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Orlando CG, Banks PB, Latty T, McArthur C. To eat, or not to eat: a phantom decoy affects information-gathering behavior by a free-ranging mammalian herbivore. Behav Ecol 2023; 34:759-768. [PMID: 37744169 PMCID: PMC10516680 DOI: 10.1093/beheco/arad057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 06/09/2023] [Accepted: 06/28/2023] [Indexed: 09/26/2023] Open
Abstract
When foraging, making appropriate food choices is crucial to an animal's fitness. Classic foraging ecology theories assume animals choose food of greatest benefit based on their absolute value across multiple dimensions. Consequently, poorer options are considered irrelevant alternatives that should not influence decision-making among better options. But heuristic studies demonstrate that irrelevant alternatives (termed decoys) can influence the decisions of some animals, indicating they use a relative rather than absolute evaluation system. Our aim was to test whether a decoy influenced the decision-making process-that is, information-gathering and food choice-of a free-ranging mammalian herbivore. We tested swamp wallabies, Wallabia bicolor, comparing their behavior toward, and choice of, two available food options over time in the absence or presence of the decoy. We used a phantom decoy-unavailable option-and ran two trials in different locations and seasons. Binary preferences (decoy absent) for the two available food options differed between trials. Irrespective of this difference, across both trials the presence of the decoy resulted in animals more likely to overtly investigate available food options. But, the decoy only shifted food choice, weakly, in one trial. Our results indicate that the decoy influenced the information-gathering behavior during decision-making, providing the first evidence that decoys can affect decision-making process of free-ranging mammalian herbivores in an ecologically realistic context. It is premature to say these findings confirm the use of relative evaluation systems. Whether the foraging outcome is more strongly affected by other decoys, food dimensions, or ecological contexts, is yet to be determined.
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Affiliation(s)
- Cristian Gabriel Orlando
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence Building A08, Science Rd., Camperdown, Sydney, NSW 2050, Australia
| | - Peter B Banks
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence Building A08, Science Rd., Camperdown, Sydney, NSW 2050, Australia
| | - Tanya Latty
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence Building A08, Science Rd., Camperdown, Sydney, NSW 2050, Australia
| | - Clare McArthur
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence Building A08, Science Rd., Camperdown, Sydney, NSW 2050, Australia
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2
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Yoneya K, Miki T, Katayama N. Plant volatiles and priority effects interactively determined initial community assembly of arthropods on multiple willow species. Ecol Evol 2023; 13:e10270. [PMID: 37492458 PMCID: PMC10364932 DOI: 10.1002/ece3.10270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 06/15/2023] [Accepted: 06/19/2023] [Indexed: 07/27/2023] Open
Abstract
Plant traits, which are often species specific, can serve as environmental filtering for community assembly on plants. At the same time, the species identity of the initially colonizing arthropods would vary between plant individuals, which would subsequently influence colonizing arthropods and community development in the later stages. However, it remains unclear whether interindividual divergence due to priority effects is equally important as plant trait-specific environmental filtering in the initial stages. In this study, we propose that plant volatile organic compounds (PVOCs) may play a crucial role as an environmental filter in the initial stages of community assembly, which can prevent the community assembly process from being purely stochastic. To test this hypothesis, we conducted short term but highly frequent monitoring (19 observations over 9 days) of arthropod community assembly on intact individuals of six willow species in a common garden. PVOC compositions were analyzed before starting the experiment and compared with arthropod compositions occurring on Days 1-2 of the experiment (earliest colonizer community) and those occurring on Days 8-9 of the experiment (subsequent colonizer community). Unintentionally, deer herbivory also occurred at night of Day 2. Distance-based statistics demonstrated that PVOC compositions were plant species specific, but neither the earliest colonizer nor the subsequent colonizer community composition could be explained by plant species identity. Rather, Procrustes analysis showed that both the PVOC composition and that of the earliest colonizer community can be used to explain the subsequent colonizer community. In addition, the linkage between PVOCs and the subsequent colonizer community was stronger on individuals with deer herbivory. These findings indicate that PVOCs have widespread effects on initial community assembly, as well as priority effects brought on by stochastic immigration, and that plant species identity only has weak and indirect effects on the actual composition of the community.
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Affiliation(s)
- Kinuyo Yoneya
- Faculty of AgricultureKindai UniversityNaraJapan
- Center for Biodiversity ScienceRyukoku UniversityOtsuJapan
| | - Takeshi Miki
- Center for Biodiversity ScienceRyukoku UniversityOtsuJapan
- Faculty of Advanced Science and TechnologyRyukoku UniversityOtsuJapan
| | - Noboru Katayama
- General EducationFaculty of CommerceOtaru University of CommerceOtaruJapan
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3
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Escobar-Bravo R, Lin PA, Waterman JM, Erb M. Dynamic environmental interactions shaped by vegetative plant volatiles. Nat Prod Rep 2023; 40:840-865. [PMID: 36727645 PMCID: PMC10132087 DOI: 10.1039/d2np00061j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Indexed: 02/03/2023]
Abstract
Covering: up to November 2022Plants shape terrestrial ecosystems through physical and chemical interactions. Plant-derived volatile organic compounds in particular influence the behavior and performance of other organisms. In this review, we discuss how vegetative plant volatiles derived from leaves, stems and roots are produced and released into the environment, how their production and release is modified by abiotic and biotic factors, and how they influence other organisms. Vegetative plant volatiles are derived from different biosynthesis and degradation pathways and are released via distinct routes. Both biosynthesis and release are regulated by other organisms as well as abiotic factors. In turn, vegetative plant volatiles modify the physiology and the behavior of a wide range of organisms, from microbes to mammals. Several concepts and frameworks can help to explain and predict the evolution and ecology of vegetative plant volatile emission patterns of specific pathways: multifunctionality of specialized metabolites, chemical communication displays and the information arms race, and volatile physiochemistry. We discuss how these frameworks can be leveraged to understand the evolution and expression patterns of vegetative plant volatiles. The multifaceted roles of vegetative plant volatiles provide fertile grounds to understand ecosystem dynamics and harness their power for sustainable agriculture.
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Affiliation(s)
| | - Po-An Lin
- Department of Entomology, National Taiwan University, Taipei, Taiwan
| | - Jamie M Waterman
- Institute of Plant Sciences, University of Bern, Bern, Switzerland.
| | - Matthias Erb
- Institute of Plant Sciences, University of Bern, Bern, Switzerland.
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4
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The deterrent effects of individual monoterpene odours on the dietary decisions of African elephants. Anim Cogn 2023; 26:1049-1063. [PMID: 36800131 PMCID: PMC10066090 DOI: 10.1007/s10071-023-01755-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 01/24/2023] [Accepted: 02/06/2023] [Indexed: 02/18/2023]
Abstract
African savanna elephants use pre-ingestive olfactory cues when making dietary choices, and previous research has observed that elephant diet choice is negatively correlated with vegetation species that contain high concentrations of monoterpenes. However, the frequency and concentration of monoterpenes can vary dramatically across plant species. Thus, we aimed to explore the effects that the odours of individual monoterpenes have on elephant diet choice and how these effects vary with concentration. To do this, we conducted three odour-based choice experiments focusing on eight common monoterpenes found in the woody plants in Southern African savannas. In the first experiment, we tested whether elephant diet choice for a frequently consumed plant (Euclea crispa) was influenced by the addition of the odour of an individual monoterpene at a set concentration. In the second experiment, we explored the relative deterrence of each monoterpene. Lastly, we tested how elephant diet choice varied as a function of the addition of individual monoterpene odours at 5%, 10%, and 20% concentrations. We found that the elephants avoided most individual monoterpenes at high concentrations, with the exception being α-pinene. Furthermore, we found that the odours of some individual monoterpenes were, in fact, more deterrent than others. In the third experiment, we found that the elephants avoided β-pinene, limonene, ocimene, γ-terpinene, and terpinolene across all concentrations, but only avoided sabinene and linalool at high concentrations. Ultimately, our results show that the odour of individual monoterpenes may deter elephant consumption, but that this deterrent effect depends on both the monoterpene and its concentration.
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Orlando CG, Possell M, Price C, Banks PB, Mercorelli L, McArthur C. A new conceptual and quantitative approach to exploring and defining potential open-access olfactory information. THE NEW PHYTOLOGIST 2022; 236:1605-1619. [PMID: 35975694 PMCID: PMC9826502 DOI: 10.1111/nph.18432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
All organisms emit odour, providing 'open-access' olfactory information for any receiver with the right sensory apparatus. Characterizing open-access information emitted by groups of organisms, such as plant species, provides the means to answer significant questions about ecological interactions and their evolution. We present a new conceptual framework defining information reliability and a practical method to characterize and recover information from amongst olfactory noise. We quantified odour emissions from two tree species, one focal group and one outgroup, to demonstrate our approach using two new R statistical functions. We explore the consequences of relaxing or tightening criteria defining information and, from thousands of odour combinations, we identify and quantify those few likely to be informative. Our method uses core general principles characterizing information while incorporating knowledge of how receivers detect and discriminate odours. We can now map information in consistency-precision reliability space, explore the concept of information, and test information-noise boundaries, and between cues and signals.
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Affiliation(s)
| | - Malcolm Possell
- School of Life and Environmental SciencesThe University of SydneySydneyNSW2006Australia
| | - Catherine Price
- School of Life and Environmental SciencesThe University of SydneySydneyNSW2006Australia
| | - Peter B. Banks
- School of Life and Environmental SciencesThe University of SydneySydneyNSW2006Australia
| | - Louis Mercorelli
- The Sydney Informatics HubThe University of SydneySydneyNSW2006Australia
| | - Clare McArthur
- School of Life and Environmental SciencesThe University of SydneySydneyNSW2006Australia
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6
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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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Pandraud A, Shrader AM, Tshipa A, Ngwenya N, Chamaillé-Jammes S. Cueing on distant conditions before migrating does not prevent false starts: a case study with African elephants. Oecologia 2022; 198:957-966. [DOI: 10.1007/s00442-022-05148-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 02/27/2022] [Indexed: 10/18/2022]
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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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10
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Scogings PF, Demmer S, Hattas D. Spinescence and Total Phenolic Content Do Not Influence Diet Preference of a Critically Endangered Megaherbivore, but the Mix of Compounds Does. J Chem Ecol 2021; 47:322-333. [PMID: 33651225 DOI: 10.1007/s10886-021-01258-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 02/17/2021] [Accepted: 02/23/2021] [Indexed: 11/30/2022]
Abstract
In contrast to understanding spinescence in savanna woody species, little is known about the functions of plant secondary metabolites (PSM). Negative effects of PSMs on individual animal performance potentially translate into negative effects on herbivore population growth. Hence, understanding PSM functions is important for the conservation of savanna megafauna. We tested the view that black rhinoceros (Diceros bicornis) diet preference is not affected by spinescence or total phenolic abundance. We hypothesized that the composition of phenolic mixtures, however, would affect preference. Furthermore, we tested our data from 71 woody species for a trade-off between structural and chemical defenses. Spinescence type, and spinescence generally, did not deter black rhino feeding. Using eco-metabolomic data, we found that total abundance of phenolics did not affect preference, but mixture composition did and that the probability of spinescence trading off against phenolics depended on the mixture. We note that our study was restricted to black rhino and that diet preferences of other mammal herbivores might be influenced by subtle differences in phenolic mixtures. However, our results did support a previous, more detailed study of phenolic profiles of six species showing the same patterns in relation to preference generalised across mammal herbivore species in savannas. Our results represent substantial advancement in the understanding of the roles of PSMs, especially flavonoid compounds, in the functioning of savanna ecosystems, and highlight the need to dig deeper into broad groups of traits such as spinescence or total phenolics to improve understanding of woody plant defenses in savannas.
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Affiliation(s)
- Peter F Scogings
- School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa.
| | - Stuart Demmer
- School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa.,Centre for Functional Biodiversity, University of KwaZulu-Natal, Scottsville, South Africa
| | - Dawood Hattas
- Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa
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11
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Gazit I, Goldblatt A, Grinstein D, Terkel J. Dogs can detect the individual odors in a mixture of explosives. Appl Anim Behav Sci 2021. [DOI: 10.1016/j.applanim.2020.105212] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Jim HL, Range F, Marshall-Pescini S, Dale R, Plotnik JM. Investigating Indirect and Direct Reputation Formation in Asian Elephants ( Elephas maximus). Front Psychol 2021; 11:604372. [PMID: 33519611 PMCID: PMC7841644 DOI: 10.3389/fpsyg.2020.604372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/17/2020] [Indexed: 11/17/2022] Open
Abstract
Reputation is a key component in social interactions of group-living animals and appears to play a role in the establishment of cooperation. Animals can form a reputation of an individual by directly interacting with them or by observing them interact with a third party, i.e., eavesdropping. Elephants are an interesting taxon in which to investigate eavesdropping as they are highly cooperative, large-brained, long-lived terrestrial mammals with a complex social organisation. The aim of this study was to investigate whether captive Asian elephants (Elephas maximus) could form reputations of humans through indirect and/or direct experience in two different paradigms: (1) a cooperative string-pulling task and (2) a scenario requiring begging. Fourteen captive Asian elephants in Thailand participated in an experimental procedure that consisted of three parts: baseline, observation, and testing. In the observation phase, the subject saw a conspecific interact with two people-one cooperative/generous and one non-cooperative/selfish. The observer could then choose which person to approach in the test phase. The elephants were tested in a second session 2-5 days later. We found no support for the hypothesis that elephants can form reputations of humans through indirect or direct experience, but these results may be due to challenges with experimental design rather than a lack of capacity. We discuss how the results may be due to a potential lack of ecological validity in this study and the difficulty of assessing motivation and attentiveness in elephants. Furthermore, we highlight the importance of designing future experiments that account for the elephants' use of multimodal sensory information in their decision-making.
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Affiliation(s)
- Hoi-Lam Jim
- Domestication Lab, Department of Interdisciplinary Life Sciences, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Friederike Range
- Domestication Lab, Department of Interdisciplinary Life Sciences, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Sarah Marshall-Pescini
- Domestication Lab, Department of Interdisciplinary Life Sciences, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Rachel Dale
- Domestication Lab, Department of Interdisciplinary Life Sciences, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine Vienna, Vienna, Austria
- Department for Psychotherapy and Biopsychosocial Health, Danube University Krems, Krems, Austria
| | - Joshua M. Plotnik
- Department of Psychology, Hunter College, City University of New York, New York, NY, United States
- Department of Psychology, The Graduate Center, City University of New York, New York, NY, United States
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Valenta K, Schmitt MH, Ayasse M, Nevo O. The sensory ecology of fear: African elephants show aversion to olfactory predator signals. CONSERVATION SCIENCE AND PRACTICE 2020. [DOI: 10.1111/csp2.333] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Kim Valenta
- Department of Anthropology University of Florida Gainesville Florida USA
| | - Melissa H. Schmitt
- Department of Ecology Evolution and Marine Biology University of California Santa Barbara Santa Barbara California USA
- South African Environmental Observation Network, Ndlovu Node Phalaborwa South Africa
| | - Manfred Ayasse
- Ulm University, Institute of Evolutionary Ecology and Conservation Genomics Ulm Germany
| | - Omer Nevo
- Ulm University, Institute of Evolutionary Ecology and Conservation Genomics Ulm Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐Leipzig Leipzig Germany
- Friedrich Schiller University Jena, Institute of Biodiversity Jena Germany
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14
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Valenta K, Schmitt MH, Ayasse M, Nevo O. Retracted: The sensory ecology of fear: African elephants show aversion to olfactory predator signals. CONSERVATION SCIENCE AND PRACTICE 2020. [DOI: 10.1111/csp2.306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Kim Valenta
- University of Florida, Department of Anthropology Gainesville Florida USA
| | - Melissa H. Schmitt
- University of California Santa Barbara, Department of Ecology Evolution and Marine Biology Santa Barbara California USA
- South African Environmental Observation Network Phalaborwa South Africa
| | - Manfred Ayasse
- Ulm University, Institute of Evolutionary Ecology and Conservation Genomics Ulm Germany
| | - Omer Nevo
- Ulm University, Institute of Evolutionary Ecology and Conservation Genomics Ulm Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐Leipzig Leipzig Germany
- Institute of Biodiversity Friedrich Schiller University Jena Jena Germany
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15
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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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16
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Orlando CG, Tews A, Banks P, McArthur C. The power of odour cues in shaping fine-scale search patterns of foraging mammalian herbivores. Biol Lett 2020; 16:20200329. [PMID: 32673541 DOI: 10.1098/rsbl.2020.0329] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Foraging by mammalian herbivores has profound impacts on natural and modified landscapes, yet we know little about how they find food, limiting our ability to predict and manage their influence. Mathematical models show that foragers exploiting odour cues outperform a random walk strategy. However, discovering how free-ranging foragers exploit odours in real, complex landscapes has proven elusive because of technological constraints. We took a novel approach, using a sophisticated purpose-built thermal camera system to record fine-scale foraging by a generalist mammalian herbivore, the swamp wallaby (Wallabia bicolor). We tested the hypothesis that odour cues shape forager movement and behaviour in vegetation patches. To do this, we compared wallaby foraging in two odour landscapes: Control (natural vegetation with food and non-food plants interspersed) and +Apple (the same natural vegetation plus a single, highly palatable food source with novel odour (apple)). The +Apple treatment led to strongly directed foraging by wallabies: earlier visits to vegetation patches, straighter movement paths, more hopping and fewer stops than in the Control treatment. Our results provide clear empirical evidence that odour cues are harnessed for efficient, directed search even at this fine scale. We conclude that random walk models miss a key feature shaping foraging within patches.
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Affiliation(s)
| | - Ashley Tews
- Cyber Physical Systems, Robotics and Autonomous Systems Group, CSIRO, Brisbane, QLD 4069, Australia
| | - Peter Banks
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Clare McArthur
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
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17
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Leiser-Miller LB, Kaliszewska ZA, Lauterbur ME, Mann B, Riffell JA, Santana SE. A Fruitful Endeavor: Scent Cues and Echolocation Behavior Used by Carollia castanea to Find Fruit. Integr Org Biol 2020; 2:obaa007. [PMID: 33791551 PMCID: PMC7671165 DOI: 10.1093/iob/obaa007] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Frugivores have evolved sensory and behavioral adaptations that allow them to find ripe fruit effectively, but the relative importance of different senses in varying foraging scenarios is still poorly understood. Within Neotropical ecosystems, short-tailed fruit bats (Carollia: Phyllostomidae) are abundant nocturnal frugivores that rely primarily on Piper fruits as a food resource. Previous research has demonstrated that Carollia employs olfaction and echolocation to locate Piper fruit, but it is unknown how their sensory use and foraging decisions are influenced by the complex diversity of chemical cues that fruiting plants produce. Using free-ranging C. castanea and their preferred food, Piper sancti-felicis, we conducted behavioral experiments to test two main hypotheses: (1) foraging decisions in C. castanea are primarily driven by ripe fruit scent and secondarily by vegetation scent, and (2) C. castanea re-weights their sensory inputs to account for available environmental cues, with bats relying more heavily on echolocation in the absence of adequate scent cues. Our results suggest that C. castanea requires olfactory information and relies almost exclusively on ripe fruit scent to make foraging attempts. Piper sancti-felicis ripe fruit scent is chemically distinct from vegetation scent; it is dominated by 2-heptanol, which is absent from vegetation scent, and has a greater abundance of β-caryophyllene, β-ocimene, γ-elemene, and α-cubebene. Although variation in echolocation call parameters was independent of scent cue presence, bats emitted longer and more frequent echolocation calls in trials where fruit scent was absent. Altogether, these results highlight the adaptations and plasticity of the sensory system in neotropical fruit bats.
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Affiliation(s)
- L B Leiser-Miller
- Department of Biology, University of Washington, Seattle, WA 98195, USA.,Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - Z A Kaliszewska
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - M E Lauterbur
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Brianna Mann
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - J A Riffell
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - S E Santana
- Department of Biology, University of Washington, Seattle, WA 98195, USA.,Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
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18
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Schmitt MH, Shuttleworth A, Shrader AM, Ward D. The role of volatile plant secondary metabolites as pre‐ingestive cues and potential toxins dictating diet selection by African elephants. OIKOS 2019. [DOI: 10.1111/oik.06665] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Melissa H. Schmitt
- School of Life Sciences, Univ. of KwaZulu‐Natal Private Bag X01 Scottsville 3209 South Africa
- South African Environmental Observation Network Ndlovu Node Phalaborwa South Africa
| | - Adam Shuttleworth
- School of Life Sciences, Univ. of KwaZulu‐Natal Private Bag X01 Scottsville 3209 South Africa
| | - Adrian M. Shrader
- School of Life Sciences, Univ. of KwaZulu‐Natal Private Bag X01 Scottsville 3209 South Africa
- Mammal Research Inst., Dept of Zoology and Entomology, Univ. of Pretoria Pretoria South Africa
| | - David Ward
- School of Life Sciences, Univ. of KwaZulu‐Natal Private Bag X01 Scottsville 3209 South Africa
- Biological Sciences, Kent State Univ Kent OH USA
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