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  1. Article ; Online: Adaptive cellular evolution or cellular system drift in hares.

    Palsson, Arnar / Steele, Sarah Elizabeth

    Molecular ecology

    2023  Volume 32, Issue 15, Page(s) 4093–4096

    Abstract: Adaptations occur at many levels, for example, from DNA sequence of regulatory elements and cellular homeostatic systems to organismal physiology and behaviour (Mayr, 1997). Established adaptations are maintained by purifying and stabilizing selection. ... ...

    Abstract Adaptations occur at many levels, for example, from DNA sequence of regulatory elements and cellular homeostatic systems to organismal physiology and behaviour (Mayr, 1997). Established adaptations are maintained by purifying and stabilizing selection. Students of animal diversity tend to focus on higher order traits, anatomy, physiology, organismal function and interactions. The core cellular and metabolic systems of metazoans evolved early in their history and are assumed to be rather similar between groups. The housekeeping functions and core metabolic functions of cells are generally considered relatively static, especially among closely related species. The extent to which evolution shapes core cellular metabolism and physiology in animals is largely unexplored. Ecological opportunities or strong positive selection can alter basal metabolic rate, activity levels and life-history traits (e.g., life span, age of maturity, offspring number) and potentially lead to divergence in core cellular and metabolic trait systems (Norin & Metcalfe, 2019; Speakman, 2005). Furthermore, systems under stabilizing selection can also change. Developmental systems of related species may produce the same phenotype or structure, but experience drift that can alter connections and even lead to turnover of cogs in the system (True & Haag, 2001). Are the cellular functions of animals highly constrained, subject to cellular system drift or affected by positive selection? This was tackled by a new study by Kateryna Gaertner and colleagues in a From the Cover manuscript in this issue of Molecular Ecology (Gaertner et al., 2022), using fibroblasts from the closely related but ecologically distinct brown and mountain hares.
    MeSH term(s) Animals ; Hares ; Phenotype
    Language English
    Publishing date 2023-05-31
    Publishing country England
    Document type Research Support, Non-U.S. Gov't ; Journal Article ; Comment
    ZDB-ID 1126687-9
    ISSN 1365-294X ; 0962-1083
    ISSN (online) 1365-294X
    ISSN 0962-1083
    DOI 10.1111/mec.17030
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  2. Article ; Online: Adaptive cellular evolution or cellular system drift in hares

    Palsson, Arnar / Steele, Sarah Elizabeth

    Molecular Ecology. 2023 Aug., v. 32, no. 15 p.4093-4096

    2023  

    Abstract: Adaptations occur at many levels, for example, from DNA sequence of regulatory elements and cellular homeostatic systems to organismal physiology and behaviour (Mayr, 1997). Established adaptations are maintained by purifying and stabilizing selection. ... ...

    Abstract Adaptations occur at many levels, for example, from DNA sequence of regulatory elements and cellular homeostatic systems to organismal physiology and behaviour (Mayr, 1997). Established adaptations are maintained by purifying and stabilizing selection. Students of animal diversity tend to focus on higher order traits, anatomy, physiology, organismal function and interactions. The core cellular and metabolic systems of metazoans evolved early in their history and are assumed to be rather similar between groups. The housekeeping functions and core metabolic functions of cells are generally considered relatively static, especially among closely related species. The extent to which evolution shapes core cellular metabolism and physiology in animals is largely unexplored. Ecological opportunities or strong positive selection can alter basal metabolic rate, activity levels and life‐history traits (e.g., life span, age of maturity, offspring number) and potentially lead to divergence in core cellular and metabolic trait systems (Norin & Metcalfe, 2019; Speakman, 2005). Furthermore, systems under stabilizing selection can also change. Developmental systems of related species may produce the same phenotype or structure, but experience drift that can alter connections and even lead to turnover of cogs in the system (True & Haag, 2001). Are the cellular functions of animals highly constrained, subject to cellular system drift or affected by positive selection? This was tackled by a new study by Kateryna Gaertner and colleagues in a From the Cover manuscript in this issue of Molecular Ecology (Gaertner et al., 2022), using fibroblasts from the closely related but ecologically distinct brown and mountain hares.
    Keywords Animalia ; animals ; basal metabolic rate ; ecology ; evolution ; fibroblasts ; life history ; longevity ; metabolism ; nucleotide sequences ; phenotype ; progeny
    Language English
    Dates of publication 2023-08
    Size p. 4093-4096.
    Publishing place John Wiley & Sons, Ltd
    Document type Article ; Online
    Note News
    ZDB-ID 1126687-9
    ISSN 1365-294X ; 0962-1083
    ISSN (online) 1365-294X
    ISSN 0962-1083
    DOI 10.1111/mec.17030
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: The prey availability and diet of juvenile Atlantic salmon (Salmo salar L.) in low-productivity rivers in northern Europe.

    Lai, Sum Yi / Pálsson, Arnar / Guðbergsson, Guðni / Jónsson, Ingi Rúnar / Ólafsson, Jón S / Bárðarson, Hlynur

    Journal of fish biology

    2024  

    Abstract: The availability of resources varies across a species distributional range, and a low-productivity area can make a species more vulnerable. We investigated the invertebrate composition and prey choice of juvenile Atlantic salmon (Salmo salar L.) in low- ... ...

    Abstract The availability of resources varies across a species distributional range, and a low-productivity area can make a species more vulnerable. We investigated the invertebrate composition and prey choice of juvenile Atlantic salmon (Salmo salar L.) in low-productivity rivers in northeast Iceland, which is one of the species' most northerly distributions. By sampling benthic and drift invertebrate populations, we found that prey availability was similar within and between rivers. Gut content samples showed that the main prey choice for juvenile S. salar was the Chironomidae. The type of food items consumed varied across different weight groups of S. salar, with smaller juveniles having more diverse diet. S. salar did not have a selection preference for chironomids, which indicates that they were eating the highly available prey in their environment, rather than hunting high biomass items such as terrestrial invertebrates and large Dipterans. Estimates of dietary niche showed that S. salar in these low-productivity rivers relied on consuming what was most readily available, the chironomids, and that they must share resources with other salmonid species. This may be due to the low diversity of freshwater invertebrates (fewer prey options), whereas S. salar in nutrient-rich rivers could rely more on terrestrial invertebrates as an additional subsidy in their diet. In conclusion, with limited prey choices, juvenile S. salar in nutrient-poor rivers, especially in a biogeographically isolated region with low species diversity, may increase in vulnerability and decrease in adaptability to environmental change. Management methods that increase benthic prey abundance and diversity are recommended for conserving the S. salar population in a nutrient-poor river.
    Language English
    Publishing date 2024-04-17
    Publishing country England
    Document type Journal Article
    ZDB-ID 410564-3
    ISSN 1095-8649 ; 0022-1112
    ISSN (online) 1095-8649
    ISSN 0022-1112
    DOI 10.1111/jfb.15757
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  4. Article ; Online: Genetic structure and relatedness of brown trout (

    Lagunas, Marcos / Pálsson, Arnar / Jónsson, Benóný / Jóhannsson, Magnús / Jónsson, Zophonías O / Snorrason, Sigurður S

    PeerJ

    2023  Volume 11, Page(s) e15985

    Abstract: Background: Lake Þingvallavatn in Iceland, a part of the river Ölfusá drainage basin, was presumably populated by brown trout soon after it formed at the end of the last Ice Age. The genetic relatedness of the brown trout in Þingvallavatn to other ... ...

    Abstract Background: Lake Þingvallavatn in Iceland, a part of the river Ölfusá drainage basin, was presumably populated by brown trout soon after it formed at the end of the last Ice Age. The genetic relatedness of the brown trout in Þingvallavatn to other populations in the Ölfusá drainage basin is unknown. After the building of a dam at the outlet of the lake in 1959 brown trout catches declined, though numbers have now increased. The aim of this study was to assess effects of geographic isolation and potential downstream gene flow on the genetic structure and diversity in brown trout sampled in several locations in the western side of the watershed of River Ölfusá. We hypothesized that brown trout in Lake Þingvallavatn constituted several local spawning populations connected by occasional gene flow before the damming of the lake. We also estimated the effective population size (N
    Methods: We sampled brown trout inhabiting four lakes and 12 rivers within and near the watershed of River Ölfusá by means of electro- and net- fishing. After stringent data filtering, 2,597 polymorphic loci obtained from ddRADseq data from 317 individuals were ascertained as putative neutral markers.
    Results: Overall, the genetic relatedness of brown trout in the Ölfusá watershed reflected the connectivity and topography of the waterways. Ancestry proportion analyses and a phylogenetic tree revealed seven distinct clusters, some of which corresponded to small populations with reduced genetic diversity. There was no evidence of downstream gene flow from Lake Þingvallavatn, although gene flow was observed from much smaller mountain populations. Most locations showed low N
    Discussion: This is the first time that the genetic structure and diversity of brown trout in the watershed of River Ölfusá have been assessed. Our results point towards the presence of a metapopulation in the watershed of Lake Þingvallavatn, which has been influenced by restoration efforts and is now dominated by a genetic component originated in River Öxará. Many of the locations studied represent different populations. Those that are isolated in headwater streams and lakes are genetically distinct presenting low genetic diversity, yet they can be important in increasing the genetic variation in downstream populations. These populations should be considered for conservation and direct management.
    MeSH term(s) Iceland ; Phylogeny ; Drainage ; Population Density ; Genetic Structures
    Language English
    Publishing date 2023-09-05
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2703241-3
    ISSN 2167-8359 ; 2167-8359
    ISSN (online) 2167-8359
    ISSN 2167-8359
    DOI 10.7717/peerj.15985
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  5. Article ; Online: Variation in personality shaped by evolutionary history, genotype and developmental plasticity in response to feeding modalities in the Arctic charr.

    Dellinger, Marion / Steele, Sarah E / Sprockel, Evert / Philip, Joris / Pálsson, Arnar / Benhaïm, David

    Proceedings. Biological sciences

    2023  Volume 290, Issue 2013, Page(s) 20232302

    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 ...

    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 (
    MeSH term(s) Humans ; Animals ; Biological Evolution ; Genotype ; Selection, Genetic ; Personality ; Trout/physiology
    Language English
    Publishing date 2023-12-13
    Publishing country England
    Document type Journal Article
    ZDB-ID 209242-6
    ISSN 1471-2954 ; 0080-4649 ; 0962-8452 ; 0950-1193
    ISSN (online) 1471-2954
    ISSN 0080-4649 ; 0962-8452 ; 0950-1193
    DOI 10.1098/rspb.2023.2302
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  6. Article: DNA methylation differences during development distinguish sympatric morphs of Arctic charr (Salvelinus alpinus)

    Matlosz, Sébastien / Sigurgeirsson, Benjamín / Franzdóttir, Sigrídur Rut / Pálsson, Arnar / Jónsson, Zophonías O.

    Molecular ecology. 2022 Sept., v. 31, no. 18

    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 ... ...

    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 bisulphite 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 1000 bp‐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.
    Keywords DNA methylation ; Salvelinus alpinus ; cell adhesion ; divergent evolution ; ecological models ; ecology ; epigenetics ; genes ; histones ; lakes ; motivation ; nucleosomes ; osteoclasts ; phenotypic variation ; sympatry
    Language English
    Dates of publication 2022-09
    Size p. 4739-4761.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 1126687-9
    ISSN 1365-294X ; 0962-1083
    ISSN (online) 1365-294X
    ISSN 0962-1083
    DOI 10.1111/mec.16620
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  7. Article ; Online: DNA methylation differences during development distinguish sympatric morphs of Arctic charr (Salvelinus alpinus).

    Matlosz, Sébastien / Sigurgeirsson, Benjamín / Franzdóttir, Sigrídur Rut / Pálsson, Arnar / Jónsson, Zophonías O

    Molecular ecology

    2022  Volume 31, Issue 18, Page(s) 4739–4761

    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 ... ...

    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 bisulphite 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 1000 bp-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.
    MeSH term(s) Animals ; Biological Evolution ; DNA Methylation/genetics ; Phenotype ; Sympatry ; Trout/genetics
    Language English
    Publishing date 2022-08-02
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1126687-9
    ISSN 1365-294X ; 0962-1083
    ISSN (online) 1365-294X
    ISSN 0962-1083
    DOI 10.1111/mec.16620
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  8. Article ; Online: Maedi-visna virus persistence: Antigenic variation and latency.

    Arnarson, Hallgrímur / Pálsson, Arnar / Gudnadóttir, Margrét / Andrésdóttir, Valgerdur

    Comparative immunology, microbiology and infectious diseases

    2017  Volume 55, Page(s) 6–12

    Abstract: Maedi-visna virus (MVV), a lentivirus of sheep, shares with other lentiviruses the ability to establish a lifelong infection. In this study five sheep were infected intravenously with MVV and housed together with a number of uninfected sheep for natural ... ...

    Abstract Maedi-visna virus (MVV), a lentivirus of sheep, shares with other lentiviruses the ability to establish a lifelong infection. In this study five sheep were infected intravenously with MVV and housed together with a number of uninfected sheep for natural transmission. All virus isolates from ten sheep that had been infected naturally had multiple mutations in the principal neutralization domain in Env and were antigenic variants, while three of four isolates from the carrier sheep had identical sequences to the infecting strain and were not antigenic variants. There was evidence of positive selection in the gene, particularly in amino acids comprising the neutralization epitope and some adjacent glycosylation sites. Together these results suggest that virus persistence is acquired by a reservoir of latent viruses, and that there is selection for antigenic variants of virus that is transmitted naturally.
    Language English
    Publishing date 2017-12
    Publishing country England
    Document type Journal Article
    ZDB-ID 436522-7
    ISSN 1878-1667 ; 0147-9571
    ISSN (online) 1878-1667
    ISSN 0147-9571
    DOI 10.1016/j.cimid.2017.08.003
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  9. Article: Fungal and cyanobacterial gene expression in a lichen symbiosis: Effect of temperature and location.

    Steinhäuser, Sophie S / Andrésson, Ólafur S / Pálsson, Arnar / Werth, Silke

    Fungal biology

    2016  Volume 120, Issue 10, Page(s) 1194–1208

    Abstract: Organisms have evolved different cellular mechanisms to deal with environmental stress, primarily through complex molecular mechanisms including protein refolding and DNA repair. As mutualistic symbioses, lichens offer the possibility of analyzing ... ...

    Abstract Organisms have evolved different cellular mechanisms to deal with environmental stress, primarily through complex molecular mechanisms including protein refolding and DNA repair. As mutualistic symbioses, lichens offer the possibility of analyzing molecular stress responses in a particularly tight interspecific relationship. We study the widespread cyanolichen Peltigera membranacea, a key player in carbon and nitrogen cycling in terrestrial ecosystems at northern latitudes. We ask whether increased temperature is reflected in mRNA levels of selected damage control genes, and do the response patterns show geographical associations? Using real-time PCR quantification of 38 transcripts, differential expression was demonstrated for nine cyanobacterial and nine fungal stress response genes (plus the fungal symbiosis-related lec2 gene) when the temperature was increased from 5 °C to 15 °C and 25 °C. Principle component analysis (PCA) revealed two gene groups with different response patterns. Whereas a set of cyanobacterial DNA repair genes and the fungal lec2 (PC1 group) showed an expression drop at 15 °C vs. 5 °C, most fungal candidates (PC2 group) showed increased expression at 25 °C vs. 5 °C. PC1 responses also correlated with elevation. The correlated downregulation of lec2 and cyanobacterial DNA repair genes suggests a possible interplay between the symbionts warranting further studies.
    MeSH term(s) Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; Cyanobacteria/classification ; Cyanobacteria/genetics ; Cyanobacteria/isolation & purification ; Cyanobacteria/physiology ; Fungal Proteins/genetics ; Fungal Proteins/metabolism ; Fungi/classification ; Fungi/genetics ; Fungi/isolation & purification ; Fungi/physiology ; Lichens/microbiology ; Lichens/physiology ; Phylogeny ; Symbiosis ; Temperature
    Chemical Substances Bacterial Proteins ; Fungal Proteins
    Language English
    Publishing date 2016-10
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 2532164-X
    ISSN 1878-6162 ; 1878-6146
    ISSN (online) 1878-6162
    ISSN 1878-6146
    DOI 10.1016/j.funbio.2016.07.002
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  10. Article: Extensive genetic differentiation between recently evolved sympatric Arctic charr morphs.

    Guðbrandsson, Jóhannes / Kapralova, Kalina H / Franzdóttir, Sigríður R / Bergsveinsdóttir, Þóra Margrét / Hafstað, Völundur / Jónsson, Zophonías O / Snorrason, Sigurður S / Pálsson, Arnar

    Ecology and evolution

    2019  Volume 9, Issue 19, Page(s) 10964–10983

    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 ... ...

    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
    Language English
    Publishing date 2019-09-12
    Publishing country England
    Document type Journal Article
    ZDB-ID 2635675-2
    ISSN 2045-7758
    ISSN 2045-7758
    DOI 10.1002/ece3.5516
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