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Rich G, Stennett R, Galloway M, McClure M, Riley R, Freeman EW, Hunt KE. Nailing it: Investigation of elephant toenails for retrospective analysis of adrenal and reproductive hormones. CONSERVATION PHYSIOLOGY 2024; 12:coae048. [PMID: 39100510 PMCID: PMC11295213 DOI: 10.1093/conphys/coae048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 06/25/2024] [Accepted: 07/15/2024] [Indexed: 08/06/2024]
Abstract
Hormone monitoring of at-risk species can be valuable for evaluation of individual physiological status. Traditional non-invasive endocrine monitoring from urine and faeces typically captures only a short window in time, poorly reflecting long-term hormone fluctuations. We examined toenail trimmings collected from African (Loxodonta africana) and Asian (Elephas maximus) elephants during routine foot care, to determine if long-term hormone patterns are preserved in these slow-growing keratinized tissues. We first measured the growth rate of elephant toenails biweekly for one year, to establish the temporal delay between deposition of hormones into nail tissue (at the proximal nail bed) and collection of toenail trimmings months later (at the distal tip of the nail). In African elephants, toenails grew ~0.18 ± 0.015 mm/day (mean ± SEM) and in Asian elephants, toenails grew ~0.24 ± 0.034 mm/day. This slow growth rate, combined with the large toenail size of elephants, may mean that toenails could contain a 'hormone timeline' of over a year between the nail bed and nail tip. Progesterone, testosterone and cortisol were readily detectable using commercial enzyme immunoassays, and all assays passed validations, indicating that these hormones can be accurately quantified in elephant toenail extract. In most cases, variations in hormone concentrations reflected expected physiological patterns for adult females and males (e.g. ovarian cycling and musth) and matched individual health records from participating zoos. Progesterone patterns aligned with our calculations of temporal delay, aligning with female ovarian cycling from over six months prior. Unexpectedly, male testosterone patterns aligned with current musth status at the time of sample collection (i.e. rather than prior musth status). Though this sample type will require further study, these results indicate that preserved hormone patterns in elephant toenails could give conservationists a new tool to aid management of elephant populations.
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Affiliation(s)
- Garrett Rich
- Department of Biology, George Mason University, 4400 University Drive, Fairfax, VA 22030, USA
| | - Rebecca Stennett
- The Maryland Zoo in Baltimore, 1 Safari Place Baltimore, MD 21217, USA
| | - Marie Galloway
- Smithsonian’s National Zoo and Conservation Biology Institute, 3001 Connecticut Ave NW, Washington, DC 20008, USA
| | - Mike McClure
- The Maryland Zoo in Baltimore, 1 Safari Place Baltimore, MD 21217, USA
| | - Rebecca Riley
- Smithsonian’s National Zoo and Conservation Biology Institute, 3001 Connecticut Ave NW, Washington, DC 20008, USA
| | - Elizabeth W Freeman
- School of Integrative Studies, George Mason University, 4400 University Drive, Fairfax, VA 22030, USA
| | - Kathleen E Hunt
- Department of Biology, George Mason University, 4400 University Drive, Fairfax, VA 22030, USA
- Smithsonian-Mason School of Conservation, 1500 Remount Road, Front Royal, VA 22630, USA
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Reynolds-Hogland M, Brooks C, Ramsey AB, Hogland JS, Pilgrim KL, Engkjer C, Ramsey PW. Long-term video and genetic data yield insights into complex sociality of a solitary large carnivore. Behav Processes 2024; 214:104972. [PMID: 38016596 DOI: 10.1016/j.beproc.2023.104972] [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: 09/29/2023] [Revised: 11/14/2023] [Accepted: 11/22/2023] [Indexed: 11/30/2023]
Abstract
American black bears (Ursus americanus) may be more social than currently understood. We used long-term video and genetic data to evaluate social interactions among wild, independent-aged black bear on a conservation property in western Montana, USA. We used multinomial logistic regression to evaluate predictions about male-male interactions within the context of individual fitness, female-female interactions within the context of inclusive fitness, and male-female interactions within the context of female counterstrategies to infanticide. Overall, our findings challenged the assumption that independent-aged bears interact only during the mating season or when concentrated feeding sites are present. We documented 169 interaction events by at least 66 bear pairs, 92 (54%) of which occurred outside of the peak mating season and in the absence of concentrated feeding sites. The probability that male-male pairs engaged in play and other non-agonistic behaviours was higher than that for female-female pairs. Conversely, the probability that female-female pairs engaged in chase behaviour was higher than that for male-male and male-female pairs. We documented evidence of female mate choice, female resource defense, sexually selected infanticide (SSI), and female counterstrategies to avoid SSI. Our findings improve our understanding of ursid ethology and underscore the complexity of ursid sociality.
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Affiliation(s)
| | | | | | - John S Hogland
- USDA Forest Service, USFS Rocky Mountain Research Station, Missoula, MT 59801, USA
| | - Kristine L Pilgrim
- USDA National Genomics Center, USFS Rocky Mountain Research Station, Missoula, MT 59801, USA
| | - Cory Engkjer
- USDA National Genomics Center, USFS Rocky Mountain Research Station, Missoula, MT 59801, USA
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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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Marliani G, Gelli D, Bellinello E, Costantin RS, Nicoloso S, Accorsi PA, Vaglio S. Effects of pharmacological castration on endocrinological and chemical profiles in captive red and fallow deer. THE EUROPEAN ZOOLOGICAL JOURNAL 2023. [DOI: 10.1080/24750263.2023.2190351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023] Open
Affiliation(s)
- G. Marliani
- Department of Veterinary Sciences, University of Bologna, Ozzano Emilia, Italy
- Animal Behaviour & Wildlife Conservation Group, School of Life Sciences, University of Wolverhampton, Wolverhampton, UK
| | - D. Gelli
- Department of Animal Medicine, Production and Health, University of Padua, Legnaro, Italy
| | - E. Bellinello
- Azienda USL Bologna, Sanità Pubblica veterinaria, Vergato, Italy
| | | | | | - P. A. Accorsi
- Department of Veterinary Sciences, University of Bologna, Ozzano Emilia, Italy
| | - S. Vaglio
- Animal Behaviour & Wildlife Conservation Group, School of Life Sciences, University of Wolverhampton, Wolverhampton, UK
- University College–The Castle, Durham University, Durham, UK
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LaDue CA, Hunt KE, Kiso WK, Freeman EW. Hormonal variation and temporal dynamics of musth in Asian elephants ( Elephas maximus) are associated with age, body condition and the social environment. CONSERVATION PHYSIOLOGY 2023; 11:coad019. [PMID: 38026805 PMCID: PMC10660383 DOI: 10.1093/conphys/coad019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 03/23/2023] [Accepted: 03/27/2023] [Indexed: 12/01/2023]
Abstract
The sustainability of endangered Asian elephants in human care is threatened in part by low breeding success and concerns over individual animal wellbeing. Male elephants have received less research attention compared to females, yet males deserve special consideration due to their unique reproductive biology (particularly the sexual state of "musth") and the complex interaction of physiological, environmental, and social pressures they face. We measured fecal androgen metabolites (FAMs), fecal glucocorticoid metabolites (FGMs), and fecal triiodothyronine metabolites (FT3s) collected weekly over approximately 12 months from 26 male Asian elephants housed in zoos across the US, hypothesizing that FAM, FGM, and FT3 concentrations would be associated with temporal correlates of musth and would vary further with intrinsic (musth status, age, body condition) and extrinsic (social environment) factors. The duration of each musth episode was positively associated with exposure to male conspecifics and negatively associated with body condition. Further, elevated FAM concentrations were associated with social exposure, age, and body condition, and FGM concentrations also varied with age and body condition. FT3 concentrations were not associated with any factor we measured. We also identified periods of lower FAM concentration than confirmed musth episodes (but still higher than baseline FAM concentrations) that we termed "elevated FAM episodes." The durations of these episodes were negatively correlated with exposure to other male elephants. Together, these results provide evidence that hormone profiles (including those that are predicted to change around musth) vary significantly between male Asian elephants in a way that may be attributed to intrinsic and extrinsic factors. Studies like these serve to enhance the sustainability of ex-situ populations by providing wildlife managers with information to enhance the health, welfare, and reproduction of threatened species like Asian elephants.
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Affiliation(s)
- Chase A LaDue
- Department of Environmental Science and Policy, 4400 University Drive, MSN 5F2, George Mason University, Fairfax, VA 22030, USA
- Oklahoma City Zoo and Botanical Garden, 2000 Remington Place, Oklahoma City, OK 73111, USA
| | - Kathleen E Hunt
- Department of Biology, George Mason University, 10900 University Boulevard, Manassas, VA 20110, USA
- Smithsonian-Mason School of Conservation, 1500 Remount Road, Front Royal, VA 22630, USA
| | - Wendy K Kiso
- White Oak Conservation Foundation, 581705 White Oak Road, Yulee, FL 32097, USA
- Colossal Biosciences, 3309 Elm Street, Dallas, TX 75226, USA
| | - Elizabeth W Freeman
- School of Integrative Studies, 4400 University Drive, MSN 5D3, George Mason University, Fairfax, VA 22030, USA
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Age and Social History Impact Social Interactions between Bull Asian Elephants (Elephas maximus) at Denver Zoo. JOURNAL OF ZOOLOGICAL AND BOTANICAL GARDENS 2023. [DOI: 10.3390/jzbg4010018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023] Open
Abstract
Wild bull Asian elephants spend time in all-male groups. Therefore, managers of ex situ populations increasingly house bulls together. We examined the social interactions of five bull Asian elephants at Denver Zoo, using instantaneous sampling to compare social interactions across adolescent and mature bulls, and bulls with a social history prior to the integration of this group compared to bulls with no social history. Both age and social history significantly affected bull behavior. Adolescent bulls exhibited more affiliative and submissive behaviors when housed with mixed-age and mature social partners compared to with only adolescents, and less non-contact agonistic behavior and less time in proximity to a conspecific with mixed-age groups compared to with only other adolescents. Mature bulls exhibited more affiliative behavior when they were with only adolescent bulls compared to only mature bulls, and more time in proximity to a conspecific and increased contact agonistic behavior with at least one adolescent compared to only mature bulls. Bulls in new social groups engaged in more affiliative, agonistic, and submissive behaviors, and spent less time in proximity, than when they were in previously established social combinations. As more institutions house bulls socially, our results provide insights into factors that may affect bull social interactions.
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Elephant Scar Prevalence in the Kasigau Wildlife Corridor, Kenya: Echoes of Human-Elephant Conflict. Animals (Basel) 2023; 13:ani13040605. [PMID: 36830392 PMCID: PMC9951691 DOI: 10.3390/ani13040605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 02/03/2023] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
Human-elephant conflict (HEC) compromises crop security and threatens elephant conservation. Most commonly, HEC manifests as crop-foraging as elephants modify natural foraging strategies to incorporate crops. Farmers may retaliate by frightening or harming elephants, leaving scars from inflicted wounds. We assessed the prevalence and distribution of scars on the bodies of African savanna elephants (Loxodonta africana) observed in the Kasigau Wildlife Corridor (KWC), part of the Greater Tsavo Ecosystem of Kenya, where conflict is prevalent. We surmised that scars on the body are largely a result of HEC as opposed to scars on the rump or head, which we attributed primarily to elephant-elephant conflict. We hypothesized that: (1) male elephants would have more scars than females; (2) older males would be more likely to have scars than younger males; and (3) most scars would be located on the bodies of elephants. We assessed scars from a photographic catalogue of elephants from the KWC. In line with our hypotheses, male elephants were more likely to have scars than females (32% of males compared to 6% of females); older males had significantly more scars than younger males (61% compared to 24%); and the majority of scars (89%) were located on the body. Scar presence may be useful as an animal-centered indicator to estimate the prevalence and demographic patterns of HEC.
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Understanding the spatial distribution and hot spots of collared Bornean elephants in a multi-use landscape. Sci Rep 2022; 12:12830. [PMID: 35896774 PMCID: PMC9329282 DOI: 10.1038/s41598-022-16630-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 07/13/2022] [Indexed: 11/08/2022] Open
Abstract
In the Kinabatangan floodplain, Sabah, Malaysian Borneo, oil palm and settlements have reduced and fragmented lowland tropical forests, home to around 200 endangered Bornean elephants (Elephas maximus borneensis). In this region, elephants range within forests, oil palm and community areas. The degree to which elephants are using these areas remains unclear. We used GPS telemetry data from 2010 to 2020 for 14 collared elephants to map their entire known ranges and highly used areas (hot spots) across four land use categories and estimate time spent within these. The use of land use types across elephants varied significantly. Typically, females had strong fidelity to forests, yet many of these forests are threatened with conversion. For the three males, and several females, they heavily used oil palm estates, and this may be due to decreased landscape permeability or foraging opportunities. At the pooled level, the entire range and hot spot extents, constituted 37% and 34% for protected areas, respectively, 8% and 11% for unprotected forests, 53% and 51% for oil palm estates, and 2% for community areas. Protecting all forested habitats and effectively managing areas outside of protected areas is necessary for the long-term survival of this population.
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Characterization of Longitudinal Testosterone, Cortisol, and Musth in Male Asian Elephants ( Elephas maximus), Effects of Aging, and Adrenal Responses to Social Changes and Health Events. Animals (Basel) 2022; 12:ani12101332. [PMID: 35625178 PMCID: PMC9137588 DOI: 10.3390/ani12101332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/04/2022] [Accepted: 05/19/2022] [Indexed: 01/09/2023] Open
Abstract
Simple Summary The conservation of endangered species and sustainability of managed populations requires good health and welfare of individuals. Male elephants experience a biological phenomenon called “musth”, characterized by a suite of physiological and behavioral changes which serve to facilitate copulation between the sexes, but can also pose unique challenges under human care. This study characterized longitudinal patterns of circulating testosterone and cortisol in relation to musth in four adult Asian elephant bulls and assessed age-related effects on musth activity and adrenal responses to social changes and clinical health events. All bulls exhibited regular annual musth cycles, and there was no clear evidence of chronically elevated cortisol secretion outside of musth. Circulating cortisol covaried positively with testosterone and musth, highlighting intrinsic patterns that should be considered when evaluating the impact of changes on adrenal glucocorticoid activity. Testosterone decreased with age in sexually mature bulls, whereas age-related changes in cortisol varied across individuals, with the three older bulls showing the greatest rate of change during musth. Changes in cortisol were associated with treatment for Mycobacterium tuberculosis in two bulls, but not with activation of disease. In contrast to physiological factors, there was no evidence that social changes involving male herdmates impacted adrenal glucocorticoid activity in the short term. This study highlights the importance of longitudinal hormone monitoring to track changes in physiological function and identify factors that may influence welfare, which is important for making more informed decisions on how to manage male elephants under varying degrees of human care. Abstract The conservation of endangered species and sustainability of managed populations requires considerations to ensure the health and welfare of individuals. Male elephants experience a biological phenomenon called “musth”, which is characterized by increased testosterone production, temporal gland secretion and urine dribbling, heightened aggression and sexual behavior, and therefore can pose unique challenges for human safety and animal welfare. This study characterized longitudinal (9 to 22 years) patterns of circulating testosterone and cortisol in relation to musth in four adult Asian elephant bulls spanning ages from 12 to 54 years. Age-related effects on musth activity and adrenal responses to social changes and clinical health events were also examined. All bulls exhibited regular annual musth cycles. Circulating cortisol covaried positively with testosterone and musth, highlighting intrinsic patterns that should be considered when evaluating the impact of social, health, and environmental changes on adrenal glucocorticoid activity. Except for an end-of-life cortisol increase in one bull, there was no clear evidence of chronically elevated cortisol secretion outside of musth in any individual. Testosterone decreased with age in sexually mature bulls, whereas age-related changes in cortisol varied across individuals, with the three older bulls showing the greatest rate of change during musth versus inter-musth periods. In contrast to physiological factors, there was no evidence of social factors, such as addition of a new male and death of male herdmates, impacting adrenal glucocorticoid activity in these bulls in the short term. Changes in cortisol were associated with treatment for Mycobacterium tuberculosis (M. tb) in two bulls, increasing after start of treatment and decreasing with cessation of treatment, but were not clearly associated with activation of disease. This study highlights the importance of longitudinal hormone monitoring to track changes in physiological function and responses to social, health, and environmental change in elephant bulls, which is important for making more informed decisions on how to manage male elephants under varying degrees of human care to ensure welfare and safety.
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Social Behavior and Group Formation in Male Asian Elephants (Elephas maximus): The Effects of Age and Musth in Wild and Zoo-Housed Animals. Animals (Basel) 2022; 12:ani12091215. [PMID: 35565641 PMCID: PMC9100748 DOI: 10.3390/ani12091215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 05/03/2022] [Accepted: 05/06/2022] [Indexed: 12/10/2022] Open
Abstract
Simple Summary The conservation of wild and zoo-housed Asian elephants partly depends on developing our understanding of male elephant social behavior. Once thought to be solitary, we now know that male elephants can display rich social exchanges with both males and females. However, these interactions are expected to change with age and around the sexually active state of “musth.” We used behavioral data from wild and zoo-housed elephant populations to investigate how age, musth, and environmental factors influence how male elephants socialize and associate with group members. In Sri Lanka, only male elephants of older age (>20 years) exhibited signs of musth, but even some of the youngest zoo-housed elephants underwent musth (as young as 11 years). Additionally, we found that age and musth status predicted whether a wild male elephant associated with females, other males or was alone, as well as the number of conspecifics (males and females) in the same group with which a male was observed. Finally, rates of aggression, prosocial behavior (affiliative behaviors that promote positive social bonds between elephants), and submissive behavior exhibited by wild and zoo-housed male elephants were associated with age, musth status, the number of elephants presented, and group type (all-male or mixed sex). These results provide motivation for future studies of social behavior in male Asian elephants, as they will contribute to the reproduction and conservation of this endangered species. Abstract Asian elephants are endangered, and the long-term viability of the species depends on integrative approaches to address the sustainability of in-situ and ex-situ populations. Growing evidence shows that male elephants exhibit extensive and flexible social behavior that rivals the complexity of that of females. Male elephant sociality is expected to change dramatically around the unique sexual state of musth. However, data related to male Asian elephant sociality is lacking. Here, we conducted complementary observations in Wasgamuwa National Park, Sri Lanka, and North American zoos of male Asian elephant social behavior. Age and musth status, along with other factors, were associated with variation in social behavior and group formation of males. In wild male elephants, both musth status and age impacted elephant associations within all-male and mixed-sex groups: non-musth elephants were generally sighted less often in mixed-sex groups as they aged, while the inverse occurred with musth elephants. Musth status interacted with age to predict the number of conspecifics with which a wild male elephant associated: younger males were observed with more females during non-musth (but the opposite was true during musth), and male elephants between 20 and 30 years were observed with the highest number of male conspecifics except during musth. Finally, we found variation in aggression, prosocial behavior, and submissive behavior was influenced by intrinsic (age and musth status) and extrinsic factors (group size and type) in similar ways in both populations; prosocial behavior was most common and was influenced by the number of conspecifics present (both populations), and age, group type, and musth status (zoo population), while aggression was rare, especially among older elephants. We suggest that longitudinal studies of this threatened species will be particularly helpful to promote the reproduction and conservation of Asian elephants in in-situ and ex-situ environments.
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Vijendravarma RK, Leopold P. Non-visual cues and indirect strategies that enable discrimination of asymmetric mates. Ecol Evol 2022; 12:e8790. [PMID: 35386879 PMCID: PMC8975790 DOI: 10.1002/ece3.8790] [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: 05/17/2021] [Accepted: 03/16/2022] [Indexed: 11/12/2022] Open
Abstract
The postulates of developmental instability-sexual selection hypothesis is intensely debated among evolutionary biologists, wherein despite a large amount of empirical data, evidence for or against it has been largely inconclusive. A key assumption of this hypothesis is that animals assess symmetry in potential mates as an indicator of genetic quality (developmental stability), and consequently use this information to discriminate against those with higher asymmetries while choosing mates. However, the perceptional basis that must underlie such discriminatory behavior (is symmetry a signal or is symmetry signaled) is not clearly defined. It is also argued that since asymmetry levels in natural populations are very low, the low signal-to-noise ratio would make accurate assessment of symmetry both difficult and costly. Rather than attempting to validate this hypothesis or even as to whether animals assess mate symmetry, this review simply aims to examine the plausibility that animals perceive symmetry (directly or indirectly) and consequently discriminate against asymmetric mates in response to perceived irregularities during courtship. For this, we review mate choice and courtship literature to identify potential sensory cues that might advertise asymmetry or lead to discrimination of asymmetric individuals. Although signaling associated with mate choice is commonly multimodal, previous studies on asymmetry have mainly focused on visual perception. In the light of a recent study (Vijendravarma et al., 2022, Proceedings of the National Academy of Sciences of the United States of America, 119, e2116136119), this review attempts to balance this bias by emphasizing on non-visual perception of asymmetry. In conclusion, we discuss the methodological challenges associated with testing the role of multimodal cues in detecting mate asymmetry, and highlight the importance of considering ecological, behavioral, and evolutionary aspects of animals while interpreting empirical data that test such hypothesis.
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Affiliation(s)
- Roshan Kumar Vijendravarma
- Institut Curie – Centre de Recherche, Genetics and Developmental Biology UnitINSERM U934 / CNRS UMR3215ParisFrance
| | - Pierre Leopold
- Institut Curie – Centre de Recherche, Genetics and Developmental Biology UnitINSERM U934 / CNRS UMR3215ParisFrance
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Behavioral characterization of musth in Asian elephants (Elephas maximus): defining progressive stages of male sexual behavior in in-situ and ex-situ populations. Appl Anim Behav Sci 2022. [DOI: 10.1016/j.applanim.2022.105639] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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13
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du Plessis K, Ganswindt SB, Bertschinger H, Crossey B, Henley MD, Ramahlo M, Ganswindt A. Social and Seasonal Factors Contribute to Shifts in Male African Elephant ( Loxodonta africana) Foraging and Activity Patterns in Kruger National Park, South Africa. Animals (Basel) 2021; 11:ani11113070. [PMID: 34827802 PMCID: PMC8614333 DOI: 10.3390/ani11113070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/16/2021] [Accepted: 10/18/2021] [Indexed: 11/16/2022] Open
Abstract
African savannah elephants (Loxodonta africana) are well-known as ecosystem engineers with the ability to modify vegetation structure. The present study aimed to examine how male elephant foraging behaviour is affected across (a) season (wet versus dry); (b) time of day (before or after noon); (c) presence or absence of other elephants; and (d) reproductive state (musth versus no musth). Six radio-collared adult elephant bulls were observed twice per week from June 2007-June 2008 in Kruger National Park (KNP), South Africa. Using generalized linear mixed effect modeling, results indicate that elephant bulls graze more during the wet season and browse more during the dry season. To potentially offset the costs associated with thermoregulation during the heat of the day, KNP elephants spent more time foraging during the morning, and more time resting during the afternoon. Male elephants also foraged significantly less when they were associated with females compared to when they were alone or with other males. This is likely due to male-female associations formed mainly for reproductive purposes, thus impeding on male foraging behaviours. In contrast, the condition of musth, defined by the presence of related physical signs, had no significant effect on foraging behaviour.
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Affiliation(s)
- Kara du Plessis
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa; (S.B.G.); (B.C.); (M.R.); (A.G.)
- Correspondence:
| | - Stefanie Birgit Ganswindt
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa; (S.B.G.); (B.C.); (M.R.); (A.G.)
| | - Henk Bertschinger
- Veterinary Population Management Laboratory, Section of Reproduction, Department of Production Animal Studies, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa;
| | - Bruce Crossey
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa; (S.B.G.); (B.C.); (M.R.); (A.G.)
| | - Michelle Deborah Henley
- Applied Behavioural Ecology and Ecosystem Research Unit, School of Environmental Sciences, University of South Africa, Private Bag X5, Florida 1710, South Africa;
- Elephants Alive, P.O. Box 960, Hoedspruit 1380, South Africa
| | - Mmatsawela Ramahlo
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa; (S.B.G.); (B.C.); (M.R.); (A.G.)
| | - André Ganswindt
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa; (S.B.G.); (B.C.); (M.R.); (A.G.)
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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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