1
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Salisbury SJ, Ruzzante DE. Genetic Causes and Consequences of Sympatric Morph Divergence in Salmonidae: A Search for Mechanisms. Annu Rev Anim Biosci 2021; 10:81-106. [PMID: 34758272 DOI: 10.1146/annurev-animal-051021-080709] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Repeatedly and recently evolved sympatric morphs exhibiting consistent phenotypic differences provide natural experimental replicates of speciation. Because such morphs are observed frequently in Salmonidae, this clade provides a rare opportunity to uncover the genomic mechanisms underpinning speciation. Such insight is also critical for conserving salmonid diversity, the loss of which could have significant ecological and economic consequences. Our review suggests that genetic differentiation among sympatric morphs is largely nonparallel apart from a few key genes that may be critical for consistently driving morph differentiation. We discuss alternative levels of parallelism likely underlying consistent morph differentiation and identify several factors that may temper this incipient speciation between sympatric morphs, including glacial history and contemporary selective pressures. Our synthesis demonstrates that salmonids are useful for studying speciation and poses additional research questions to be answered by future study of this family. Expected final online publication date for the Annual Review of Animal Biosciences, Volume 10 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- S J Salisbury
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada; ,
| | - D E Ruzzante
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada; ,
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2
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Smith SR, Normandeau E, Djambazian H, Nawarathna PM, Berube P, Muir AM, Ragoussis J, Penney CM, Scribner KT, Luikart G, Wilson CC, Bernatchez L. A chromosome-anchored genome assembly for Lake Trout (Salvelinus namaycush). Mol Ecol Resour 2021; 22:679-694. [PMID: 34351050 PMCID: PMC9291852 DOI: 10.1111/1755-0998.13483] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 07/25/2021] [Accepted: 07/28/2021] [Indexed: 01/23/2023]
Abstract
Here, we present an annotated, chromosome‐anchored, genome assembly for Lake Trout (Salvelinus namaycush) – a highly diverse salmonid species of notable conservation concern and an excellent model for research on adaptation and speciation. We leveraged Pacific Biosciences long‐read sequencing, paired‐end Illumina sequencing, proximity ligation (Hi‐C) sequencing, and a previously published linkage map to produce a highly contiguous assembly composed of 7378 contigs (contig N50 = 1.8 Mb) assigned to 4120 scaffolds (scaffold N50 = 44.975 Mb). Long read sequencing data were generated using DNA from a female double haploid individual. 84.7% of the genome was assigned to 42 chromosome‐sized scaffolds and 93.2% of Benchmarking Universal Single Copy Orthologues were recovered, putting this assembly on par with the best currently available salmonid genomes. Estimates of genome size based on k‐mer frequency analysis were highly similar to the total size of the finished genome, suggesting that the entirety of the genome was recovered. A mitochondrial genome assembly was also produced. Self‐versus‐self synteny analysis allowed us to identify homeologs resulting from the salmonid specific autotetraploid event (Ss4R) as well as regions exhibiting delayed rediploidization. Alignment with three other salmonid genomes and the Northern Pike (Esox lucius) genome also allowed us to identify homologous chromosomes in related taxa. We also generated multiple resources useful for future genomic research on Lake Trout, including a repeat library and a sex‐averaged recombination map. A novel RNA sequencing data set for liver tissue was also generated in order to produce a publicly available set of annotations for 49,668 genes and pseudogenes. Potential applications of these resources to population genetics and the conservation of native populations are discussed.
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Affiliation(s)
- Seth R Smith
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA.,Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, USA
| | - Eric Normandeau
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Quebec, QC, Canada
| | - Haig Djambazian
- McGill Genome Centre, Department of Human Genetics, Montreal, QC, Canada
| | - Pubudu M Nawarathna
- Department of Human Genetics, Canadian Centre for Computational Genomics (C3G, McGill University, Montréal, QC, Canada
| | - Pierre Berube
- McGill Genome Centre, Department of Human Genetics, Montreal, QC, Canada
| | | | - Jiannis Ragoussis
- McGill Genome Centre, Department of Human Genetics, Montreal, QC, Canada
| | - Chantelle M Penney
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | - Kim T Scribner
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA.,Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, USA.,Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI, USA
| | - Gordon Luikart
- Fish and Wildlife Genomics Group, University of Montana, Missoula, MT, USA.,Flathead Lake Biological Station, Division of Biological Sciences, University of Montana, Polson, MT, USA
| | - Chris C Wilson
- Aquatic Research and Monitoring Section, Ontario Ministry of Natural Resources and Forestry, Peterborough, ON, Canada
| | - Louis Bernatchez
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Quebec, QC, Canada
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3
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Chavarie L, Howland KL, Harris LN, Gallagher CP, Hansen MJ, Tonn WM, Muir AM, Krueger CC. Among-individual diet variation within a lake trout ecotype: Lack of stability of niche use. Ecol Evol 2021; 11:1457-1475. [PMID: 33598144 PMCID: PMC7863394 DOI: 10.1002/ece3.7158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/17/2020] [Accepted: 12/02/2020] [Indexed: 11/22/2022] Open
Abstract
In a polyphenic species, differences in resource use are expected among ecotypes, and homogeneity in resource use is expected within an ecotype. Yet, using a broad resource spectrum has been identified as a strategy for fishes living in unproductive northern environments, where food is patchily distributed and ephemeral. We investigated whether specialization of trophic resources by individuals occurred within the generalist piscivore ecotype of lake trout from Great Bear Lake, Canada, reflective of a form of diversity. Four distinct dietary patterns of resource use within this lake trout ecotype were detected from fatty acid composition, with some variation linked to spatial patterns within Great Bear Lake. Feeding habits of different groups within the ecotype were not associated with detectable morphological or genetic differentiation, suggesting that behavioral plasticity caused the trophic differences. A low level of genetic differentiation was detected between exceptionally large-sized individuals and other piscivore individuals. We demonstrated that individual trophic specialization can occur within an ecotype inhabiting a geologically young system (8,000-10,000 yr BP), a lake that sustains high levels of phenotypic diversity of lake trout overall. The characterization of niche use among individuals, as done in this study, is necessary to understand the role that individual variation can play at the beginning of differentiation processes.
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Affiliation(s)
- Louise Chavarie
- Faculty of Environmental Sciences and Natural Resource ManagementNorwegian University of Life SciencesÅsNorway
- Scottish Centre for Ecology and the Natural EnvironmentIBAHCMGlasgowUK
- Department of Fisheries and WildlifeCenter for Systems Integration and SustainabilityMichigan State UniversityEast LansingMIUSA
| | - Kimberly L. Howland
- Fisheries and Oceans CanadaWinnipegMBCanada
- Department of Biological SciencesUniversity of AlbertaEdmontonABCanada
| | | | | | - Michael J. Hansen
- U.S. Geological Survey (retired)Hammond Bay Biological StationMillersburgMIUSA
| | - William M. Tonn
- Department of Biological SciencesUniversity of AlbertaEdmontonABCanada
| | | | - Charles C. Krueger
- Department of Fisheries and WildlifeCenter for Systems Integration and SustainabilityMichigan State UniversityEast LansingMIUSA
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4
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Guðbrandsson J, Kapralova KH, Franzdóttir SR, Bergsveinsdóttir ÞM, Hafstað V, Jónsson ZO, Snorrason SS, Pálsson A. Extensive genetic differentiation between recently evolved sympatric Arctic charr morphs. Ecol Evol 2019; 9:10964-10983. [PMID: 31641448 PMCID: PMC6802010 DOI: 10.1002/ece3.5516] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 07/11/2019] [Accepted: 07/12/2019] [Indexed: 12/22/2022] Open
Abstract
The availability of diverse ecological niches can promote adaptation of trophic specializations and related traits, as has been repeatedly observed in evolutionary radiations of freshwater fish. The role of genetics, environment, and history in ecologically driven divergence and adaptation, can be studied on adaptive radiations or populations showing ecological polymorphism. Salmonids, especially the Salvelinus genus, are renowned for both phenotypic diversity and polymorphism. Arctic charr (Salvelinus alpinus) invaded Icelandic streams during the glacial retreat (about 10,000 years ago) and exhibits many instances of sympatric polymorphism. Particularly, well studied are the four morphs in Lake Þingvallavatn in Iceland. The small benthic (SB), large benthic (LB), planktivorous (PL), and piscivorous (PI) charr differ in many regards, including size, form, and life history traits. To investigate relatedness and genomic differentiation between morphs, we identified variable sites from RNA-sequencing data from three of those morphs and verified 22 variants in population samples. The data reveal genetic differences between the morphs, with the two benthic morphs being more similar and the PL-charr more genetically different. The markers with high differentiation map to all linkage groups, suggesting ancient and pervasive genetic separation of these three morphs. Furthermore, GO analyses suggest differences in collagen metabolism, odontogenesis, and sensory systems between PL-charr and the benthic morphs. Genotyping in population samples from all four morphs confirms the genetic separation and indicates that the PI-charr are less genetically distinct than the other three morphs. The genetic separation of the other three morphs indicates certain degree of reproductive isolation. The extent of gene flow between the morphs and the nature of reproductive barriers between them remain to be elucidated.
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Affiliation(s)
- Jóhannes Guðbrandsson
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
- Marine and Freshwater Research InstituteReykjavikIceland
| | - Kalina H. Kapralova
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
| | - Sigríður R. Franzdóttir
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
- Biomedical CenterUniversity of IcelandReykjavikIceland
| | | | - Völundur Hafstað
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
| | - Zophonías O. Jónsson
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
- Biomedical CenterUniversity of IcelandReykjavikIceland
| | | | - Arnar Pálsson
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
- Biomedical CenterUniversity of IcelandReykjavikIceland
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5
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Wilson KL, De Gisi J, Cahill CL, Barker OE, Post JR. Life‐history variation along environmental and harvest clines of a northern freshwater fish: Plasticity and adaptation. J Anim Ecol 2019; 88:717-733. [DOI: 10.1111/1365-2656.12965] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 12/05/2018] [Indexed: 01/02/2023]
Affiliation(s)
- Kyle L. Wilson
- Department of Biological SciencesUniversity of Calgary Calgary AB Canada
- Earth to Ocean Research GroupSimon Fraser University Burnaby BC Canada
| | - Joe De Gisi
- Fish and Wildlife SectionBritish Columbia Ministry of Forests, Lands, and Natural Resource Operations Smithers BC Canada
| | | | | | - John R. Post
- Department of Biological SciencesUniversity of Calgary Calgary AB Canada
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6
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Chavarie L, Howland KL, Harris LN, Hansen MJ, Harford WJ, Gallagher CP, Baillie SM, Malley B, Tonn WM, Muir AM, Krueger CC. From top to bottom: Do Lake Trout diversify along a depth gradient in Great Bear Lake, NT, Canada? PLoS One 2018; 13:e0193925. [PMID: 29566015 PMCID: PMC5863968 DOI: 10.1371/journal.pone.0193925] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 02/21/2018] [Indexed: 11/19/2022] Open
Abstract
Depth is usually considered the main driver of Lake Trout intraspecific diversity across lakes in North America. Given that Great Bear Lake is one of the largest and deepest freshwater systems in North America, we predicted that Lake Trout intraspecific diversity to be organized along a depth axis within this system. Thus, we investigated whether a deep-water morph of Lake Trout co-existed with four shallow-water morphs previously described in Great Bear Lake. Morphology, neutral genetic variation, isotopic niches, and life-history traits of Lake Trout across depths (0-150 m) were compared among morphs. Due to the propensity of Lake Trout with high levels of morphological diversity to occupy multiple habitat niches, a novel multivariate grouping method using a suite of composite variables was applied in addition to two other commonly used grouping methods to classify individuals. Depth alone did not explain Lake Trout diversity in Great Bear Lake; a distinct fifth deep-water morph was not found. Rather, Lake Trout diversity followed an ecological continuum, with some evidence for adaptation to local conditions in deep-water habitat. Overall, trout caught from deep-water showed low levels of genetic and phenotypic differentiation from shallow-water trout, and displayed higher lipid content (C:N ratio) and occupied a higher trophic level that suggested an potential increase of piscivory (including cannibalism) than the previously described four morphs. Why phenotypic divergence between shallow- and deep-water Lake Trout was low is unknown, especially when the potential for phenotypic variation should be high in deep and large Great Bear Lake. Given that variation in complexity of freshwater environments has dramatic consequences for divergence, variation in the complexity in Great Bear Lake (i.e., shallow being more complex than deep), may explain the observed dichotomy in the expression of intraspecific phenotypic diversity between shallow- vs. deep-water habitats. The ambiguity surrounding mechanisms driving divergence of Lake Trout in Great Bear Lake should be seen as reflective of the highly variable nature of ecological opportunity and divergent natural selection itself.
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Affiliation(s)
- Louise Chavarie
- Department of Fisheries and Wildlife, Center for Systems Integration and Sustainability, Michigan State University, East Lansing, MI, United States of America
- * E-mail:
| | - Kimberly L. Howland
- Fisheries and Oceans Canada, Winnipeg, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | | | - Michael J. Hansen
- U.S. Geological Survey, Hammond Bay Biological Station, Millersburg, MI, United States of America
| | - William J. Harford
- Cooperative Institute of Marine & Atmospheric Studies, University of Miami, Miami, FL, United States of America
| | | | | | | | - William M. Tonn
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | - Andrew M. Muir
- Great Lakes Fishery Commission, Ann Arbor, MI, United States of America
| | - Charles C. Krueger
- Department of Fisheries and Wildlife, Center for Systems Integration and Sustainability, Michigan State University, East Lansing, MI, United States of America
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7
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Markevich G, Esin E, Anisimova L. Basic description and some notes on the evolution of seven sympatric morphs of Dolly Varden Salvelinus malma from the Lake Kronotskoe Basin. Ecol Evol 2018; 8:2554-2567. [PMID: 29531676 PMCID: PMC5838070 DOI: 10.1002/ece3.3806] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 11/11/2017] [Accepted: 12/07/2017] [Indexed: 11/29/2022] Open
Abstract
The study examines the basic morphological and ecological features of Dolly Varden from Lake Kronotskoe (Russia, Kamchatka). Seven valid morphs different in head proportions, feeding, timing, and place of spawning have been determined in this ecosystem. The basic morphometric characteristics clearly separate Lake Kronotskoe morphs from each other, as well as from its potential ancestor (Dolly Varden). According to CVA analysis, the most notable morphological characteristics determining the mouth position are the length of a lower jaw and rostrum. Furthermore, five of seven morphs inhabit different depth zones of the lake and feed on different food resources. Our data suggest that reproductive isolation may be maintained by temporal/spatial isolation for two morphs with lacustrine spawning, and by spatial isolation only for the rest of the morphs with riverine spawning. The sympatric diversity of the Lake Kronotskoe charrs is exceptionally wide, and there are no other examples for seven sympatric morphs of genus Salvelinus to coexist within a single ecosystem. This study puts forward a three-step hypothetical model of charr divergence in Lake Kronotskoe as a potential ground for future studies.
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8
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Perreault-Payette A, Muir AM, Goetz F, Perrier C, Normandeau E, Sirois P, Bernatchez L. Investigating the extent of parallelism in morphological and genomic divergence among lake trout ecotypes in Lake Superior. Mol Ecol 2017; 26:1477-1497. [DOI: 10.1111/mec.14018] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 11/21/2016] [Accepted: 11/29/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Alysse Perreault-Payette
- Département de Biologie; Institut de Biologie Intégrative et des Systèmes (IBIS); Université Laval; 1030 avenue de la Médecine Québec Quebec Canada G1V 0A6 Canada
| | - Andrew M. Muir
- Department of Fisheries and Wildlife; Michigan State University; 13 Natural Resources Building East Lansing MI 48824 USA
- Great Lakes Fishery Commission; 2100 Commonwealth Boulevard Suite 100 Ann Arbor MI 48105 USA
| | - Frederick Goetz
- Northwest Fisheries Science Center; Port Orchard WA 98366 USA
| | - Charles Perrier
- Centre d’Écologie Fonctionnelle et Évolutive (UMR CEFE CNRS 5175); 1919, route de Mende, 34293; Montpellier France
| | - Eric Normandeau
- Département de Biologie; Institut de Biologie Intégrative et des Systèmes (IBIS); Université Laval; 1030 avenue de la Médecine Québec Quebec Canada G1V 0A6 Canada
| | - Pascal Sirois
- Chaire de recherche sur les espèces aquatiques exploitées; Laboratoire des sciences aquatiques; Département des sciences fondamentales; Université du Québec à Chicoutimi; 555 boulevard de l'Université Chicoutimi Quebec Canada G7H 2B1
| | - Louis Bernatchez
- Département de Biologie; Institut de Biologie Intégrative et des Systèmes (IBIS); Université Laval; 1030 avenue de la Médecine Québec Quebec Canada G1V 0A6 Canada
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9
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Chavarie L, Muir AM, Zimmerman MS, Baillie SM, Hansen MJ, Nate NA, Yule DL, Middel T, Bentzen P, Krueger CC. Challenge to the model of lake charr evolution: shallow- and deep-water morphs exist within a small postglacial lake. Biol J Linn Soc Lond 2016. [DOI: 10.1111/bij.12913] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Louise Chavarie
- Center for Systems Integration and Sustainability; Michigan State University; 115 Manly Miles Building, 1405 South Harrison Road East Lansing Michigan USA
| | - Andrew M. Muir
- Great Lakes Fishery Commission; 2100 Commonwealth Blvd. Suite 100 Ann Arbor Michigan USA
| | - Mara S. Zimmerman
- Washington Department of Fish and Wildlife; 600 Capitol Way N. Olympia Washington USA
| | - Shauna M. Baillie
- Department of Biology; Dalhousie University; 1355 Oxford St. Halifax Nova Scotia Canada
| | - Michael J. Hansen
- United States Geological Survey; Hammond Bay Biological Station; 11188 Ray Road Millersburg Michigan USA
| | - Nancy A. Nate
- Center for Systems Integration and Sustainability; Michigan State University; 115 Manly Miles Building, 1405 South Harrison Road East Lansing Michigan USA
| | - Daniel L. Yule
- United States Geological Survey; Lake Superior Biological Station; 2800 Lakeshore Drive Ashland Wisconsin USA
| | - Trevor Middel
- Harkness Laboratory of Fisheries Research; Ontario Ministry of Natural Resources and Forestry; Trent University; 2140 East Bank Drive Peterborough Ontario Canada
| | - Paul Bentzen
- Department of Biology; Dalhousie University; 1355 Oxford St. Halifax Nova Scotia Canada
| | - Charles C. Krueger
- Center for Systems Integration and Sustainability; Michigan State University; 115 Manly Miles Building, 1405 South Harrison Road East Lansing Michigan USA
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10
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Baillie SM, Muir AM, Hansen MJ, Krueger CC, Bentzen P. Genetic and phenotypic variation along an ecological gradient in lake trout Salvelinus namaycush. BMC Evol Biol 2016; 16:219. [PMID: 27756206 PMCID: PMC5069848 DOI: 10.1186/s12862-016-0788-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 10/04/2016] [Indexed: 01/24/2023] Open
Abstract
Background Adaptive radiation involving a colonizing phenotype that rapidly evolves into at least one other ecological variant, or ecotype, has been observed in a variety of freshwater fishes in post-glacial environments. However, few studies consider how phenotypic traits vary with regard to neutral genetic partitioning along ecological gradients. Here, we present the first detailed investigation of lake trout Salvelinus namaycush that considers variation as a cline rather than discriminatory among ecotypes. Genetic and phenotypic traits organized along common ecological gradients of water depth and geographic distance provide important insights into diversification processes in a lake with high levels of human disturbance from over-fishing. Results Four putative lake trout ecotypes could not be distinguished using population genetic methods, despite morphological differences. Neutral genetic partitioning in lake trout was stronger along a gradient of water depth, than by locality or ecotype. Contemporary genetic migration patterns were consistent with isolation-by-depth. Historical gene flow patterns indicated colonization from shallow to deep water. Comparison of phenotypic (Pst) and neutral genetic variation (Fst) revealed that morphological traits related to swimming performance (e.g., buoyancy, pelvic fin length) departed more strongly from neutral expectations along a depth gradient than craniofacial feeding traits. Elevated phenotypic variance with increasing water depth in pelvic fin length indicated possible ongoing character release and diversification. Finally, differences in early growth rate and asymptotic fish length across depth strata may be associated with limiting factors attributable to cold deep-water environments. Conclusion We provide evidence of reductions in gene flow and divergent natural selection associated with water depth in Lake Superior. Such information is relevant for documenting intraspecific biodiversity in the largest freshwater lake in the world for a species that recently lost considerable genetic diversity and is now in recovery. Unknown is whether observed patterns are a result of an early stage of incipient speciation, gene flow-selection equilibrium, or reverse speciation causing formerly divergent ecotypes to collapse into a single gene pool. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0788-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shauna M Baillie
- Marine Gene Probe Lab, Department of Biology, Dalhousie University, 1355 Oxford Street, PO Box 15000, Halifax, NS, B3H 4R2, Canada.
| | - Andrew M Muir
- Great Lakes Fishery Commission, 2100 Commonwealth Boulevard, Ann Arbor, MI, 48105, USA
| | - Michael J Hansen
- U.S. Geological Survey, Great Lakes Science Center, Hammond Bay Biological Station, 11188 Ray Road, Millersburg, MI, 49759, USA
| | - Charles C Krueger
- Department of Fisheries and Wildlife, Center for Systems Integration and Sustainability, Michigan State University, East Lansing, MI, 48824-1222, USA
| | - Paul Bentzen
- Marine Gene Probe Lab, Department of Biology, Dalhousie University, 1355 Oxford Street, PO Box 15000, Halifax, NS, B3H 4R2, Canada
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11
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Chavarie L, Harford WJ, Howland KL, Fitzsimons J, Muir AM, Krueger CC, Tonn WM. Multiple generalist morphs of Lake Trout: Avoiding constraints on the evolution of intraspecific divergence? Ecol Evol 2016; 6:7727-7741. [PMID: 30128124 PMCID: PMC6093156 DOI: 10.1002/ece3.2506] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 08/26/2016] [Accepted: 08/30/2016] [Indexed: 12/29/2022] Open
Abstract
A generalist strategy, as an adaptation to environmental heterogeneity, is common in Arctic freshwater systems, often accompanied, however, by intraspecific divergence that promotes specialization in niche use. To better understand how resources may be partitioned in a northern system that supports intraspecific diversity of Lake Trout, trophic niches were compared among four shallow‐water morphotypes in Great Bear Lake (N65° 56′ 39″, W120° 50′ 59″). Bayesian mixing model analyses of stable isotopes of carbon and nitrogen were conducted on adult Lake Trout. Major niche overlap in resource use among four Lake Trout morphotypes was found within littoral and pelagic zones, which raises the question of how such polymorphism can be sustained among opportunistic generalist morphotypes. Covariances of our morphological datasets were tested against δ13C and δ15N values. Patterns among morphotypes were mainly observed for δ15N. This link between ecological and morphological differentiation suggested that selection pressure(s) operate at the trophic level (δ15N), independent of habitat, rather than along the habitat‐foraging opportunity axis (δ13C). The spatial and temporal variability of resources in Arctic lakes, such as Great Bear Lake, may have favored the presence of multiple generalists showing different degrees of omnivory along a weak benthic–pelagic gradient. Morphs 1–3 had more generalist feeding habits using both benthic and pelagic habitats than Morph 4, which was a top‐predator specialist in the pelagic habitat. Evidence for frequent cannibalism in Great Bear Lake was found across all four morphotypes and may also contribute to polymorphism. We suggest that the multiple generalist morphs described here from Great Bear Lake are a unique expression of diversity due to the presumed constraints on the evolution of generalists and contrast with the development of multiple specialists, the standard response to intraspecific divergence.
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Affiliation(s)
- Louise Chavarie
- Center for Systems Integration and Sustainability Michigan State University East Lansing MI USA.,Department of Biological Sciences University of Alberta Edmonton AB Canada
| | - William J Harford
- Cooperative Institute of Marine & Atmospheric Studies University of Miami Miami FL USA
| | - Kimberly L Howland
- Department of Biological Sciences University of Alberta Edmonton AB Canada.,Fisheries and Oceans Canada Winnipeg MB Canada
| | | | | | - Charles C Krueger
- Center for Systems Integration and Sustainability Michigan State University East Lansing MI USA
| | - William M Tonn
- Department of Biological Sciences University of Alberta Edmonton AB Canada
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12
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Marin K, Coon A, Carson R, Debes PV, Fraser DJ. Striking Phenotypic Variation yet Low Genetic Differentiation in Sympatric Lake Trout (Salvelinus namaycush). PLoS One 2016; 11:e0162325. [PMID: 27680019 PMCID: PMC5040267 DOI: 10.1371/journal.pone.0162325] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 08/19/2016] [Indexed: 11/24/2022] Open
Abstract
The study of population differentiation in the context of ecological speciation is commonly assessed using populations with obvious discreteness. Fewer studies have examined diversifying populations with occasional adaptive variation and minor reproductive isolation, so factors impeding or facilitating the progress of early stage differentiation are less understood. We detected non-random genetic structuring in lake trout (Salvelinus namaycush) inhabiting a large, pristine, postglacial lake (Mistassini Lake, Canada), with up to five discernible genetic clusters having distinctions in body shape, size, colouration and head shape. However, genetic differentiation was low (FST = 0.017) and genetic clustering was largely incongruent between several population- and individual-based clustering approaches. Genotype- and phenotype-environment associations with spatial habitat, depth and fish community structure (competitors and prey) were either inconsistent or weak. Striking morphological variation was often more continuous within than among defined genetic clusters. Low genetic differentiation was a consequence of relatively high contemporary gene flow despite large effective population sizes, not migration-drift disequilibrium. Our results suggest a highly plastic propensity for occupying multiple habitat niches in lake trout and a low cost of morphological plasticity, which may constrain the speed and extent of adaptive divergence. We discuss how factors relating to niche conservatism in this species may also influence how plasticity affects adaptive divergence, even where ample ecological opportunity apparently exists.
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Affiliation(s)
- Kia Marin
- Department of Biology, Concordia University, Montréal, Québec, Canada
| | - Andrew Coon
- Tourism Department, Cree Nation of Mistissini, Québec, Canada
| | - Robert Carson
- Department of Biology, Concordia University, Montréal, Québec, Canada
| | - Paul V Debes
- Department of Biology, University of Turku, Turku, Finland
| | - Dylan J Fraser
- Department of Biology, Concordia University, Montréal, Québec, Canada
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