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Martin M, Gridley T, Immerz A, Elwen SH, Charrier I. Use of acoustic signals in Cape fur seal mother-pup reunions: individual signature, signal propagation and pup home range. J Exp Biol 2024; 227:jeb246917. [PMID: 38953226 DOI: 10.1242/jeb.246917] [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: 10/21/2023] [Accepted: 05/31/2024] [Indexed: 07/03/2024]
Abstract
The Cape fur seal (Arctocephalus pusillus pusillus) is one of the most colonial mammals, with colonies of up to hundreds of thousands of individuals during the breeding season. During the lactation period, mothers and pups are regularly separated as females undertake multi-day foraging trips at sea. Mothers and pups use a mutual vocal recognition system to reunite after separation. Such communication is highly constrained by both high background noise and risk of individual confusion owing to the density of seals. This study aimed to experimentally assess the acoustic features relevant for mother-pup vocal identification and the propagation properties of their calls. Playback experiments revealed that mother and pup individual vocal signatures rely on both temporal and frequency parameters: amplitude and frequency modulations, timbre and fundamental frequency (f0). This is more parameters than in any colonial species studied so far. The combinational use of acoustic features reinforces the concept that both environmental and social constraints may have acted as selective pressures on the individual vocal recognition systems. Theoretical propagation distances of mother and pup vocalisations were estimated to be below the range of distances at which mother-pup reunions can occur. This suggests that Cape fur seals may have strong abilities to extract vocal signals from the background noise, as previously demonstrated in the highly colonial king penguin. Investigating the transmission of information throughout the propagation of the signal as well as the ability of the receiving individual to decipher vocal signatures is crucial to understanding vocal recognition systems in the wild.
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Affiliation(s)
- Mathilde Martin
- Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, CNRS, 151 Route de la Rotonde, 91400 Saclay, France
- Sea Search Research and Conservation NPC, 4 Bath Road, Muizenberg, Cape Town 7945, South-Africa
| | - Tess Gridley
- Sea Search Research and Conservation NPC, 4 Bath Road, Muizenberg, Cape Town 7945, South-Africa
- Department of Botany and Zoology, Faculty of Science, Stellenbosch University, Stellenbosch 7605, South Africa
| | - Antonia Immerz
- Mammal Research Institute Whale Unit, Department of Zoology and Entomology, University of Pretoria, 0028 Pretoria, South Africa
| | - Simon H Elwen
- Sea Search Research and Conservation NPC, 4 Bath Road, Muizenberg, Cape Town 7945, South-Africa
- Department of Botany and Zoology, Faculty of Science, Stellenbosch University, Stellenbosch 7605, South Africa
| | - Isabelle Charrier
- Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, CNRS, 151 Route de la Rotonde, 91400 Saclay, France
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Nagel R, Pohle K, Jordán L, Tuponja I, Stainfield C, Toscani C, Fox-Clarke C, Costantini D, Czirják GÁ, Forcada J, Hoffman JI. Life-history stage influences immune investment and oxidative stress in response to environmental heterogeneity in Antarctic fur seals. Commun Biol 2024; 7:788. [PMID: 38951600 PMCID: PMC11217341 DOI: 10.1038/s42003-024-06499-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 06/24/2024] [Indexed: 07/03/2024] Open
Abstract
Immune defenses are crucial for survival but costly to develop and maintain. Increased immune investment is therefore hypothesized to trade-off with other life-history traits. Here, we examined innate and adaptive immune responses to environmental heterogeneity in wild Antarctic fur seals. In a fully crossed, repeated measures design, we sampled 100 pups and their mothers from colonies of contrasting density during seasons of contrasting food availability. Biometric and cortisol data as well as blood for the analysis of 13 immune and oxidative status markers were collected at two key life-history stages. We show that immune responses of pups are more responsive than adults to variation in food availability, but not population density, and are modulated by cortisol and condition. Immune investment is associated with different oxidative status markers in pups and mothers. Our results suggest that early life stages show greater sensitivity to extrinsic and intrinsic effectors, and that immunity may be a strong target for natural selection even in low-pathogen environments such as Antarctica.
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Affiliation(s)
- Rebecca Nagel
- Department of Evolutionary Population Genetics, Faculty of Biology, Bielefeld University, 33501, Bielefeld, Germany.
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany.
- School of Biology, University of St Andrews, St Andrews, KY16 9TH, UK.
| | - Katja Pohle
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, 10315, Berlin, Germany
| | - Lilla Jordán
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, 10315, Berlin, Germany
| | - Iva Tuponja
- Department of Evolutionary Population Genetics, Faculty of Biology, Bielefeld University, 33501, Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany
| | - Claire Stainfield
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK
- Scotland's Rural College, Craibstone Estate, Ferguson Building, Aberdeen, AB21 9YA, UK
| | - Camille Toscani
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK
| | - Cameron Fox-Clarke
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK
| | - David Costantini
- Department of Ecological and Biological Sciences, University of Tuscia, 01100, Viterbo, Italy
| | - Gábor Á Czirják
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, 10315, Berlin, Germany
| | - Jaume Forcada
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK
| | - Joseph I Hoffman
- Department of Evolutionary Population Genetics, Faculty of Biology, Bielefeld University, 33501, Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK
- Center for Biotechnology, Faculty of Biology, Bielefeld University, 33615, Bielefeld, Germany
- Joint Institute for Individualisation in a Changing Environment, Bielefeld University and University of Münster, 33501, Bielefeld, Germany
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Paijmans AJ, Berthelsen AL, Nagel R, Christaller F, Kröcker N, Forcada J, Hoffman JI. Little evidence of inbreeding depression for birth mass, survival and growth in Antarctic fur seal pups. Sci Rep 2024; 14:12610. [PMID: 38824161 PMCID: PMC11144264 DOI: 10.1038/s41598-024-62290-x] [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: 01/12/2024] [Accepted: 05/15/2024] [Indexed: 06/03/2024] Open
Abstract
Inbreeding depression, the loss of offspring fitness due to consanguineous mating, is generally detrimental for individual performance and population viability. We investigated inbreeding effects in a declining population of Antarctic fur seals (Arctocephalus gazella) at Bird Island, South Georgia. Here, localised warming has reduced the availability of the seal's staple diet, Antarctic krill, leading to a temporal increase in the strength of selection against inbred offspring, which are increasingly failing to recruit into the adult breeding population. However, it remains unclear whether selection operates before or after nutritional independence at weaning. We therefore used microsatellite data from 885 pups and their mothers, and SNP array data from 98 mother-offspring pairs, to quantify the effects of individual and maternal inbreeding on three important neonatal fitness traits: birth mass, survival and growth. We did not find any clear or consistent effects of offspring or maternal inbreeding on any of these traits. This suggests that selection filters inbred individuals out of the population as juveniles during the time window between weaning and recruitment. Our study brings into focus a poorly understood life-history stage and emphasises the importance of understanding the ecology and threats facing juvenile pinnipeds.
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Affiliation(s)
- A J Paijmans
- Department of Evolutionary Population Genetics, Bielefeld University, 33615, Bielefeld, Germany.
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany.
| | - A L Berthelsen
- Department of Evolutionary Population Genetics, Bielefeld University, 33615, Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany
| | - R Nagel
- Department of Evolutionary Population Genetics, Bielefeld University, 33615, Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany
- Centre for Biological Diversity, University of St. Andrews, St Andrews, KY16 9TH, UK
| | - F Christaller
- Department of Evolutionary Population Genetics, Bielefeld University, 33615, Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany
| | - N Kröcker
- Department of Evolutionary Population Genetics, Bielefeld University, 33615, Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany
| | - J Forcada
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK
| | - J I Hoffman
- Department of Evolutionary Population Genetics, Bielefeld University, 33615, Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK
- Joint Institute for Individualisation in a Changing Environment (JICE), Bielefeld University and University of Münster, Bielefeld, Germany
- Center for Biotechnology (CeBiTec), Faculty of Biology, Bielefeld University, 33615, Bielefeld, Germany
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Tebbe J, Havenstein K, Forcada J, Tiedemann R, Caspers B, Hoffman JI. No evidence for a role of MHC class II genotype in the chemical encoding of heterozygosity and relatedness in Antarctic fur seals. Proc Biol Sci 2024; 291:20232519. [PMID: 38503331 PMCID: PMC10950461 DOI: 10.1098/rspb.2023.2519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/22/2024] [Indexed: 03/21/2024] Open
Abstract
Despite decades of research, surprisingly little is known about the mechanism(s) by which an individual's genotype is encoded in odour. Many studies have focused on the role of the major histocompatibility complex (MHC) owing to its importance for survival and mate choice. However, the salience of MHC-mediated odours compared to chemicals influenced by the rest of the genome remains unclear, especially in wild populations where it is challenging to quantify and control for the effects of the genomic background. We addressed this issue in Antarctic fur seals by analysing skin swabs together with full-length MHC DQB II exon 2 sequences and data from 41 genome-wide distributed microsatellites. We did not find any effects of MHC relatedness on chemical similarity and there was also no relationship between MHC heterozygosity and chemical diversity. However, multilocus heterozygosity showed a significant positive association with chemical diversity, even after controlling for MHC heterozygosity. Our results appear to rule out a dominant role of the MHC in the chemical encoding of genetic information in a wild vertebrate population and highlight the need for genome-wide approaches to elucidate the mechanism(s) and specific genes underlying genotype-odour associations.
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Affiliation(s)
- Jonas Tebbe
- Department of Evolutionary Population Genetics, Faculty of Biology, Bielefeld University, 33615 Bielefeld, Germany
- Department of Behavioural Ecology, Bielefeld University, 33501 Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501 Bielefeld, Germany
| | - Katja Havenstein
- Unit of Evolutionary Biology / Systematic Zoology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
| | - Jaume Forcada
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 OET, UK
| | - Ralph Tiedemann
- Unit of Evolutionary Biology / Systematic Zoology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
| | - Barbara Caspers
- Department of Behavioural Ecology, Bielefeld University, 33501 Bielefeld, Germany
- Joint Institute for Individualisation in a Changing Environment (JICE), Bielefeld University and University of Münster, Bielefeld, Germany
| | - Joseph I. Hoffman
- Department of Evolutionary Population Genetics, Faculty of Biology, Bielefeld University, 33615 Bielefeld, Germany
- Department of Animal Behaviour, Bielefeld University, 33501 Bielefeld, Germany
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 OET, UK
- Joint Institute for Individualisation in a Changing Environment (JICE), Bielefeld University and University of Münster, Bielefeld, Germany
- Center for Biotechnology (CeBiTec), Faculty of Biology, Bielefeld University, 33615 Bielefeld, Germany
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Intronic primers reveal unexpectedly high major histocompatibility complex diversity in Antarctic fur seals. Sci Rep 2022; 12:17933. [PMID: 36289307 PMCID: PMC9606363 DOI: 10.1038/s41598-022-21658-7] [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: 05/10/2022] [Accepted: 09/29/2022] [Indexed: 01/20/2023] Open
Abstract
The major histocompatibility complex (MHC) is a group of genes comprising one of the most important components of the vertebrate immune system. Consequently, there has been much interest in characterising MHC variation and its relationship with fitness in a variety of species. Due to the exceptional polymorphism of MHC genes, careful PCR primer design is crucial for capturing all of the allelic variation present in a given species. We therefore developed intronic primers to amplify the full-length 267 bp protein-coding sequence of the MHC class II DQB exon 2 in the Antarctic fur seal. We then characterised patterns of MHC variation among mother-offspring pairs from two breeding colonies and detected 19 alleles among 771 clone sequences from 56 individuals. The distribution of alleles within and among individuals was consistent with a single-copy, classical DQB locus showing Mendelian inheritance. Amino acid similarity at the MHC was significantly associated with genome-wide relatedness, but no relationship was found between MHC heterozygosity and genome-wide heterozygosity. Finally, allelic diversity was several times higher than reported by a previous study based on partial exon sequences. This difference appears to be related to allele-specific amplification bias, implying that primer design can strongly impact the inference of MHC diversity.
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