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Christensen KA, Flores AM, Sakhrani D, Biagi CA, Devlin RH, Sutherland BJG, Withler RE, Rondeau EB, Koop BF. Revealing the evolutionary history and contemporary population structure of Pacific salmon in the Fraser River through genome resequencing. G3 (BETHESDA, MD.) 2024; 14:jkae169. [PMID: 39041834 DOI: 10.1093/g3journal/jkae169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 04/29/2024] [Accepted: 07/15/2024] [Indexed: 07/24/2024]
Abstract
The Fraser River once supported massive salmon returns. However, over the last century, the largest returns have consistently been less than half of the recorded historical maximum. There is substantial interest from surrounding communities and governments to increase salmon returns for both human use and functional ecosystems. To generate resources for this endeavor, we resequenced genomes of Chinook (Oncorhynchus tshawytscha), coho (Oncorhynchus kisutch), and sockeye salmon (Oncorhynchus nerka) from the Fraser River at moderate coverage (∼16×). A total of 954 resequenced genomes were analyzed, with 681 collected specifically for this study from tissues sampled between 1997 and 2021. An additional 273 were collected from previous studies. At the species level, Chinook salmon appeared to have 1.6-2.1× more SNPs than coho or sockeye salmon, respectively. This difference may be attributable to large historical declines of coho and sockeye salmon. At the population level, 3 Fraser River genetic groups were identified for each species using principal component and admixture analyses. These were consistent with previous research and supports the continued use of these groups in conservation and management efforts. Environmental factors and a migration barrier were identified as major factors influencing the boundaries of these genetic groups. Additionally, 20 potentially adaptive loci were identified among the genetic groups. This information may be valuable in new management and conservation efforts. Furthermore, the resequenced genomes are an important resource for contemporary genomics research on Fraser River salmon and have been made publicly available.
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Affiliation(s)
- Kris A Christensen
- Department of Biology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Anne-Marie Flores
- Department of Biology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Dionne Sakhrani
- Fisheries and Oceans Canada, West Vancouver, BC V7V 1H2, Canada
| | - Carlo A Biagi
- Fisheries and Oceans Canada, West Vancouver, BC V7V 1H2, Canada
| | - Robert H Devlin
- Fisheries and Oceans Canada, West Vancouver, BC V7V 1H2, Canada
| | - Ben J G Sutherland
- Sutherland Bioinformatics, Lantzville, BC V0R 2H0, Canada
- Faculty of Science and Technology, Vancouver Island University, Nanaimo, BC V9R 5S5, Canada
| | - Ruth E Withler
- Pacific Salmon Foundation, Vancouver, BC V6H 3V9, Canada
| | - Eric B Rondeau
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, Canada
| | - Ben F Koop
- Department of Biology, University of Victoria, Victoria, BC V8W 2Y2, Canada
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2
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May SA, Shedd KR, Rand PS, Westley PAH. Tidal gradients, fine-scale homing and a potential cryptic ecotype of wild spawning pink salmon (Oncorhynchus gorbuscha). Mol Ecol 2023; 32:5838-5848. [PMID: 37830261 DOI: 10.1111/mec.17154] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 09/20/2023] [Accepted: 09/22/2023] [Indexed: 10/14/2023]
Abstract
The homing behaviour of salmon is a remarkable natural phenomenon, critical for shaping the ecology and evolution of populations yet the spatial scale at which it occurs is poorly understood. This study investigated the spatial scale and mechanisms driving homing as depicted by spawning site-choice behaviour in pink salmon (Oncorhynchus gorbuscha) in Prince William Sound, Alaska. Molecular pedigree analyses of over 30,000 adult spawners in four streams revealed that pink salmon exhibit fine-scale site fidelity within a stream, returning to within <100 m of their parents. Homing behaviours were driven in part by a salinity gradient between intertidal and freshwater environments, with individuals incubated in freshwater environments more than twice as likely to spawn upstream of tidal influence than those incubated in the intertidal. Our findings challenge the traditional view that pink salmon populations are genetically and phenotypically homogenous due to their short freshwater residency as juveniles and high rates of dispersal as returning adults (i.e. straying). This study has important implications for rates of inbreeding, local adaptation and gene flow within populations, and is particularly relevant to the management of salmon hatcheries, given the high incidence of hatchery-origin pink salmon, reared in freshwater hatchery environments, that stray into wild populations of Prince William Sound.
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Affiliation(s)
- Samuel A May
- Department of Fisheries, College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska, USA
| | - Kyle R Shedd
- Alaska Department of Fish & Game, Anchorage, Alaska, USA
| | - Peter S Rand
- Prince William Sound Science Center (PWSSC), Cordova, Alaska, USA
| | - Peter A H Westley
- Department of Fisheries, College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska, USA
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3
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Sparks MM, Schraidt CE, Yin X, Seeb LW, Christie MR. Rapid genetic adaptation to a novel ecosystem despite a large founder event. Mol Ecol 2023. [PMID: 37668092 DOI: 10.1111/mec.17121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 07/17/2023] [Accepted: 08/09/2023] [Indexed: 09/06/2023]
Abstract
Introduced and invasive species make excellent natural experiments for investigating rapid evolution. Here, we describe the effects of genetic drift and rapid genetic adaptation in pink salmon (Oncorhynchus gorbuscha) that were accidentally introduced to the Great Lakes via a single introduction event 31 generations ago. Using whole-genome resequencing for 134 fish spanning five sample groups across the native and introduced range, we estimate that the source population's effective population size was 146,886 at the time of introduction, whereas the founding population's effective population size was just 72-a 2040-fold decrease. As expected with a severe founder event, we show reductions in genome-wide measures of genetic diversity, specifically a 37.7% reduction in the number of SNPs and an 8.2% reduction in observed heterozygosity. Despite this decline in genetic diversity, we provide evidence for putative selection at 47 loci across multiple chromosomes in the introduced populations, including missense variants in genes associated with circadian rhythm, immunological response and maturation, which match expected or known phenotypic changes in the Great Lakes. For one of these genes, we use a species-specific agent-based model to rule out genetic drift and conclude our results support a strong response to selection occurring in a period gene (per2) that plays a predominant role in determining an organism's daily clock, matching large day length differences experienced by introduced salmon during important phenological periods. Together, these results inform how populations might evolve rapidly to new environments, even with a small pool of standing genetic variation.
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Affiliation(s)
- Morgan M Sparks
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Claire E Schraidt
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana, USA
| | - Xiaoshen Yin
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Lisa W Seeb
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, USA
| | - Mark R Christie
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana, USA
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4
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Rougemont Q, Leroy T, Rondeau EB, Koop B, Bernatchez L. Allele surfing causes maladaptation in a Pacific salmon of conservation concern. PLoS Genet 2023; 19:e1010918. [PMID: 37683018 PMCID: PMC10545117 DOI: 10.1371/journal.pgen.1010918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 10/02/2023] [Accepted: 08/11/2023] [Indexed: 09/10/2023] Open
Abstract
How various factors, including demography, recombination or genome duplication, may impact the efficacy of natural selection and the burden of deleterious mutations, is a central question in evolutionary biology and genetics. In this study, we show that key evolutionary processes, including variations in i) effective population size (Ne) ii) recombination rates and iii) chromosome inheritance, have influenced the genetic load and efficacy of selection in Coho salmon (Oncorhynchus kisutch), a widely distributed salmonid species on the west coast of North America. Using whole genome resequencing data from 14 populations at different migratory distances from their southern glacial refugium, we found evidence supporting gene surfing, wherein reduced Ne at the postglacial recolonization front, leads to a decrease in the efficacy of selection and a surf of deleterious alleles in the northernmost populations. Furthermore, our results indicate that recombination rates play a prime role in shaping the load along the genome. Additionally, we identified variation in polyploidy as a contributing factor to within-genome variation of the load. Overall, our results align remarkably well with expectations under the nearly neutral theory of molecular evolution. We discuss the fundamental and applied implications of these findings for evolutionary and conservation genomics.
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Affiliation(s)
- Quentin Rougemont
- Centre d’Ecologie Fonctionnelle et Evolutive, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | - Thibault Leroy
- GenPhySE, INRAE, INP, ENVT, Université de Toulouse, Auzeville- Tolosane, France
| | - Eric B. Rondeau
- Department of Fisheries and Ocean, Pacific Biological Station, Nanaimo, Canada
| | - Ben Koop
- Department of Biology, University of Victoria, Victoria, Canada
| | - Louis Bernatchez
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada
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5
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Rondeau EB, Christensen KA, Johnson HA, Sakhrani D, Biagi CA, Wetklo M, Despins CA, Leggatt RA, Minkley DR, Withler RE, Beacham TD, Koop BF, Devlin RH. Insights from a chum salmon (Oncorhynchus keta) genome assembly regarding whole-genome duplication and nucleotide variation influencing gene function. G3 (BETHESDA, MD.) 2023; 13:jkad127. [PMID: 37293843 PMCID: PMC10411575 DOI: 10.1093/g3journal/jkad127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 05/30/2023] [Accepted: 06/04/2023] [Indexed: 06/10/2023]
Abstract
Chum salmon are ecologically important to Pacific Ocean ecosystems and commercially important to fisheries. To improve the genetic resources available for this species, we sequenced and assembled the genome of a male chum salmon using Oxford Nanopore read technology and the Flye genome assembly software (contig N50: ∼2 Mbp, complete BUSCOs: ∼98.1%). We also resequenced the genomes of 59 chum salmon from hatchery sources to better characterize the genome assembly and the diversity of nucleotide variants impacting phenotype variation. With genomic sequences from a doubled haploid individual, we were able to identify regions of the genome assembly that have been collapsed due to high sequence similarity between homeologous (duplicated) chromosomes. The homeologous chromosomes are relics of an ancient salmonid-specific genome duplication. These regions were enriched with genes whose functions are related to the immune system and responses to toxins. From analyzing nucleotide variant annotations of the resequenced genomes, we were also able to identify genes that have increased levels of variants thought to moderately impact gene function. Genes related to the immune system and the detection of chemical stimuli (olfaction) had increased levels of these variants based on a gene ontology enrichment analysis. The tandem organization of many of the enriched genes raises the question of why they have this organization.
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Affiliation(s)
- Eric B Rondeau
- Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC V7V 1N6, Canada
- Department of Biology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8W 2Y2, Canada
- Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada
| | - Kris A Christensen
- Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC V7V 1N6, Canada
- Department of Biology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8W 2Y2, Canada
| | - Hollie A Johnson
- Department of Biology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8W 2Y2, Canada
| | - Dionne Sakhrani
- Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC V7V 1N6, Canada
| | - Carlo A Biagi
- Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC V7V 1N6, Canada
| | - Mike Wetklo
- Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada
| | - Cody A Despins
- Department of Biology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8W 2Y2, Canada
| | - Rosalind A Leggatt
- Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC V7V 1N6, Canada
| | - David R Minkley
- Department of Biology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8W 2Y2, Canada
| | - Ruth E Withler
- Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada
| | - Terry D Beacham
- Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada
| | - Ben F Koop
- Department of Biology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8W 2Y2, Canada
| | - Robert H Devlin
- Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC V7V 1N6, Canada
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6
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Kochneva A, Efremov D, Murzina SA. Proteins journey-from marine to freshwater ecosystem: blood plasma proteomic profiles of pink salmon Oncorhynchus gorbuscha Walbaum, 1792 during spawning migration. Front Physiol 2023; 14:1216119. [PMID: 37383149 PMCID: PMC10293649 DOI: 10.3389/fphys.2023.1216119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 06/02/2023] [Indexed: 06/30/2023] Open
Abstract
The pink salmon (Oncorhynchus gorbuscha) is a commercial anadromous fish species of the family Salmonidae. This species has a 2-year life cycle that distinguishes it from other salmonids. It includes the spawning migration from marine to freshwater environments, accompanied by significant physiological and biochemical adaptive changes in the body. This study reveals and describes variability in the blood plasma proteomes of female and male pink salmon collected from three biotopes-marine, estuarine and riverine-that the fish pass through in spawning migration. Identification and comparative analysis of blood plasma protein profiles were performed using proteomics and bioinformatic approaches. The blood proteomes of female and male spawners collected from different biotopes were qualitatively and quantitatively distinguished. Females differed primarily in proteins associated with reproductive system development (certain vitellogenin and choriogenin), lipid transport (fatty acid binding protein) and energy production (fructose 1,6-bisphosphatase), and males in proteins involved in blood coagulation (fibrinogen), immune response (lectins) and reproductive processes (vitellogenin). Differentially expressed sex-specific proteins were implicated in proteolysis (aminopeptidases), platelet activation (β- and γ-chain fibrinogen), cell growth and differentiation (a protein containing the TGF_BETA_2 domain) and lipid transport processes (vitellogenin and apolipoprotein). The results are of both fundamental and practical importance, adding to existing knowledge of the biochemical adaptations to spawning of pink salmon, a representative of economically important migratory fish species.
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Affiliation(s)
- Albina Kochneva
- Environmental Biochemistry Laboratory, Institute of Biology of the Karelian Research Centre of the Russian Academy of Sciences, Petrozavodsk, Russia
| | - Denis Efremov
- Ecology of Fishes and Water Invertebrates Laboratory, Institute of Biology of the Karelian Research Centre of the Russian Academy of Sciences, Petrozavodsk, Russia
| | - Svetlana A. Murzina
- Environmental Biochemistry Laboratory, Institute of Biology of the Karelian Research Centre of the Russian Academy of Sciences, Petrozavodsk, Russia
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7
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Dimos B, Phelps M. A homology guide for Pacific salmon genus Oncorhynchus resolves patterns of ohnolog retention, resolution and local adaptation following the salmonid-specific whole-genome duplication event. Ecol Evol 2023; 13:e9994. [PMID: 37091557 PMCID: PMC10119027 DOI: 10.1002/ece3.9994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 03/17/2023] [Accepted: 03/21/2023] [Indexed: 04/25/2023] Open
Abstract
Salmonid fishes have emerged as a tractable model to study whole-genome duplications (WGDs) as this group has undergone four rounds of WGDs. While most of the salmonid genome has returned to a diploid state, a significant proportion of genes are maintained as duplicates and are referred to as ohnologs. The fact that much of the modern salmonid gene repertoire is comprised of ohnologs, while other genes have returned to their singleton state creates complications for genetic studies by obscuring homology relationships. The difficulty this creates is particularly prominent in Pacific salmonids belonging to genus Oncorhynchus who are the focus of intense genetics-based conservation and management efforts owing to the important ecological and cultural roles these fish play. To address this gap, we generated a homology guide for six species of Oncorhynchus with available genomes and used this guide to describe patterns of ohnolog retention and resolution. Overall, we find that ohnologs comprise approximately half of each species modern gene repertoires, which are functionally enriched for genes involved in DNA binding, while the less numerous singleton genes are heavily enriched in dosage-sensitive processes such as mitochondrial metabolism. Additionally, by reanalyzing published expression data from locally adapted strains of O. mykiss, we show that numerous ohnologs exhibit adaptive expression profiles; however, ohnologs are not more likely to display adaptive signatures than either paralogs or singletons. Finally, we demonstrate the utility of our homology guide by investigating the evolutionary relationship among genes highlighted as playing a role in salmonid life-history traits or gene editing targets.
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Affiliation(s)
- Bradford Dimos
- Department of Animal SciencesWashington State UniversityPullmanWashingtonUSA
| | - Michael Phelps
- Department of Animal SciencesWashington State UniversityPullmanWashingtonUSA
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Shedd KR, Lescak EA, Habicht C, Knudsen EE, Dann TH, Hoyt HA, Prince DJ, Templin WD. Reduced relative fitness in hatchery-origin Pink Salmon in two streams in Prince William Sound, Alaska. Evol Appl 2022; 15:429-446. [PMID: 35386398 PMCID: PMC8965367 DOI: 10.1111/eva.13356] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 01/21/2022] [Accepted: 02/03/2022] [Indexed: 12/02/2022] Open
Abstract
Previous studies generally report that hatchery-origin Pacific Salmon (Oncorhynchus spp.) have lower relative reproductive success (RRS) than their natural-origin counterparts. We estimated the RRS of Pink Salmon (O. gorbuscha) in Prince William Sound (PWS), Alaska using incomplete pedigrees. In contrast to other RRS studies, Pink Salmon have a short freshwater life history, freshwater habitats in PWS are largely unaltered by development, and sampling was conducted without the aid of dams or weirs resulting in incomplete sampling of spawning individuals. Pink Salmon released from large-scale hatchery programs in PWS have interacted with wild populations for more than 15 generations. Hatchery populations were established from PWS populations but have subsequently been managed as separate broodstocks. Gene flow is primarily directional, from hatchery strays to wild populations. We used genetic-based parentage analysis to estimate the RRS of a single generation of stray hatchery-origin Pink Salmon in two streams, and across the odd- and even-year lineages. Despite incomplete sampling, we assigned 1745 offspring to at least one parent. Reproductive success (RS), measured as sampled adult offspring that returned to their natal stream, was significantly lower for hatchery- vs. natural-origin parents in both lineages, with RRS ranging from 0.03 to 0.47 for females and 0.05 to 0.86 for males. Generalized linear modeling for the even-year lineage indicated that RRS was lower for hatchery-origin fish, ranging from 0.42 to 0.60, after accounting for sample date (run timing), sample location within the stream, and fish length. Our results strongly suggest that hatchery-origin strays have lower fitness in the wild. The consequences of reduced RRS on wild productivity depend on whether the mechanisms underlying reduced RRS are environmentally driven, and likely ephemeral, or genetically driven, and likely persistent across generations.
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