We are biologists working with ecology and evolution of plants. Our research focus on how species evolve to conquer new terrain. We are passionate about our research, but we are also dedicated to teaching and outreach to inspire and enlighten other scientists, students and public outside academia.

We use the subfamily Pooideae as a model system to study evolution of adaptations to temperate climate over the last 65 million years. The temperate climate is highly seasonal with strong winters and cool short summers. We study how Pooideae have evolved to coordinate responses like frost tolerance and flowering time with the appropriate time in the seasonal environment. Furthermore, we study the evolution of the mechanisms plants use to endure extreme conditions in cold temperate and arctic climates such as winter survival, frost and drought tolerance. Recently, we have developed an interest in evolution of life history strategies and we seek out to find what differentiates annual and perennial life history forms and how these differences have evolved.


Evolution of cold acclimation and frost tolerance in Pooideae

The grass subfamily Pooideae dominate the grass flora in the Northern temperate region and we explore how Pooideae has evolved to cope with winter. In particular, we study cold acclimation and frost tolerance. We test phylogenetically diverse species for physiological responses to cold and frost under controlled conditions and use transcriptomics, metabolomics and studies of candidate genes to explore the molecular basis for evolution of cold acclimation and frost tolerance.

Cold adaptations Siri Fjellheim

Evolution of flowering time in Pooideae

The Northern temperate region is characterized by a short, intense growing season. Timing of flowering for maximum reproductive output in this short growing season is essential. In Pooideae model species like barley and wheat, vernalization followed by long days initiate flowering in the spring. We study how the two-step induction of flowering has evolved in Pooideae. We test phylogenetically diverse Pooideae species for flowering in response to vernalization and photoperiod and use transcriptome data and candidate gene analyses to understand the molecular basis for evolution of flowering time.

Ane mai 2020

Evolution of life history strategies in Pooideae

Many plants avoid seasonal stressors like drought and frost by adopting an annual life cycle strategy. An alternative strategy is to survive stressful conditions by adopting coping mechanisms to live through many seasons, referred to as the perennial life cycle strategy. Annual plants flower a single time during their one-year life cycle, investing much of their energy into rapid reproduction. In contrast, perennial plants flower multiple times over several years, and partition their resources between reproduction and persistence. These two adaptive strategies require fundamentally different physiology and growth traits. Annuals have high growth rates, large leaf area, large allocation of resources to reproductive structures and high biomass production. Perennials have traits allowing for persistence and defense, like high tissue density and allocation of higher proportion of biomass into roots. Even with these fundamental differences in growth strategies, the evolutionary distance between annual and perennial species may be very small, indicating that small differences in genetic makeup differentiate the growth habits. However, what these differences are is to a large degree unknown. We seek out to identify genes contributing to the differences between annual and perennial life history strategies in temperate grasses and determine how physiology and development are influenced by these genes.


Together we are involved in teaching a broad specter of basic biology courses. Our goal is to contribute to give the students at NMBU the best education and we work hard to develop our courses and learning methods to achieve our goal. We contribute to courses in general biology, botany, plant ecology, genetics, molecular ecology, evolution, and population genetics (BIO140, BOT100, BOT230, BIO120, BIO223, BIO321, BIO421).


Siri Fjellheim
Professor & Principal Investigator
Botanist Geneticist Mentor Motivator Facilitator
Marian Schubert

As an evolutionary biologist I am generally interested in the molecular evolution of adaptive traits. Currently, I am studying how Pooideae grasses adapted to the conditions in temperate environments.

Camilla Lorange Lindberg
PhD Candidate
I study the evolution of cold acclimation and its role in the successful adaptation of the grass subfamily Pooideae. Did the grasses evolve the possibility to accumulate fructan as a response to cold?
Martin Paliocha
PhD Candidate

How, why, and when do complex physiological traits evolve in plants? I try to find answers to these questions by studying the evolution of photoperiod-mediated flowering in temperate grasses.

Tesfakiros Semere Gebrelibanos
PhD Candidate
Together with Ola T. Westengen, I study the genetic structure and ethnobotany of Sorghum landraces in the State of Tigray, Ethiopia.
Ane Charlotte Hjertaas
MSc Student

Flowering once or several times over multiple growing seasons are two distinct life history strategies in plants. I study the genetic and physiological bases of annual and perennial growth habit using Pooideae as a model system.

Martine Molland
MSc Student
Eirin Landsem
MSc Student

My project focuses on the evolution of overwintering capacity in temperate grasses. I try to explain the biogeography of Pooideae by analysing carbohydrate accumulation during winter.

Magnus Flåten Nickelsen
BSc Student
Sondre Gretland Harstad
BSc Student
Felix Hernández Nohr
BSc Student


PhD Candidates

Marian Schubert (2012 – 2016)

Researchers & Postdocs

Erica Helen Leder (2016 – 2018)
Thomas Marcussen (2015 – 2017)

PhD Candidates, co-supervised

Ursula Brandes (2013 – 2019), with Line Rosef
Lars Grønvold (2013 – 2017), with Torgeir R. Hvidsten
Murat Bağcıoğlu (2012 – 2016), with Achim Kohler
Anna M. Lewandowska-Sabat (2006 – 2009), with Odd Arne Rognli

MSc Students

Sylvia Pal Stolsmo (2018 – 2019)
Darshan Anthony Young (2016 – 2018)
Beate Beatriz Furevik (2014 – 2016)
Torbjørn H. Kornstad (2012 – 2014)
Nina Zoric (2011 – 2013)
Nadine Hofman (2010 – 2012)

BSc Students

Rebekka E. Ween
Mika Kirkhus


Lindberg CL, Hanslin HM, Schubert M, Marcussen T, Trevaskis B, Preston JC, Fjellheim S (2020) Increased above-ground resource allocation is a likely precursor for independent evolutionary origins of annuality in the Pooideae grass subfamily. New Phytologist 227 (4). doi:10.1111/nph.16666

Preston JC, Fjellheim S (2020) Understanding past, and predicting future, niche transitions based on grass flowering time variation. Plant Physiology 183 (3): 822–839. doi:10.1104/pp.20.00100

Diehn S, Zimmermann B, Tafintseva S, Bağcıoğlu M, Kohler A, Ohlson M, Fjellheim S, Kneipp J (2020) Discrimination of grass pollen of different species by FTIR spectroscopy of individual pollen grains. Analytical and Bioanalytical Chemistry 412. doi:10.1007/s00216-020-02628-2

Diehn S, Zimmermann B, Tafintseva V, Seifert S, Bağcıoğlu M, Ohlson M, Weidner S, Fjellheim S, Kohler A, Kneipp J (2020) Combining chemical information form grass pollen in multimodal characterization. Frontiers in Plant Science 10: 1788. doi:10.3389/fpls.2019.01788

Aspholm M, Borch-Pedersen K, O’Sullivan K, Fjellheim S, Aardal IHB, Granum PE, Lindbäck T (2019) Importance of individual germination receptor subunits in the cooperative function between GerA and Ynd. Journal of Bacteriology 201 (21): e00451-19. doi:10.1128/jb.00451-19

Brandes U, Furevik BB, Nielsen LR, Kjær ED, Rosef L, Fjellheim S (2019) Introduction history and population genetics of intracontinental scotch broom (Cytisus scoparius) invasion. Diversity and Distributions 25 (11): 1173–1786. doi:10.1111/ddi.12979

Schubert M, Marcussen T, Meseguer AS, Fjellheim S (2019) The grass subfamily Pooideae: Cretaceous–Palaeocene origin and climate‐driven Cenozoic diversification. Global Ecology and Biogeography 28 (8): 1168–1182. doi:10.1111/geb.12923

Schubert M, Grønvold L, Sandve SR, Hvidsten TR, Fjellheim S (2019) Evolution of cold acclimation and its role in niche transition in the temperate grass subfamily Pooideae. Plant Physiology 180 (1): 404–419. doi:10.1104/pp.18.01448

Diehn S, Zimmermann B, Bağcıoğlu M, Seifert S, Kohler A, Ohlson M, Fjellheim S, Weidner S, Kneipp J (2018) Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) shows adaptation of grass pollen composition. Scientific Reports 8: 16591. doi:10.1038/s41598-018-34800-1

Fjellheim S, Preston JC (2018) Shedding light on the role of seasonal flowering in plant niche transitions. American Journal of Botany 105 (2): 136–138. doi:10.1002/ajb2.1037

Sydenham MAK, Eldegard K, Hegland SJ, Nielsen A, Totland Ø, Fjellheim S, Moe SR (2018) Community level niche overlap and broad scale biogeographic patterns of bee communities are driven by phylogenetic history. Journal of Biogeography 40 (2): 461–472. doi:10.1111/jbi.13103

Zimmermann B, Bağcıoğlu M, Tafintseva V, Kohler M, Ohlson M, Fjellheim S (2017) A high-throughput FTIR spectroscopy approach to assess adaptive variation in the chemical composition of pollen. Ecology and Evolution 7 (24): 10839–10849. doi:10.1002/ece3.3619

Lewandowska-Sabat AM, Fjellheim S, Olsen JE, Rognli OA (2017) Photoperiodic sensitivity of flowering time in local populations of Arabidopsis thaliana show clinal variation in a climatic gradient associated with altitude. Frontiers in Plant Science 8: 1046. doi:10.3389/fpls.2017.01046

McKeown M, Schubert M, Preston JC, Fjellheim S (2017) Evolution of the miR5200-FLOWERING LOCUS T regulon in the temperate grass family Pooideae. Molecular Phylogenetics and Evolution 114: 111–121. doi:10.1016/j.ympev.2017.06.005

McKeown M, Schubert M, Marcussen T, Fjellheim S, Preston JC (2016) Evidence for an early origin of vernalization responsiveness in temperate Pooideae grasses. Plant Physiology 172 (1): 416–426. doi:10.1104/pp.16.01023

Nielsen LR, Brandes U, Kjær ED, Fjellheim S (2016) Introduced Scotch broom (Cytisus scoparius) invades the genome of native populations in vulnerable heathland habitats. Molecular Ecology 25 (12): 2790–2804. doi:10.1111/mec.13666

Jørgensen MH, Elameen A, Hofman N, Klemsdal S, Malaval S, Fjellheim S (2016) What’s the meaning of local? Using molecular markers to define seed transfer zones for ecological restoration in Norway. Evolutionary Applications 9 (5): 673–684. doi:10.1111/eva.12378

Kovi MR, Fjellheim S, Sandve SR, Larsen A, Rudi H, Asp T, Kent MP, Rognli OA (2015) Population structure, genetic variation, and linkage disequilibrium in perennial ryegrass populations divergently selected for freezing tolerance. Frontiers in Plant Science 6: 929. doi:10.3389/fpls.2015.00929

Fjellheim S, Tanhuanpää P, Marum P, Manninen O, Rognli OA (2015) Phenotypic or molecular diversity screening for conservation of genetic resources? An example from a genebank collection of the temperate forage grass timothy. Crop Science 55 (4): 1646–1659. doi:10.2135/cropsci2014.12.0825

Fjellheim S, Boden S, Trevaskis B (2014) The role of seasonal flowering responses in adaptation of grasses to temperate climates. Frontiers in Plant Science 5: 431. doi:10.3389/fpls.2014.00431

Vigeland MD, Spannagl M, Asp T, Paina C, Rudi H, Rognli OA, Fjellheim S, Sandve SR (2013) Evidence for adaptive evolution of low-temperature stress response genes in a Pooideae grass ancestor. New Phytologist 199 (4): 1060–1068. doi:10.111/nph.12337

Li C, Rudi H, Stockinger EJ, Cheng H, Cao M, Fox SE, Mockler TC, Westereng B, Fjellheim S, Rognli OA, Sandve SR (2012) Comparative analyses reveal potential uses of Brachypodium distachyon as a model for cold stress responses in temperate grasses. BMC Plant Biology 12: 65. doi:10.1186/1471-2229-12-65

Lewandowska-Sabat AM, Fjellheim S, Rognli OA (2012) The continental-oceanic climatic gradient impose clinal variation in vernalization response in Arabidopsis thaliana. Environmental and Experimental Botany 78: 109–116. doi:10.1016/j.envexpbot.2011.12.033

Lewandowska-Sabat AM, Winge P, Fjellheim S, Dørum G, Bones AM, Rognli OA (2012) Genome wide transcriptional profiling of acclimation to photoperiod in high-latitude accessions of Arabidopsis thaliana. Plant Science 185: 143–155. doi:10.1016/j.plantsci.2011.10.009

Fiil A, Bach-Jensen L, Fjellheim S, Lübberstedt T, Andersen JR (2011) Variation in the vernalization response of a geographically diverse collection of timothy genotypes. Crop Science 51 (6): 2689–2697. doi:10.2135/cropsci2010.12.0677

Sandve SR, Kosmala A, Rudi H, Fjellheim S, Rapacz M, Yamada T, Rognli OA (2011) Molecular mechanisms underlying frost tolerance in perennial grasses adapted to cold climates. Plant Science 180: 69–77. doi:10.1016/j.plantsci.2010.07.011

Elameen A, Larsen A, Klemsdal SS, Fjellheim S, Sundheim L, Msolla S, Masumba E, Rognli OA (2011) Phenotypic diversity of plant morphological and root descriptor traits within a sweet potato, Ipomoea batatas (L.) Lam., germplasm collection from Tanzania. Genetic Resources and Crop Evolution 58 (3): 397–407. doi:10.1007/s10722-010-9585-1

Lewandowska-Sabat AM, Fjellheim S, Rognli OA (2010) Extremely low genetic variability and highly structured local populations of Arabidopsis thaliana at higher latitudes. Molecular Ecology 19 (21): 4753–4764. doi:10.1111/j.1365-294x.2010.04840.x

Sandve SR, Fjellheim S (2010) Did gene family expansions during the Eocene–Oligocene boundary climate cooling play a role in Pooideae adaptation to cool climates? Molecular Ecology 19 (10): 2075–2088. doi:10.1111/j.1365-294X.2010.04629.x

Kjos M, Fjellheim S, Rognli OA, Hvoslef-Eide AK (2010) Amplified fragment length polymorphism (AFLP) markers for fingerprinting of Argyranthemum frutescens cultivars. Scientia Horticulturae 124 (4): 506–510. doi:10.1016/j.scienta.2010.01.023

Fjellheim S, Jørgensen MH, Kjos M, Borgen L (2009) A molecular study of hybridization and homoploid hybrid speciation in Argyranthemum (Asteraceae) on Tenerife, the Canary Islands. Botanical Journal of the Linnean Society 159 (1): 19–31. doi:10.1111/j.1095-8339.2008.00947.x

Fjellheim S, Pašakinskienė I, Grønnerød S, Paplauskienė V, Rognli OA (2009) Genetic structure of local populations and cultivars of meadow fescue from the Nordic and Baltic regions. Crop Science 49 (1): 200–210. doi:10.2135/cropsci2007.08.0422

Elameen A, Klemsdal SS, Dragland S, Fjellheim S, Rognli OA (2008) Genetic diversity in a germplasm collection of roseroot (Rhodiola rosea) in Norway studied by AFLP. Biochemical Systematics and Ecology 36 (9): 706–715. doi:10.1016/j.bse.2008.07.009

Elameen A, Fjellheim S, Larsen A, Rognli OA, Sundheim L, Masumba E, Mtunda K, Klemsdal SS (2008) Analysis of genetic diversity in a sweet potato (Ipomoea batatas L.) germplasm collection from Tanzania. Genetic Resources and Crop Evolution 55 (3): 397–408. doi:10.1007/s10722-007-9247-0

Saski C, Lee SB, Fjellheim S, Guda C, Jansen RK, Luo H, Tomkins J, Rognli OA, Daniell H, Clarke JL (2007) Complete chloroplast genome sequences of Hordeum vulgare, Sorghum bicolor and Agrostis stolonifera, and comparative analyses with other grass genomes. Theoretical and Applied Genetics 115 (4): 571–590. doi:10.1007/s00122-007-0567-4

Fjellheim S, Blomlie ÅB, Marum P, Rognli OA (2007) Phenotypic variation in local populations and cultivars of meadow fescue – potential for improving cultivars by utilizing wild germplasm. Plant Breeding 126 (3): 279–286. doi:10.1111/j.1439-0523.2007.01363.x

Fjellheim S, Rognli OA, Fosnes K, Brochmann C (2006) Phylogeographical history of the widespread meadow fescue (Festuca pratensis Huds.) inferred from chloroplast DNA sequences. Journal of Biogeography 33 (8): 1470–1478. doi:10.1111/j.1365-2699.2006.01521.x

Fjellheim S, Rognli OA (2005) Molecular diversity of local Norwegian meadow fescue (Festuca pratensis Huds.) populations and Nordic cultivars – consequences for management and utilisation. Theoretical and Applied Genetics 111 (4): 640–650. doi:10.1007/s00122-005-2006-8

Fjellheim S, Elven R, Brochmann C (2001) Molecules and morphology in concert. II. The Festuca brachyphylla complex (Poaceae) in Svalbard. American Journal of Botany 88 (5): 869–882. doi:10.2307/2657039