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      • Bjarni Kristófer Kristjánsson
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      • Evolution of cognition: A study of sympatric morphs of Arctic charr
      • Microevolutionary processes in small populations
      • The importance of egg size for phenotypic variations and divergence in wild populations
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      • Egg quality and growth in selected Arctic charr
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​Bjarni Kristófer Kristjánsson


​Professor

bjakk@holar.is


​Curriculum Vitae
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​
Orcid 
​Google scholar

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Research Interest

My research focus is on understanding factors, both ecological and evolutionary, that shape biological diversity. My work focuses on biological diversity at various levels within freshwater, from within species to communities. To answer the questions I'm interested in, I work both in the field and use controlled laboratory experiments. I am a strong believer that for successful research and greater knowledge scientists need to collaborate, often across disciplines. I thus have many good research collaborators that bring in specialization.
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Ongoing Research Projects

PI on ECO-EVO-DEVO dynamics of biodiversity - Mývatn threespine stickleback as a model.

PI on Biological diversity in Icelandic sub-surface freshwater

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Collaborator in the project Micro evolutionary Processes in Small Populations.
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Students

Alessandra Schnider, PhD student 

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​Sigurður H. Árnason, PhD student
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Daniel P. Govoni, PhD student

Former Graduate Students
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PhD

2024 - Bethany Smith, co-supervised with Kevin Parsons, University of Glasgow
2020 - ​Agnes-Katharina Kreiling, University of Iceland
2019 – Samantha Victoria Beck, University of Iceland
2013 – Antone Millet, University of Iceland
M.Sc. 
2024 Spencer William Edwards, Hólar University
2023 Ragna Guðrún Snorradóttir, Hólar University
2018 Marlene Kundruhn, University of Cologne Germany
2018 Doriane Combot, Hólar University
2016 Coralie Delarue, Hólar University
2015 Jónína Herdís Ólafsdóttir, Hólar University
2015 Jóhann Garðar Þorbjörnsson, Hólar University
2012 Tamara Diethelm, ETH, Switzerland
2011 Mathew Stephen Seymour, Hólar University
2011 Daniel P. Govoni, Hólar University
2010 Andrea Koopmans, ETH, Switzerland
2010 Mike Senn, University of Zurich

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Selected Publications
Mittell, E. A., Leblanc, C. A., Kristjánsson, B. K., Ferguson, M. M., Räsänen, K., & Morrissey, M. B. (2025). Spatiotemporal variation in size-dependent growth rates in small isolated populations of Arctic charr (Salvelinus alpinus). Royal Society Open Science, 12(1). https://doi.org/10.1098/rsos.241802
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Docker, M. F., & Kristjánsson, B. K. (2024). Advisory editor profile: Bjarni K. Kristjánsson. Environmental Biology of Fishes, 107, 155. https://doi.org/10.1007/s10641-024-01521-6

Judson, B. J., Kristjánsson, B. K., Leblanc, C. A.-L., & Ferguson, M. M. (2024). The role of neutral and adaptive evolutionary processes on patterns of genetic diversity across small cave-dwelling populations of Icelandic Arctic charr (Salvelinus alpinus). Ecology and Evolution, 14, Article e11363. https://doi.org/10.1002/ece3.11363

Koene, J. P., Bean, C. W., Kristjánsson, B. K., Skúlason, S., Leblanc, C. A., & Adams, C. (2024). Patterns, processes and conservation management consequences of intraspecific diversity, illustrated by fishes from recently glaciated lakes. Aquatic Conservation: Marine and Freshwater Ecosystems, 34, Article e4076. https://doi.org/10.1002/aqc.4076

Kristjánsson, B. K., Combot, D., Reilent, A., Phillips, J. S., & Leblanc, C. A.-L. (2024). Invertebrate diversity in groundwater-filled lava caves is influenced by both neutral- and niche-based processes. Ecology and Evolution, 14, Article e11560. https://doi.org/10.1002/ece3.11560

Leblanc, C. A., Räsänen, K., Morrissey, M., Skúlason, S., Ferguson, M., & Kristjánsson, B. K. (2024). Fine-scale diversity in the lava: Genetic and phenotypic diversity in small populations of Arctic charr (Salvelinus alpinus). BMC Ecology and Evolution, 24, Article 45. https://doi.org/10.1186/s12862-024-02232-3

Smith, B., Costa, A., Kristjánsson, B. K., & Parsons, K. (2024). Experimental evidence for adaptive divergence in response to a warmed habitat reveals roles for morphology, allometry and parasite resistance. Ecology and Evolution, 14, Article e10907. https://doi.org/10.1002/ece3.10907

Strickland, K., Matthews, B., Jónsson, Z. O., Kristjánsson, B. K., Phillips, J. S., Einarsson, Á., & Räsänen, K. (2024). Microevolutionary change in wild stickleback: Using integrative time-series data to infer responses to selection. Proceedings of the National Academy of Sciences of the United States of America, 121, Article e2410324121. https://doi.org/10.1073/pnas.2410324121

Eme, D., Westfall, K. M., Matthíasardóttir, B., Kristjánsson, B. K., & Pálsson, S. (2023). Contrasting phylogeographic patterns of mitochondrial and genome-wide variation in the groundwater amphipod Crangonyx islandicus that survived the ice age in Iceland. Diversity, 15(1), 24. https://doi.org/10.3390/d15010088

Phillips, J. S., Einarsson, A., Strickland, K., Ives, A. R., Kristjánsson, B. K., & Räsänen, K. (2023). Demographic basis of spatially structured fluctuations in a threespine stickleback metapopulation. American Naturalist, 15. https://doi.org/10.1086/722741

Pilakouta, N., Humble, J. L., Hill, I. D. C., Arthur, J., Costa, A. P. B., Smith, B. A., Kristjánsson, B. K., Skúlason, S., Killen, S. S., Lindström, J., Metcalfe, N. B., & Parsons, K. J. (2023). Testing the predictability of morphological evolution in contrasting thermal environments. Evolution, 77(1), 239-253. https://doi.org/10.1093/evolut/qpac018

Pilakouta, N., Killen, S. S., Kristjánsson, B. K., Skúlason, S., Lindström, J., Metcalfe, N. B., & Parsons, K. J. (2023). Geothermal stickleback populations prefer cool water despite multigenerational exposure to a warm environment. Ecology and Evolution, 13(1), 8. https://doi.org/10.1002/ece3.9654

Strickland, K., Räsänen, K., Kristjánsson, B. K., Phillips, J. S., Einarsson, A., Snorradóttir, R. G., Bartrons, M., & Jónsson, Z. O. (2023). Genome-phenotype-environment associations identify signatures of selection in a panmictic population of threespine stickleback. Molecular Ecology, 32(7), 1708-1725. https://doi.org/10.1111/mec.16845

Beck, S. V., Räsänen, K., Kristjánsson, B. K., Skúlason, S., Jónsson, Z. O., Tsinganis, M., & Leblanc, C. A. (2022). Variation in egg size and offspring phenotype among and within seven Arctic charr morphs. Ecology and Evolution, 12, e9427. https://doi.org/10.1002/ece3.9427

Bouvier, L. D., Baylis, J. R., Klementsen, A., Kristjánsson, B. K., Li, J. L., Magnan, P., McLaughlin, R. L., Muir, A. M., Sakakura, Y., & Skúlason, S. (2022). What is fish? The life and legend of David L.G. Noakes. Environmental Biology of Fishes. https://doi.org/10.1007/s10641-022-01344-3
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Kreiling, A.-K., Govoni, D. P., Pálsson, S., Ólafsson, J. S., & Kristjánsson, B. K. (2022). Invertebrate communities in springs across a gradient in thermal regimes. PLOS ONE, 17, e0264501. https://doi.org/10.1371/journal.pone.0264501

Leblanc, C. A., Schreck, C., Kristjánsson, B. K., Skúlason, S., & Noakes, D. L. G. (2022). Egg size-related traits during the first year of growth and smolting in hatchery and wild juveniles of steelhead trout (Oncorhynchus mykiss). Environmental Biology of Fishes. https://doi.org/10.1007/s10641-022-01377-8

Pilakouta, N., O'Donnell, P. J., Crespel, A., Levet, M., Claireaux, M., Humble, J. L., Kristjánsson, B. K., Skúlason, S., Lindström, J., Metcalfe, N. B., Killen, S. S., & Parsons, K. J. (2022). A warmer environment can reduce sociability in an ectotherm. Global Change Biology, 29, 2341–2352. https://doi.org/10.1111/gcb.16451

Dębicki I.T., Mittell E. A., Kristjánsson B. K., Leblanc, C. A., Morrissey M. B., & Terzić K.. (2021). Re-identification of individuals from images using spot constellations; a case study in Arctic charr (Salvelinus alpinus). Royal Society Open Science. https://doi.org/10.1098/rsos.201768

Kreiling, A. K., O'Gorman, E., Palsson, S., Benhaim, D., Leblanc, C., Ólafsson, J., & Kristjansson, B. K. (2021). Seasonal variation in the invertebrate community and diet of an apex fish predator in a thermally stable spring. Hydrobiologia, 848(3), 531–545. https://doi.org/10.1007/s10750-020-04409-5

Karvonen, A., Beck, S., Skúlason S., Kristjánsson B. K., Leblanc C. A. (2021). Variation in parasite resistance of Arctic charr (Salvelinus alpinus), between and within sympatric morphs. Ecology and Evolution, 11, 14024–14032. https://doi.org/10.1002/ece3.8109

Beck, S. V., Räsänen, K., Leblanc, C. A., Skulason, S., Jónsson, Z. O., & Kristjánsson, B. K. (2020). Differences among families in craniofacial shape at early life-stages of Arctic charr (Salvelinus alpinus). BMC Developmental Biology, 20(21), 1-15. https://doi.org/10.1186/s12861-020-00226-0

Guðmundsdóttir, R., Kreiling, A. K., Kristjánsson, B. K., Marteinsson. V. Þ.
, & Pálsson, S. (2020). Ciliate diversity in cold water spring sources in Iceland. Aquatic Microbial Ecology, 84, 191-203. https://doi.org/10.3354/ame01936

Kreiling, A. K., Gíslason, G. M., & Kristjánsson, B. K. (2020).  Trichoptera diversity in Icelandic springs. Zoosymposia, 18. https://doi.org/10.11646/zoosymposia.18.1

Kreiling, A. K., O’Gorman, E. J., Pálsson,S., Benhaim, D., Leblanc, C. A., & Kristjánsson, B. K. (2020). Seasonal variation in the invertebrate community and diet of a top fish predator in a thermally stable spring. Hydrobiologia, 848, 531-545. https://doi.org/10.1007/s10750-020-04409-5

Paccard, A.,  Hanson, D., Stuart, E. Y., von Hippel, F. A.,  Kalbe, M., Klepaker, T.,
Skúlason, S., Kristjánsson, B. K., Bolnick, I. D., Hendry, A. P., & Barrett, R. D. H. (2020). Repeatability of Adaptive Radiation Depends on Spatial Scale: Regional Versus Global Replicates of Stickleback in Lake Versus Stream Habitats. Journal of Heredity, 111(1),  43–56.  https://doi.org/10.1093/jhered/esz056

Pilakouta, N., Humble, J. L., Hill, I. D. C., Arthur, J., Costa, A. P. B., Smith, B. A., Kristjánsson, B. K., Skúlason, S., Killen, S. S., Lindström, J., Metcalfe, N. B., & Parsons, K. J.(2020). Testing the predictability of morphological evolution in contrasting thermal environments. bioRxiv, https://doi.org/10.1101/609933

Pilakouta, N,. Killen, S. S., Kristjánsson, B. K., Skúlason, S., Lindström, J., Metcalfe, N. B., & Parsons, K. J. (2020). Multigenerational exposure to elevated temperatures leads to a reduction in standard metabolic rate in the wild. Functional Ecology, 34(6), 1205–1214. https://doi.org/10.1111/1365-2435.13538

Pálsson, S., Guðmundsdóttir, R.
, & Kristjánsson, B. K. (2020). Náttúrufræðingurinn, 90, 16-22.

Þorbjörnsson, J. G., Ólafsdóttir, J. H., Kristjánsson, B. K., Chambers, C., & Burns, G. L. (2020). Recreational scuba diving in a groundwater ecosystem: Disturbance mechanisms, ecological impacts and stakeholder perceptions. Aquatic Conservation Marine and Freshwater Ecosystem, 30(5), 1012–1022. https://doi.org/10.1002/aqc.3308

Beck, S. V., Räsänen, B. K., Ahi, E. P., Kristjánsson, B. K., Skúlason, S., Jónsson, Z. O., & Leblanc, C. A. (2019). Gene expression in the phenotypically plastic Arctic charr (Salvelinus alpinus): A focus on growth and ossification at early stages of development. Evolution & development, 21(1), 16–30. https://doi.org/10.1111/ede.12275

Ólafsdóttir, J. H., Þorbjörnsson, J. G.,  Kristjánsson B. K., &  Ólafsson, J. S. (2019). Invertebrate biodiversity in cold groundwater fissures in Iceland. Ecology and Evolution, 9(11), 6399– 6409. https://doi.org/10.1002/ece3.5213

Pilakouta, N., Killen, S. S., Kristjánsson, B. K., Skúlason, S., Lindström, J., Metcalfe, N. B., & Parsons, K. J. (2019). Temperature preference does not evolve in sticklebacks despite multigenerational exposure to elevated temperatures. bioRxiv. https://doi.org/10.1101/615005

Seymour, M., Räsänen, K., & Kristjánsson, B. K. (2019). Drift versus selection as drivers of phenotypic divergence at small spatial scales: The case of Belgjarskógur threespine stickleback. Ecology and Evolution, 9(14), 8133– 8145. https://doi.org/10.1002/ece3.5381

Skúlason, S., Parsons, K. J., Svanbäck, R., Räsänen, K., Ferguson, M. M., Adams, C. E., Amundsen, P. A., Bartels, P., Bean, C. W., Boughman, J. W., Guðbrandsson, G. E. J., Hooker, O. E., Hudson, A. G., Kahilainen, K. K., Knudsen, R., Kristjánsson, B. K.,  Leblanc, C. A. L.,  Jónsson, Z., Öhlund, G., Smith, C., & Snorrason, S. S. (2019). A way forward with eco evo devo: an extended theory of resource polymorphism with postglacial fishes as model systems. Biological Reviews, 94(5), 1786-1808. https://doi.org/10.1111/brv.12534

Govoni, D. P., Kristjánsson, B. K., & Ólafsson, J. S. (2018). Spring type influences invertebrate communities at cold spring sources. Hydrobiologia, 808, 315-325.  https://doi.org/10.1007/s10750-017-3434-6

Kristjánsson, B. K., & Leblanc, C. A. L. (2018). Variation in the magnitude of morphological and dietary differences between individuals among populations of small benthic Arctic charr in relation to ecological factors. Ecology and evolution, 8(3). https://doi.org/10.1002/ece3.3761

Kreiling, A.-K., Ólafsson, J. S., & Kristjánsson, B. K. (2018). Chironomidae fauna of springs in Iceland – assessing the ecological relevance behind Tuxen´s spring classification. Journal of Limnology, 77(S1), 145-1. https://doi.org/10.4081/jlimnol.2018.1754

Kristjánsson, B. K., Leblanc, C. A. L., Skúlason, S., Snorrason, S. S., &  Noakes, D. L. G. (2018). Phenotypic plasticity in the morphology of small benthic Icelandic Arctic charr (Salvelinus alpinus). Ecology of Freshwater Fish, 27(3), 636-645. https://doi.org/10.1111/eff.12380

Leblanc, C. A. L., Kristjánsson, B. K., & Skúlason, S. (2016). The importance of egg size and egg energy density for early size patterns and performance of Arctic charr Salvelinus alpinus. Aquaculture Research, 47(4), 1100-1111. https://doi.org/10.1111/are.12566

Gudbrandsson, J., Ahi, E., Franzdottir, S., Kapralova, K., Kristjánsson, B. K., Steinhauser, S., Maier, V., Jóhannesson, I., Snorrason, S.,  Jonsson, Z., & Pálsson, A. (2015). The developmental transcriptome of contrasting Arctic charr (Salvelinus alpinus) morphs. F1000Research, 4(136), 1-54. https://doi.org/10.12688/f1000research.6402.3

Kapralova, K. H., Jónsson, Z. O., Pálsson, A., Franzdóttir, S. R., le Deuff, S., Kristjánsson, B. K., & Snorrason, S. S. (2015). Bones in motion: Ontogeny of craniofacial development in sympatric arctic charr morphs. Developmental Dynamics 244(9), 1168-1178. https://doi.org/10.1002/dvdy.24302

Leblanc, C. A., Kristjánsson, B. K., & Skúlason, S. (2014). The importance of egg size and egg energy density for early size patterns and performance of Arctic charr Salvelinus alpinus. Aquaculture Research, 47(4), 1100-1111. https://doi.org/10.1111/are.12566

Lucek, K., Sivasundar, A., Kristjánsson, B. K., Skúlason, S., & Seehausen, O. (2014). Quick divergence but slow convergence during ecotype formation in lake and stream stickleback pairs of variable age. Journal of Evolutionary Biology, 27(9), 1878-1892.  https://doi.org/10.1111/jeb.12439

Quintela, M., Johansson, M. P., Kristjánsson, B. K., Barreiro, R.
, & Laurila, A. (2014). AFLPs and mitochondrial haplotypes reveal local adaptation to extreme thermal environments in a freshwater gastropod. PLoS One, 9(7). https://doi.org/10.1371/journal.pone.0101821

Karvonen, A., Kristjánsson, B. K., Skúlason, S., Lanki, M., Reilstab, C.
, & Jokela, J. (2013). Water temperature, not fish morph, determines parasite infections of sympatric icelandic threespine sticklebacks (Gasterosteus aculeatus). Ecology and Evolution, 3(6), 1507-1517. https://doi.org/10.1002/ece3.568

Millet, A., Kristjánsson, B. K., Einarsson, Á., & Räsänen, K. (2013). Spatial phenotypic and genetic structure of threespine stickleback (Gasterosteus aculeatus) in a heterogneous natural system, Lake Mývatn. Ecology and Evolution, 3(10), 3219-3232. https://doi.org/10.1002/ece3.712

Seymour, M., Räsänene, K., Holderegger, R., & Kristjánsson, B. K. (2013). Connectivity in a pond system influences migration and genetic structure in threespine stickleback. Ecology and Evolution, 3(3), 492-502. https://doi.org/10.1002/ece3.476

​Woods, P. J., Skúlason, S., Snorrason, S. S., Kristjánsson, B. K., Ingimarsson, F., & Malmquist, H. (2013). Variability in the functional role of Arctic charr Salvelinus alpinus as it relates to lake ecosystem characteristics. Environmental Biology of Fishes, 96, 131-1376. https://doi.org/10.1002/ece3.476

Kristjansson, B. K., Skúlason, S., Snorrason, S. S., & Noakes, D. L. G. (2012). Fine scale parallel patterns in diversity of small benthic Arctic charr (Salvelinus alpinus) in relation to the ecology of lava/ groundwater habitats. Ecology and Evolution, 2(6), 1099-1112. https://doi.org/10.1002/ece3.235

Woods, P. J., Skúlason, S., Snorrason, S. S., Kristjánsson, B. K., Malmquist, H. J., & Quinn, T. P. (2012). Intraspecific diversity in Arctic charr, Salvelinus alpinus, in Iceland: II. What environmental factors affect life history in lakes? Evolutionary Ecology Research, 14, 973-992.

Woods, P. J., Skúlason, S., Snorrason, S. S., Kristjánsson, B.K., Malmquist, H. J., & Quinn, T. P. (2012). Intraspecific diversity in Arctic charr, Salvelinus alpinus, in Iceland: I. Detection using mixture models. Evolutionary Ecology Research, 14, 93-1013.

Kristjansson, B. K., & Svavarsson, J. (2007). Subglacial refugia in Iceland enabled groundwater amphipods to survive glaciations. The American Naturalist 170, 292-296. https://doi.org/10.1086/518951



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  • Home
  • People +
    • ACADEMIC STAFF >
      • Bjarni Kristófer Kristjánsson
      • Camille A. Leblanc
      • David Benhaim
      • Paul V. Debes
      • Skúli Skúlason
      • Stefán Óli Steingrímsson
    • SUPPORT STAFF >
      • Marie Delbasty
    • STUDENTS AND POSTDOC >
      • Grant Haines
    • ALUMNI
  • Education
    • AQUACULTURE DIPLOMA
    • MASTER IN AQUATIC BIOLOGY
    • NORDIC MASTER - MARBIO
  • Research +
    • Biodiversity lab >
      • FishFAR
      • ECO-EVO-DEVO
      • Evolution of cognition: A study of sympatric morphs of Arctic charr
      • Microevolutionary processes in small populations
      • The importance of egg size for phenotypic variations and divergence in wild populations
    • Aquaculture lab >
      • Development of personality in the Arctic charr
      • Egg quality and growth in selected Arctic charr
      • Enhanced Soy Protein for Salmonid Aquafeeds
      • Breeding program
    • Publications
    • Research policy >
      • Research Policy of the Department of Aquaculture & Fish Biology
      • Appendix 1 - Focus of Research
      • Appendix 2 - Storage and access to databases
      • Appendix 3 - Storage and registration of samples
  • Facilities+
    • Our research station
    • Breeding station
  • SYMPOSIUM
    • SEMINAR SERIES
    • Mývatn Conference 2024
    • Stickleback 2022
  • News
  • WORK WITH US
    • INTERNSHIPS AND JOBS
    • LIVE AT HÓLAR
  • CONTACT