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  • 1
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Counts of the Antarctic fur seal Arctocephalus gazella and location of colonies at Heard Island in the 1987-88 summer (1989)
    Kingston : Department of Science and Technology, Antarctic Division
    Dazugehörige Bände
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    Signatur: ZSP-124-72
    In: ANARE research notes
    Beschreibung / Inhaltsverzeichnis: The Antarctic fur seal Arctocephalus gezella has increased in numbers at Heard Island since the Australian National Antarctic Research Expeditions (ANARE) station was established in 1947. Increases have also been recorded at other breeding sites in the South Atlantic and South Indian Oceans this century, particulary at South Georgia. In the 1987-88 summer, fur seals at Heard Island were counted in several age and sex categories. The aims of the project were to determine the location of pupping sites, the extent of the pupping season and the size of the population, and to record the changes in numbers of animals ashore during the summer. Maps of the colonies and main haul-out areas, together with descriptions of census areas and tabulations of counts, provide a basis fr future comparison.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 25 S. : Ill.
    ISBN: 0642149585
    Serie: ANARE research notes 72
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    POPULATION SIZE AND BREEDING SEASON OF THE ANTARCTIC FUR SEAL ARCTOCEPHALUS GAZELLA AT HEARD ISLAND—1987/88 (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 6 (1990), S. 0 
    Details
    ISSN: 1748-7692
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Breeding colonies of the antarctic fur seal Arctocephalus gazella on Heard Island (53°10′S, 73°30′E) are situated on the sheltered northern and eastern coasts on flat vegetated terrain near streams and pools. Pupping in the 1987/88 summer began on 21 November, with 90% of births in 26 d. The median birth date was 11 December. Pup counts at Heard Island made in seven breeding seasons from 1962/63 to 1987/88 show an exponential rate of increase of 21%, which may be inflated due to undercounting in early years. The total of 248 births in 1987/88 represents an exponential increase of 37% since the previous year, but pups may have been undercounted then. Based on the number of pups born, the breeding population is estimated at 870–1,120. During the breeding season, the largest number of animals ashore was 835. Many non-breeding fur seals began hauling out from early January and 15,000 animals were estimated to be ashore by late February, a fat larger number than expected from the size of the breeding population. Both the breeding and non-breeding components of the population may be augmented by immigration. The source of immigrants may be undiscovered breeding colonies of this species in the northwestern sector of the Kerguelen Archipelago or the concentration at South Georgia. Further censuses are required at Heard Island to monitor the population growth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1748-7692.1990.tb00359.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Subantarctic fur seals Arctocephalus tropicalis at Heard Island (1989)
    Springer
    Polar biology 9 (1989), S. 337-339 
    Details
    ISSN: 1432-2056
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00287434
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  • 4
    Digitale Medien
    Digitale Medien
    Maternal attendance behaviour of sympatrically breeding Antarctic and subantarctic fur seals, Arctocephalus spp., at Macquarie Island (1999)
    Springer
    Polar biology 21 (1999), S. 316-325 
    Details
    ISSN: 1432-2056
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Maternal attendance behaviour was studied in Antarctic (Arctocephalus gazella) and subantarctic fur seals (Arctocephalus tropicalis) which breed sympatrically at subantarctic Macquarie Island. Data on attendance were obtained using telemetric methods. Both species undertook two types of foraging trips: overnight foraging trips which were of less than 1 day duration and occurred exclusively overnight, and extended foraging trips which lasted longer than 1 day. The mean duration of overnight foraging trips was 0.43 and 0.39 days, while the duration of extended foraging trips was 3.6 and 3.8 days in A. gazella and A. tropicalis, respectively. The duration of overnight and extended foraging trips did not differ significantly between species. Two types of shore attendance bouts that differed in duration were also observed in these species. Short attendance bouts lasted less than 0.9 days, while long attendance bouts lasted longer than 0.9 days. Short attendance bouts lasted 0.4 and 0.5 days, while long attendance bouts lasted 1.6 and 1.7 days in A. gazella and A. tropicalis, respectively, and did not differ significantly between species. The most significant differences between the attendance behaviour of both species was in the percentage of foraging time allocated to overnight foraging trips (15% and 25% in A. gazella and A. tropicalis, respectively), and the percentage of time spent ashore (30% and 38% in A. gazella and A. tropicalis, respectively). The nearness of pelagic waters to Macquarie Island is considered to be the main reason that lactating females are able to undertake overnight foraging trips. These trips may be used by females as a means of optimising the costs of fasting and nursing ashore. Females may be able to save energy by only nursing pups when milk transfer efficiencies are high, and reduce the time and energy costs of fasting ashore when milk transfer efficiency is low. Of the female A. gazella that still carried transmitters at the end of lactation, 83% continued regular attendance for between 21 and 150 days post-lactation (when data collection ceased). Overwintering of A. gazella females at breeding sites has not been previously reported in other populations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003000050368
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  • 5
    Digitale Medien
    Digitale Medien
    Mate choice among sympatric fur seals: female preference for conphenotypic males (1999)
    Springer
    Behavioral ecology and sociobiology 45 (1999), S. 253-267 
    Details
    ISSN: 1432-0762
    Schlagwort(e): Key words Mate choice ; Mating success ; Hybridization ; DNA fingerprinting ; Mitochondrial DNA ; Fur seal ; Arctocephalus spp.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract When closely related species breed in sympatry, and where hybrids have lower fitness, reinforcement theory predicts that selection should favour mechanisms that reduce the probability of interspecific matings. If this situation arises among species that exhibit resource defence polygyny where males and females of different species reside in the same territories, there may be some conflict between mate choice based on territory-holding ability (sexual selection) and mate choice for correct species. We investigated this in a population of fur seals where three species are sympatric and where some females breed in the territories of heterospecific males, and where interspecific matings and hybrid pups are observed. The territorial status of males and the birthing sites of females were determined during daily observations, as were the movements of males and females, the location of matings and mating partners. DNA extracted from skin samples was used to determine paternities using DNA fingerprinting and the mtDNA genotype of individuals. Individuals were also classed on the basis of species-typical phenotype. We found that extra-territory inseminations (ETIs) were significantly more prevalent (67%) when territorial males and resident females were of different phenotype than when of similar phenotype (27%), but mtDNA genotype had no effect on the rate of ETIs. ETIs were probably by males with the same phenotype, as pups born to these females in the following season had the same phenotype as their mothers, suggesting they were not hybrids. These results suggest that within the resource defence polygynous mating system of these sympatric fur seals, female mate choice is more influenced by male phenotype than genotype. Contrary to our predictions, our study indicates that potential conflict between mate choice based on sexual selection and species recognition is unlikely, because females have some capacity to discriminate between males both within and between species on phenotypic traits additional to those under sexual selection. Although at least 25% of the pups born in this study were hybrid, this study can only support reinforcement theory if hybrids have reduced fitness. The fitness of hybrids among the species studied is currently unknown.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002650050560
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  • 6
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    Convergence of marine megafauna movement patterns in coastal and open oceans (2018)
    National Academy of Sciences
    Details
    Publikationsdatum: 2018-02-26
    Beschreibung: The extent of increasing anthropogenic impacts on large marine vertebrates partly depends on the animals’ movement patterns. Effective conservation requires identification of the key drivers of movement including intrinsic properties and extrinsic constraints associated with the dynamic nature of the environments the animals inhabit. However, the relative importance of intrinsic versus extrinsic factors remains elusive. We analyze a global dataset of ∼2.8 million locations from 〉2,600 tracked individuals across 50 marine vertebrates evolutionarily separated by millions of years and using different locomotion modes (fly, swim, walk/paddle). Strikingly, movement patterns show a remarkable convergence, being strongly conserved across species and independent of body length and mass, despite these traits ranging over 10 orders of magnitude among the species studied. This represents a fundamental difference between marine and terrestrial vertebrates not previously identified, likely linked to the reduced costs of locomotion in water. Movement patterns were primarily explained by the interaction between species-specific traits and the habitat(s) they move through, resulting in complex movement patterns when moving close to coasts compared with more predictable patterns when moving in open oceans. This distinct difference may be associated with greater complexity within coastal microhabitats, highlighting a critical role of preferred habitat in shaping marine vertebrate global movements. Efforts to develop understanding of the characteristics of vertebrate movement should consider the habitat(s) through which they move to identify how movement patterns will alter with forecasted severe ocean changes, such as reduced Arctic sea ice cover, sea level rise, and declining oxygen content.
    Print ISSN: 0027-8424
    Digitale ISSN: 1091-6490
    Thema: Biologie , Medizin , Allgemeine Naturwissenschaft
    Publiziert von National Academy of Sciences
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  • 7
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    A quantitative comparison of the diets of sympatric pelagic sharks in gulf and shelf ecosystems off southern Australia (2012)
    Oxford University Press
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    Publikationsdatum: 2012-08-22
    Beschreibung: Rogers, P. J., Huveneers, C., Page, B., Hamer, D. J., Goldsworthy, S. D., Mitchell, J. G., and Seuront, L. 2012. A quantitative comparison of the diets of sympatric pelagic sharks in gulf and shelf ecosystems off southern Australia. – ICES Journal of Marine Science, 69: . Predator–prey dynamics represent an important determinant in the functioning of marine ecosystems. This study provides the first quantitative investigation of the diets of sympatric pelagic shark species in gulf and shelf waters off southern Australia. Stomachs of 417 sharks collected from fishery catches between 2007 and 2011 were examined, including 250 bronze whalers, 52 shortfin makos, 49 dusky sharks, 39 smooth hammerheads, and 27 common threshers. Dusky sharks had the highest dietary diversity of the five species examined. We found overlap in the consumption of cephalopods, small pelagic teleosts, crustaceans, and benthic teleosts in bronze whalers, dusky sharks, and smooth hammerheads, and preliminary evidence of specialization in the highly migratory species, the common thresher and the shortfin mako. Findings were discussed and compared with previous studies in other temperate marine ecosystems. This study will significantly improve the understanding of the ecological roles of these top predators in the gulf and shelf habitats off southern Australia, and enhance the ecosystem models being developed for this unique bioregion.
    Print ISSN: 1054-3139
    Digitale ISSN: 1095-9289
    Thema: Biologie , Geologie und Paläontologie , Physik
    Publiziert von Oxford University Press
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  • 8
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    A global cline in a colour polymorphism suggests a limited contribution of gene flow towards the recovery of a heavily exploited marine mammal (2018)
    Royal Society
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    Publikationsdatum: 2018-10-18
    Beschreibung: Evaluating how populations are connected by migration is important for understanding species resilience because gene flow can facilitate recovery from demographic declines. We therefore investigated the extent to which migration may have contributed to the global recovery of the Antarctic fur seal ( Arctocephalus gazella ), a circumpolar distributed marine mammal that was brought to the brink of extinction by the sealing industry in the eighteenth and nineteenth centuries. It is widely believed that animals emigrating from South Georgia, where a relict population escaped sealing, contributed to the re-establishment of formerly occupied breeding colonies across the geographical range of the species. To investigate this, we interrogated a genetic polymorphism (S291F) in the melanocortin 1 receptor gene, which is responsible for a cream-coloured phenotype that is relatively abundant at South Georgia and which appears to have recently spread to localities as far afield as Marion Island in the sub-Antarctic Indian Ocean. By sequencing a short region of this gene in 1492 pups from eight breeding colonies, we showed that S291F frequency rapidly declines with increasing geographical distance from South Georgia, consistent with locally restricted gene flow from South Georgia mainly to the South Shetland Islands and Bouvetøya. The S291F allele was not detected farther afield, suggesting that although emigrants from South Georgia may have been locally important, they are unlikely to have played a major role in the recovery of geographically more distant populations.
    Schlagwort(e): genetics, ecology
    Digitale ISSN: 2054-5703
    Thema: Allgemeine Naturwissenschaft
    Publiziert von Royal Society
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  • 9
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    RAD Sequencing and a Hybrid Antarctic Fur Seal Genome Assembly Reveal Rapidly Decaying Linkage Disequilibrium, Global Population Structure and Evidence for Inbreeding (2018)
    Genetics Society of America (GSA)
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    Publikationsdatum: 2018-08-01
    Beschreibung: Recent advances in high throughput sequencing have transformed the study of wild organisms by facilitating the generation of high quality genome assemblies and dense genetic marker datasets. These resources have the potential to significantly advance our understanding of diverse phenomena at the level of species, populations and individuals, ranging from patterns of synteny through rates of linkage disequilibrium (LD) decay and population structure to individual inbreeding. Consequently, we used PacBio sequencing to refine an existing Antarctic fur seal ( Arctocephalus gazella ) genome assembly and genotyped 83 individuals from six populations using restriction site associated DNA (RAD) sequencing. The resulting hybrid genome comprised 6,169 scaffolds with an N50 of 6.21 Mb and provided clear evidence for the conservation of large chromosomal segments between the fur seal and dog ( Canis lupus familiaris ). Focusing on the most extensively sampled population of South Georgia, we found that LD decayed rapidly, reaching the background level by around 400 kb, consistent with other vertebrates but at odds with the notion that fur seals experienced a strong historical bottleneck. We also found evidence for population structuring, with four main Antarctic island groups being resolved. Finally, appreciable variance in individual inbreeding could be detected, reflecting the strong polygyny and site fidelity of the species. Overall, our study contributes important resources for future genomic studies of fur seals and other pinnipeds while also providing a clear example of how high throughput sequencing can generate diverse biological insights at multiple levels of organization.
    Digitale ISSN: 2160-1836
    Thema: Biologie
    Publiziert von Genetics Society of America (GSA)
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  • 10
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    Head start: Australian sea lion pups gain experience of adult foraging grounds before weaning (2012)
    Springer
    Details
    Publikationsdatum: 2012-08-02
    Print ISSN: 0025-3162
    Digitale ISSN: 1432-1793
    Thema: Biologie
    Publiziert von Springer
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