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Volzke S, Cleeland JB, Hindell MA, Corney SP, Wotherspoon SJ, McMahon CR. Extreme polygyny results in intersex differences in age-dependent survival of a highly dimorphic marine mammal. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221635. [PMID: 36968236 PMCID: PMC10031410 DOI: 10.1098/rsos.221635] [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: 01/25/2023] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
Developmental differences in vital rates are especially profound in polygamous mating systems. Southern elephant seals (Mirounga leonina) are highly dimorphic and extremely polygynous marine mammals. A demographic model, supported by long-term capture-mark-recapture records, investigated the influence of sex and age on survival in this species. The study revealed clear differences between female and male age-dependent survival rates. Overall juvenile survival estimates were stable around 80-85% for both sexes. However, male survival estimates were 5-10% lower than females in the same age classes until 8 years of age. At this point, male survival decreased rapidly to 50% ± 10% while female estimates remained constant at 80% ± 5%. Different energetic requirements could underpin intersex differences in adult survival. However, the species' strong sexual dimorphism diverges during early juvenile development when sex-specific survival rates were less distinct. Maximizing growth is especially advantageous for males, with size being a major determinant of breeding probability. Maturing males may employ a high-risk high-reward foraging strategy to compensate for extensive sexual selection pressures and sex-specific energetic needs. Our findings suggest sex-specific adult survival is a result of in situ ecological interactions and evolutionary specialization associated with being a highly polygynous marine predator.
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Affiliation(s)
- Sophia Volzke
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7005, Australia
- Australian Antarctic Division, Department of Agriculture, Water and the Environment, Kingston, TAS 7050, Australia
| | - Jaimie B. Cleeland
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7005, Australia
- Australian Antarctic Division, Department of Agriculture, Water and the Environment, Kingston, TAS 7050, Australia
| | - Mark A. Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7005, Australia
| | - Stuart P. Corney
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7005, Australia
- Centre for Marine Socioecology, University of Tasmania, Hobart, TAS 7005, Australia
- Australian Antarctic Partnership Program, University of Tasmania, Hobart, TAS 7005, Australia
| | - Simon J. Wotherspoon
- Australian Antarctic Division, Department of Agriculture, Water and the Environment, Kingston, TAS 7050, Australia
| | - Clive R. McMahon
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7005, Australia
- IMOS Animal Tagging, Sydney Institute of Marine Science, Mosman, NSW 2088, Australia
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Movements of southern elephant seals (Mirounga leonina) from Davis Base, Antarctica: combining population genetics and tracking data. Polar Biol 2022. [DOI: 10.1007/s00300-022-03058-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
AbstractMarine animals such as the southern elephant seal (Mirounga leonina) rely on a productive marine environment and are vulnerable to oceanic changes that can affect their reproduction and survival rates. Davis Base, Antarctica, acts as a moulting site for southern elephant seals that forage in Prydz Bay, but the mitochondrial haplotype diversity and natal source populations of these seals have not been characterized. In this study, we combined genetic and animal tracking data on these moulting seals to identify levels of mitochondrial haplotype diversity, natal source population, and movement behaviours during foraging and haul-out periods. Using partial sequences of the mitochondrial control region, we identified two major breeding mitochondrial lineages of seals at Davis Base. We found that the majority of the seals originated from breeding stocks within the South Atlantic Ocean and South Indian Ocean. One seal was grouped with the Macquarie Island breeding stock (South Pacific Ocean). The Macquarie Island population, unlike the other two stocks, is decreasing in size. Tracking data revealed long-distance foraging activity of the Macquarie Island seal around Crozet Islands. We speculate that changes to the Antarctic marine environment can result in a shift in foraging and movement strategies, which subsequently affects seal population growth rates.
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Arce F, Hindell MA, McMahon CR, Wotherspoon SJ, Guinet C, Harcourt RG, Bestley S. Elephant seal foraging success is enhanced in Antarctic coastal polynyas. Proc Biol Sci 2022; 289:20212452. [PMID: 35078353 PMCID: PMC8790345 DOI: 10.1098/rspb.2021.2452] [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: 11/09/2021] [Accepted: 12/02/2021] [Indexed: 01/28/2023] Open
Abstract
Antarctic polynyas are persistent open water areas which enable early and large seasonal phytoplankton blooms. This high primary productivity, boosted by iron supply from coastal glaciers, attracts organisms from all trophic levels to form a rich and diverse community. How the ecological benefit of polynya productivity is translated to the highest trophic levels remains poorly resolved. We studied 119 southern elephant seals feeding over the Antarctic shelf and demonstrated that: (i) 96% of seals foraging here used polynyas, with individuals spending on average 62% of their time there; (ii) the seals exhibited more area-restricted search behaviour when in polynyas; and (iii) these seals gained more energy (indicated by increased buoyancy from greater fat stores) when inside polynyas. This higher-quality foraging existed even when ice was not present in the study area, indicating that these are important and predictable foraging grounds year-round. Despite these energetic advantages from using polynyas, not all the seals used them extensively. Factors other than food supply may influence an individual's choice in their use of feeding grounds, such as exposure to predation or the probability of being able to return to distant sub-Antarctic breeding sites.
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Affiliation(s)
- Fernando Arce
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129 Hobart, TAS 7001, Australia
- Australian Antarctic Division, 203 Channel Highway, Kingston, TAS 7050, Australia
| | - Mark A. Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129 Hobart, TAS 7001, Australia
| | - Clive R. McMahon
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129 Hobart, TAS 7001, Australia
- IMOS Animal Tagging, Sydney Institute of Marine Science, Mosman, NSW 2088, Australia
- Department of Biological Sciences, Macquarie University, North Ryde, NSW 2113, Australia
| | - Simon J. Wotherspoon
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129 Hobart, TAS 7001, Australia
- Australian Antarctic Division, 203 Channel Highway, Kingston, TAS 7050, Australia
| | - Christophe Guinet
- Centre d'Etudes Biologiques de Chizé, CNRS, Villiers en Bois 79360, France
| | - Robert G. Harcourt
- Department of Biological Sciences, Macquarie University, North Ryde, NSW 2113, Australia
| | - Sophie Bestley
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129 Hobart, TAS 7001, Australia
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Allegue H, Guinet C, Patrick SC, Hindell MA, McMahon CR, Réale D. Sex, body size, and boldness shape the seasonal foraging habitat selection in southern elephant seals. Ecol Evol 2022; 12:e8457. [PMID: 35127010 PMCID: PMC8796948 DOI: 10.1002/ece3.8457] [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: 07/14/2021] [Revised: 11/22/2021] [Accepted: 11/25/2021] [Indexed: 12/04/2022] Open
Abstract
Selecting foraging habitat is a fundamental behavior in the life of organisms as it directly links resource acquisition to fitness. Differences in habitat selection among individuals may arise from several intrinsic and extrinsic factors, and yet, their interaction has been given little attention in the study of wild populations. We combine sex, body size, and boldness to explain individual differences in the seasonal foraging habitat selection of southern elephant seals (Mirounga leonina) from the Kerguelen Archipelago. We hypothesize that habitat selection is linked to the trade-off between resource acquisition and risk, and that individuals differ in their position along this trade-off because of differences in reproductive strategies, life stages, and metabolic requirements. Before the post-molt foraging trip, we used a novel object approach test to quantify the boldness of 28 subadult and adult females and 42 subadult males and equipped them with data loggers to track their movements at sea. Subadult males selected neritic and oceanic habitats, whereas females mostly selected less productive oceanic habitats. Both sexes showed a seasonal shift from Antarctic habitats in the south in the summer to the free of ice subantarctic and subtropical habitats in the north in the winter. Males avoided oceanic habitats and selected more productive neritic and Antarctic habitats with body size mostly in the winter. Bolder males selected northern warmer waters in winter, while shyer ones selected the Kerguelen plateau and southern colder oceanic waters. Bolder females selected the Kerguelen plateau in the summer when prey profitability is assumed to be the highest. This study not only provides new insights into the spatiotemporal foraging ecology of elephant seals in relation to personality but also emphasizes the relevance of combining several intrinsic and extrinsic factors in understanding among-individual variation in space use essential in wildlife management and conservation.
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Affiliation(s)
- Hassen Allegue
- Département des Sciences BiologiquesUniversité du Québec à MontréalMontréalQCCanada
| | | | | | - Mark A. Hindell
- Institute for Marine and Antarctic StudiesBattery PointTASAustralia
- Antarctic Climate and Ecosystems Cooperative Research CentreUniversity of TasmaniaHobartTASAustralia
| | - Clive R. McMahon
- Institute for Marine and Antarctic StudiesBattery PointTASAustralia
- Sydney Institute of Marine ScienceSydneyNSWAustralia
- Department of Biological SciencesMacquarie UniversitySydneyNSWAustralia
| | - Denis Réale
- Département des Sciences BiologiquesUniversité du Québec à MontréalMontréalQCCanada
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Kienle SS, Friedlaender AS, Crocker DE, Mehta RS, Costa DP. Trade-offs between foraging reward and mortality risk drive sex-specific foraging strategies in sexually dimorphic northern elephant seals. ROYAL SOCIETY OPEN SCIENCE 2022; 9:210522. [PMID: 35116140 PMCID: PMC8767210 DOI: 10.1098/rsos.210522] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 12/14/2021] [Indexed: 05/04/2023]
Abstract
Sex-specific phenotypic differences are widespread throughout the animal kingdom. Reproductive advantages provided by trait differences come at a cost. Here, we link sex-specific foraging strategies to trade-offs between foraging reward and mortality risk in sexually dimorphic northern elephant seals (Mirounga angustirostris). We analyse a decadal dataset on movement patterns, dive behaviour, foraging success and mortality rates. Females are deep-diving predators in open ocean habitats. Males are shallow-diving benthic predators in continental shelf habitats. Males gain six times more mass and acquire energy 4.1 times faster than females. High foraging success comes with a high mortality rate. Males are six times more likely to die than females. These foraging strategies and trade-offs are related to different energy demands and life-history strategies. Males use a foraging strategy with a high mortality risk to attain large body sizes necessary to compete for females, as only a fraction of the largest males ever mate. Females use a foraging strategy with a lower mortality risk, maximizing reproductive success by pupping annually over a long lifespan. Our results highlight how sex-specific traits can drive disparity in mortality rates and expand species' niche space. Further, trade-offs between foraging rewards and mortality risk can differentially affect each sex's ability to maximize fitness.
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Affiliation(s)
- Sarah S. Kienle
- Ecology and Evolutionary Biology, University of California, 130 McAllister Way, Santa Cruz, CA 95060, USA
- Department of Biology, Baylor University, One Bear Place #97399, Waco, TX 76798, USA
| | - Ari S. Friedlaender
- Ocean Science, University of California, 130 McAllister Way, Santa Cruz, CA 95060, USA
| | - Daniel E. Crocker
- Biology, Sonoma State University, 1801 East Cotati Avenue, Rohnert Park, CA 94928, USA
| | - Rita S. Mehta
- Ecology and Evolutionary Biology, University of California, 130 McAllister Way, Santa Cruz, CA 95060, USA
| | - Daniel P. Costa
- Ecology and Evolutionary Biology, University of California, 130 McAllister Way, Santa Cruz, CA 95060, USA
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Hays GC, Laloë J, Rattray A, Esteban N. Why do Argos satellite tags stop relaying data? Ecol Evol 2021; 11:7093-7101. [PMID: 34141278 PMCID: PMC8207149 DOI: 10.1002/ece3.7558] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 03/17/2021] [Accepted: 03/22/2021] [Indexed: 11/18/2022] Open
Abstract
Satellite tracking of animals is very widespread across a range of marine, freshwater, and terrestrial taxa. Despite the high cost of tags and the advantages of long deployments, the reasons why tracking data from tags stop being received are rarely considered, but possibilities include shedding of the tag, damage to the tag (e.g., the aerial), biofouling, battery exhaustion, or animal mortality.We show how information relayed via satellite tags can be used to assess why tracking data stop being received. As a case study to illustrate general approaches that are broadly applicable across taxa, we examined data from Fastloc-GPS Argos tags deployed between 2012 and 2019 on 78 sea turtles of two species, the green turtle (Chelonia mydas) and the hawksbill turtle (Eretmochelys imbricata).Tags transmitted for a mean of 267 days (SD = 113 days, range: 26-687 days, median = 251 days). In 68 of 78 (87%) cases, battery failure was implicated as the reason why tracking data stopped being received. Some biofouling of the saltwater switches, which synchronize transmissions with surfacing, was evident in a few tags but never appeared to be the reason that data reception ceased.Objectively assessing why tags fail will direct improvements to tag design, setup, and deployment regardless of the study taxa. Assessing why satellite tags stop transmitting will also inform on the fate of tagged animals, for example, whether they are alive or dead at the end of the study, which may allow improved estimates of survival rates.
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Affiliation(s)
- Graeme C. Hays
- School of Life and Environmental SciencesDeakin UniversityGeelongVic.Australia
| | | | - Alex Rattray
- School of Life and Environmental SciencesDeakin UniversityGeelongVic.Australia
| | - Nicole Esteban
- Faculty of Science and EngineeringSwansea UniversitySwanseaUK
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Hindell MA, McMahon CR, Jonsen I, Harcourt R, Arce F, Guinet C. Inter- and intrasex habitat partitioning in the highly dimorphic southern elephant seal. Ecol Evol 2021; 11:1620-1633. [PMID: 33613994 PMCID: PMC7882946 DOI: 10.1002/ece3.7147] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/25/2020] [Accepted: 12/02/2020] [Indexed: 01/15/2023] Open
Abstract
Partitioning resources is a key mechanism for avoiding intraspecific competition and maximizing individual energy gain. However, in sexually dimorphic species it is difficult to discern if partitioning is due to competition or the different resource needs of morphologically distinct individuals. In the highly dimorphic southern elephant seal, there are intersexual differences in habitat use; at Iles Kerguelen, males predominantly use shelf waters, while females use deeper oceanic waters. There are equally marked intrasexual differences, with some males using the nearby Kerguelen Plateau, and others using the much more distant Antarctic continental shelf (~2,000 km away). We used this combination of inter and intrasexual behavior to test two hypotheses regarding habitat partitioning in highly dimorphic species. (a) that intersexual differences in habitat use will not appear until the seals diverge in body size and (b) that some habitats have higher rates of energy return than others. In particular, that the Antarctic shelf would provide higher energy returns than the Kerguelen Shelf, to offset the greater cost of travel. We quantified the habitat use of 187 southern elephant seals (102 adult females and 85 subadult males). The seals in the two groups were the same size (~2.4 m) removing the confounding effect of body size. We found that the intersexual differences in habitat use existed before the divergence in body size. Also, we found that the amount of energy gained was the same in all of the major habitats. This suggests that the use of shelf habitats by males is innate, and a trade-off between the need to access the large benthic prey available on shelf waters, against the higher risk of predation there. Intrasexual differences in habitat use are another trade-off; although there are fewer predators on the Antarctic shelf, it is subject to considerable interannual fluctuations in sea-ice extent. In contrast, the Kerguelen Plateau presents more consistent foraging opportunities, but contains higher levels of predation. Habitat partitioning in this highly dimorphic species is therefore the result of complex interplay of life history strategies, environmental conditions and predation pressure.
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Affiliation(s)
- Mark A. Hindell
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobartTasmaniaAustralia
| | - Clive R. McMahon
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobartTasmaniaAustralia
- IMOS Animal Tagging, Sydney Institute of Marine ScienceMosmanNew South WalesAustralia
- Department of Biological SciencesMacquarie UniversityNorth Ryde, SydneyNew South WalesAustralia
| | - Ian Jonsen
- Department of Biological SciencesMacquarie UniversityNorth Ryde, SydneyNew South WalesAustralia
| | - Robert Harcourt
- IMOS Animal Tagging, Sydney Institute of Marine ScienceMosmanNew South WalesAustralia
- Department of Biological SciencesMacquarie UniversityNorth Ryde, SydneyNew South WalesAustralia
| | - Fernando Arce
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobartTasmaniaAustralia
| | - Christophe Guinet
- Centre d’Etudes Biologiques de Chizé (CEBC)UMR 7372Université de la Rochelle‐CNRSVilliers en BoisFrance
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Hinke JT, Watters GM, Reiss CS, Santora JA, Santos MM. Acute bottlenecks to the survival of juvenile Pygoscelis penguins occur immediately after fledging. Biol Lett 2020; 16:20200645. [PMID: 33321063 PMCID: PMC7775978 DOI: 10.1098/rsbl.2020.0645] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/26/2020] [Indexed: 11/12/2022] Open
Abstract
Estimating when and where survival bottlenecks occur in free-ranging marine predators is critical for effective demographic monitoring and spatial planning. This is particularly relevant to juvenile stages of long-lived species for which direct observations of death are typically not possible. We used satellite telemetry data from fledgling Adélie, chinstrap and gentoo penguins near the Antarctic Peninsula to estimate the spatio-temporal scale of a bottleneck after fledging. Fledglings were tracked up to 106 days over distances of up to 2140 km. Cumulative losses of tags increased to 73% within 16 days of deployment, followed by an order-of-magnitude reduction in loss rates thereafter. The timing and location of tag losses were consistent with at-sea observations of penguin carcasses and bioenergetics simulations of mass loss to thresholds associated with low recruitment probability. A bootstrapping procedure is used to assess tag loss owing to death versus other factors. Results suggest insensitivity in the timing of the bottleneck and quantify plausible ranges of mortality rates within the bottleneck. The weight of evidence indicates that a survival bottleneck for fledgling penguins is acute, attributable to predation and starvation, and may account for at least 33% of juvenile mortality.
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Affiliation(s)
- Jefferson T. Hinke
- Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA 92037, USA
| | - George M. Watters
- Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA 92037, USA
| | - Christian S. Reiss
- Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA 92037, USA
| | - Jarrod A. Santora
- Fisheries Ecology Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Santa Cruz, CA 95060, USA
| | - M. Mercedes Santos
- Departamento Biología de Predadores Tope, Instituto Antártico Argentino, San Martín B1650CSP, Argentina
- Laboratorios Anexos, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata B1904AMA, Argentina
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