores. J Anim Ecol 2017; 86:1317-1328. [DOI: 10.1111/1365-2656.12748] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 08/09/2017] [Indexed: 11/29/2022]
Affiliation(s)
- Patrick B. Finnerty
- School of Life & Environmental SciencesThe University of Sydney Sydney NSW Australia
| | - Rebecca S. Stutz
- School of Life & Environmental SciencesThe University of Sydney Sydney NSW Australia
- Department of ZoologyStockholm University Stockholm Sweden
| | - Catherine J. Price
- School of Life & Environmental SciencesThe University of Sydney Sydney NSW Australia
| | - Peter B. Banks
- School of Life & Environmental SciencesThe University of Sydney Sydney NSW Australia
| | - Clare McArthur
- School of Life & Environmental SciencesThe University of Sydney Sydney NSW Australia
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24
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Wright HF, Wilkinson A, Croxton RS, Graham DK, Harding RC, Hodkinson HL, Keep B, Cracknell NR, Zulch HE. Animals can assign novel odours to a known category. Sci Rep 2017; 7:9019. [PMID: 28827742 PMCID: PMC5567083 DOI: 10.1038/s41598-017-09454-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/14/2017] [Indexed: 11/21/2022] Open
Abstract
The ability to identify a novel stimulus as a member of a known category allows an organism to respond appropriately towards it. Categorisation is thus a fundamental component of cognition and an essential tool for processing and responding to unknown stimuli. Therefore, one might expect to observe it throughout the animal kingdom and across sensory domains. There is much evidence of visual categorisation in non-human animals, but we currently know little about this process in other modalities. In this experiment, we investigated categorisation in the olfactory domain. Dogs were trained to discriminate between 40 odours; the presence or absence of accelerants formed the categorical rule. Those in the experimental group were rewarded for responding to substrates with accelerants (either burnt or un-burnt) and inhibit responses to the same substrates (either burnt or un-burnt) without accelerants (S+ counterbalanced). The pseudocategory control group was trained on the same stimuli without the categorical rule. The experimental group learned the discrimination and animals were able to generalise to novel stimuli from the same category. None of the control animals were able to learn the discrimination within the maximum number of trials. This study provides the first evidence that non-human animals can learn to categorise non-biologically relevant odour information.
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Affiliation(s)
- Hannah F Wright
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln, LN6 7DL, UK
| | - Anna Wilkinson
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln, LN6 7DL, UK.
| | - Ruth S Croxton
- School of Chemistry, University of Lincoln, Joseph Banks Laboratories, Lincoln, LN6 7DL, UK
| | - Deanna K Graham
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln, LN6 7DL, UK
| | - Rebecca C Harding
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln, LN6 7DL, UK
| | - Hayley L Hodkinson
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln, LN6 7DL, UK
| | - Benjamin Keep
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln, LN6 7DL, UK
| | - Nina R Cracknell
- Defence Science and Technology Laboratory, Fort Halstead, Sevenoaks, Kent, TN14 7BP, UK
| | - Helen E Zulch
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln, LN6 7DL, UK
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25
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26
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Block E, Batista VS, Matsunami H, Zhuang H, Ahmed L. The role of metals in mammalian olfaction of low molecular weight organosulfur compounds. Nat Prod Rep 2017; 34:529-557. [PMID: 28471462 PMCID: PMC5542778 DOI: 10.1039/c7np00016b] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Covering: up to the end of 2017While suggestions concerning the possible role of metals in olfaction and taste date back 50 years, only recently has it been possible to confirm these proposals with experiments involving individual olfactory receptors (ORs). A detailed discussion of recent experimental results demonstrating the key role of metals in enhancing the response of human and other vertebrate ORs to specific odorants is presented against the backdrop of our knowledge of how the sense of smell functions both at the molecular and whole animal levels. This review emphasizes the role of metals in the detection of low molecular weight thiols, sulfides, and other organosulfur compounds, including those found in strong-smelling animal excretions and plant volatiles, and those used in gas odorization. Alternative theories of olfaction are described, with evidence favoring the modified "shape" theory. The use of quantum mechanical/molecular modeling (QM/MM), site-directed mutagenesis and saturation-transfer-difference (STD) NMR is discussed, providing support for biological studies of mouse and human receptors, MOR244-3 and OR OR2T11, respectively. Copper is bound at the active site of MOR244-3 by cysteine and histidine, while cysteine, histidine and methionine are involved with OR2T11. The binding pockets of these two receptors are found in different locations in the three-dimensional seven transmembrane models. Another recently deorphaned human olfactory receptor, OR2M3, highly selective for a thiol from onions, and a broadly-tuned thiol receptor, OR1A1, are also discussed. Other topics covered include the effects of nanoparticles and heavy metal toxicants on vertebrate and fish ORs, intranasal zinc products and the loss of smell (anosmia).
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Affiliation(s)
- Eric Block
- Department of Chemistry, University at Albany, State University of New York, Albany, New York 12222, USA.
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27
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Yohe LR, Abubakar R, Giordano C, Dumont E, Sears KE, Rossiter SJ, Dávalos LM. Trpc2 pseudogenization dynamics in bats reveal ancestral vomeronasal signaling, then pervasive loss. Evolution 2017; 71:923-935. [PMID: 28128447 DOI: 10.1111/evo.13187] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Accepted: 12/30/2016] [Indexed: 01/08/2023]
Abstract
Comparative methods are often used to infer loss or gain of complex phenotypes, but few studies take advantage of genes tightly linked with complex traits to test for shifts in the strength of selection. In mammals, vomerolfaction detects chemical cues mediating many social and reproductive behaviors and is highly conserved, but all bats exhibit degraded vomeronasal structures with the exception of two families (Phyllostomidae and Miniopteridae). These families either regained vomerolfaction after ancestral loss, or there were many independent losses after diversification from an ancestor with functional vomerolfaction. In this study, we use the Transient receptor potential cation channel 2 (Trpc2) as a molecular marker for testing the evolutionary mechanisms of loss and gain of the mammalian vomeronasal system. We sequenced Trpc2 exon 2 in over 100 bat species across 17 of 20 chiropteran families. Most families showed independent pseudogenizing mutations in Trpc2, but the reading frame was highly conserved in phyllostomids and miniopterids. Phylogeny-based simulations suggest loss of function occurred after bat families diverged, and purifying selection in two families has persisted since bats shared a common ancestor. As most bats still display pheromone-mediated behavior, they might detect pheromones through the main olfactory system without using the Trpc2 signaling mechanism.
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Affiliation(s)
- Laurel R Yohe
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York, 11794
| | - Ramatu Abubakar
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York, 11794
| | - Christina Giordano
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York, 11794
| | - Elizabeth Dumont
- Department of Biology, University of Massachusetts, Amherst, Massachusetts, 01003
| | - Karen E Sears
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois, 61801.,School of Integrative Biology, Institute for Genome Biology, University of Illinois, Urbana, Illinois, 61801
| | - Stephen J Rossiter
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, United Kingdom
| | - Liliana M Dávalos
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York, 11794.,Consortium for Inter-Disciplinary Environmental Research, Stony Brook University, Stony Brook, New York, 11794
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28
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Valenta K, Nevo O, Martel C, Chapman CA. Plant attractants: integrating insights from pollination and seed dispersal ecology. Evol Ecol 2016. [DOI: 10.1007/s10682-016-9870-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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29
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Estienne V, Mundry R, Kühl HS, Boesch C. Exploitation of underground bee nests by three sympatric consumers in Loango National Park, Gabon. Biotropica 2016. [DOI: 10.1111/btp.12354] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Vittoria Estienne
- Max Planck Institute for Evolutionary Anthropology; Deutscher Platz 6 Leipzig 04103 Germany
| | - Roger Mundry
- Max Planck Institute for Evolutionary Anthropology; Deutscher Platz 6 Leipzig 04103 Germany
| | - Hjalmar S. Kühl
- Max Planck Institute for Evolutionary Anthropology; Deutscher Platz 6 Leipzig 04103 Germany
- German Centre for Integrative Biodiversity Research; Halle-Jena-Leipzig; Deutscher Platz 6 Leipzig 04103 Germany
| | - Christophe Boesch
- Max Planck Institute for Evolutionary Anthropology; Deutscher Platz 6 Leipzig 04103 Germany
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30
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Ferrer I, Garcia-Esparcia P, Carmona M, Carro E, Aronica E, Kovacs GG, Grison A, Gustincich S. Olfactory Receptors in Non-Chemosensory Organs: The Nervous System in Health and Disease. Front Aging Neurosci 2016; 8:163. [PMID: 27458372 PMCID: PMC4932117 DOI: 10.3389/fnagi.2016.00163] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 06/21/2016] [Indexed: 12/22/2022] Open
Abstract
Olfactory receptors (ORs) and down-stream functional signaling molecules adenylyl cyclase 3 (AC3), olfactory G protein α subunit (Gαolf), OR transporters receptor transporter proteins 1 and 2 (RTP1 and RTP2), receptor expression enhancing protein 1 (REEP1), and UDP-glucuronosyltransferases (UGTs) are expressed in neurons of the human and murine central nervous system (CNS). In vitro studies have shown that these receptors react to external stimuli and therefore are equipped to be functional. However, ORs are not directly related to the detection of odors. Several molecules delivered from the blood, cerebrospinal fluid, neighboring local neurons and glial cells, distant cells through the extracellular space, and the cells’ own self-regulating internal homeostasis can be postulated as possible ligands. Moreover, a single neuron outside the olfactory epithelium expresses more than one receptor, and the mechanism of transcriptional regulation may be different in olfactory epithelia and brain neurons. OR gene expression is altered in several neurodegenerative diseases including Parkinson’s disease (PD), Alzheimer’s disease (AD), progressive supranuclear palsy (PSP) and sporadic Creutzfeldt-Jakob disease (sCJD) subtypes MM1 and VV2 with disease-, region- and subtype-specific patterns. Altered gene expression is also observed in the prefrontal cortex in schizophrenia with a major but not total influence of chlorpromazine treatment. Preliminary parallel observations have also shown the presence of taste receptors (TASRs), mainly of the bitter taste family, in the mammalian brain, whose function is not related to taste. TASRs in brain are also abnormally regulated in neurodegenerative diseases. These seminal observations point to the need for further studies on ORs and TASRs chemoreceptors in the mammalian brain.
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Affiliation(s)
- Isidro Ferrer
- Institute of Neuropathology, Bellvitge University Hospital, Hospitalet de Llobregat, University of BarcelonaBarcelona, Spain; Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED)Madrid, Spain; Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de LlobregatBarcelona, Spain
| | - Paula Garcia-Esparcia
- Institute of Neuropathology, Bellvitge University Hospital, Hospitalet de Llobregat, University of BarcelonaBarcelona, Spain; Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED)Madrid, Spain; Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de LlobregatBarcelona, Spain
| | - Margarita Carmona
- Institute of Neuropathology, Bellvitge University Hospital, Hospitalet de Llobregat, University of BarcelonaBarcelona, Spain; Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED)Madrid, Spain; Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de LlobregatBarcelona, Spain
| | - Eva Carro
- Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED)Madrid, Spain; Neuroscience Group, Research Institute HospitalMadrid, Spain
| | - Eleonora Aronica
- Department of Neuropathology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| | - Gabor G Kovacs
- Institute of Neurology, Medical University of Vienna Vienna, Austria
| | - Alice Grison
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), Area of Neuroscience Trieste, Italy
| | - Stefano Gustincich
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), Area of Neuroscience Trieste, Italy
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31
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Performance of domestic dogs on an olfactory discrimination of a homologous series of alcohols. Appl Anim Behav Sci 2016. [DOI: 10.1016/j.applanim.2016.03.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Sievert T, Laska M. Behavioral Responses of CD-1 Mice to Six Predator Odor Components. Chem Senses 2016; 41:399-406. [PMID: 26892309 DOI: 10.1093/chemse/bjw015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mammalian prey species are able to detect predator odors and to display appropriate defensive behavior. However, there is only limited knowledge about whether single compounds of predator odors are sufficient to elicit such behavior. Therefore, we assessed if predator-naïve CD-1 mice (n = 60) avoid sulfur-containing compounds that are characteristic components of natural predator odors and/or display other indicators of anxiety. A 2-compartment test arena was used to assess approach/avoidance behavior, general motor activity, and the number of fecal pellets excreted when the animals were presented with 1 of 6 predator odor components in one compartment and a blank control in the other compartment. We found that 2 of the 6 predator odor components (2-propylthietane and 3-methyl-1-butanethiol) were significantly avoided by the mice. The remaining 4 predator odor components (2,2-dimethylthietane, 3-mercapto-3-methylbutan-1-ol, 3-mercapto-3-methylbutyl-1-formate, and methyl-2-phenylethyl sulphide) as well as a nonpredator-associated fruity odor (n-pentyl acetate) were not avoided. Neither the general motor activity nor the number of excreted fecal pellets, both widely used measures of stress- or anxiety-related behavior, were systematically affected by any of the odorants tested. Further, we found that small changes in the molecular structure of a predator odor component can have a marked effect on its behavioral significance as 2-propylthietane was significantly avoided by the mice whereas the structurally related 2,2-dimethylthietane was not. We conclude that sulfur-containing volatiles identified as characteristic components of the urine, feces, and anal gland secretions of mammalian predators can be, but are not necessarily sufficient to elicit defensive behaviors in a mammalian prey species.
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Affiliation(s)
| | - Matthias Laska
- IFM Biology, Linköping University, SE-581 83 Linköping, Sweden
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33
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Miller AK, Hensman MC, Hensman S, Schultz K, Reid P, Shore M, Brown J, Furton KG, Lee S. African elephants ( Loxodonta africana ) can detect TNT using olfaction: Implications for biosensor application. Appl Anim Behav Sci 2015. [DOI: 10.1016/j.applanim.2015.08.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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34
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Takai Y, Touhara K. Enantioselective recognition of menthol by mouse odorant receptors. Biosci Biotechnol Biochem 2015; 79:1980-6. [PMID: 26248186 DOI: 10.1080/09168451.2015.1069697] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The olfactory system has a remarkable ability to detect and discriminate a vast variety of odorant molecules. In mammals, hundreds to thousands of odorant receptors (ORs) expressed in olfactory sensory neurons play an essential role in this discrimination. Odorants are recognized by ORs in a combinatorial fashion in which a single odorant activates a particular combination of receptors, leading to its perception as a particular aroma. It is well known that enantiomers emit different aromas in spite of exhibiting otherwise identical chemical properties. To elucidate the molecular basis for the difference, we recorded responses to l- and d-menthol in the mouse olfactory bulb and found that enantiomers elicited similar but overlapping and distinct receptor activation patterns. We then identified l-menthol-specific and d-menthol-biased receptors and performed detailed structure-activity relationship studies, revealing high stereoselectivity of the enantiospecific menthol receptor. The binding site on ORs appears to have evolved to distinguish subtle differences in very similar odorant structures.
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Affiliation(s)
- Yoshiki Takai
- a Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences , The University of Tokyo , Tokyo , Japan
| | - Kazushige Touhara
- a Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences , The University of Tokyo , Tokyo , Japan.,b ERATO Touhara Chemosensory Signal Project, JST , The University of Tokyo , Tokyo , Japan
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Abstract
Olfaction, the sense of smell, was a latecomer to the systematic investigation of primate sensory ecology after long years in which it was considered to be of minor importance. This view shifted with the growing understanding of its role in social behavior and the accumulation of physiological studies demonstrating that the olfactory abilities of some primates are on a par with those of olfactory-dependent mammals such as dogs and rodents. Recent years have seen a proliferation of physiological, behavioral, anatomical, and genetic investigations of primate olfaction. These investigations have begun to shed light on the importance of olfaction in the process of food acquisition. However, integration of these works has been limited. It is therefore still difficult to pinpoint large-scale evolutionary scenarios, namely the functions that the sense of smell fulfills in primates' feeding ecology and the ecological niches that favor heavier reliance on olfaction. Here, we review available behavioral and physiological studies of primates in the field or captivity and try to elucidate how and when the sense of smell can help them acquire food.
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Laska M. Olfactory Discrimination Learning in an Outbred and an Inbred Strain of Mice. Chem Senses 2015; 40:489-96. [DOI: 10.1093/chemse/bjv032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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37
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Block E, Jang S, Matsunami H, Sekharan S, Dethier B, Ertem MZ, Gundala S, Pan Y, Li S, Li Z, Lodge SN, Ozbil M, Jiang H, Penalba SF, Batista VS, Zhuang H. Implausibility of the vibrational theory of olfaction. Proc Natl Acad Sci U S A 2015; 112:E2766-74. [PMID: 25901328 PMCID: PMC4450420 DOI: 10.1073/pnas.1503054112] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the active sites of odorant receptors (ORs), serving as a sensitive measure of odorant vibrational frequencies, ultimately leading to olfactory perception. A previous study reported that human subjects differentiated hydrogen/deuterium isotopomers (isomers with isotopic atoms) of the musk compound cyclopentadecanone as evidence supporting the theory. Here, we find no evidence for such differentiation at the molecular level. In fact, we find that the human musk-recognizing receptor, OR5AN1, identified using a heterologous OR expression system and robustly responding to cyclopentadecanone and muscone, fails to distinguish isotopomers of these compounds in vitro. Furthermore, the mouse (methylthio)methanethiol-recognizing receptor, MOR244-3, as well as other selected human and mouse ORs, responded similarly to normal, deuterated, and (13)C isotopomers of their respective ligands, paralleling our results with the musk receptor OR5AN1. These findings suggest that the proposed vibration theory does not apply to the human musk receptor OR5AN1, mouse thiol receptor MOR244-3, or other ORs examined. Also, contrary to the vibration theory predictions, muscone-d30 lacks the 1,380- to 1,550-cm(-1) IR bands claimed to be essential for musk odor. Furthermore, our theoretical analysis shows that the proposed electron transfer mechanism of the vibrational frequencies of odorants could be easily suppressed by quantum effects of nonodorant molecular vibrational modes. These and other concerns about electron transfer at ORs, together with our extensive experimental data, argue against the plausibility of the vibration theory.
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Affiliation(s)
- Eric Block
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222;
| | - Seogjoo Jang
- Department of Chemistry and Biochemistry, Queens College, and Graduate Center, City University of New York, Flushing, NY 11367;
| | - Hiroaki Matsunami
- Department of Molecular Genetics and Microbiology and Department of Neurobiology, Duke Institute for Brain Sciences, Duke University Medical Center, Durham, NC 27710;
| | | | - Bérénice Dethier
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222
| | - Mehmed Z Ertem
- Department of Chemistry, Yale University, New Haven, CT 06520; Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973
| | - Sivaji Gundala
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222
| | - Yi Pan
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and
| | - Shengju Li
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and
| | - Zhen Li
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and
| | - Stephene N Lodge
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222
| | - Mehmet Ozbil
- Department of Chemistry, Yale University, New Haven, CT 06520
| | - Huihong Jiang
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and
| | - Sonia F Penalba
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222
| | | | - Hanyi Zhuang
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and Institute of Health Sciences, Shanghai Jiao tong University School of Medicine/Shanghai Institutes for Biological Sciences of Chinese Academy of Sciences, Shanghai 200031, China
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Niimura Y, Matsui A, Touhara K. Extreme expansion of the olfactory receptor gene repertoire in African elephants and evolutionary dynamics of orthologous gene groups in 13 placental mammals. Genome Res 2014; 24:1485-96. [PMID: 25053675 PMCID: PMC4158756 DOI: 10.1101/gr.169532.113] [Citation(s) in RCA: 204] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Olfactory receptors (ORs) detect odors in the environment, and OR genes constitute the largest multigene family in mammals. Numbers of OR genes vary greatly among species—reflecting the respective species' lifestyles—and this variation is caused by frequent gene gains and losses during evolution. However, whether the extent of gene gains/losses varies among individual gene lineages and what might generate such variation is unknown. To answer these questions, we used a newly developed phylogeny-based method to classify >10,000 intact OR genes from 13 placental mammal species into 781 orthologous gene groups (OGGs); we then compared the OGGs. Interestingly, African elephants had a surprisingly large repertoire (∼2000) of functional OR genes encoded in enlarged gene clusters. Additionally, OR gene lineages that experienced more gene duplication had weaker purifying selection, and Class II OR genes have evolved more dynamically than those in Class I. Some OGGs were highly expanded in a lineage-specific manner, while only three OGGs showed complete one-to-one orthology among the 13 species without any gene gains/losses. These three OGGs also exhibited highly conserved amino acid sequences; therefore, ORs in these OGGs may have physiologically important functions common to every placental mammal. This study provides a basis for inferring OR functions from evolutionary trajectory.
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Affiliation(s)
- Yoshihito Niimura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan; ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo 113-8657, Japan
| | - Atsushi Matsui
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan; ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo 113-8657, Japan
| | - Kazushige Touhara
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan; ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo 113-8657, Japan
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Yoder WM, Setlow B, Bizon JL, Smith DW. Characterizing olfactory perceptual similarity using carbon chain discrimination in Fischer 344 rats. Chem Senses 2014; 39:323-31. [PMID: 24488965 DOI: 10.1093/chemse/bju001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Performance on olfactory tests can be influenced by a number of stimulus characteristics including chemical structure, concentration, perceptual similarity, and previous experience with the test odorants. Few of these parameters have been extensively characterized in the Fischer 344 rat strain. To investigate how odor quality affects perception in this rat strain, we measured how graded perceptual similarity, created by varying carbon chain length across a series of homologous alcohol pairs, influenced odor discrimination using a liquid-motivated go/no-go task. We employed an automated, liquid-dilution olfactometer to train Fischer 344 rats (N = 8) on a 2-odor discrimination task. Six odorants (1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol) were arranged to produce 15 novel odorant pairs differing between 1 and 5 carbon atoms; testing sessions included presentation of only 1 pseudorandomly assigned pair daily (200 trials). Results show that although rats can learn to discriminate between any 2 odorant pairs, performance declines systematically as the pairs become more structurally similar and, therefore, more perceptually confusing. As such, the easier discrimination pairs produced reliable ceiling effects across all rats, whereas performance for the difficult discrimination pairs was consistently worse, even after repeated testing. These data emphasize the importance of considering odorant stimulus dimensions in experimental designs employing olfactory stimuli. Moreover, establishing baseline olfactory performance in Fischer 344 rats may be particularly useful for predicting age-related cognitive decline in this model.
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Affiliation(s)
- Wendy M Yoder
- Department of Psychology, University of Florida, 114 Psychology Building, PO Box 11250, Gainesville, FL 32611, USA.
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