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Jónsdóttir GÓ, von Elm LM, Ingimarsson F, Tersigni S, Snorrason SS, Pálsson A, Steele SE. Diversity in the internal functional feeding elements of sympatric morphs of Arctic charr (Salvelinus alpinus). PLoS One 2024; 19:e0300359. [PMID: 38771821 PMCID: PMC11108142 DOI: 10.1371/journal.pone.0300359] [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: 09/22/2023] [Accepted: 02/23/2024] [Indexed: 05/23/2024] Open
Abstract
The diversity of functional feeding anatomy is particularly impressive in fishes and correlates with various interspecific ecological specializations. Intraspecific polymorphism can manifest in divergent feeding morphology and ecology, often along a benthic-pelagic axis. Arctic charr (Salvelinus alpinus) is a freshwater salmonid known for morphological variation and sympatric polymorphism and in Lake Þingvallavatn, Iceland, four morphs of charr coexist that differ in preferred prey, behaviour, habitat use, and external feeding morphology. We studied variation in six upper and lower jaw bones in adults of these four morphs using geometric morphometrics and univariate statistics. We tested for allometric differences in bone size and shape among morphs, morph effects on bone size and shape, and divergence along the benthic-pelagic axis. We also examined the degree of integration between bone pairs. We found differences in bone size between pelagic and benthic morphs for two bones (dentary and premaxilla). There was clear bone shape divergence along a benthic-pelagic axis in four bones (dentary, articular-angular, premaxilla and maxilla), as well as allometric shape differences between morphs in the dentary. Notably for the dentary, morph explained more shape variation than bone size. Comparatively, benthic morphs possess a compact and taller dentary, with shorter dentary palate, consistent with visible (but less prominent) differences in external morphology. As these morphs emerged in the last 10,000 years, these results indicate rapid functional evolution of specific feeding structures in arctic charr. This sets the stage for studies of the genetics and development of rapid and parallel craniofacial evolution.
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Affiliation(s)
| | - Laura-Marie von Elm
- Institute of Life- and Environmental Science, University of Iceland, Reykjavik, Iceland
| | | | - Samuel Tersigni
- Institute of Life- and Environmental Science, University of Iceland, Reykjavik, Iceland
| | | | - Arnar Pálsson
- Institute of Life- and Environmental Science, University of Iceland, Reykjavik, Iceland
| | - Sarah Elizabeth Steele
- Institute of Life- and Environmental Science, University of Iceland, Reykjavik, Iceland
- Canadian Museum of Nature, Ottawa, Canada
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2
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Fenton S, Jacobs A, Bean CW, Adams CE, Elmer KR. Genomic underpinnings of head and body shape in Arctic charr ecomorph pairs. Mol Ecol 2024; 33:e17305. [PMID: 38421099 DOI: 10.1111/mec.17305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 01/31/2024] [Accepted: 02/05/2024] [Indexed: 03/02/2024]
Abstract
Across its Holarctic range, Arctic charr (Salvelinus alpinus) populations have diverged into distinct trophic specialists across independent replicate lakes. The major aspect of divergence between ecomorphs is in head shape and body shape, which are ecomorphological traits reflecting niche use. However, whether the genomic underpinnings of these parallel divergences are consistent across replicates was unknown but key for resolving the substrate of parallel evolution. We investigated the genomic basis of head shape and body shape morphology across four benthivore-planktivore ecomorph pairs of Arctic charr in Scotland. Through genome-wide association analyses, we found genomic regions associated with head shape (89 SNPs) or body shape (180 SNPs) separately and 50 of these SNPs were strongly associated with both body and head shape morphology. For each trait separately, only a small number of SNPs were shared across all ecomorph pairs (3 SNPs for head shape and 10 SNPs for body shape). Signs of selection on the associated genomic regions varied across pairs, consistent with evolutionary demography differing considerably across lakes. Using a comprehensive database of salmonid QTLs newly augmented and mapped to a charr genome, we found several of the head- and body-shape-associated SNPs were within or near morphology QTLs from other salmonid species, reflecting a shared genetic basis for these phenotypes across species. Overall, our results demonstrate how parallel ecotype divergences can have both population-specific and deeply shared genomic underpinnings across replicates, influenced by differences in their environments and demographic histories.
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Affiliation(s)
- Sam Fenton
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Arne Jacobs
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Colin W Bean
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
- NatureScot, Clydebank, UK
| | - Colin E Adams
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
- Scottish Centre for Ecology and the Natural Environment, University of Glasgow, Glasgow, UK
| | - Kathryn R Elmer
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
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3
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Dellinger M, Steele SE, Sprockel E, Philip J, Pálsson A, Benhaïm D. Variation in personality shaped by evolutionary history, genotype and developmental plasticity in response to feeding modalities in the Arctic charr. Proc Biol Sci 2023; 290:20232302. [PMID: 38087921 PMCID: PMC10716646 DOI: 10.1098/rspb.2023.2302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 11/16/2023] [Indexed: 12/18/2023] Open
Abstract
Animal personality has been shown to be influenced by both genetic and environmental factors and shaped by natural selection. Currently, little is known about mechanisms influencing the development of personality traits. This study examines the extent to which personality development is genetically influenced and/or environmentally responsive (plastic). We also investigated the role of evolutionary history, assessing whether personality traits could be canalized along a genetic and ecological divergence gradient. We tested the plastic potential of boldness in juveniles of five Icelandic Arctic charr morphs (Salvelinus alpinus), including two pairs of sympatric morphs, displaying various degrees of genetic and ecological divergence from the ancestral anadromous charr, split between treatments mimicking benthic versus pelagic feeding modalities. We show that differences in mean boldness are mostly affected by genetics. While the benthic treatment led to bolder individuals overall, the environmental effect was rather weak, suggesting that boldness lies under strong genetic influence with reduced plastic potential. Finally, we found hints of differences by morphs in boldness canalization through reduced variance and plasticity, and higher consistency in boldness within morphs. These findings provide new insights on how behavioural development may impact adaptive diversification.
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Affiliation(s)
- Marion Dellinger
- Department of Aquaculture and Fish Biology, Hólar University, Hólar, Iceland
- Institute of Life and Environmental Sciences, School of Engineering and Natural Sciences, University of Iceland, Reykjavík, Iceland
| | - Sarah E. Steele
- Institute of Life and Environmental Sciences, School of Engineering and Natural Sciences, University of Iceland, Reykjavík, Iceland
- Canadian Museum of Nature, Ottawa, Canada
| | - Evert Sprockel
- Department of Aquaculture and Fish Biology, Hólar University, Hólar, Iceland
- HAS University of Applied Sciences, 's-Hertogenbosch, The Netherlands
| | - Joris Philip
- Department of Aquaculture and Fish Biology, Hólar University, Hólar, Iceland
- Scottish Centre for Ecology and the Natural Environment, University of Glasgow, Glasgow, UK
| | - Arnar Pálsson
- Institute of Life and Environmental Sciences, School of Engineering and Natural Sciences, University of Iceland, Reykjavík, Iceland
| | - David Benhaïm
- Department of Aquaculture and Fish Biology, Hólar University, Hólar, Iceland
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4
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Horta-Lacueva QJB, Jónsson ZO, Thorholludottir DAV, Hallgrímsson B, Kapralova KH. Rapid and biased evolution of canalization during adaptive divergence revealed by dominance in gene expression variability during Arctic charr early development. Commun Biol 2023; 6:897. [PMID: 37652977 PMCID: PMC10471602 DOI: 10.1038/s42003-023-05264-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/21/2023] [Indexed: 09/02/2023] Open
Abstract
Adaptive evolution may be influenced by canalization, the buffering of developmental processes from environmental and genetic perturbations, but how this occurs is poorly understood. Here, we explore how gene expression variability evolves in diverging and hybridizing populations, by focusing on the Arctic charr (Salvelinus alpinus) of Thingvallavatn, a classic case of divergence between feeding habitats. We report distinct profiles of gene expression variance for both coding RNAs and microRNAs between the offspring of two contrasting morphs (benthic/limnetic) and their hybrids reared in common conditions and sampled at two key points of cranial development. Gene expression variance in the hybrids is substantially affected by maternal effects, and many genes show biased expression variance toward the limnetic morph. This suggests that canalization, as inferred by gene expression variance, can rapidly diverge in sympatry through multiple gene pathways, which are associated with dominance patterns possibly biasing evolutionary trajectories and mitigating the effects of hybridization on adaptive evolution.
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Affiliation(s)
- Quentin Jean-Baptiste Horta-Lacueva
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland.
- Department of Biology, Lund University, Lund, Sweden.
| | | | - Dagny A V Thorholludottir
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
- University of Veterinary Medicine Vienna, Institute of Population Genetics, Vienna, Austria
| | - Benedikt Hallgrímsson
- Department of Cell Biology and Anatomy, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Kalina Hristova Kapralova
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland.
- The Institute for Experimental Pathology at Keldur, University of Iceland, Reykjavík, Iceland.
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5
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Brachmann MK, Parsons K, Skúlason S, Gaggiotti O, Ferguson M. Variation in the genomic basis of parallel phenotypic and ecological divergence in benthic and pelagic morphs of Icelandic Arctic charr (Salvelinus alpinus). Mol Ecol 2022; 31:4688-4706. [PMID: 35861579 DOI: 10.1111/mec.16625] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 06/22/2022] [Accepted: 07/06/2022] [Indexed: 11/28/2022]
Abstract
Sympatric adaptive phenotypic divergence should be underlain by genomic differentiation between sub-populations. When divergence drives similar patterns of phenotypic and ecological variation within species we expect evolution to draw on common allelic variation. We investigated divergence histories and genomic signatures of adaptive divergence between benthic and pelagic morphs of Icelandic Arctic charr. Divergence histories for each of four populations were reconstructed using coalescent modelling and 14,187 single nucleotide polymorphisms. Sympatric divergence with continuous gene flow was supported in two populations while allopatric divergence with secondary contact was supported in one population; we could not differentiate between demographic models in the fourth population. We detected parallel patterns of phenotypic divergence along benthic-pelagic evolutionary trajectories among populations. Patterns of genomic differentiation between benthic and pelagic morphs were characterized by outlier loci in many narrow peaks of differentiation throughout the genome, which may reflect the eroding effects of gene flow on nearby neutral loci. We then used genome-wide association analyses to relate both phenotypic (body shape and size) and ecological (carbon and nitrogen stable isotopes) variation to patterns of genomic differentiation. Many peaks of genomic differentiation were associated with phenotypic and ecological variation in the three highly divergent populations, suggesting a genomic basis for adaptive divergence. We detected little evidence for a parallel genomic basis of differentiation as most regions and outlier loci were not shared among populations. Our results show that adaptive divergence can have varied genomic consequences in populations with relatively recent common origins, similar divergence histories, and parallel phenotypic divergence.
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Affiliation(s)
| | - Kevin Parsons
- Institute of Biodiversity, Animal Health and Comparative Medicine, School of Life Science, University of Glasgow, Glasgow, UK
| | - Skúli Skúlason
- Department of Aquaculture and Fish Biology, Hólar University, Saudárkrókur, Iceland.,Icelandic Museum of Natural History, Reykjavik, Iceland
| | - Oscar Gaggiotti
- School of biology, Scottish Oceans Institute, University of St. Andrews, St. Andrews, UK
| | - Moira Ferguson
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
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6
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Matlosz S, Sigurgeirsson B, Franzdóttir SR, Pálsson A, Jónsson ZO. DNA methylation differences during development distinguish sympatric morphs of Arctic charr (Salvelinus alpinus). Mol Ecol 2022; 31:4739-4761. [PMID: 35848921 DOI: 10.1111/mec.16620] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 06/13/2022] [Accepted: 07/04/2022] [Indexed: 11/29/2022]
Abstract
Changes in DNA methylation in specific coding or non-coding regions can influence development and potentially divergence in traits within species and groups. While the impact of epigenetic variation on developmental pathways associated with evolutionary divergence is the focus of intense investigation, few studies have looked at recently diverged systems. Phenotypic diversity between closely related populations of Arctic charr (Salvelinus alpinus), which diverged within the last 10 000 years, offers an interesting ecological model to address such effects. Using bisulfite sequencing, we studied general DNA methylation patterns during development in the four sympatric morphs of Arctic charr from Lake Thingvallavatn. The data revealed strong differences between developmental timepoints and between morphs (mainly along the benthic - limnetic axis), both at single CpG sites and in 1,000bp-regions. Genes located close to differentially methylated CpG sites were involved in nucleosome assembly, regulation of osteoclast differentiation, and cell-matrix adhesion. Differentially methylated regions were enriched in tRNA and rRNA sequences, and half of them were located close to transcription start sites. The expression of 14 genes showing methylation differences over time or between morphs was further investigated by qPCR and nine of these were found to be differentially expressed between morphs. Four genes (ARHGEF37-like, H3-like, MPP3 and MEGF9) showed a correlation between methylation and expression. Lastly, histone gene clusters displayed interesting methylation differences between timepoints and morphs, as well as intragenic methylation variation. The results presented here provide a motivation for further studies on the contribution of epigenetic traits, such as DNA methylation, to phenotypic diversity and developmental mechanisms.
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Affiliation(s)
- Sebastien Matlosz
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
| | | | | | - Arnar Pálsson
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
| | - Zophonías O Jónsson
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
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7
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Salisbury S, McCracken GR, Perry R, Keefe D, Layton KKS, Kess T, Nugent CM, Leong JS, Bradbury IR, Koop BF, Ferguson MM, Ruzzante DE. The Genomic Consistency of the Loss of Anadromy in an Arctic Fish (Salvelinus alpinus). Am Nat 2022; 199:617-635. [DOI: 10.1086/719122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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8
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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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9
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Jónsson EP, Campana SE, Sólmundsson J, Jakobsdóttir KB, Bárðarson H. The effect of growth rate on otolith-based discrimination of cod (Gadus morhua) ecotypes. PLoS One 2021; 16:e0247630. [PMID: 34587180 PMCID: PMC8480848 DOI: 10.1371/journal.pone.0247630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 09/09/2021] [Indexed: 01/10/2023] Open
Abstract
Otolith shape has previously been used to identify ecotypes within the Icelandic cod (Gadus morhua) stock, using DST profiles to validate the results. Fish otolith shape variation has repeatedly been found to be largely determined by growth rate. To examine the effect of growth rate on the relationship between otolith shape and cod ecotypes (using the Pan I genotype as a proxy for ecotype), 826 archived sagittal otoliths collected over a 58 year sampling period were retrieved, the individual growth rate calculated, and otolith shape described using both Normalized Elliptic Fourier transform and Discrete Wavelet transform. Discriminant functions of otolith shape successfully classified ecotype, whether using Fourier or Wavelet descriptors, but only when excluding a heterozygous genotype from the analysis. The otolith shape variability of this genotype lowered the classification success, while otolith shape, in turn, was significantly affected by growth rate and cohort. Growth rate differences previously reported for the ecotypes were present, but were less marked than expected and indeed, growth rate variance attributable to ecotype identity was dwarfed by cohort- and location-related variance in growth. Such a strong effect of growth rate suggests that cod ecotype discrimination based on otolith shape is sensitive to both temporal and spatial variations in growth, which can mask the effect of ecotype-related growth rate differences on otolith shape.
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Affiliation(s)
- Einar Pétur Jónsson
- School of Engineering and Natural Sciences, University of Iceland, Askja, Reykjavík, Iceland
- Marine and Freshwater Research Institute, Hafnarfjörður, Iceland
| | - Steven E. Campana
- School of Engineering and Natural Sciences, University of Iceland, Askja, Reykjavík, Iceland
| | - Jón Sólmundsson
- Marine and Freshwater Research Institute, Hafnarfjörður, Iceland
| | | | - Hlynur Bárðarson
- Marine and Freshwater Research Institute, Hafnarfjörður, Iceland
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10
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Horta-Lacueva QJB, Snorrason SS, Morrissey MB, Leblanc CAL, Kapralova KH. Multivariate analysis of morphology, behaviour, growth and developmental timing in hybrids brings new insights into the divergence of sympatric Arctic charr morphs. BMC Ecol Evol 2021; 21:170. [PMID: 34493202 PMCID: PMC8422654 DOI: 10.1186/s12862-021-01904-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/18/2021] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Studying the development of fitness related traits in hybrids from populations diverging in sympatry is a fundamental approach to understand the processes of speciation. However, such traits are often affected by covariance structures that complicate the comprehension of these processes, especially because the interactive relationships between traits of different nature (e.g. morphology, behaviour, life-history) remain largely unknown in this context. In a common garden setup, we conducted an extensive examination of a large suit of traits putatively involved in the divergence of two morphs of Arctic charr (Salvelinus alpinus), and investigated the consequences of potential patterns of trait covariance on the phenotype of their hybrids. These traits were measured along ontogeny and involved growth, yolk sac resorption, developmental timing (hatching and the onset of exogeneous feeding), head morphology and feeding behaviour. RESULTS Growth trajectories provided the strongest signal of phenotypic divergence between the two charr. Strikingly, the first-generation hybrids did not show intermediate nor delayed growth but were similar to the smallest morph, suggesting parental biases in the inheritance of growth patterns. However, we did not observe extensive multivariate trait differences between the two morphs and their hybrids. Growth was linked to head morphology (suggesting that morphological variations in early juveniles relate to simple allometric effects) but this was the only strong signal of covariance observed between all the measured traits. Furthermore, we did not report evidence for differences in overall phenotypic variance between morphs, nor for enhanced phenotypic variability in their hybrids. CONCLUSION Our study shed light on the multivariate aspect of development in a context of adaptive divergence. The lack of evidence for the integration of most traits into a single covariance structure suggested that phenotypic constraints may not always favour nor impede divergence toward ecological niches differing in numerous physical and ecological variables, as observed in the respective habitats of the two charr. Likewise, the role of hybridization as a disruptive agent of trait covariance may not necessarily be significant in the evolution of populations undergoing resource polymorphism.
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Affiliation(s)
- Quentin J-B Horta-Lacueva
- Institute of Life and Environmental Sciences, University of Iceland, Askja - Náttúrufræðihús, Sturlugötu 7, 102, Reykjavík, Iceland.
| | - Sigurður S Snorrason
- Institute of Life and Environmental Sciences, University of Iceland, Askja - Náttúrufræðihús, Sturlugötu 7, 102, Reykjavík, Iceland
| | - Michael B Morrissey
- School of Biology, University of St Andrews, Sir Harold Mitchell Building, Greenside Place, St Andrews, UK
| | - Camille A-L Leblanc
- Department of Aquaculture and Fish Biology, Hólar University, Háeyri 1, 550, Sauðárkrókur, Iceland
| | - Kalina H Kapralova
- Institute of Life and Environmental Sciences, University of Iceland, Askja - Náttúrufræðihús, Sturlugötu 7, 102, Reykjavík, Iceland
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11
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Kess T, Dempson JB, Lehnert SJ, Layton KKS, Einfeldt A, Bentzen P, Salisbury SJ, Messmer AM, Duffy S, Ruzzante DE, Nugent CM, Ferguson MM, Leong JS, Koop BF, O'Connell MF, Bradbury IR. Genomic basis of deep-water adaptation in Arctic Charr (Salvelinus alpinus) morphs. Mol Ecol 2021; 30:4415-4432. [PMID: 34152667 DOI: 10.1111/mec.16033] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/28/2021] [Accepted: 06/03/2021] [Indexed: 12/30/2022]
Abstract
The post-glacial colonization of Gander Lake in Newfoundland, Canada, by Arctic Charr (Salvelinus alpinus) provides the opportunity to study the genomic basis of adaptation to extreme deep-water environments. Colonization of deep-water (>50 m) habitats often requires extensive adaptation to cope with novel environmental challenges from high hydrostatic pressure, low temperature, and low light, but the genomic mechanisms underlying evolution in these environments are rarely known. Here, we compare genomic divergence between a deep-water morph adapted to depths of up to 288 m and a larger, piscivorous pelagic morph occupying shallower depths. Using both a SNP array and resequencing of whole nuclear and mitochondrial genomes, we find clear genetic divergence (FST = 0.11-0.15) between deep and shallow water morphs, despite an absence of morph divergence across the mitochondrial genome. Outlier analyses identified many diverged genomic regions containing genes enriched for processes such as gene expression and DNA repair, cardiac function, and membrane transport. Detection of putative copy number variants (CNVs) uncovered 385 genes with CNVs distinct to piscivorous morphs, and 275 genes with CNVs distinct to deep-water morphs, enriched for processes associated with synapse assembly. Demographic analyses identified evidence for recent and local morph divergence, and ongoing reductions in diversity consistent with postglacial colonization. Together, these results show that Arctic Charr morph divergence has occurred through genome-wide differentiation and elevated divergence of genes underlying multiple cellular and physiological processes, providing insight into the genomic basis of adaptation in a deep-water habitat following postglacial recolonization.
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Affiliation(s)
- Tony Kess
- Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, St. John's, NL, Canada
| | - J Brian Dempson
- Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, St. John's, NL, Canada
| | - Sarah J Lehnert
- Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, St. John's, NL, Canada
| | - Kara K S Layton
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - Anthony Einfeldt
- Department of Biology, Dalhousie University, Halifax, NS, Canada
| | - Paul Bentzen
- Department of Biology, Dalhousie University, Halifax, NS, Canada
| | | | - Amber M Messmer
- Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, St. John's, NL, Canada
| | - Steven Duffy
- Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, St. John's, NL, Canada
| | | | - Cameron M Nugent
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - Moira M Ferguson
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - Jong S Leong
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Ben F Koop
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Michael F O'Connell
- Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, St. John's, NL, Canada
| | - Ian R Bradbury
- Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, St. John's, NL, Canada
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12
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Brachmann MK, Parsons K, Skúlason S, Ferguson MM. The interaction of resource use and gene flow on the phenotypic divergence of benthic and pelagic morphs of Icelandic Arctic charr ( Salvelinus alpinus). Ecol Evol 2021; 11:7315-7334. [PMID: 34188815 PMCID: PMC8216915 DOI: 10.1002/ece3.7563] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 02/09/2021] [Accepted: 03/02/2021] [Indexed: 12/11/2022] Open
Abstract
Conceptual models of adaptive divergence and ecological speciation in sympatry predict differential resource use, phenotype-environment correlations, and reduced gene flow among diverging phenotypes. While these predictions have been assessed in past studies, connections among them have rarely been assessed collectively. We examined relationships among phenotypic, ecological, and genetic variation in Arctic charr (Salvelinus alpinus) from six Icelandic localities that have undergone varying degrees of divergence into sympatric benthic and pelagic morphs. We characterized morphological variation with geometric morphometrics, tested for differential resource use between morphs using stable isotopes, and inferred the amount of gene flow from single nucleotide polymorphisms. Analysis of stable isotopic signatures indicated that sympatric morphs showed similar difference in resource use across populations, likely arising from the common utilization of niche space within each population. Carbon isotopic signature was also a significant predictor of individual variation in body shape and size, suggesting that variation in benthic and pelagic resource use is associated with phenotypic variation. The estimated percentage of hybrids between sympatric morphs varied across populations (from 0% to 15.6%) but the majority of fish had genotypes (ancestry coefficients) characteristic of pure morphs. Despite evidence of reduced gene flow between sympatric morphs, we did not detect the expected negative relationship between divergence in resource use and gene flow. Three lakes showed the expected pattern, but morphs in the fourth showed no detectable hybridization and had relatively low differences in resource use between them. This coupled with the finding that resource use and genetic differentiation had differential effects on body shape variation across populations suggests that reproductive isolation maintains phenotypic divergence between benthic and pelagic morphs when the effects of resource use are relatively low. Our ability to assess relationships between phenotype, ecology, and genetics deepens our understanding of the processes underlying adaptive divergence in sympatry.
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Affiliation(s)
| | - Kevin Parsons
- Institute of Biodiversity, Animal Health and Comparative MedicineSchool of Life ScienceUniversity of GlasgowGlasgowUK
| | - Skúli Skúlason
- Department of Aquaculture and Fish BiologyHólar UniversitySaudárkrókurIceland
- Icelandic Museum of Natural HistoryReykjavíkIceland
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13
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Salisbury SJ, McCracken GR, Perry R, Keefe D, Layton KK, Kess T, Nugent CM, Leong JS, Bradbury IR, Koop BF, Ferguson MM, Ruzzante DE. Limited genetic parallelism underlies recent, repeated incipient speciation in geographically proximate populations of an Arctic fish (
Salvelinus alpinus
). Mol Ecol 2020; 29:4280-4294. [DOI: 10.1111/mec.15634] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 08/20/2020] [Accepted: 08/24/2020] [Indexed: 12/16/2022]
Affiliation(s)
| | | | - Robert Perry
- Department of Environment Fish and Wildlife Division Government of Yukon Whitehorse YT Canada
| | - Donald Keefe
- Department of Environment and Conservation Wildlife Division Government of Newfoundland and Labrador Corner Brook NL Canada
| | - Kara K.S. Layton
- Department of Fisheries and Oceans Northwest Atlantic Fisheries Centre St. John's NL Canada
- Department of Ocean Sciences Memorial University of Newfoundland St. John's NL Canada
| | - Tony Kess
- Department of Fisheries and Oceans Northwest Atlantic Fisheries Centre St. John's NL Canada
| | - Cameron M. Nugent
- Department of Integrative Biology University of Guelph Guelph ON Canada
| | - Jong S. Leong
- Department of Biology University of Victoria Victoria BC Canada
| | - Ian R. Bradbury
- Department of Biology Dalhousie University Halifax NS Canada
- Department of Fisheries and Oceans Northwest Atlantic Fisheries Centre St. John's NL Canada
- Department of Ocean Sciences Memorial University of Newfoundland St. John's NL Canada
| | - Ben F. Koop
- Department of Biology University of Victoria Victoria BC Canada
- Centre for Biomedical Research University of Victoria Victoria BC Canada
| | - Moira M. Ferguson
- Department of Integrative Biology University of Guelph Guelph ON Canada
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14
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Østbye K, Hagen Hassve M, Peris Tamayo AM, Hagenlund M, Vogler T, Præbel K. " And if you gaze long into an abyss, the abyss gazes also into thee": four morphs of Arctic charr adapting to a depth gradient in Lake Tinnsjøen. Evol Appl 2020; 13:1240-1261. [PMID: 32684957 PMCID: PMC7359846 DOI: 10.1111/eva.12983] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 04/14/2020] [Accepted: 04/16/2020] [Indexed: 12/24/2022] Open
Abstract
The origin of species is a central topic in biology. Ecological speciation might be a driver in adaptive radiation, providing a framework for understanding mechanisms, level, and rate of diversification. The Arctic charr Salvelinus alpinus L. is a polymorphic species with huge morphological and life‐history diversity in Holarctic water systems. We studied adaptive radiation of Arctic charr in the 460‐m‐deep Lake Tinnsjøen to (a) document eco‐morphology and life‐history traits of morphs, (b) estimate reproductive isolation of morphs, and (c) illuminate Holarctic phylogeography and lineages colonizing Lake Tinnsjøen. We compared Lake Tinnsjøen with four Norwegian outgroup populations. Four field‐assigned morphs were identified in Lake Tinnsjøen: the planktivore morph in all habitats except deep profundal, the dwarf morph in shallow‐moderate profundal, the piscivore morph mainly in shallow‐moderate profundal, and a new undescribed abyssal morph in the deep profundal. Morphs displayed extensive life‐history variation in age and size. A moderate‐to‐high concordance was observed among morphs and four genetic clusters from microsatellites. mtDNA suggested two minor endemic clades in Lake Tinnsjøen originating from one widespread colonizing clade in the Holarctic. All morphs were genetically differentiated at microsatellites (FST: 0.12–0.20), associated with different mtDNA clade frequencies. Analyses of outgroup lakes implied colonization from a river below Lake Tinnsjøen. Our findings suggest postglacial adaptive radiation of one colonizing mtDNA lineage with niche specialization along a depth–temperature–productivity–pressure gradient. Concordance between reproductive isolation and habitats of morphs implies ecological speciation as a mechanism. Particularly novel is the extensive morph diversification with depth into the often unexplored deepwater profundal habitat, suggesting we may have systematically underestimated biodiversity in lakes. In a biological conservation framework, it is imperative to protect endemic below‐species‐level biodiversity, particularly so since within‐species variation comprises an extremely important component of the generally low total biodiversity observed in the northern freshwater systems.
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Affiliation(s)
- Kjartan Østbye
- Faculty of Applied Ecology, Agricultural Sciences and Biotechnology Inland Norway University of Applied Sciences Campus Evenstad Norway.,Department of Biosciences Centre for Ecological and Evolutionary Synthesis (CEES) University of Oslo Oslo Norway
| | - Marius Hagen Hassve
- Faculty of Applied Ecology, Agricultural Sciences and Biotechnology Inland Norway University of Applied Sciences Campus Evenstad Norway
| | - Ana-Maria Peris Tamayo
- Faculty of Applied Ecology, Agricultural Sciences and Biotechnology Inland Norway University of Applied Sciences Campus Evenstad Norway
| | - Mari Hagenlund
- Faculty of Applied Ecology, Agricultural Sciences and Biotechnology Inland Norway University of Applied Sciences Campus Evenstad Norway
| | - Thomas Vogler
- Faculty of Applied Ecology, Agricultural Sciences and Biotechnology Inland Norway University of Applied Sciences Campus Evenstad Norway
| | - Kim Præbel
- Faculty of Biosciences, Fisheries and Economics Norwegian College of Fishery Science UiT Arctic University of Norway Tromsø Norway
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