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Kaland H, Harvey AC, Skaala Ø, Wennevik V, Besnier F, Fjeldheim PT, Knutar S, Andersen KC, Glover KA. DNA and scale reading to identify repeat spawning in Atlantic salmon: Unique insights into patterns of iteroparity. Evol Appl 2023; 16:1921-1936. [PMID: 38143898 PMCID: PMC10739089 DOI: 10.1111/eva.13612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 07/13/2023] [Accepted: 10/12/2023] [Indexed: 12/26/2023] Open
Abstract
Iteroparity represents an important but often overlooked component of life history in anadromous Atlantic salmon. Here, we combined individual DNA profiling and scale reading to identify repeat spawners among ~8000 adult salmon captured in a fish trap in the river Etne, Norway, in the period 2015-2019. Additionally, 171 outward migrating kelts were captured in the spring of 2018-2020 and identified using molecular methods to estimate weight loss since ascending the river to spawn. The overall frequency of repeat spawners identified using molecular methods and scale reading combined was 7% in females and 3% in males (5% in total). Most of these (83%) spent one full year reconditioning at sea before returning for their second spawning, with a larger body size compared with their size at first spawning, gaining on average 15.9 cm. A single female migrating back into the river for a fifth breeding season was also identified. On average, kelts lost 40% bodyweight in the river, and more female than male kelts were captured during outward migration. The date of arrival in the upstream fish trap was significantly but moderately correlated between maiden and second entry to the river for alternate and consecutive spawners. The estimated contribution from repeat spawners to the total number of eggs deposited in the river each year varied between 2% and 17% (average 12%). Molecular-based methods marginally underestimated the number of repeat spawners compared with scale reading (5% vs 7%) likely due to a small number of returning spawners not being trapped and sampled. Differences between the methods were most evident when classifying the spawning strategy (alternate or consecutive-year repeat spawners), where the scale method identified proportionally more consecutive-year repeat spawners than the molecular method. This unique data set reveals previously unstudied components of this life history strategy and demonstrates the importance of repeat spawners in population recruitment.
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Affiliation(s)
- Håvard Kaland
- Institute of Marine ResearchBergenNorway
- Department of Biological Sciences ÅlesundNorwegian University of Science and TechnologyTrondheimNorway
| | | | | | | | | | | | | | | | - Kevin Alan Glover
- Institute of Marine ResearchBergenNorway
- Department of BiologyUniversity of BergenBergenNorway
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Rutle KH, Skern‐Mauritzen R, Nilsen F, Mateos‐Rivera A, Eide AGS, Jansson E, Quintela M, Besnier F, Allyon F, Fjørtoft HB, Glover KA. Aquaculture-driven evolution of the salmon louse mtDNA genome. Evol Appl 2023; 16:1328-1344. [PMID: 37492153 PMCID: PMC10363823 DOI: 10.1111/eva.13572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 05/17/2023] [Accepted: 06/06/2023] [Indexed: 07/27/2023] Open
Abstract
Resistance toward the antiparasitic pyrethroid, deltamethrin, is reported in the Atlantic salmon louse (Lepeophtheirus salmonis salmonis), a persistent ectoparasite of farmed and wild salmonids. The resistance mechanism is linked to mitochondrial DNA (mtDNA), where genetic markers for resistance have been identified. Here, we investigated how widespread pyrethroid use in aquaculture may have influenced mtDNA variation in lice, and the dispersion of resistant haplotypes across the North Atlantic, using historical (2000-2002 "pre-resistance") and contemporary (2014-2017 "post-resistance") samples. To study this, we sequenced ATPase 6 and cytochrome b, genotyped two genetic markers for deltamethrin resistance, and genotyped microsatellites as "neutral" controls of potential population bottlenecks. Overall, we observed a modest reduction in mtDNA diversity in the period 2000-2017, but no reduction in microsatellite variation was observed. The reduction in mtDNA variation was especially distinct in two of the contemporary samples, fixed for one and two haplotypes, respectively. By contrast, all historical samples consisted of close to one mtDNA haplotype per individual. No population genetic structure was detected among the historical samples for mtDNA nor microsatellites. By contrast, significant population genetic differentiation was observed for mtDNA among some of the contemporary samples. However, the observed population genetic structure was tightly linked with the pattern of deltamethrin resistance, and we therefore conclude that it primarily reflects the transient mosaic of pyrethroid usage in time and space. Two historically undetected mtDNA haplotypes dominated in the contemporary samples, both of which were linked to deltamethrin resistance, demonstrating primarily two origins of deltamethrin resistance in the North Atlantic. Collectively, these data demonstrate that the widespread use of pyrethroids in commercial aquaculture has substantially altered the patterns of mtDNA diversity in lice across the North Atlantic, and that long-distance dispersion of resistance is rapid due to high level of genetic connectivity that is observed in this species.
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Affiliation(s)
| | | | - Frank Nilsen
- Department of Biological SciencesUniversity of BergenBergenNorway
| | | | | | | | | | | | | | - Helene Børretzen Fjørtoft
- Department of Biological SciencesUniversity of BergenBergenNorway
- Department of Biological Sciences in AalesundNorwegian University of Science and TechnologyAalesundNorway
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3
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Breistein B, Dahle G, Johansen T, Besnier F, Quintela M, Jorde PE, Knutsen H, Westgaard JI, Nedreaas K, Farestveit E, Glover KA. Geographic variation in gene‐flow from a genetically distinct migratory ecotype drives population genetic structure of coastal Atlantic cod (
Gadus morhua
L.). Evol Appl 2022; 15:1162-1176. [PMID: 35899259 PMCID: PMC9309456 DOI: 10.1111/eva.13422] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 05/10/2022] [Accepted: 05/12/2022] [Indexed: 11/30/2022] Open
Affiliation(s)
- B. Breistein
- Institute of Marine Research Bergen Norway
- Department of Biology University of Bergen Bergen Norway
| | - G. Dahle
- Institute of Marine Research Bergen Norway
- Department of Biology University of Bergen Bergen Norway
| | | | - F. Besnier
- Institute of Marine Research Bergen Norway
| | | | - P. E. Jorde
- Institute of Marine Research Flødevigen Norway
| | - H. Knutsen
- Institute of Marine Research Flødevigen Norway
- Centre for Coastal Research, Department of Natural Sciences University of Agder Norway
| | | | | | | | - K. A. Glover
- Institute of Marine Research Bergen Norway
- Department of Biology University of Bergen Bergen Norway
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Besnier F, Ayllon F, Skaala Ø, Solberg MF, Fjeldheim PT, Anderson K, Knutar S, Glover KA. Introgression of domesticated salmon changes life history and phenology of a wild salmon population. Evol Appl 2022; 15:853-864. [PMID: 35603027 PMCID: PMC9108307 DOI: 10.1111/eva.13375] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 03/03/2022] [Accepted: 03/09/2022] [Indexed: 11/29/2022] Open
Affiliation(s)
- F. Besnier
- Institute of Marine Research PO box 1870 Nordnes N‐5817 Norway
| | - F. Ayllon
- Institute of Marine Research PO box 1870 Nordnes N‐5817 Norway
| | - Ø. Skaala
- Institute of Marine Research PO box 1870 Nordnes N‐5817 Norway
| | - M. F. Solberg
- Institute of Marine Research PO box 1870 Nordnes N‐5817 Norway
| | | | - K. Anderson
- Institute of Marine Research PO box 1870 Nordnes N‐5817 Norway
| | - S. Knutar
- Institute of Marine Research PO box 1870 Nordnes N‐5817 Norway
| | - K. A. Glover
- Institute of Marine Research PO box 1870 Nordnes N‐5817 Norway
- Department of Biological Sciences University of Bergen N‐5020 Bergen Norway
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Skern-Mauritzen R, Malde K, Eichner C, Dondrup M, Furmanek T, Besnier F, Komisarczuk AZ, Nuhn M, Dalvin S, Edvardsen RB, Klages S, Huettel B, Stueber K, Grotmol S, Karlsbakk E, Kersey P, Leong JS, Glover KA, Reinhardt R, Lien S, Jonassen I, Koop BF, Nilsen F. The salmon louse genome: Copepod features and parasitic adaptations. Genomics 2021; 113:3666-3680. [PMID: 34403763 DOI: 10.1016/j.ygeno.2021.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/06/2021] [Accepted: 08/03/2021] [Indexed: 12/13/2022]
Abstract
Copepods encompass numerous ecological roles including parasites, detrivores and phytoplankton grazers. Nonetheless, copepod genome assemblies remain scarce. Lepeophtheirus salmonis is an economically and ecologically important ectoparasitic copepod found on salmonid fish. We present the 695.4 Mbp L. salmonis genome assembly containing ≈60% repetitive regions and 13,081 annotated protein-coding genes. The genome comprises 14 autosomes and a ZZ-ZW sex chromosome system. Assembly assessment identified 92.4% of the expected arthropod genes. Transcriptomics supported annotation and indicated a marked shift in gene expression after host attachment, including apparent downregulation of genes related to circadian rhythm coinciding with abandoning diurnal migration. The genome shows evolutionary signatures including loss of genes needed for peroxisome biogenesis, presence of numerous FNII domains, and an incomplete heme homeostasis pathway suggesting heme proteins to be obtained from the host. Despite repeated development of resistance against chemical treatments L. salmonis exhibits low numbers of many genes involved in detoxification.
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Affiliation(s)
| | - Ketil Malde
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway; Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Christiane Eichner
- Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Michael Dondrup
- Computational Biology Unit, Department of Informatics, University of Bergen, Thormøhlens Gate 55, 5008 Bergen, Norway
| | - Tomasz Furmanek
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway
| | - Francois Besnier
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway
| | - Anna Zofia Komisarczuk
- Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Michael Nuhn
- EMBL-The European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, CB10 1SD, UK
| | - Sussie Dalvin
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway
| | - Rolf B Edvardsen
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway
| | - Sven Klages
- Sequencing Core Facility, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Bruno Huettel
- Max Planck Genome Centre Cologne, Carl von Linné Weg 10, D-50829 Köln, Germany
| | - Kurt Stueber
- Max Planck Genome Centre Cologne, Carl von Linné Weg 10, D-50829 Köln, Germany
| | - Sindre Grotmol
- Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Egil Karlsbakk
- Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Paul Kersey
- EMBL-The European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, CB10 1SD, UK; Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AE, UK
| | - Jong S Leong
- Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada
| | - Kevin A Glover
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway; Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway
| | - Richard Reinhardt
- Max Planck Genome Centre Cologne, Carl von Linné Weg 10, D-50829 Köln, Germany
| | - Sigbjørn Lien
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Oluf Thesens vei 6, 1433 Ås, Norway
| | - Inge Jonassen
- Computational Biology Unit, Department of Informatics, University of Bergen, Thormøhlens Gate 55, 5008 Bergen, Norway
| | - Ben F Koop
- Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada
| | - Frank Nilsen
- Institute of Marine Research, Postboks 1870 Nordnes, 5817 Bergen, Norway; Sea Lice Research Centre. Department of Biological Sciences, University of Bergen, Thormøhlens Gate 53, 5006 Bergen, Norway.
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Fjørtoft HB, Nilsen F, Besnier F, Stene A, Tveten AK, Bjørn PA, Aspehaug VT, Glover KA. Losing the 'arms race': multiresistant salmon lice are dispersed throughout the North Atlantic Ocean. R Soc Open Sci 2021; 8:210265. [PMID: 34084551 PMCID: PMC8150044 DOI: 10.1098/rsos.210265] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
Nothing lasts forever, including the effect of chemicals aimed to control pests in food production. As old pesticides have been compromised by emerging resistance, new ones have been introduced and turned the odds back in our favour. With time, however, some pests have developed multi-pesticide resistance, challenging our ability to control them. In salmonid aquaculture, the ectoparasitic salmon louse has developed resistance to most of the available delousing compounds. The discovery of genetic markers associated with resistance to organophosphates and pyrethroids made it possible for us to investigate simultaneous resistance to both compounds in approximately 2000 samples of salmon lice from throughout the North Atlantic in the years 2000-2016. We observed widespread and increasing multiresistance on the European side of the Atlantic, particularly in areas with intensive aquaculture. Multiresistant lice were also found on wild Atlantic salmon and sea trout, and also on farmed salmonid hosts in areas where delousing chemicals have not been used. In areas with intensive aquaculture, there are almost no lice left that are sensitive to both compounds. These results demonstrate the speed to which this parasite can develop widespread multiresistance, illustrating why the aquaculture industry has repeatedly lost the arms race with this highly problematic parasite.
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Affiliation(s)
- Helene Børretzen Fjørtoft
- Department of Biological Sciences in Aalesund, Norwegian University of Science and Technology, PO Box 1517, 6025 Aalesund, Norway
- Department of Biology, Sea Lice Research Center, University of Bergen, PO Box 7803, 5020 Bergen, Norway
| | - Frank Nilsen
- Department of Biology, Sea Lice Research Center, University of Bergen, PO Box 7803, 5020 Bergen, Norway
| | | | - Anne Stene
- Department of Biological Sciences in Aalesund, Norwegian University of Science and Technology, PO Box 1517, 6025 Aalesund, Norway
| | - Ann-Kristin Tveten
- Department of Biological Sciences in Aalesund, Norwegian University of Science and Technology, PO Box 1517, 6025 Aalesund, Norway
| | - Pål Arne Bjørn
- Institute of Marine Research, PO Box 1870, 5817 Bergen, Norway
| | | | - Kevin Alan Glover
- Department of Biology, Sea Lice Research Center, University of Bergen, PO Box 7803, 5020 Bergen, Norway
- Institute of Marine Research, PO Box 1870, 5817 Bergen, Norway
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7
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Jansson E, Besnier F, Malde K, André C, Dahle G, Glover KA. Genome wide analysis reveals genetic divergence between Goldsinny wrasse populations. BMC Genet 2020; 21:118. [PMID: 33036553 PMCID: PMC7547435 DOI: 10.1186/s12863-020-00921-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 09/24/2020] [Indexed: 12/11/2022] Open
Abstract
Background Marine fish populations are often characterized by high levels of gene flow and correspondingly low genetic divergence. This presents a challenge to define management units. Goldsinny wrasse (Ctenolabrus rupestris) is a heavily exploited species due to its importance as a cleaner-fish in commercial salmonid aquaculture. However, at the present, the population genetic structure of this species is still largely unresolved. Here, full-genome sequencing was used to produce the first genomic reference for this species, to study population-genomic divergence among four geographically distinct populations, and, to identify informative SNP markers for future studies. Results After construction of a de novo assembly, the genome was estimated to be highly polymorphic and of ~600Mbp in size. 33,235 SNPs were thereafter selected to assess genomic diversity and differentiation among four populations collected from Scandinavia, Scotland, and Spain. Global FST among these populations was 0.015–0.092. Approximately 4% of the investigated loci were identified as putative global outliers, and ~ 1% within Scandinavia. SNPs showing large divergence (FST > 0.15) were picked as candidate diagnostic markers for population assignment. One hundred seventy-three of the most diagnostic SNPs between the two Scandinavian populations were validated by genotyping 47 individuals from each end of the species’ Scandinavian distribution range. Sixty-nine of these SNPs were significantly (p < 0.05) differentiated (mean FST_173_loci = 0.065, FST_69_loci = 0.140). Using these validated SNPs, individuals were assigned with high probability (≥ 94%) to their populations of origin. Conclusions Goldsinny wrasse displays a highly polymorphic genome, and substantial population genomic structure. Diversifying selection likely affects population structuring globally and within Scandinavia. The diagnostic loci identified now provide a promising and cost-efficient tool to investigate goldsinny wrasse populations further.
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Affiliation(s)
- Eeva Jansson
- Institute of Marine Research, P. O. Box 1870, Nordnes, 5817, Bergen, Norway.
| | - Francois Besnier
- Institute of Marine Research, P. O. Box 1870, Nordnes, 5817, Bergen, Norway
| | - Ketil Malde
- Institute of Marine Research, P. O. Box 1870, Nordnes, 5817, Bergen, Norway
| | - Carl André
- Department of Marine Sciences-Tjärnö, University of Gothenburg, 45296, Strömstad, Sweden
| | - Geir Dahle
- Institute of Marine Research, P. O. Box 1870, Nordnes, 5817, Bergen, Norway
| | - Kevin A Glover
- Institute of Marine Research, P. O. Box 1870, Nordnes, 5817, Bergen, Norway.,Institute of Biology, University of Bergen, P. O. Box 7803, 5020, Bergen, Norway
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Besnier F, Solberg MF, Harvey AC, Carvalho GR, Bekkevold D, Taylor MI, Creer S, Nielsen EE, Skaala Ø, Ayllon F, Dahle G, Glover KA. Epistatic regulation of growth in Atlantic salmon revealed: a QTL study performed on the domesticated-wild interface. BMC Genet 2020; 21:13. [PMID: 32033538 PMCID: PMC7006396 DOI: 10.1186/s12863-020-0816-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 01/28/2020] [Indexed: 12/23/2022] Open
Abstract
Background Quantitative traits are typically considered to be under additive genetic control. Although there are indications that non-additive factors have the potential to contribute to trait variation, experimental demonstration remains scarce. Here, we investigated the genetic basis of growth in Atlantic salmon by exploiting the high level of genetic diversity and trait expression among domesticated, hybrid and wild populations. Results After rearing fish in common-garden experiments under aquaculture conditions, we performed a variance component analysis in four mapping populations totaling ~ 7000 individuals from six wild, two domesticated and three F1 wild/domesticated hybrid strains. Across the four independent datasets, genome-wide significant quantitative trait loci (QTLs) associated with weight and length were detected on a total of 18 chromosomes, reflecting the polygenic nature of growth. Significant QTLs correlated with both length and weight were detected on chromosomes 2, 6 and 9 in multiple datasets. Significantly, epistatic QTLs were detected in all datasets. Discussion The observed interactions demonstrated that the phenotypic effect of inheriting an allele deviated between half-sib families. Gene-by-gene interactions were also suggested, where the combined effect of two loci resulted in a genetic effect upon phenotypic variance, while no genetic effect was detected when the two loci were considered separately. To our knowledge, this is the first documentation of epistasis in a quantitative trait in Atlantic salmon. These novel results are of relevance for breeding programs, and for predicting the evolutionary consequences of domestication-introgression in wild populations.
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Affiliation(s)
- Francois Besnier
- Population Genetics Research group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817, Bergen, Norway.
| | - Monica F Solberg
- Population Genetics Research group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817, Bergen, Norway
| | - Alison C Harvey
- Population Genetics Research group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817, Bergen, Norway.,Molecular Ecology and Fisheries Genetics Laboratory, School of Biological Sciences, Bangor University, Deiniol Road, Bangor, LL57 2UW, UK
| | - Gary R Carvalho
- Molecular Ecology and Fisheries Genetics Laboratory, School of Biological Sciences, Bangor University, Deiniol Road, Bangor, LL57 2UW, UK
| | - Dorte Bekkevold
- Section for Marine Living Resources, National Institute of Aquatic Resources, Technical University of Denmark, Vejlsøvej 39, 8600, Silkeborg, Denmark
| | - Martin I Taylor
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Simon Creer
- Molecular Ecology and Fisheries Genetics Laboratory, School of Biological Sciences, Bangor University, Deiniol Road, Bangor, LL57 2UW, UK
| | - Einar E Nielsen
- Section for Marine Living Resources, National Institute of Aquatic Resources, Technical University of Denmark, Vejlsøvej 39, 8600, Silkeborg, Denmark
| | - Øystein Skaala
- Population Genetics Research group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817, Bergen, Norway
| | - Fernando Ayllon
- Population Genetics Research group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817, Bergen, Norway
| | - Geir Dahle
- Population Genetics Research group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817, Bergen, Norway.,Sea Lice Research Centre, Department of Biology, University of Bergen, Bergen, Norway
| | - Kevin A Glover
- Population Genetics Research group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817, Bergen, Norway.,Sea Lice Research Centre, Department of Biology, University of Bergen, Bergen, Norway
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Skaala Ø, Besnier F, Borgstrøm R, Barlaup B, Sørvik AG, Normann E, Østebø BI, Hansen MM, Glover KA. An extensive common-garden study with domesticated and wild Atlantic salmon in the wild reveals impact on smolt production and shifts in fitness traits. Evol Appl 2019; 12:1001-1016. [PMID: 31080511 PMCID: PMC6503829 DOI: 10.1111/eva.12777] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/18/2019] [Accepted: 01/19/2019] [Indexed: 01/15/2023] Open
Abstract
Interactions between domesticated escapees and wild conspecifics represent a threat to the genetic integrity and fitness of native populations. For Atlantic salmon, the recurrent presence of large numbers of domesticated escapees in the wild makes it necessary to better understand their impacts on native populations. We planted 254,400 eggs from 75 families of domesticated, F1-hybrid, and wild salmon in a river containing up- and downstream traps. Additionally, 41,630 hatchery smolts of the same pedigrees were released into the river. Over 8 years, 6,669 out-migrating smolts and 356 returning adults were recaptured and identified to their families of origin with DNA. In comparison with wild salmon, domesticated fish had substantially lower egg to smolt survival (1.8% vs. 3.8% across cohorts), they migrated earlier in the year (11.8 days earlier across years), but they only displayed marginally larger smolt sizes and marginally lower smolt ages. Upon return to freshwater, domesticated salmon were substantially larger at age than wild salmon (2.4 vs. 2.0, 4.8 vs. 3.2, and 8.5 vs. 5.6 kg across sexes for 1, 2, and 3 sea-winter fish) and displayed substantially lower released smolt to adult survival (0.41% vs. 0.94% across releases). Overall, egg-to-returning adult survival ratios were 1:0.76:0.30 and 1:0.44:0.21 for wild:F1-hybrid:domesticated salmon, respectively, using two different types of data. This study represents the most updated and extensive analysis of domesticated, hybrid, and wild salmon in the wild and provides the first documentation of a clear genetic difference in the timing of smolt migration-an adaptive trait presumed to be linked with optimal timing of entry to seawater. We conclude that spawning and hybridization of domesticated escapees can lead to (i) reduced wild smolt output and therefore wild adult abundance, through resource competition in freshwater, (ii) reduced total adult abundance due to freshwater competition and reduced marine survival of domesticated salmon, and (iii) maladaptive changes in phenotypic traits.
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Affiliation(s)
| | | | - Reidar Borgstrøm
- Faculty of Environmental Sciences and Natural Resource ManagementÅsNorway
| | | | | | | | | | - Michael Møller Hansen
- Institute of Marine ResearchNordnes, BergenNorway
- Department of BioscienceAarhus UniversityAarhus CDenmark
| | - Kevin Alan Glover
- Institute of Marine ResearchNordnes, BergenNorway
- Department of Biological SciencesUniversity of BergenBergenNorway
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Perry WB, Solberg MF, Besnier F, Dyrhovden L, Matre IH, Fjelldal PG, Ayllon F, Creer S, Llewellyn M, Taylor MI, Carvalho G, Glover KA. Evolutionary drivers of kype size in Atlantic salmon ( Salmo salar): domestication, age and genetics. R Soc Open Sci 2019; 6:190021. [PMID: 31183145 PMCID: PMC6502380 DOI: 10.1098/rsos.190021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
The diversity of reproduction and associated mating patterns in Atlantic salmon (Salmo salar) has long captivated evolutionary biologists. Salmo salar exhibit strategies involving migration, bold mating behaviours and radical morphological and physiological change. One such radical change is the elongation and curvature of the lower jaw in sexually mature males into a hook-like appendage called the kype. The kype is a secondary sexual characteristic used in mating hierarchies and a prime candidate for sexual selection. As one of the core global aquaculture fish species, however, mate choice, and thus sexual selection, has been replaced by industrial artificial fertilization seeking to develop more commercially viable strains. Removal of mate choice provides a unique opportunity to examine the kype over successive generations in the absence of sexual selection. Here we use a large-scale common-garden experiment, incorporating six experimental strains (wild, farmed and wild × farmed hybrids), experiencing one to three sea winters, to assess the impact of age and genetic background. After controlling for allometry, fork length-adjusted kype height (AKH) was significantly reduced in the domesticated strain in comparison to two wild strains. Furthermore, genetic variation at a locus on linkage group SSA1 was associated with kype height, and a locus on linkage group SSA23 was associated with fork length-adjusted kype length (AKL). The reduction in fork length-AKH in domesticated salmon suggests that the kype is of importance in mate choice and that it has decreased due to relaxation of sexual selection. Fork length-AKL showed an increase in domesticated individuals, highlighting that it may not be an important cue in mate choice. These results give us insight into the evolutionary significance of the kype, as well as implications of genetic induced phenotypic change caused by domesticated individuals escaping into the natural environment.
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Affiliation(s)
- William Bernard Perry
- Molecular Ecology and Fisheries Genetics Laboratory, School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK
| | - Monica Favnebøe Solberg
- Population Genetics Research Group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway
| | - Francois Besnier
- Population Genetics Research Group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway
| | - Lise Dyrhovden
- Matre Research Station, Institute of Marine Research, Matredal, Norway
| | - Ivar Helge Matre
- Matre Research Station, Institute of Marine Research, Matredal, Norway
| | - Per Gunnar Fjelldal
- Population Genetics Research Group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway
| | - Fernando Ayllon
- Population Genetics Research Group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway
| | - Simon Creer
- Molecular Ecology and Fisheries Genetics Laboratory, School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK
| | - Martin Llewellyn
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Martin I. Taylor
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | - Gary Carvalho
- Molecular Ecology and Fisheries Genetics Laboratory, School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK
| | - Kevin Alan Glover
- Population Genetics Research Group, Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway
- Institute of Biology, University of Bergen, N-5020 Bergen, Norway
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11
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Harvey AC, Skilbrei OT, Besnier F, Solberg MF, Sørvik AGE, Glover KA. Implications for introgression: has selection for fast growth altered the size threshold for precocious male maturation in domesticated Atlantic salmon? BMC Evol Biol 2018; 18:188. [PMID: 30558529 PMCID: PMC6298023 DOI: 10.1186/s12862-018-1294-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Accepted: 11/16/2018] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Mature male parr (MMP) represent an important alternative life-history strategy in Atlantic salmon populations. Previous studies indicate that the maturation size threshold for male parr varies among wild populations and is influenced by individual growth, environmental conditions, and genetics. More than ten generations of breeding have resulted in domesticated salmon displaying many genetic differences to wild salmon, including greatly increased growth rates. This may have resulted in domesticated fish with the potential to outgrow the size threshold for early maturation, or evolution of the size threshold of the trait itself. To investigate this, we performed a common-garden experiment under farming conditions using 4680 salmon from 39 families representing four wild, two wild-domesticated hybrid, and two domesticated strains. RESULTS Domesticated salmon outgrew wild salmon 2-5-fold, and hybrids displayed intermediate growth. Overall, the numbers of MMP varied greatly among families and strains: averaging 4-12% in domesticated, 18-25% in hybrid, and 43-74% in the wild populations. However, when the influence of growth was accounted for, by dividing fish into lower and upper size modes, no difference in the incidence of MMP was detected among domesticated and wild strains in either size mode. In the lower size mode, hybrids displayed significantly lower incidences of mature males than their wild parental strains. No consistent differences in the body size of MMP, connected to domestication, was detected. CONCLUSIONS Our data demonstrate: 1- no evidence for the evolution of the size threshold for MMP in domesticated salmon, 2- the vastly lower incidence of MMP in domesticated strains under aquaculture conditions is primarily due to their genetically increased growth rate causing them to outgrow the size threshold for early maturation, 3- the incidence of MMP is likely to overlap among domesticated and wild salmon in the natural habitat where they typically display overlapping growth, although hybrid offspring may display lower incidences of mature male parr. These results have implications for wild salmon populations that are exposed to introgression from domesticated escapees.
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Affiliation(s)
- A C Harvey
- Institute of Marine Research, P. O. Box 1870, Nordnes, NO-5817, Bergen, Norway.
| | - O T Skilbrei
- Institute of Marine Research, P. O. Box 1870, Nordnes, NO-5817, Bergen, Norway
| | - F Besnier
- Institute of Marine Research, P. O. Box 1870, Nordnes, NO-5817, Bergen, Norway
| | - M F Solberg
- Institute of Marine Research, P. O. Box 1870, Nordnes, NO-5817, Bergen, Norway
| | - A-G E Sørvik
- Institute of Marine Research, P. O. Box 1870, Nordnes, NO-5817, Bergen, Norway
| | - K A Glover
- Institute of Marine Research, P. O. Box 1870, Nordnes, NO-5817, Bergen, Norway.,Department of Biology, University of Bergen, P. O. Box 7803, N-5020, Bergen, Norway
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12
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Glover KA, Solberg MF, Besnier F, Skaala Ø. Cryptic introgression: evidence that selection and plasticity mask the full phenotypic potential of domesticated Atlantic salmon in the wild. Sci Rep 2018; 8:13966. [PMID: 30228303 PMCID: PMC6143624 DOI: 10.1038/s41598-018-32467-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 09/03/2018] [Indexed: 01/13/2023] Open
Abstract
Domesticated Atlantic salmon grow much faster than wild salmon when reared together in fish tanks under farming conditions (size ratios typically 1:2-3). In contrast, domesticated salmon only display marginally higher growth than wild salmon when reared together in rivers (size ratios typically 1:1-1.2). This begs the question why? Is this a difference in the plastic response driven by divergent energy budgets between the two environments, or is it a result of selection, whereby domesticated salmon that display the greatest growth-potential are those at greatest risk of mortality in the wild? We reared domesticated, hybrid and wild salmon in a river until they smoltified at age 2 or 4, and thereafter in fish tanks for a further 2 years. In the river, there was no difference in the mean size between the groups. In contrast, after being transferred from the river to fish tanks, the domesticated salmon significantly outgrew the wild salmon (maximum size ratio of ~1:1.8). This demonstrates that selection alone cannot be responsible for the lack of growth differences observed between domesticated and wild salmon in rivers. Nevertheless, the final size ratios observed after rearing in tanks were lower than expected in that environment, thus suggesting that plasticity, as for selection, cannot be the sole mechanism. We therefore conclude that a combination of energy-budget plasticity, and selection via growth-potential mortality, cause the differences in growth reaction norms between domesticated and wild salmon across these contrasting environments. Our results imply that if phenotypic changes are not observed in wild populations following introgression of domesticated conspecifics, it does not mean that functional genetic changes have not occurred in the admixed population. Clearly, under the right environmental conditions, the underlying genetic changes will manifest themselves in the phenotype.
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Affiliation(s)
- Kevin A Glover
- Institute of Marine Research, P.O. Box 1870, N-5817, Bergen, Norway. .,University of Bergen, Department of Biology, P.O. Box 7803, N-5020, Bergen, Norway.
| | - Monica F Solberg
- Institute of Marine Research, P.O. Box 1870, N-5817, Bergen, Norway
| | - Francois Besnier
- Institute of Marine Research, P.O. Box 1870, N-5817, Bergen, Norway
| | - Øystein Skaala
- Institute of Marine Research, P.O. Box 1870, N-5817, Bergen, Norway
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13
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Malde K, Seliussen BB, Quintela M, Dahle G, Besnier F, Skaug HJ, Øien N, Solvang HK, Haug T, Skern-Mauritzen R, Kanda N, Pastene LA, Jonassen I, Glover KA. Whole genome resequencing reveals diagnostic markers for investigating global migration and hybridization between minke whale species. BMC Genomics 2017; 18:76. [PMID: 28086785 PMCID: PMC5237217 DOI: 10.1186/s12864-016-3416-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 12/12/2016] [Indexed: 11/24/2022] Open
Abstract
Background In the marine environment, where there are few absolute physical barriers, contemporary contact between previously isolated species can occur across great distances, and in some cases, may be inter-oceanic. An example of this can be seen in the minke whale species complex. Antarctic minke whales are genetically and morphologically distinct from the common minke found in the north Atlantic and Pacific oceans, and the two species are estimated to have been isolated from each other for 5 million years or more. Recent atypical migrations from the southern to the northern hemisphere have been documented and fertile hybrids and back-crossed individuals between both species have also been identified. However, it is not known whether this represents a contemporary event, potentially driven by ecosystem changes in the Antarctic, or a sporadic occurrence happening over an evolutionary time-scale. We successfully used whole genome resequencing to identify a panel of diagnostic SNPs which now enable us address this evolutionary question. Results A large number of SNPs displaying fixed or nearly fixed allele frequency differences among the minke whale species were identified from the sequence data. Five panels of putatively diagnostic markers were established on a genotyping platform for validation of allele frequencies; two panels (26 and 24 SNPs) separating the two species of minke whale, and three panels (22, 23, and 24 SNPs) differentiating the three subspecies of common minke whale. The panels were validated against a set of reference samples, demonstrating the ability to accurately identify back-crossed whales up to three generations. Conclusions This work has resulted in the development of a panel of novel diagnostic genetic markers to address inter-oceanic and global contact among the genetically isolated minke whale species and sub-species. These markers, including a globally relevant genetic reference data set for this species complex, are now openly available for researchers interested in identifying other potential whale hybrids in the world’s oceans. The approach used here, combining whole genome resequencing and high-throughput genotyping, represents a universal approach to develop similar tools for other species and population complexes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3416-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ketil Malde
- Institute of Marine Research, PO box 1870, Nordnes, N-5817, Bergen, Norway.,Department of Informatics, University of Bergen, N-5020, Bergen, Norway
| | | | - María Quintela
- Institute of Marine Research, PO box 1870, Nordnes, N-5817, Bergen, Norway
| | - Geir Dahle
- Institute of Marine Research, PO box 1870, Nordnes, N-5817, Bergen, Norway
| | - Francois Besnier
- Institute of Marine Research, PO box 1870, Nordnes, N-5817, Bergen, Norway
| | - Hans J Skaug
- Institute of Marine Research, PO box 1870, Nordnes, N-5817, Bergen, Norway.,Department of Mathematics, University of Bergen, N-5020, Bergen, Norway
| | - Nils Øien
- Institute of Marine Research, PO box 1870, Nordnes, N-5817, Bergen, Norway
| | - Hiroko K Solvang
- Institute of Marine Research, PO box 1870, Nordnes, N-5817, Bergen, Norway
| | - Tore Haug
- Institute of Marine Research, PO box 6404, N-9294, Tromsø, Norway
| | | | - Naohisa Kanda
- Institute of Cetacean Research, Toyomi-cho 4-5, Chuo-ku, Tokyo, 104-0055, Japan.,Japan NUS Co., Ltd, Nishi-Shinjuku Kimuraya Bldg 5F, 7-5-25, Nishi-Shinjuku, 160-0023, Japan
| | - Luis A Pastene
- Institute of Cetacean Research, Toyomi-cho 4-5, Chuo-ku, Tokyo, 104-0055, Japan
| | - Inge Jonassen
- Department of Informatics, University of Bergen, N-5020, Bergen, Norway
| | - Kevin A Glover
- Institute of Marine Research, PO box 1870, Nordnes, N-5817, Bergen, Norway. .,Department of Biology, University of Bergen, N-5020, Bergen, Norway.
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14
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Alexander M, Ho SYW, Molak M, Barnett R, Carlborg Ö, Dorshorst B, Honaker C, Besnier F, Wahlberg P, Dobney K, Siegel P, Andersson L, Larson G. Mitogenomic analysis of a 50-generation chicken pedigree reveals a rapid rate of mitochondrial evolution and evidence for paternal mtDNA inheritance. Biol Lett 2016; 11:rsbl.2015.0561. [PMID: 26510672 PMCID: PMC4650172 DOI: 10.1098/rsbl.2015.0561] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Mitochondrial genomes represent a valuable source of data for evolutionary research, but studies of their short-term evolution have typically been limited to invertebrates, humans and laboratory organisms. Here we present a detailed study of 12 mitochondrial genomes that span a total of 385 transmissions in a well-documented 50-generation pedigree in which two lineages of chickens were selected for low and high juvenile body weight. These data allowed us to test the hypothesis of time-dependent evolutionary rates and the assumption of strict maternal mitochondrial transmission, and to investigate the role of mitochondrial mutations in determining phenotype. The identification of a non-synonymous mutation in ND4L and a synonymous mutation in CYTB, both novel mutations in Gallus, allowed us to estimate a molecular rate of 3.13 × 10(-7) mutations/site/year (95% confidence interval 3.75 × 10(-8)-1.12 × 10(-6)). This is substantially higher than avian rate estimates based upon fossil calibrations. Ascertaining which of the two novel mutations was present in an additional 49 individuals also revealed an instance of paternal inheritance of mtDNA. Lastly, an association analysis demonstrated that neither of the point mutations was strongly associated with the phenotypic differences between the two selection lines. Together, these observations reveal the highly dynamic nature of mitochondrial evolution over short time periods.
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Affiliation(s)
- Michelle Alexander
- BioArCh Biology S Block, University of York, Wentworth Way, Heslington, York YO10 5DD, UK Department of Archaeology, School of Geosciences, University of Aberdeen, St. Mary's, Elphinstone Road, AB24 3UF, UK
| | - Simon Y W Ho
- School of Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Martyna Molak
- Museum and Institute of Zoology, Polish Academy of Sciences, Warsaw 00-679, Poland
| | - Ross Barnett
- Palaeogenomics and Bio-Archaeology Research Network, Research Laboratory for Archaeology, Dyson Perrins Building, South Parks Road, Oxford OX1 3QY, UK
| | - Örjan Carlborg
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, PO Box 7078, 75007 Uppsala, Sweden
| | - Ben Dorshorst
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, PO Box 582, 75123 Uppsala, Sweden Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Christa Honaker
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Francois Besnier
- Section of Population Genetics, Institute of Marine Research, Nordnes 5817, Bergen, Norway
| | - Per Wahlberg
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, PO Box 582, 75123 Uppsala, Sweden
| | - Keith Dobney
- Department of Archaeology, School of Geosciences, University of Aberdeen, St. Mary's, Elphinstone Road, AB24 3UF, UK
| | - Paul Siegel
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Leif Andersson
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, PO Box 582, 75123 Uppsala, Sweden Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, PO Box 7023, 75007 Uppsala, Sweden
| | - Greger Larson
- Palaeogenomics and Bio-Archaeology Research Network, Research Laboratory for Archaeology, Dyson Perrins Building, South Parks Road, Oxford OX1 3QY, UK
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15
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Besnier F, Kent M, Skern-Mauritzen R, Lien S, Malde K, Edvardsen RB, Taylor S, Ljungfeldt LER, Nilsen F, Glover KA. Human-induced evolution caught in action: SNP-array reveals rapid amphi-atlantic spread of pesticide resistance in the salmon ecotoparasite Lepeophtheirus salmonis. BMC Genomics 2014; 15:937. [PMID: 25344698 PMCID: PMC4223847 DOI: 10.1186/1471-2164-15-937] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 10/16/2014] [Indexed: 12/23/2022] Open
Abstract
Background The salmon louse, Lepeophtheirus salmonis, is an ectoparasite of salmonids that causes huge economic losses in salmon farming, and has also been causatively linked with declines of wild salmonid populations. Lice control on farms is reliant upon a few groups of pesticides that have all shown time-limited efficiency due to resistance development. However, to date, this example of human-induced evolution is poorly documented at the population level due to the lack of molecular tools. As such, important evolutionary and management questions, linked to the development and dispersal of pesticide resistance in this parasite, remain unanswered. Here, we introduce the first Single Nucleotide Polymorphism (SNP) array for the salmon louse, which includes 6000 markers, and present a population genomic scan using this array on 576 lice from twelve farms distributed across the North Atlantic. Results Our results support the hypothesis of a single panmictic population of lice in the Atlantic, and importantly, revealed very strong selective sweeps on linkage groups 1 and 5. These sweeps included candidate genes potentially connected to pesticide resistance. After genotyping a further 576 lice from 12 full sibling families, a genome-wide association analysis established a highly significant association between the major sweep on linkage group 5 and resistance to emamectin benzoate, the most widely used pesticide in salmonid aquaculture for more than a decade. Conclusions The analysis of conserved haplotypes across samples from the Atlantic strongly suggests that emamectin benzoate resistance developed at a single source, and rapidly spread across the Atlantic within the period 1999 when the chemical was first introduced, to 2010 when samples for the present study were obtained. These results provide unique insights into the development and spread of pesticide resistance in the marine environment, and identify a small genomic region strongly linked to emamectin benzoate resistance. Finally, these results have highly significant implications for the way pesticide resistance is considered and managed within the aquaculture industry. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-937) contains supplementary material, which is available to authorized users.
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16
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Glover KA, Pertoldi C, Besnier F, Wennevik V, Kent M, Skaala Ø. Atlantic salmon populations invaded by farmed escapees: quantifying genetic introgression with a Bayesian approach and SNPs. BMC Genet 2013; 14:74. [PMID: 23968202 PMCID: PMC3765417 DOI: 10.1186/1471-2156-14-74] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Accepted: 08/15/2013] [Indexed: 11/12/2022] Open
Abstract
Background Many native Atlantic salmon populations have been invaded by domesticated escapees for three decades or longer. However, thus far, the cumulative level of gene-flow that has occurred from farmed to wild salmon has not been reported for any native Atlantic salmon population. The aim of the present study was to investigate temporal genetic stability in native populations, and, quantify gene-flow from farmed salmon that caused genetic changes where they were observed. This was achieved by genotyping historical and contemporary samples from 20 populations covering all of Norway with recently identified single nucleotide polymorphism markers that are collectively diagnostic for farmed and wild salmon. These analyses were combined with analysis of farmed salmon and implementation of Approximate Bayesian computation based simulations. Results Five of the populations displayed statistically significant temporal genetic changes. All five of these populations became more similar to a pool of farmed fish with time, strongly suggesting introgression of farmed fish as the primary cause. The remaining 15 populations displayed weak or non-significant temporal genetic changes. Estimated introgression of farmed fish ranged from 2-47% per population using approximate Bayesian computation. Thus, some populations exhibited high degrees of farmed salmon introgression while others were more or less unaffected. The observed frequency of escapees in each population was moderately correlated with estimated introgression per population R2 = 0.47 P < 0.001. Genetic isolation by distance existed within the historical and contemporary data sets, however, the among-population level of divergence decreased with time. Conclusions This is the first study to quantify cumulative introgression of farmed salmon in any native Atlantic salmon population. The estimations demonstrate that the level of introgression has been population-specific, and that the level of introgression is not solely predicted by the frequency of escapees observed in the population. However, some populations have been strongly admixed with farmed salmon, and these data provide policy makers with unique information to address this situation.
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Affiliation(s)
- Kevin Alan Glover
- Section of Population Genetics and Ecology, Institute of Marine Research, Bergen, Norway.
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17
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Besnier F, Glover KA. ParallelStructure: a R package to distribute parallel runs of the population genetics program STRUCTURE on multi-core computers. PLoS One 2013; 8:e70651. [PMID: 23923012 PMCID: PMC3726640 DOI: 10.1371/journal.pone.0070651] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Accepted: 06/20/2013] [Indexed: 11/18/2022] Open
Abstract
This software package provides an R-based framework to make use of multi-core computers when running analyses in the population genetics program STRUCTURE. It is especially addressed to those users of STRUCTURE dealing with numerous and repeated data analyses, and who could take advantage of an efficient script to automatically distribute STRUCTURE jobs among multiple processors. It also consists of additional functions to divide analyses among combinations of populations within a single data set without the need to manually produce multiple projects, as it is currently the case in STRUCTURE. The package consists of two main functions: MPI_structure() and parallel_structure() as well as an example data file. We compared the performance in computing time for this example data on two computer architectures and showed that the use of the present functions can result in several-fold improvements in terms of computation time. ParallelStructure is freely available at https://r-forge.r-project.org/projects/parallstructure/.
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Affiliation(s)
- Francois Besnier
- Department of Population Genetics, Institute of Marine Research, Bergen, Norway.
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18
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Skern-Mauritzen R, Malde K, Besnier F, Nilsen F, Jonassen I, Reinhardt R, Koop B, Dalvin S, Mæhle S, Kongshaug H, Glover K. How does sequence variability affectde novoassembly quality? J NAT HIST 2013. [DOI: 10.1080/00222933.2012.738833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Pettersson M, Besnier F, Siegel PB, Carlborg Ö. Replication and explorations of high-order epistasis using a large advanced intercross line pedigree. PLoS Genet 2011; 7:e1002180. [PMID: 21814519 PMCID: PMC3140984 DOI: 10.1371/journal.pgen.1002180] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 05/26/2011] [Indexed: 12/11/2022] Open
Abstract
Dissection of the genetic architecture of complex traits persists as a major challenge in biology; despite considerable efforts, much remains unclear including the role and importance of genetic interactions. This study provides empirical evidence for a strong and persistent contribution of both second- and third-order epistatic interactions to long-term selection response for body weight in two divergently selected chicken lines. We earlier reported a network of interacting loci with large effects on body weight in an F(2) intercross between these high- and low-body weight lines. Here, most pair-wise interactions in the network are replicated in an independent eight-generation advanced intercross line (AIL). The original report showed an important contribution of capacitating epistasis to growth, meaning that the genotype at a hub in the network releases the effects of one or several peripheral loci. After fine-mapping of the loci in the AIL, we show that these interactions were persistent over time. The replication of five of six originally reported epistatic loci, as well as the capacitating epistasis, provides strong empirical evidence that the originally observed epistasis is of biological importance and is a contributor in the genetic architecture of this population. The stability of genetic interaction mechanisms over time indicates a non-transient role of epistasis on phenotypic change. Third-order epistasis was for the first time examined in this study and was shown to make an important contribution to growth, which suggests that the genetic architecture of growth is more complex than can be explained by two-locus interactions only. Our results illustrate the importance of designing studies that facilitate exploration of epistasis in populations for obtaining a comprehensive understanding of the genetics underlying a complex trait.
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Affiliation(s)
- Mats Pettersson
- Department of Animal Breeding and Genetics, Swedish University of Agriculture Sciences (SLU), Uppsala, Sweden
| | - Francois Besnier
- Department of Animal Breeding and Genetics, Swedish University of Agriculture Sciences (SLU), Uppsala, Sweden
| | - Paul B. Siegel
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - Örjan Carlborg
- Department of Animal Breeding and Genetics, Swedish University of Agriculture Sciences (SLU), Uppsala, Sweden
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- * E-mail:
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20
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Albert FW, Hodges E, Jensen JD, Besnier F, Xuan Z, Rooks M, Bhattacharjee A, Brizuela L, Good JM, Green RE, Burbano HA, Plyusnina IZ, Trut L, Andersson L, Schöneberg T, Carlborg O, Hannon GJ, Pääbo S. Targeted resequencing of a genomic region influencing tameness and aggression reveals multiple signals of positive selection. Heredity (Edinb) 2011; 107:205-14. [PMID: 21304545 DOI: 10.1038/hdy.2011.4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The identification of the causative genetic variants in quantitative trait loci (QTL) influencing phenotypic traits is challenging, especially in crosses between outbred strains. We have previously identified several QTL influencing tameness and aggression in a cross between two lines of wild-derived, outbred rats (Rattus norvegicus) selected for their behavior towards humans. Here, we use targeted sequence capture and massively parallel sequencing of all genes in the strongest QTL in the founder animals of the cross. We identify many novel sequence variants, several of which are potentially functionally relevant. The QTL contains several regions where either the tame or the aggressive founders contain no sequence variation, and two regions where alternative haplotypes are fixed between the founders. A re-analysis of the QTL signal showed that the causative site is likely to be fixed among the tame founder animals, but that several causative alleles may segregate among the aggressive founder animals. Using a formal test for the detection of positive selection, we find 10 putative positively selected regions, some of which are close to genes known to influence behavior. Together, these results show that the QTL is probably not caused by a single selected site, but may instead represent the joint effects of several sites that were targets of polygenic selection.
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Affiliation(s)
- F W Albert
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
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21
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Besnier F, Wahlberg P, Rönnegård L, Ek W, Andersson L, Siegel PB, Carlborg O. Fine mapping and replication of QTL in outbred chicken advanced intercross lines. Genet Sel Evol 2011; 43:3. [PMID: 21241486 PMCID: PMC3034666 DOI: 10.1186/1297-9686-43-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 01/17/2011] [Indexed: 11/20/2022] Open
Abstract
Background Linkage mapping is used to identify genomic regions affecting the expression of complex traits. However, when experimental crosses such as F2 populations or backcrosses are used to map regions containing a Quantitative Trait Locus (QTL), the size of the regions identified remains quite large, i.e. 10 or more Mb. Thus, other experimental strategies are needed to refine the QTL locations. Advanced Intercross Lines (AIL) are produced by repeated intercrossing of F2 animals and successive generations, which decrease linkage disequilibrium in a controlled manner. Although this approach is seen as promising, both to replicate QTL analyses and fine-map QTL, only a few AIL datasets, all originating from inbred founders, have been reported in the literature. Methods We have produced a nine-generation AIL pedigree (n = 1529) from two outbred chicken lines divergently selected for body weight at eight weeks of age. All animals were weighed at eight weeks of age and genotyped for SNP located in nine genomic regions where significant or suggestive QTL had previously been detected in the F2 population. In parallel, we have developed a novel strategy to analyse the data that uses both genotype and pedigree information of all AIL individuals to replicate the detection of and fine-map QTL affecting juvenile body weight. Results Five of the nine QTL detected with the original F2 population were confirmed and fine-mapped with the AIL, while for the remaining four, only suggestive evidence of their existence was obtained. All original QTL were confirmed as a single locus, except for one, which split into two linked QTL. Conclusions Our results indicate that many of the QTL, which are genome-wide significant or suggestive in the analyses of large intercross populations, are true effects that can be replicated and fine-mapped using AIL. Key factors for success are the use of large populations and powerful statistical tools. Moreover, we believe that the statistical methods we have developed to efficiently study outbred AIL populations will increase the number of organisms for which in-depth complex traits can be analyzed.
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Affiliation(s)
- Francois Besnier
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
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Thomas L, Brouste Y, Najioullah F, Hochedez P, Hatchuel Y, Moravie V, Kaidomar S, King J, Besnier F, Abel S, Carmès S, Schmitt S, Brihier P, Meunier C, Cardoso T, Rosine J, Quenel P, Césaire R, Cabié A. Prospective and descriptive study of adult dengue cases in an emergency department, in Martinique. Med Mal Infect 2010; 40:480-9. [DOI: 10.1016/j.medmal.2009.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 04/30/2009] [Accepted: 10/27/2009] [Indexed: 11/29/2022]
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Abstract
Background The linkage phase, or haplotype, is an extra level of information that in addition to genotype and pedigree can be useful for reconstructing the inheritance pattern of the alleles in a pedigree, and computing for example Identity By Descent probabilities. If a haplotype is provided, the precision of estimated IBD probabilities increases, as long as the haplotype is estimated without errors. It is therefore important to only use haplotypes that are strongly supported by the available data for IBD estimation, to avoid introducing new errors due to erroneous linkage phases. Results We propose a genetic algorithm based method for haplotype estimation in family data that includes a stringency parameter. This allows the user to decide the error tolerance level when inferring parental origin of the alleles. This is a novel feature compared to existing methods for haplotype estimation. We show that using a high stringency produces haplotype data with few errors, whereas a low stringency provides haplotype estimates in most situations, but with an increased number of errors. Conclusion By including a stringency criterion in our haplotyping method, the user is able to maintain the error rate at a suitable level for the particular study; one can select anything from haplotyped data with very small proportion of errors and a higher proportion of non-inferred haplotypes, to data with phase estimates for every marker, when haplotype errors are tolerable. Giving this choice makes the method more flexible and useful in a wide range of applications as it is able to fulfil different requirements regarding the tolerance for haplotype errors, or uncertain marker-phases.
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Affiliation(s)
- Francois Besnier
- Linnaeus Centre for Bioinformatics, Uppsala University, SE-75124 Uppsala, Sweden.
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Abstract
BACKGROUND The aim of this paper is to develop a flexible model for analysis of quantitative trait loci (QTL) in outbred line crosses, which includes both additive and dominance effects. Our flexible intercross analysis (FIA) model accounts for QTL that are not fixed within founder lines and is based on the variance component framework. Genome scans with FIA are performed using a score statistic, which does not require variance component estimation. RESULTS Simulations of a pedigree with 800 F2 individuals showed that the power of FIA including both additive and dominance effects was almost 50% for a QTL with equal allele frequencies in both lines with complete dominance and a moderate effect, whereas the power of a traditional regression model was equal to the chosen significance value of 5%. The power of FIA without dominance effects included in the model was close to those obtained for FIA with dominance for all simulated cases except for QTL with overdominant effects. A genome-wide linkage analysis of experimental data from an F2 intercross between Red Jungle Fowl and White Leghorn was performed with both additive and dominance effects included in FIA. The score values for chicken body weight at 200 days of age were similar to those obtained in FIA analysis without dominance. CONCLUSION We have extended FIA to include QTL dominance effects. The power of FIA was superior, or similar, to standard regression methods for QTL effects with dominance. The difference in power for FIA with or without dominance is expected to be small as long as the QTL effects are not overdominant. We suggest that FIA with only additive effects should be the standard model to be used, especially since it is more computationally efficient.
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Affiliation(s)
- Lars Rönnegård
- Statistics Unit, Dalarna University, Borlänge, Sweden
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Francois Besnier
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Örjan Carlborg
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Groenen MAM, Wahlberg P, Foglio M, Cheng HH, Megens HJ, Crooijmans RPMA, Besnier F, Lathrop M, Muir WM, Wong GKS, Gut I, Andersson L. A high-density SNP-based linkage map of the chicken genome reveals sequence features correlated with recombination rate. Genes Dev 2009; 19:510-9. [PMID: 19088305 PMCID: PMC2661806 DOI: 10.1101/gr.086538.108] [Citation(s) in RCA: 200] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Accepted: 12/04/2008] [Indexed: 11/25/2022]
Abstract
The resolution of the chicken consensus linkage map has been dramatically improved in this study by genotyping 12,945 single nucleotide polymorphisms (SNPs) on three existing mapping populations in chicken: the Wageningen (WU), East Lansing (EL), and Uppsala (UPP) mapping populations. As many as 8599 SNPs could be included, bringing the total number of markers in the current consensus linkage map to 9268. The total length of the sex average map is 3228 cM, considerably smaller than previous estimates using the WU and EL populations, reflecting the higher quality of the new map. The current map consists of 34 linkage groups and covers at least 29 of the 38 autosomes. Sex-specific analysis and comparisons of the maps based on the three individual populations showed prominent heterogeneity in recombination rates between populations, but no significant heterogeneity between sexes. The recombination rates in the F(1) Red Jungle fowl/White Leghorn males and females were significantly lower compared with those in the WU broiler population, consistent with a higher recombination rate in purebred domestic animals under strong artificial selection. The recombination rate varied considerably among chromosomes as well as along individual chromosomes. An analysis of the sequence composition at recombination hot and cold spots revealed a strong positive correlation between GC-rich sequences and high recombination rates. The GC-rich cohesin binding sites in particular stood out from other GC-rich sequences with a 3.4-fold higher density at recombination hot spots versus cold spots, suggesting a functional relationship between recombination frequency and cohesin binding.
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Affiliation(s)
- Martien A M Groenen
- Animal Breeding and Genomics Centre, Wageningen University, 6700 AH Wageningen, The Netherlands.
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Besnier F, Carlborg O. A general and efficient method for estimating continuous IBD functions for use in genome scans for QTL. BMC Bioinformatics 2007; 8:440. [PMID: 17999749 PMCID: PMC2194736 DOI: 10.1186/1471-2105-8-440] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Accepted: 11/13/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Identity by descent (IBD) matrix estimation is a central component in mapping of Quantitative Trait Loci (QTL) using variance component models. A large number of algorithms have been developed for estimation of IBD between individuals in populations at discrete locations in the genome for use in genome scans to detect QTL affecting various traits of interest in experimental animal, human and agricultural pedigrees. Here, we propose a new approach to estimate IBD as continuous functions rather than as discrete values. RESULTS Estimation of IBD functions improved the computational efficiency and memory usage in genome scanning for QTL. We have explored two approaches to obtain continuous marker-bracket IBD-functions. By re-implementing an existing and fast deterministic IBD-estimation method, we show that this approach results in IBD functions that produces the exact same IBD as the original algorithm, but with a greater than 2-fold improvement of the computational efficiency and a considerably lower memory requirement for storing the resulting genome-wide IBD. By developing a general IBD function approximation algorithm, we show that it is possible to estimate marker-bracket IBD functions from IBD matrices estimated at marker locations by any existing IBD estimation algorithm. The general algorithm provides approximations that lead to QTL variance component estimates that even in worst-case scenarios are very similar to the true values. The approach of storing IBD as polynomial IBD-function was also shown to reduce the amount of memory required in genome scans for QTL. CONCLUSION In addition to direct improvements in computational and memory efficiency, estimation of IBD-functions is a fundamental step needed to develop and implement new efficient optimization algorithms for high precision localization of QTL. Here, we discuss and test two approaches for estimating IBD functions based on existing IBD estimation algorithms. Our approaches provide immediately useful techniques for use in single QTL analyses in the variance component QTL mapping framework. They will, however, be particularly useful in genome scans for multiple interacting QTL, where the improvements in both computational and memory efficiency are the key for successful development of efficient optimization algorithms to allow widespread use of this methodology.
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Affiliation(s)
- Francois Besnier
- Linnaeus Centre for Bioinformatics, Uppsala University, SE-75124 Uppsala, Sweden.
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Besnier F, Toussaint R, Garcera Y, Chout R, Grolier-Bois L, Malvy DM. Evaluation des procédures d'hygiène des spéculums auriculaires (SA). Enquête microbiologique et étude de comportement. Med Mal Infect 1997. [DOI: 10.1016/s0399-077x(97)80078-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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