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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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Elkin J, Martin A, Courtier-Orgogozo V, Santos ME. Analysis of the genetic loci of pigment pattern evolution in vertebrates. Biol Rev Camb Philos Soc 2023; 98:1250-1277. [PMID: 37017088 DOI: 10.1111/brv.12952] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/08/2023] [Accepted: 03/14/2023] [Indexed: 04/06/2023]
Abstract
Vertebrate pigmentation patterns are amongst the best characterised model systems for studying the genetic basis of adaptive evolution. The wealth of available data on the genetic basis for pigmentation evolution allows for analysis of trends and quantitative testing of evolutionary hypotheses. We employed Gephebase, a database of genetic variants associated with natural and domesticated trait variation, to examine trends in how cis-regulatory and coding mutations contribute to vertebrate pigmentation phenotypes, as well as factors that favour one mutation type over the other. We found that studies with lower ascertainment bias identified higher proportions of cis-regulatory mutations, and that cis-regulatory mutations were more common amongst animals harbouring a higher number of pigment cell classes. We classified pigmentation traits firstly according to their physiological basis and secondly according to whether they affect colour or pattern, and identified that carotenoid-based pigmentation and variation in pattern boundaries are preferentially associated with cis-regulatory change. We also classified genes according to their developmental, cellular, and molecular functions. We found a greater proportion of cis-regulatory mutations in genes implicated in upstream developmental processes compared to those involved in downstream cellular functions, and that ligands were associated with a higher proportion of cis-regulatory mutations than their respective receptors. Based on these trends, we discuss future directions for research in vertebrate pigmentation evolution.
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Affiliation(s)
- Joel Elkin
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Arnaud Martin
- Department of Biological Sciences, The George Washington University, 800 22nd St. NW, Suite 6000, Washington, DC, 20052, USA
| | | | - M Emília Santos
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
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Convey P, Hughes KA. Untangling unexpected terrestrial conservation challenges arising from the historical human exploitation of marine mammals in the Atlantic sector of the Southern Ocean. AMBIO 2023; 52:357-375. [PMID: 36048407 PMCID: PMC9755428 DOI: 10.1007/s13280-022-01782-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 07/06/2022] [Accepted: 08/08/2022] [Indexed: 06/15/2023]
Abstract
Intensive human exploitation of the Antarctic fur seal (Arctocephalus gazella) in its primary population centre on sub-Antarctic South Georgia, as well as on other sub-Antarctic islands and parts of the South Shetland Islands, in the eighteenth and nineteenth centuries rapidly brought populations to the brink of extinction. The species has now recovered throughout its original distribution. Non-breeding and yearling seals, almost entirely males, from the South Georgia population now disperse in the summer months far more widely and in higher numbers than there is evidence for taking place in the pre-exploitation era. Large numbers now haul out in coastal terrestrial habitats in the South Orkney Islands and also along the north-east and west coast of the Antarctic Peninsula to at least Marguerite Bay. In these previously less- or non-visited areas, the seals cause levels of damage likely never to have been experienced previously to fragile terrestrial habitats through trampling and over-fertilisation, as well as eutrophication of sensitive freshwater ecosystems. This increased area of summer impact is likely to have further synergies with aspects of regional climate change, including reduction in extent and duration of sea ice permitting seals access farther south, and changes in krill abundance and distribution. The extent and conservation value of terrestrial habitats and biodiversity now threatened by fur seal distribution expansion, and the multiple anthropogenic factors acting in synergy both historically and to the present day, present a new and as yet unaddressed challenge to the agencies charged with ensuring the protection and conservation of Antarctica's unique ecosystems.
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Affiliation(s)
- Peter Convey
- British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge, CB3 0ET, UK.
- Department of Zoology, University of Johannesburg, Auckland Park 2006, South Africa.
| | - Kevin A Hughes
- British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
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Hoffman JI, Chen RS, Vendrami DLJ, Paijmans AJ, Dasmahapatra KK, Forcada J. Demographic Reconstruction of Antarctic Fur Seals Supports the Krill Surplus Hypothesis. Genes (Basel) 2022; 13:541. [PMID: 35328094 PMCID: PMC8954904 DOI: 10.3390/genes13030541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 03/10/2022] [Indexed: 11/16/2022] Open
Abstract
Much debate surrounds the importance of top-down and bottom-up effects in the Southern Ocean, where the harvesting of over two million whales in the mid twentieth century is thought to have produced a massive surplus of Antarctic krill. This excess of krill may have allowed populations of other predators, such as seals and penguins, to increase, a top-down hypothesis known as the 'krill surplus hypothesis'. However, a lack of pre-whaling population baselines has made it challenging to investigate historical changes in the abundance of the major krill predators in relation to whaling. Therefore, we used reduced representation sequencing and a coalescent-based maximum composite likelihood approach to reconstruct the recent demographic history of the Antarctic fur seal, a pinniped that was hunted to the brink of extinction by 18th and 19th century sealers. In line with the known history of this species, we found support for a demographic model that included a substantial reduction in population size around the time period of sealing. Furthermore, maximum likelihood estimates from this model suggest that the recovered, post-sealing population at South Georgia may have been around two times larger than the pre-sealing population. Our findings lend support to the krill surplus hypothesis and illustrate the potential of genomic approaches to shed light on long-standing questions in population biology.
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Affiliation(s)
- Joseph I. Hoffman
- Department of Animal Behavior, University of Bielefeld, P.O. BOX 100131, 33615 Bielefeld, Germany; (R.S.C.); (D.L.J.V.); (A.J.P.)
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 OET, UK;
| | - Rebecca S. Chen
- Department of Animal Behavior, University of Bielefeld, P.O. BOX 100131, 33615 Bielefeld, Germany; (R.S.C.); (D.L.J.V.); (A.J.P.)
| | - David L. J. Vendrami
- Department of Animal Behavior, University of Bielefeld, P.O. BOX 100131, 33615 Bielefeld, Germany; (R.S.C.); (D.L.J.V.); (A.J.P.)
| | - Anna J. Paijmans
- Department of Animal Behavior, University of Bielefeld, P.O. BOX 100131, 33615 Bielefeld, Germany; (R.S.C.); (D.L.J.V.); (A.J.P.)
| | | | - Jaume Forcada
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 OET, UK;
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Cleary AC, Hoffman JI, Forcada J, Lydersen C, Lowther AD, Kovacs KM. 50,000 years of ice and seals: Impacts of the Last Glacial Maximum on Antarctic fur seals. Ecol Evol 2021; 11:14003-14011. [PMID: 34707834 PMCID: PMC8525082 DOI: 10.1002/ece3.8104] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/22/2021] [Accepted: 08/26/2021] [Indexed: 11/11/2022] Open
Abstract
Ice is one of the most important drivers of population dynamics in polar organisms, influencing the locations, sizes, and connectivity of populations. Antarctic fur seals, Arctocephalus gazella, are particularly interesting in this regard, as they are concomitantly reliant on both ice-associated prey and ice-free coastal breeding areas. We reconstructed the history of this species through the Last Glacial Maximum (LGM) using genomic sequence data from seals across their range. Population size trends and divergence events were investigated using continuous-time size estimation analysis and divergence time estimation models. The combined results indicated that a panmictic population present prior to the LGM split into two small refugial populations during peak ice extent. Following ice decline, the western refugial population founded colonies at the South Shetlands, South Georgia, and Bouvetøya, while the eastern refugial population founded the colony on Iles Kerguelen. Postglacial population divergence times closely match geological estimates of when these coastal breeding areas became ice free. Given the predictions regarding continued future warming in polar oceans, these responses of Antarctic fur seals to past climate variation suggest it may be worthwhile giving conservation consideration to potential future breeding locations, such as areas further south along the Antarctic Peninsula, in addition to present colony areas.
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Affiliation(s)
- Alison C. Cleary
- Department of Natural SciencesUniversity of AgderKristiansandNorway
- Norwegian Polar InstituteFram CentreTromsøNorway
| | - Joseph I. Hoffman
- Department of Animal BehaviourUniversity of BielefeldBielefeldGermany
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Antarctic fur seal (Arctocephalus gazella) annual migration and temporal patterns of on-shore occurrence of leucistic individuals on King George Island. Polar Biol 2020. [DOI: 10.1007/s00300-020-02694-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
AbstractNon-invasive tracking the on-shore occurrence of the atypically pigmented animals and determination of land residency duration of leucistic seals would help us find out more about the rotation of the migrating population. During seven austral summer seasons (2011–2018), by counting the animals every 10 days at the Cape Lions Rump shore, King George Island, South Shetlands, in the Antarctic Specially Protected Area No. 151 and the adjacent ice-free land (31.52 km2) we registered fourteen leucistic individuals per a total of 43,919 animals. Moreover, daily monitoring of local fauna resulted in further 33 leucistic animals (together 47, in all seasons). Whilst the results of 10-day censuses of the total population were similar inter-seasonally, a tendency for increased occurrence of leucistic individuals in successive seasons was revealed. Generally, the number of animals increased significantly as season progressed. Since leucistic individuals stayed on-shore for 1–2 days usually, it can be hypothesised that the observation of migrating Antarctic fur seals every 3 days does not involve the same individuals. Also, additional every 5-day censuses taken in one season in ASPA 151 resulted in a higher seasonal number of animals, which proves that more frequent counts help us estimate population abundance more efficiently. Thus, every 5-day counts are proposed as a feasible and justified method of population monitoring.
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Paijmans AJ, Stoffel MA, Bester MN, Cleary AC, De Bruyn PJN, Forcada J, Goebel ME, Goldsworthy SD, Guinet C, Lydersen C, Kovacs KM, Lowther A, Hoffman JI. The genetic legacy of extreme exploitation in a polar vertebrate. Sci Rep 2020; 10:5089. [PMID: 32198403 PMCID: PMC7083876 DOI: 10.1038/s41598-020-61560-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 01/24/2020] [Indexed: 12/12/2022] Open
Abstract
Understanding the effects of human exploitation on the genetic composition of wild populations is important for predicting species persistence and adaptive potential. We therefore investigated the genetic legacy of large-scale commercial harvesting by reconstructing, on a global scale, the recent demographic history of the Antarctic fur seal (Arctocephalus gazella), a species that was hunted to the brink of extinction by 18th and 19th century sealers. Molecular genetic data from over 2,000 individuals sampled from all eight major breeding locations across the species' circumpolar geographic distribution, show that at least four relict populations around Antarctica survived commercial hunting. Coalescent simulations suggest that all of these populations experienced severe bottlenecks down to effective population sizes of around 150-200. Nevertheless, comparably high levels of neutral genetic variability were retained as these declines are unlikely to have been strong enough to deplete allelic richness by more than around 15%. These findings suggest that even dramatic short-term declines need not necessarily result in major losses of diversity, and explain the apparent contradiction between the high genetic diversity of this species and its extreme exploitation history.
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Affiliation(s)
- Anneke J Paijmans
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany.
| | - Martin A Stoffel
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, EH9 3FL, United Kingdom
| | - Marthán N Bester
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Alison C Cleary
- Norwegian Polar Institute, Fram Centre, 9296, Tromsø, Norway
- Department of Natural Sciences, University of Agder, 4630, Kristiansand, Norway
| | - P J Nico De Bruyn
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Jaume Forcada
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK
| | - Michael E Goebel
- Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries, National Oceanographic and Atmospheric Administration, 8901 La Jolla Shores Drive, La Jolla, CA, 92037, USA
- Institute of Marine Science, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
| | - Simon D Goldsworthy
- South Australian Research and Development Institute, 2 Hamra Avenue, West Beach, South Australia, 5024, Australia
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Christophe Guinet
- Centre d'Etudes Biologiques de Chizé (CEBC), CNRS and Université de La Rochelle - UMR 7372, 79360, Villiers en Bois, France
| | | | - Kit M Kovacs
- Norwegian Polar Institute, Fram Centre, 9296, Tromsø, Norway
| | - Andrew Lowther
- Norwegian Polar Institute, Fram Centre, 9296, Tromsø, Norway
| | - Joseph I Hoffman
- Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany.
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK.
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Anomalous lanugo coat colourations in sub-Antarctic fur seal (Arctocephalus tropicalis) pups born on Marion Island. Polar Biol 2019. [DOI: 10.1007/s00300-019-02487-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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