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New Paper: Steps Towards Consciousness

In a new paper in Frontiers in Ecology and Evolution, Sergey Budaev, Jarl Giske, and colleagues in TEG argue that an animal is a prediction machine that uses its brain and nervous system to model how one or several potential choices will be felt by the body before the decision is made.

The fundamental state to consider is therefore not stomach contents, fat reserves, or body mass per se, but a state of its mind: the global organismic state. The animal's subjective internal model can, via control of the nervous system, set the animal in a mental state that will dominate many aspects of its cognition and behavior, including decision-making.
Budaev S, Jørgensen C, Mangel M, Eliassen S, Giske J. 2019.
Decision-making from the animal perspective: Bridging ecology and subjective cognition
Frontiers in Ecology and Evolution. 7: 164. [ doi:10.3389/fevo.2019.00164 ] [ open access ] [ pdf ]

[22 May 2019]


Tom Langbehn Defends PhD Thesis on Light in the Pelagic

Today Tom J. Langbehn defended his PhD Thesis with the title Light and visual foraging in the pelagic: Opportunities and constraints along gradients of seasonality. His focus has been how the increasing seasonality at higher latitudes enforce ever stricter constraints on annual cycles of marine organisms.

Tom has had a particular focus on how seasonality in light affects visual foragers. At high latitudes, the polar night and midnight sun are challenging for the many marine organisms that perform diel vertical migrations, migrating up and down in the water column on a daily basis to balance foraging opportunities and predation risk. For mesopelagic fish, the main bottleneck is midnight sun, as they then are prevented from migrating to the productive surface layers in the protection of darkness, over time causing depleted energy reserves and risky behaviours. Were the sea ice to disappear in a warming climate, then visual feeders such as planktivorous fish will have much higher expected foraging success.

From left to right: supervisor Christian Jørgensen, opponent Michael T. Burrows, internal committee leader Anne Gro Vea Salvanes, supervisor Øystein Varpe, a happy and smiling candidate, opponent Xabier Irigoien, and supervisor Øyvind Fiksen.

[30 April 2019]


The Role of Jellyfish in Marine Ecosystems

Do jellyfish matter? A new study recently published in Scientific Reports suggests perhaps not as much as we thought.

Long-standing hypotheses regarding the negative effects of jellyfish on small pelagic fish recruitment or as an important competitor for their crustacean zooplankton prey are difficult to test against data. Authors Anders F. Opdal and Dag L. Aksnes at UiB have, together with colleagues in the US, Bulgaria, and South Africa, collected historic and recent data from the Bering Sea, the California Current, the Black Sea, and the Benguela to test a series of jellyfish-related hypotheses at the ecosystem level. By calculating the energy requirements of both fish and jellyfish, they find that although jellyfish in many areas exceed the biomass of fish, their energy requirements are low, and their energetic footprint moderate. In addition, they find little signs of fish biomass, or their crustacean zooplankton prey, being influenced by jellyfish biomass. They conclude that the best available time-series data do not suggest that jellyfish are outcompeting, or have replaced, small pelagic fish on a regional scale in any of the four investigated ecosystems.
Opdal AF, Brodeur RD, Cieciel K, Daskalov GM, Mihneva V, Ruzicka JJ, Verheye HM, Aksnes DL. 2019.
Unclear associations between small pelagic fish and jellyfish in several major marine ecosystems
Scientific Reports. 9: 2997. [ doi:10.1038/s41598-019-39351-7 ] [ open access ] [ pdf ]

An overview of the hypotheses tested.

[1 March 2019]


Nadia Fouzai Defends Her PhD Thesis

Congratulations to Nadia Fouzai who defended her PhD Thesis Adaptive Behaviour along Environmental Gradients in Larval Cod - An Optimality Modelling Approach on 9 January 2019!

From left: UiB representative in the committee professor Mikko Heino, a very happy Nadia Fouzai, and external opponents Irja Ratikainen (NTNU, Norway) and Peter Grønkjær (Aarhus University, Denmark).

The opponents Peter Grønkjær (Aarhus University, Denmark) and Irja Ratikainen (NTNU, Trondheim, Norway) provided stimulating and thoughtful discussions. Supervisors have been Øyvind Fiksen, Anders F. Opdal, and Christian Jørgensen.

Nadia was part of the NorMER network funded by the Nordic countries through Nordforsk.

[9 January 2019]



Marc Mangel Receives AIFRB Outstanding Achievement Award

In December 2018, Marc Mangel was awarded the Outstanding Achievement Award from the American Institute of Fishery Research Biologists (AIFRB).

AIRFB is an association to establish and maintain high professional standards of recognition of achievement and competence. The President of AIRFR emphasizes that the scientific merit and broad-reaching impacts of Marc’s research exemplify the fishery science that AIFRB promotes and recognizes.

Congratulations Marc! We are very pleased to have you as adjunct professor, and we see that you play an important role in the formation of young researchers in the Theoretical Ecology Group!

[12 December 2018]


Why Do Fish Aggregate on Banks?

Large zooplankton avoid predation from fish by sinking into deep and dark depths of the ocean. However, over sea summits and banks they are blocked from sinking very deep by the bottom already at depths that are quite illuminated during daytime. This gives visual foragers such as fish an advantage, and they are more likely to find food over banks than over deep trenches.

In a new study published in Limnology and Oceanography, Johanna Aarflot, Øyvind Fiksen, Anders F. Opdal, Dag L. Aksnes, and others show that large zooplankton in the Barents Sea are generally distributed much closer to the surface in shallower areas. The consequence of this is that large zooplankton are exposed to several orders of magnitude more light during daytime over the 100 m deep banks compared to where the bottom depth is 300 meter or more. A planktivore fish therefore encounter 400 times more prey above the bank, even if prey abundance is the same!
Aarflot J, Aksnes DL, Opdal AF, Skjoldal HR, Fiksen Ø. In press.
Caught in broad daylight: topographic constraints of zooplankton depth distributions
Limnology and Oceanography. [ doi:10.1002/lno.11079 ] [ open access ]

News articles (in Norwegian):

[23 November 2018]


Tom Received Best Presentation Award at the ICES Conference

Tom J. Langbehn, PhD student with us and part of the European training Network MArmaED, presented two chapters of his PhD at the 2018 ICES Annual Science Conference in Hamburg.

As part of the Theme session D on the Nordic Seas and the Arctic, he highlighted published work (see reference below))quantifying how more light as sea ice declines will boost visual search in pelagic fish. His second talk, in Theme session A on mesopelagic ecosystems, quantified how seasons, in particular in light, may limit the poleward distribution of mesopelagic fish. It was for this talk he received the Best Presentation Award. Congratulations!
Langbehn TJ, Varpe Ø. 2017.
Sea-ice loss boosts visual search: fish foraging and changing pelagic interactions in polar oceans
Global Change Biology. 23: 5318-5330 . [ doi:10.1111/gcb.13797 ] [ open access ] [ pdf ]

[4 October 2018]


Johanna Is Researching the World's Strongest Animal

Johanna Myrseth Aarflot is participating in Researcher Grand Prix, with a popularized version of her research on tiny copepods and their enormous role in the oceans.

The Institute of Marine Research has interviewed her about her research and her way towards becoming a biologist. You can read the full interview here [in Norwegian]:

[14 September 2018]


Julianne Netteland Defends Her Masters Thesis

Julianne, supervisors, and examiners. From left: Sigrunn Eliassen (supervisor), Irja Ratikainen (examiner, NTNU), Julianne Netteland, Svein Rune Erga (internal examiner, BIO), Christian Jørgensen, supervisor).

Julianne Netteland defended her MSc thesis on 31 August. In her thesis work, she studied the physics of light and vision in relation to dawn song.

In her thesis, entitled Predation risk at dawn: How changing light and birds' traits affect the temporal risk landscape during sunrise, she goes on to identify numerous trade-offs that affect vision, foraging efficiency, and risk of being encountered by predators throughout the dynamic light environment around sunrise.

[31 August 2018]


Digital Fish - An Interview With Aha Researchers

The Digital Life Norway network is fostering cross-disciplinary studies based in biotechnology, and interviewed several of their projects related to aquaculture, among them our Aha project which aims to model cognition in fish.

The interview can be read here: Bli med på en digital fisketur (

[2 August 2018]


Two PhD positions Available on Evolution of Sex and Mating Systems

There are currently two open PhD positions in the Theoretical Ecology Group, on the evolution of sex and mating systems. Application deadline was 27 May 2018. Sigrunn Eliassen and Christian Jørgensen will be supervisors.

[6 April 2018]


Adèle Mennerat on the Future of Parasitology

Researcher Adéle Mennerat of the Theoretical Ecology Group is sharing her views on the future of parasitology at the University of Bergen website.

I am frustrated that we know so little, says Adèle Mennerat. We know that the global human impact on ecosystems is enormous, and is not limited to climate change. For parasites perhaps the biggest change lies in how we humans are modifying the availability of their hosts, she continues.

You can read the full interview here:

[23 March 2018]



A Successful Third Workshop on Trait-Based Approaches to Ocean Life

How can the essential properties of community structure and ecosystem functioning be captured from a limited number of traits in organisms? 120 researchers from 31 nations met over four days at Solstrand to answer this question.

Ecosystems are complex machineries and our ability to predict how changing drivers and environmental forcing influence them are limited. One way to represent and understand organisms, communities and ecosystems is to think in terms of specific traits, not species, and how the dominant traits appear in an evolutionary or ecological process from fundamental trade-offs between alternative traits. If we can identify the trade-offs between traits, and the trade-offs with the environment, we may have a tool for predicting trait distributions in nature or from given environmental perturbations.

Marine ecologists and oceanographers have over the last decade turned to trait-based approaches to develop models and to understand ocean communities. The third workshop on trait-based approaches to ocean life was held in Solstrand, outside Bergen, Norway during 20-23rd of August. The earlier meetings in 2013 (Copenhagen) and 2015 (New Hampshire) set the stage for this arena as a key meeting place for researchers working in this direction. This year, 120 researchers attended the workshop, covering a wide range of ecosystems from reefs to pelagic microbes.

The trait-based approach has deeper roots in terrestrial ecology, and the workshops have always focused on bringing in perspectives from general ecology. The first keynote this year was Oswald Schmitz, from Yale University. His talk was on the evolutionary ecology of ecosystem functioning - with examples on how behavioural plasticity in grazers in response to fear from specific predators can shift grazing pressure, plant communities and nutrient budgets in the soil. The couplings between ecology and evolutionary or adaptive responses are fundamental and cannot be ignored.

Helmut Hillebrand followed up the next day with a keynote on how trait variability and environmental heterogeneity constrain community composition and ecosystem processes. The keynote gave an overview of biodiversity-ecosystem functioning themes, and showed how trait-based perspectives are useful in this debate. Zoe Finkel's keynote brought us to the unicellular domain, focusing on macromolecular and elemental composition of microalgae. The size and content of phytoplankton cells, their element-ratios and carbon content are key traits and state variables which feed back on ecosystem functioning. Frede Thingstad took us even further into the microbial world, to the interactions between viruses and bacteria, to the competition between algae and bacteria and the mixture of drivers shaping structure of microbial communities.

The workshop included 20 contributed talks, 80 posters and a set of break-out sessions, round-table group discussions and plenary discussions with prepared comments. The programme was relaxed with one afternoon session walk-and-talk to the Borgafjell, combining opportunities for individual communication with some exercise and a view over the Bjørnafjord and the Folgefonna glacier.

Next meeting in 2019 will be organized by Ben Ward - in the UK.

Solstrand Hotel provided a relaxed and social atmosphere for scientific discussion. (Photo: Øyvind Fiksen)

Considerable time was set aside for discussion and interaction. In these groups, a host was given a specific topic, but the participants were shifting groups every 15 minutes. In this way, multiple viewpoints and perspectives were heard. (Photo: Øyvind Fiksen)

Another way participants had time to discuss was during the walk-and-talk to Borgarfjellet, in stunning weather. (Photo: Øyvind Fiksen)

All participants (almost) of the Third Workshop on Trait-Based Approaches to Ocean Life.

[4 September 2017]


New Paper on Sea Ice Loss and Changing Pelagic Interactions

The Arctic sea-ice cover is rapidly shrinking and light increasingly reaches the previously darkened waters. In a new paper in Global Change Biology, Tom J. Langbehn and co-author Øystein Varpe predict that increased visibility helps fish that hunt by sight to detect their prey.

Under rising temperatures and given the more favourable feeding conditions, southerly-distributed species are likely to expand their distribution poleward. However, the foraging gains will be limited to the summer months, as the polar nigh remains dark regardless of sea-ice loss, a seasonality favouring migratory fish. Changes to the fish community will have multiple consequences for the polar marine ecosystem, particularly for the prey of fish.

The article was picked up by Frontiers in Ecology, which wrote a news story about it.
Langbehn TJ, Varpe Ø. 2017.
Sea-ice loss boosts visual search: fish foraging and changing pelagic interactions in polar oceans
Global Change Biology. 23: 5318-5330 . [ doi:10.1111/gcb.13797 ] [ open access ] [ pdf ]

[31 July 2017]


Evolution of Virulence in Salmon Lice Covered by The Scientist

Fish farming is one of the fastest growing food production sectors in the world, but is also increasingly burdened by infections caused by bacteria, viruses, and parasites. Now, emerging research suggests that diseases of farmed fish may be evolving to become even more harmful to the animals.

In a recent study published in Journal of Evolutionary Biology, Adéle Mennerat and coauthors report that salmon lice seem to have evolved higher levels of virulence (i.e. parasite-induced damage to the host) on salmon farms, as compared to lice coming from areas unaffected by farming. Another study by Sundberg et al. (Proceedings B, 2017), reports similar findings in Flavobacterium columnare, a bacterial pathogen of salmonids. This study remains correlative, and now calls for further research to decipher the causes and mechanisms of such evolution. All of this, and more, explained in The Scientist: Does farming drive fish disease?
Sundberg L-R, Ketola T, Laanto E, Kinnula H, Bamford JKH, Penttinen R, Mappes J. 2016.
Intensive aquaculture selects for increased virulence and interference competition in bacteria
Proceedings of the Royal Society B. 283. [ doi:10.1098/rspb.2015.3069 ]
Ugelvik MS, Skorping A, Moberg O, Mennerat A. 2017.
Evolution of virulence under intensive farming: Salmon lice increase skin lesions and reduce host growth in salmon farms
Journal of Evolutionary Biology. 30: 1136-1142. [ doi:10.1111/jeb.13082 ]

[20 April 2017]


TEG Members Convening ICES Session on Movement Ecology

Together with Sue Lowerre-Barbieri, Ignacio Catalán, and Ross Boucek, Anders F. Opdal and Christian Jørgensen are convening a Theme Session on Movement Ecology at the ICES Annual Science Conference in Florida 18-22 September 2017; Linkages between spatial ecology and sustainable fisheries.

Key-note speakers for the session are are Mike Sinclair (Bedford Institute of Oceanography, Canada), Patricia Reglero (Instituto Español de Oceanografia, Mallorca, Spain) and David Secor (University of Maryland, USA).

Abstracts can be submitted at the conference website (deadline Sunday 30 April). A Themed Article Set in the ICES Journal of Marine Science is planned as follow-up from the session.

[18 February 2017]



Evolution of Cod Migrations in the University Museum Year Book

The cover photo for the 2016 Year Book of the Bergen University Museum is related to Anders Opdal's chapter.

Anders F. Opdal, postdoc in the Theoretical Ecology group, contributed a chapter to the Bergen University Musem Year Book on the evolution and dynamics of the Northeast Arctic cod spawning migrations from the late 1800s to modern times.

Although the Northeast Arctic cod has its main spawning grounds around the Lofoten archipelago, a mere 700 km swim from their feeding areas in the Barents Sea, historical records show that the Northeast Arctic cod has spawned as far south as Bergen and Lindesnes (1700-1900 km). Anders asks, what could be the evolutionary drivers for such strenuous migrations, and why don't we find theses southern spawners today? The chapter is in Norwegian.
Opdal AF. 2016.
Hvor ble det av skreien som gytte på Vestlandet? [In Norwegian]
Pages 62-69 in Havet - Årbok for Universitetsmuseet i Bergen 2016, edited by Høyer J. Bergen, Norway: University of Bergen. [ open access ] [ pdf ]

[20 December 2016]


3rd International Workshop in Trait-based Approaches to Ocean Life

The 3rd International Workshop in Trait-based Approaches to Ocean Life will be arranged at Solstrand Hotel 20-23 August 2017, and the Hjort Centre and the Theoretical Ecology Group will be involved in organizing and planning the event.

Anyone interested in or curious about this approach in ecology and contemporary oceanography should reserve the dates and be there! Updated information can always be found at the workshop's website:

[22 September 2016]


Two in a Row: Poster Prizes for Tom Langbehn

Tom Langbehn, PhD student in the Theoretical Ecology Group as part of the EU-training network MARmaED has recently been awarded two prizes for his poster on the effects of photoperiod and sea ice decline on pelagic foraging interactions.

As light seasonality increases by latitude, so does its biological relevance. At high latitudes all life is adapted to the change of seasons. The general perception of the Arctic Ocean is that of an ecosystem driven by pulses of autotrophic production. However, climate-driven decline in sea ice is fundamentally bound to change the Arctic lightscape. With less sea ice, more light will reach the water. This will change both levels of primary productivity and foraging interactions of higher trophic level visual predators and their zooplankton prey. In his work, Tom demonstrates that dwindling sea ice will seasonally boost foraging of pelagic fish and that the role of light merits consideration in determining species distribution patterns and community composition beyond phytoplankton.

His poster Photoperiodic implications on visual foraging in polar marine ecosystems got awarded the student choice and special mention award at the ClimEco5 IMBER summer school and the best poster award at the YOUMARES7 conference for young marine researchers in Germany. The poster can be downloaded here.

[20 September 2016]


Randi Elisabeth Åsly Defended Her Masters Thesis

Randi Elisabeth Åsly defended her MSc thesis Tuesday 28 June on the link between extra-pair paternity and cooperation in bird neighbourhoods.

Elisabeth with her two thesis examiners: Odd Jacobsen (external, to the left) and Arill Engås (internal, right).

Extra-pair paternity is common in socially monogamous species, but explaining the adaptive benefit of this mating behaviour has proven difficult from a female point of view. In her MSc thesis, Elisabeth focused on the potential benefit of male cooperation in anti-predator behaviour, and used evolutionary modelling to explore how the number of breeding neighbours may influence cooperative benefits and mating patterns.

She found that extra-pair paternity increased male cooperative investment under most conditions, but that the best male strategy varied for different types of anti-predator behaviours. High extra-pair paternity levels were predicted to be more common in small than in large neighbourhoods, when extra-pair mating is controlled by females. This is contraty to several empirical observations, and raises interesting questions of which additional ecological factors are at play in nature, or, conversely, which factors are missing from the models.

Supervisors were Sigrunn Eliassen and Christian Jørgensen.

[1 July 2016]


Thomas Njerve Olsen Defended His Masters Thesis

On Friday 17 June Thomas Njerve Olsen defended his Masters Thesis A Killing the Winner study of visual and tactile organisms in the Black Sea.

Thomas Njerve Olsen during the presentation of his thesis work.

Killing the Winner is a theoretical framework originally developed within the field of microbial ecology to explain the coexistence of two organisms competing for a shared resource in a homogeneous environment. The premise being that one organism is specializing in defence and the other in growth (competition). In his thesis, Thomas has shown that the Killing the Winner framework is not only applicable to the microbial world, but can also largely explain the observed dynamics and coexistence between jellyfish (defence specialist) and zooplanktivorous pelagic fish (competition specialist) in the Black Sea.

Supervisors were Anders F. Opdal and Dag L. Aksnes.

[29 June 2016]


The Meaning of Life is 36.8

The answer to life, the universe, and everything is not 42 - when it comes to reproduction it is another number that matters.

Postdoc Adèle Mennerat and Professor Arne Skorping explain their latest finding at the Unviersity of Bergen's web pages: Meningen med livet er 36,8 [In Norwegian]

[24 June 2016]


Blue Tit Field Work in France

The blue tit lays clutches of 6-12 eggs, which hatch after ca. 2 weeks and the chicks fledge ca. 3 weeks later. During this period they rely on food and protection provided by both parents. (Photo: Sigrunn Eliassen)

Does predation risk affect extra-pair mating behaviour? And is there a difference in how male and female blue tits respond to approaching predators? These are among the questions that researchers from the FRIMEDBIO project on bird mating behaviour set out to investigate this spring. The researchers were running play-back experiments and doing behavioural observations on blue tits in a population near Montpellier in southern France.

The weasel Mustela nivalis and the common genet Genetta genetta are major brood predators in this area. When blue tit parents perceive a potential risk to their nest, they typically emit loud alarm calls and move around the trees to chase the predator away. In the experiments the researchers were interested in knowing to what extent males and females participated in the anti-predator behaviour and whether distance from the nest influenced the intensity of alarm calling.

Measuring, weighing, blood sampling and ringing are part of the standard monitoring protocol for this blue tit population near Montpellier, France. (Photo: Sigrunn Eliassen)

The study site is situated in a beautiful deciduous forest and contains a network of nest-boxes that has been monitored as part of a long-term, multi-site study initiated more than 40 years ago by Jacques Blondel, and now led by Anne Charmantier at CNRS in Montpellier. From the time when nests are occupied until the chicks fledge, several hundred boxes are checked at regular intervals. Chicks are ringed and measured, and blood samples of young and adults are collected to determine parentage. Master student Marie Danielsen and postdoc Adéle Mennerat at BIO will analyse these data focusing on the link between extra-pair paternity and anti-predator behaviours.

Adèle Mennerat holding a 15-day old blue tit chick during routine measurements and ringing. (Photo: Sigrunn Eliassen)

[15 June 2016]


Social Science Meets the Mating Behaviour of Birds

Adéle Mennerat spends part her time at the Centre for Women's and Gender Research, and by contrasting her experiences from bird mating systems with social scientists focussing on human gender studies, a common ground is now emerging and being picked up by the national science news

Researcher Claus Halberg at Department of Philosophy, UiB, draws perspectives from the work of Robert Trivers in the 1970s to new developments in evolutionary ecology, and finds an interesting change of focus towards understanding the female as being more active in mate choice with consequences for construction of social interactions.

You can read the whole story here [in Norwegian]: Parer seg med flere hanner for å sikre ungene.

[3 June 2016]


Ljungström and Langbehn Are New PhD Students

The Theoretical Ecology Group welcomes Gabriella Ljungström and Tom Langbehn, two new PhD candidates within the EU-training network MARmaED.

Gabriella and Tom will model climate change effects in marine fish stocks with a focus on fish life histories. Their work is part of the EU training network MARmaED (Marine Management and Ecosystem Dynamics under Climate Change), with 8 partner institutions across Europe. The common goal is to investigate how sustainable exploitation of marine living resources and the maintenance of biodiversity can be achieved in the face of overexploitation, climate change, and other anthropogenic stressors.

Gabriella Ljungström has a broad background in science with a BSc majoring in Climate Science from Macquarie University in Sydney, Australia, and a Master of Atmospheric Science with orientation towards Environmental Sciences from the University of Gothenburg, Sweden. This broad background stems from a profound interest in how human activities lead to changes in our atmosphere and oceans, and how these changes are altering biological systems. Gabriella's PhD work within the Theoretical Ecology Group will focus on optimal harvesting under multiple human stressors by modelling how fishing and climate warming jointly determine new optima for behavioural and life history traits.

Tom J. Langbehn recently graduated from the international and interdisciplinary MSc program Marine Biology at the University of Bremen. Prior to this he took an international BSc in Environmental and Industrial Biology from the University of Applied Science Bremen, Germany. Tom is a cold water-enthusiast and therefore he choose to spend extended study and research periods abroad in Iceland, Norway, and Arctic Svalbard. Throughout his graduate and postgraduate training the focus of his work has been on (polar) marine ecology, fisheries, and fish biology, with particular emphasis on the effects that ocean climate and human activities have on the biology and adaptive strategies of fish populations. Within the Theoretical Ecology Group he will work on limits to northwards range shifts of fish stocks under climate warming.

[3 February 2016]


Annual Retreat 2016

The annual retreat for the extended Theoretical Ecology Group took place in Myrkdalen in early January. We went to a skiing resort as we often do, where some time was reserved for various skiing activities in the slopes, mountains or in the groomed tracks nearby.

The group has increased in numbers recently, with the new PhD students Tom Langbehn and Gabriella Ljungström in the MARmaED project and Johanna Fall and Johanna Aarfloth from Institute of Marine Research as our associated members, and Ryan Dillon as a visiting PhD from University of Tromsø. Also, this was the first annual retreat for a number of people who arrived last year - exciting times for all of us!

At the retreat we focussed on getting to know each other, our research interests and we discussed how to structure group activities to the benefit all of us. The first day we discussed modelling and theory as a scientific method, and then we all gave short presentations on our main research agenda, and at last we developed our structure as a group. We certainly are a diverse group in terms of research themes and questions, but at the same time we share many common approaches and methods.

The Theoretical Ecology Group has grown the last year. From left to right: Sergey Buadev, Anders Opdal, Camilla H. Jensen, Christian Jørgensen, Jaqueline Weidner (partly hidden), Elisabeth Åsly, Johanna Fall, Sigrunn Eliassen, Ryan Dillon, Adèle Mennerat, Dag Aksnes, Øyvind Fiksen, Tom Langbehn, Gabriella Ljungström, Chris Lindemann, and Johanna Aarfloth.

[15 January 2016]


Sigrunn Eliassen Presents Bird Mating Systems on National Radio

Sigrunn Eliassen talked [in Norwegian] about female birds and sexual infidelity on the popular science radio show Ekko, aired by the NRK, Norway's national public broadcasting service.

Most bird species live in socially monogamous pair relationships, but paternity tests have shown that the offpsring often belong to another father than the male who provides care at the nest. It is easy to understand why extra-pair mating is advantageous to a male, who then can sire offspring without costly and time-consuming investments in care. It is harder to explain why extra-pair mating can be advantageous to the females. Eliassen discusses how female birds can use extra-pair matings to promote cooperation between the males in the neighbourhood. The theory provides new perspective on how cooperation may arise and be maintained, and explains observed patterns of the sexual division of labour.

Norwegian text: De fleste fugler lever i sosialt monogame parforhold, men farskapstester viser at ungene ofte har en annen far enn han som bidrar med foreldreomsorgen i reiret. Fordelen med sideparinger er lett å se for hanner som slipper kostbar investering i avkom, men det er vanskeligere å forklare hvordan hunnene kan dra fordeler av dette. I følge teorier foreslått av Eliassen og Jørgensen kan hunfugler bruke sideparinger til å fremme samarbeid mellom hanner i et nabolag. Teorien gir nye perspektiver på hvordan samarbeid oppstår og forklarer mønstre i arbeidsdeling mellom kjønn.

You can listen to the podcasts here:
Short version, Saturday 9 January 2016:
Longer version, Wednesday 13 January 2016:

And the theory is presented in this paper:
Eliassen S, Jørgensen C. 2014.
Extra-pair mating and evolution of cooperative neighbourhoods
PLoS One. 9: e99878. [ doi:10.1371/journal.pone.0099878 ] [ open access ] [ pdf ] [ News & Views article by Sheldon and Mangel in Nature ]

[14 January 2016]



Hjort Summer School 2015

The first Hjort Summer school was a held at Espegrend field station in early September, with about 30 participants from all over the world and from a broad range of disciplines. The topic was Fishing and physics as drivers of marine ecosystem dynamics, with Ken Frank, Anna Gårdmark, and Hjalmar Hatun as invited teachers and lecturers. They gave an overview over current state-of-the-art in the science of how marine ecosystems are functioning, with core examples from continental shelf areas, the Baltic, and the Fareoe Islands. In addition, several of the Hjort Centre scientists contributed lectures on microbial food webs, fish-jellies, the Barents Sea, and fisheries management.

The students also presented their own research and participated actively in discussions, computer- and group exercises, and even some field work (beach seining).

As usual in Bergen, the weather was warm and sunny, and allowed for barbecue on the beach and swimming in the sea. We also made an excursion to Bergen to see the town and to do some of the touristic hikes to the surrounding mountains.

This summer school was a great success, and will be continued next year if funding is secured. Hopefully it will be a tradition, and an opportunity to bring together marine scientists in a range of disciplines to learn from the leading scientists in the field.

The 2015 Hjort Summer School had about 30 participants from all over the world.

Ken Frank, Anna Gårdmark, and Hjalmar Hatun were the main teachers, and the students also presented their own research to each other.

The topic was Fishing and physics as drivers of marine ecosystem dynamics and there was also time for socializing in nice weather and beautiful surroundings at Espegrend. The bravest ones even went for a (cold) swim.

[11 October 2015]


Open positions: Two PhDs for Modelling Climate Change Effects

We are currently seeking two PhDs (3 years each) to model effects of climate change on fish life histories. The positions are part of the EU training network MARmaED. Application deadline is 18 October 2015.

PhD project A: How may climate-driven evolution of fish life histories and behaviours interact with effects of fishing?

PhD project B: With climate warming, species are expected to move northwards, but what happens when they approach high latitudes with increasing seasonality and even a long polar night?

The PhD students will be taking part in the activities of the Theoretical Ecology Group. The PhD positions will be part of the EU training network MARmaED, with 8 partner institutions across Europe. Because the positions are EU-funded, special mobility requirements apply: You cannot have been resident in Norway (the host country) for more than 12 months in total during the last 36 months (counted from starting date of the PhD position), and you are ineligible if your research experience (beyond the MSc degree) exceeds 4 years.

PhD supervisors will be Christian Jørgensen (email: and Øyvind Fiksen (email: The workplace will be the Theoretical Ecology Group at the University of Bergen. Application deadline is 18 October 2015 and we hope the candidate can start by January 2016.

You can read the whole advertisement here:

[10 September 2015]


Rebecca Holt Defended Her PhD Thesis

On Friday 21 August Rebecca Holt defended her PhD thesis entitled Climate-induced evolution of the behaviour and life-history strategies of Atlantic cod (Gadus morhua). Opponnents were Joseph Bernardo (Texas A&M) and Tara Marshall (Univ Aberdeen).

Two of the chapters have already been published:
Holt RE, Jørgensen C. 2014.
Climate warming causes life history evolution in a model for Atlantic cod (Gadus morhua)
Conservation Physiology. 2: cou050. [ doi:10.1093/conphys/cou050 ] [ open access ] [ pdf ]
Holt RE, Jørgensen C. 2015.
Climate change in fish: Effects of respiratory constraints on optimal life-history and behaviour
Biology Letters. 11: 20141032. [ doi:10.1098/rsbl.2014.1032 ] [ open access ] [ pdf ] [ matlab code ]

[31 August 2015]



Rebecca Holt Is Blogging for National Science News

Rebecca E. Holt, PhD student in the Theoretical Ecology Group, recently initiated her blog at, the national online science news. Public outreach is part of the PhD education at the University of Bergen, and hopefully a blog can lead to more feedback than more classical, printed outlets. Stay tuned to her blog for more...

[8 December 2014]


Daniel Sellæg Defends Masters Thesis

A proud Daniel with his thesis. (Photo: Bjørn Snorre Andersen.)
On Thursday 30 October Daniel Sellæg defended his Masters thesis Inferring female extra-pair mating behaviour from observed patterns of extra-pair paternity with a process-based model.

Using numerical models, Daniel showed that many more female birds can have extra-pair mating behaviour than end up having extra-pair young in their nest. Particularly, the difference between the female behaviour and the quantifiable output, extra-pair chicks, is large when the rate of extra-pair paternity is low or clutch size small. Supervisor were Sigrunn Eliassen and Christian Jørgensen.

[7 December 2014]


Love Thy Neighbour

Recently, Theoretical Ecology Group researchers Eliassen and Jørgensen showed in PLoSONE how female-driven extra-pair mating creates powerful incentives for male cooperation among neighbours. This week, a News & Views article in Nature by Ben Sheldon and Marc Mangel argues that the new model represents an important shift in focus for empirical studies of extra-pair mating, and that it also has broad implications for our understanding of the evolution of cooperation among unrelated individuals.

Our understanding of avian mating systems was completely overturned by the invention of molecular techniques and paternity analysis, revealing that the majority of bird species, once thought to be monogamous, were instead genetically polyandrous. Since then, hundreds of studies have shown that extra-pair paternity is widespread, and sometimes as many as half of the young in a nest can be sired by a male other than the putative father. The benefits of extra-pair paternity to males are quite obvious, whereas the adaptive explanations for female-driven extra-pair mating have revolved around 'good genes' effects. Despite an extensive, and, according to Sheldon and Mangel, "rather fruitless effort," the evidence for 'good gene' benefits is weak at best.

According to the new model by Sigrunn Eliassen and Christian Jørgensen, the key evolutionary driver in the evolution of extra-pair mating lies in the distribution of a male's potential paternity across nests. When a male gains interests in several neighbouring families, this creates incentives for him to cooperate with other male neighbours and produce public goods that in turn benefit females. Sheldon and Mangel further extend this perspective, claiming that the use of adaptive dynamic modelling lays "the groundwork for investigating the broader goal of understanding the emergence of societies as complex adaptive systems."

Although data are yet not available for testing the model's predictions in ways that exclude other hypotheses, the new theory may spark a shift in empirical focus from genetic effects to the ecological costs and benefits of extra-pair mating. In conclusion, Sheldon and Mangel argue that this perspective also "has broad consequences for our understanding of the evolution of cooperation among interacting, but non-related, individuals."
Sheldon BC, Mangel M. 2014.
Behavioural ecology: Love thy neighbour
Nature. 512: 381-382. [ doi:10.1038/512381a ] [ online at ] [ pdf ]
Eliassen S, Jørgensen C. 2014.
Extra-pair mating and evolution of cooperative neighbourhoods
PLoS One. 9: e99878. [ doi:10.1371/journal.pone.0099878 ] [ open access ] [ pdf ] [ News & Views article by Sheldon and Mangel in Nature ]

[29 August 2014]


How Fish Emotions May Be Adaptive

"I think, therefore I am", said the French philosopher Rene Descartes almost 400 years ago. Wrong, said Antonio Damasio and several others: "I feel, therefore I am". While the rational mind is pretty young on this planet, feelings and their evolutionary precursors are ancient.

When psychologists use the word "feeling", they mean that there is a conscious recognition of the phenomenon in the person who feels. This does not apply to emotions. The emotions are evolutionarily much older than feelings, from a time when no living being was aware its own existence.

Two emotions in a simple fish brain. (Illustration: Bjørn Snorre Andersen.)
A research team of the Hjort Centre for Marine Ecosystem Dynamics has studied what emotions do with fish, through a mathematical model for a fish that lives deep in the open ocean. Theories and models of behaviour in animals are usually formulated based on mathematical analysis of what will be the optimal behaviour if the individual knows everything that is relevant to know. Two new studies instead ask what happens if the fish makes emotional rather than rational choices.

The first study (Giske et al. 2013), which was published in The American Naturalist in December 2013, showed that "emotional" fish are more limited in their behaviour than "rational" fish, and that this restriction leads to the possible coexistence of several different "personalities" in a population. It also showed that emotions enable individuals to make good behavioural choices also in situations they have never before experienced, even if the individuals are unable to judge whether the choice was good or bad.

The second study (Giske et al. 2014), published in Proceedings of the Royal Society of London Series B, Biological Sciences in August 2014, shows that populations consisting of individuals with emotions have greater genetic variation than is necessary in relation to the environment they live in, and that this variation makes the population more adaptable to environmental changes. It therefore seems that emotions, and feelings which came much later, both led to individuals being better able to meet a wide range of challenges in a fairly good way, and to populations which are better equipped to evolve when environmental conditions so dictate.
Giske J, Eliassen S, Fiksen Ø, Jakobsen PJ, Aksnes DL, Jørgensen C, Mangel M. 2013.
Effects of the emotion system on adaptive behavior
American Naturalist. 182: 689-703. [ doi:10.1086/673533 ] [ open access ] [ pdf ] [ popularized version ]
Giske J, Eliassen S, Fiksen Ø, Jakobsen PJ, Aksnes DL, Mangel M, Jørgensen C. 2014.
The emotion system promotes diversity and evolvability
Proceedings of the Royal Society B. 281: 20141096. [ doi:10.1098/rspb.2014.1096 ] [ open access ] [ pdf ] [ fortran code for model at ]

[8 August 2014]


From Extra-Pair Mating to Cooperation

When molecular paternity testing became available, ornithologists were shocked to reveal that birds, generally thought to be monogamous, commonly had mixed broods where some of the offspring were sired by the social male while the rest, often a substantial proportion, originated from matings with an extra-pair male. Later studies have revealed that extra-pair mating is often initiated by females, but the adaptive significance has remained elusive. In PLoS One today, Eliassen and Jørgensen argue that one of its key benefits is that it promotes neighbourhood cooperation.

For males the advantages of extra-pair mating are clear: they may sire extra offspring without having to provide costly care. It is less clear why females seem to accept, or even solicit, matings outside the pair-bond. Why would a female mate with extra-pair males when it normally entails a risk that her social male will reduce on his contribution to offspring care, on which she relies?

Researchers have long looked into so-called 'good gene' effects, investigating whether extra-pair mates have better genes. One of the main predictions from the 'good genes' hypothesis is that in a brood, those offspring with an extra-pair sire should have better survival, faster growth, or otherwise higher fitness than siblings sired by the social male. Despite vast effort across several decades, few such advantages to extra-pair offspring have been found and there is emerging consensus that something else than a desire for good genes must explain the adaptive benefits to females.

In the new study, Sigrunn Eliassen and Christian Jørgensen use evolutionary models to turn the question around. A consequence of extra-pair mating is that males may have offspring in several nests. Males should therefore not aggressively monopolize a territory because that makes resources unavailable to their extra-pair offspring, by sharing they would increase their fitness. And if males face a trade-off between protecting the neighbourhood and protecting their own nest, then it may pay to cooperate over shared vigilance and defence because that safeguards all their potential offspring. Through extra-pair mating, females thus incentivize males to collectively contribute to a secure and productive neighbourhood. The advantage of extra-pair mating to females is thus a cooperative benefit produced by males.

The models further predict sex-specific division of labour, that whole nests and neighbourhoods benefit from extra-pair mating (not only the extra-pair half-siblings), and integrates with existing theory with the prediction that extra-pair mating should be more common in short-lived species.

And does it apply beyond birds? There are two key premises: paternity uncertainty, which is present also in fish, particularly those with internal fertilization, and in mammals; and paternal care interpreted in a broad sense. Within mammals, it might be rodents and primates that best fulfil the requirements.

For more details, please see the paper:
Eliassen S, Jørgensen C. 2014.
Extra-pair mating and evolution of cooperative neighbourhoods
PLoS One. 9: e99878. [ doi:10.1371/journal.pone.0099878 ] [ open access ] [ pdf ] [ News & Views article by Sheldon and Mangel in Nature ]

[2 July 2014]


Snorre Andersen is Defending his Masters Thesis on Fish Emotions

Snorre Andersen has handed in his Masters Thesis:
Title: Effects of genetic complexity and time resolution in an individual-based model of mesopelagic fish with hunger and fear.
Supervisor: Jarl Giske.
Defence: Wednesday 25 June at 9:15 in K1. External examiner will be Geir Huse from IMR.

The thesis is a sensitivity analysis of the temporal resolution in a mathematical model for planktivorous mesopelagic fish. In addition, the genetic complexity of the model was increased by adding more genes, allowing more complex neuronal responses with better precision.

The increased temporal resolution of each diel cycle gave higher population egg production, the only evolutionary measure of quality in the model. Individuals changed also more frequently between the two states 'Hungry' and 'Afraid' when allowed to do so by the increased resolution. However, the overall level of fear did not stabilize or converge between simulations with higher genetic complexity, higher temporal resolution or more generations. It was found that for almost all stages of life, the increased genetic complexity was not needed and it did not yield higher population egg production. Simulation time can be shortened by a factor of 10 by reducing number of generations and diel cycles even when increasing the number of time steps in each cycle.

[20 June 2014]


Successful Marine Microorganisms in PNAS

Scientists from the Marine Microbiology Group and the Theoretical Ecology Group at the University of Bergen recently described in PNAS how the world's most abundant organism may result from an evolutionary arms race between viruses and bacteria.

The existence of the world's presumably most abundant organism was unknown to science until its appearance in DNA samples from the Sargasso Sea in 1990, which gave this organism the somewhat obscure name SAR11. This is a small bacteria whose number has been estimated to make up one quarter of all marine bacteria, implying that there are probably more than 1028 SAR11 bacteria on Earth (for comparison, the estimated number of stars in the universe is roughly 1023, i.e. there are 100 000 SAR11 bacteria for each star).

The question of what lies behind this success has fascinated microbiologists, not the least because SAR11 is a simple organism with a small genome and hence few genes. Why is such a minimalistic strategy apparently key to success? The debate has first and foremost been guided by the ideas that SAR11 either is so successful due to its ability to defend itself against viruses and predators, or due to its ability to compete with other bacteria for limiting resources. In the last issue of the prestigious American science journal PNAS (Proceedings of the National Academy of Sciences), scientists from the Department of Biology at the University of Bergen have analysed the following trade-off: If the cost of viral defence is high in terms of reduced growth and reproductive ability (and vice versa), then those individuals investing too much into competition will be eaten or get infected, and those who invest too much into defence will starve. A logical consequence is that the key to success appears not to lay in either of the two extremes, but rather in using a level of defence where the price in terms of reduced competitive ability is minimal. Instead of considering SAR11 as a species composed of similar individuals, the scientists show how an evolutionary arms-race between SAR11 bacteria and their viruses leads to a number of different clones within the SAR11 bacteria, where some clones are strong competitors for limiting resources and others have strong defence against viruses, while most of the clones lie between these two extremes.

The work is part of the recently completed PhD thesis by Selina Våge and was conducted as part of the ERC Advanced Grant project MINOS to professor Frede Thingstad. The work gives a theoretical framework that can link genetic information from molecular analyses to marine ecosystem properties.

Read more in the original article, which was published in PNAS online on 13 May 2014:
Thingstad TF, Våge S, Storesund JE, Sandaa R-A, Giske J. 2014.
A theoretical analysis of how strain-specific viruses can control microbial species diversity
Proceedings of the National Academy of Sciences. 111: 7813-7818. [ doi:10.1073/pnas.1400909111 ]

[14 May 2014]


Selina Våge is Defending Her PhD Thesis 4 April

Friday 4 April at 10:15 Selina Våge is defending her thesis entitled Pelagic microbial food web organization: Extending the theory for structure and diversity generating mechanisms based on life strategy trade-offs .

Opponents are Mick Follows (Massachusetts Institute of Technology, USA) and Andy Visser (Technical University of Denmark), adn the defence will take place in Stort auditorium, Høyteknologisenteret, Thormøhlensgate 55.

For more info see the UiB press release (in Norwegian).

[29 Mar 2014]


Seminars with Visitors from Lund University

We had a wonderful day with seminars and discussions as the Theoretical Population Ecology and Evolution Group from Lund University, Sweden, visited us in Bergen. They were on a week-long Nordic road-trip, and arrived from the University of Oslo by train and, despite the stormy weather, continued to NTNU in Trondheim with the coastal ferry Hurtigruten.

Per Lundberg led the group to the Department of Biology with astonishing temporal and spatial precision. He talked about the utility, or lack thereof, associated with theoretical modelling. Jacob Johansson presented a model for phenology in migrating birds, with a follow-up talk by Nadiah Kristensen. Mikael Pontarp and Jörgen Ripa were also visiting. After lunch it was time for seminars given by Bergen researchers.

[21 Mar 2014]


Hjort Centre for Marine Ecosystem Dynamics Officially Opened

Norway's Prime Minister Erna Solberg officially opened the Hjort Centre for Marine Ecosystem Dynamics on 18 February, Hjort's 145th birthday. Present were also the Fisheries Minister Elisabeth Aspaker and the City Mayor of Bergen Trude Drevland. The Hjort Centre is a collaboration between University of Bergen, Uni Research, Institute of Marine Research, and Nansen Environmental and Remote Sensing Center, and several researchers from the Theoretical Ecology group have been central in developing the concept and drafting the Science Plan.

You can read more about the Hjort Centre opening (in Norwegian) at:

Here are some further background news stories:

[20 Feb 2014]


Aksnes and Mesopelagic Fish in National News

The Norwegian Public Broadcaster NRK has picked up the article by Dag L. Aksnes and colleagues in Nature Communications, which claims that about ten billion tonnes of mesopelagic fish remain unexploited in the deep oceans.

- We might need to start fishing further down in the food chain to provide the world's growing population with enough nutrients. The vast abundance of mesopelagic fish represents an obvious opportunity, Dag says.

Read the full story at the NRK webpages.

The article itself can be found here:
Irigoien X, Klevjer TA, Røstad A, Martinez U, Boyra G, Acuña JL, Bode A, Echevarria F, Gonzalez-Gordillo JI, Hernandez-Leon S, Agusti S, Aksnes DL, Duarte CM, Kaartvedt S. 2014.
Large mesopelagic fishes biomass and trophic efficiency in the open ocean
Nature Communications. 5: 3271. [ doi:10.1038/ncomms4271 ] [ online ]

[13 Feb 2014]


Trial Lecture Selina Våge

Title: Mechanisms for and population diversity consequences of parasite defense throughout the tree of life.
Evaluation Committee: Professor Arne Skorping, Researcher Sigrunn Eliassen, Professor Ruth-Anne Sandaa.
Time and place: Friday 14 February 12:15, Seminar room K3, Biologen (Thormøhlensgate 53B).
Everyone is welcome.
Selina will defend her thesis Friday 4 April.
Opponents: Mick Follows (MIT), Andy Visser (DTU), and Lise Øvreås (UiB).
Thesis title: Pelagic microbial food web organization. Extending the theory for structure and diversity generating mechanisms based on life strategy trade-offs.
[10 Feb 2014]


Mesopelagic Fish in Nature Communications

Mesopelagic fishes dominate the global fish biomass, yet there exist major uncertainties regarding their real abundance. In Nature Communications today, Dag L. Aksnes is co-author on a paper arguing that the commonly accepted biomass estimate of mesopelagic fishes of one billion tonnes should be raised by an order of magnitude. The new estimate is based on analysis of nine months of acoustic data collected during a circum-global scientific cruise.

Irigoien X, Klevjer TA, Røstad A, Martinez U, Boyra G, Acuña JL, Bode A, Echevarria F, Gonzalez-Gordillo JI, Hernandez-Leon S, Agusti S, Aksnes DL, Duarte CM, Kaartvedt S. 2014.
Large mesopelagic fishes biomass and trophic efficiency in the open ocean
Nature Communications. 5: 3271. [ doi:10.1038/ncomms4271 ] [ online ]

This finding is consistent with a recent paper (Kaartvedt et al. 2012, see link below) which suggested that mesopelagic fish have been drastically underestimated because of their efficient avoidance of traditional sampling gear. The contribution of the mesopelagic fishes to e.g. ocean biogeochemical cycling was deemed insignificant based on previous estimates of their biomass, but this thinking may have to be revised. Furthermore, it appears that the trophic efficiency in the open ocean is much higher than previously assumed.

Kaartvedt S, Staby A, Aksnes DL. 2012.
Efficient trawl avoidance by mesopelagic fishes causes large underestimation of their biomass
Marine Ecology-Progress Series. 456: 1-6. [ doi:10.3354/meps09785 ] [ open access ] [ pdf ] [ feature article ]

[7 Feb 2014]


New Postdoc: Adèle Mennerat

Why do females engage in extra-pair copulation (mating with other males than their own partner) - and what are the resulting selective pressures on male behaviour (how should males respond to this)? The (scientific) temptation was too big: Adèle Mennerat has joined TEG for four years to work with Sigrunn Eliassen and Christian Jørgensen on an ongoing project studying promiscuity and the evolution of cooperative neighbourhoods, and funded by the Research Council of Norway. She is also holding an Associate Professorship at the University of Amiens (France), from which she could take a temporary leave for the duration of the project.

Adèle with two blue tits.
Her research interests lie at the interface of evolution, ecology, and behaviour. She has background in both Molecular Biology (ENS Lyon, France) and Evolution & Ecology (University of Montpellier, France) and a PhD in Population Biology and Ecology (CEFE / University of Montpellier, France). Her PhD thesis focused on the adaptive value of animal self-medication behaviours. She has previously worked at UiB as a researcher (2008-2010) in the Evolutionary Ecology Group, working on life history and virulence evolution of parasites with Arne Skorping. She then spent two years as a Marie Curie fellow at the Edward Grey Institute at the Department of Zoology of Oxford University, studying the links between disease transmission and social behaviour. In Amiens she is exploring life history evolution and terminal investment, invasion ecology, and epidemiological consequences of climate variability. She has addressed those questions using various model species from bacteria to fish although birds remain her favourite group.

In Bergen she will use empirical data from the "real world" to test assumptions and predictions from models developed by Sigrunn & Christian, starting with birds and later on expanding the scope to other groups (including primates).

[22 Jan 2014]


Kristina Kvile Visits TEG

Kristina Kvile is a visiting PhD student through the Nordic Centre of Excellence network NorMER. She will stay in Bergen for almost two months, and the focus of the stay is to investigate zooplankton survey data from the Barents Sea in the light of a hydrodynamic model of the area and an individual based model of Calanus finmarchicus. With this, she hopes to shed light on the spatial dynamics of C. finmarchicus in the Barents Sea. Kristina is normally based at the Centre for Ecological and Evolutionary Synthesis (CEES) at the University of Oslo.
You can read more about her project here:
[20 Jan 2014]


Hjort Centre for Marine Ecosystem Dynamics

The small city of Bergen already produces so many peer-reviewed publications within marine science that it is on the top 10 list worldwide, but a challenge has been to convert mass into momentum. In an attempt to raise ambitions and put the big questions on the agenda, four institutions in Bergen have now agreed to collaborate in a Hjort Centre for Marine Ecosystem Dynamics: Institute of Marine Research, University of Bergen, Nansen Environmental and Remote Sensing Center, and Uni Research. The centre's ambition is to become an international point of gravity in marine ecosystem research worldwide.

The Centre is named after Johan Hjort, often referred to as the founder of modern fisheries science due to his contributions and particularly the book Fluctuations in the great fisheries of Northern Europe (1914). Most of his groundbreaking research was done in Bergen, where Hjort became Norwegian Fisheries Director and simultaneously the first director of the Institute of Marine Research.

The Hjort Centre will have its official opening on Tuesday 18 February 2014, and there is currently hectic activity on developing the Science Plan with heavy involvement from the Theoretical Ecology Group.

[19 Jan 2014]



We Are Moving to New Offices

Since the Department of Biology became co-located in its new buildings roughly three years ago, the Theoretical Ecology Group has been living a life in isolation in the building next door. Although the distance has not been more than a few meters, we have missed the daily joy of bumping into colleagues in the corridors. Not so any more. By the end of August all members of the Theoretical Ecology Group will have moved to their new offices within the main building of the Department of Biology. From then on you find us in Thormøhlensgate 53B, floor 3, with postdocs on floor 2. Further good news is that we now will share corridor with Evofish and the Evolutionary Ecology Research Group. We are looking forward to new interactions!
[18 Aug 2013]


Selina Våge in Nature on Why SAR11 Bacteria Are So Successful in the Pelagic Ocean

Selina Våge
PhD student Selina Våge, together with PhD student Julia E. Storesund and professor Frede Thingstad, extend the ongoing discussion of why SAR11, an abundant bacterial group in the pelagic ocean, is so successful. Recent findings of highly abundant SAR11 viruses could indicate that SAR11 bacteria are good competitors, little specialized in viral defence. By including different bacterial strains in a virus-host community model, Selina and coauthors offer an alternative explanation, where the majority of SAR11 bacteria are defence specialists. Discerning the success of SAR11 is important for our understanding of biogeochemical cycling in the microbial food web, which is basic to ecosystem functioning.

A figure from the article, illustrating two possible scenarios (clustered (A) and interspersed (B)) of how strains of bacterial species may be distributed along the growth rate axis. The interspersed scenario (B) supports the highest total virus abundance according to our model, and allows for a dominance of defensive SAR11 strains despite a high SAR11 virus abundance.

Link to the article on Nature's website:
Våge S, Storesund JE, Thingstad TF. 2013.
SAR11 viruses and defensive host strains
Nature. 499: E3-E4. [ doi:10.1038/nature12387 ]

[6 Aug 2013]


Evolution of Growth Most Read in Marine Ecology in 2012

Our paper on fishing-induced evolution of growth was listed first among the most accessed papers in Marine Ecology in 2012:
Enberg K, Jørgensen C, Dunlop ES, Varpe Ø, Boukal DS, Baulier L, Eliassen S, Heino M. 2012.
Fishing-induced evolution of growth: concepts, mechanisms, and the empirical evidence
Marine Ecology. 33: 1-25. [ doi:10.1111/j.1439-0485.2011.00460.x ] [ open access ] [ pdf ]
[11 Jul 2013]


New PhD Student: Nadia Fouzai

We have a new PhD student in the group - Nadia Fouzai started late last year and is already developing her first paper on how temperature operates to influence physiology, behaviour and eventually growth and survival in larval cod. Her PhD project is connected to the Nordic Centre of Excellence NorMER (The Nordic Centre for Research on Marine Ecosystems and Resources under Climate Change). Her thesis will be on how temperature and other climate-related environmental factors can affect the survival of larval cod. Supervisors will be Øyvind Fiksen, Anders F. Opdal, and Christian Jørgensen.

Nadia is from Tunisia, and did her undergraduate at National Institute of Agronomy of Tunisia (INAT), then she went to Spain to take a Masters of Science degree within the field of Fisheries economics and management, at University of Barcelona. Her Masters thesis was entitled Management of the Adriatic Sea Exploited Marine Ecosystem by means of the Application of Ecopath Modelling and the Simulation Tool Ecospace, taken at Institute of Marine Science (ICM-CSIC), Barcelona, Spain. Her thesis was later published in Journal of Marine Systems, see below. She speaks Arabic, French, Spanish and English - and has just started on a Norwegian course.

According to her own words she is not deterred by the climate in Bergen. We hope she will adapt to the climate, just as her cod larvae!
Fouzai N, Coll M, Palomera I, Santojanni A, Arneri E, Christensen V. 2012.
Fishing management scenarios to rebuild exploited resources and ecosystems of the Northern-Central Adriatic (Mediterranean Sea)
Journal of Marine Systems. 102–104: 39-51. [ doi:10.1016/j.jmarsys.2012.05.003 ] [ pdf ]

[11 Feb 2013]


Negative Effects of Trawling Receives Attention in National Newspaper

The Norwegian national newspaper VG recently published an article focusing on the negative effects of trawling, directed towards the ongoing debate concerning future oil production in Lofoten, an important spawning area for the Northeast Arctic cod. Journalist Inga R. Holst argued that not only the oil industry, but also the fishing industry faces serious environmental challenges. Researcher Anders F. Opdal commented on the ongoing research in the Theoretical Ecology Group regarding the negative consequences trawling, and how a modern trawl fishery has altered the both demography and spawning distribution of the Northeast Arctic cod stock. You can read the whole story here.
[10 Feb 2013]


Darwin Day 2013 with Andrew Read and Evolutionary Medicine

The program for the annual Darwin Day, on Tuesday 12 February, is now out. Professor Andrew Read from Pennsylvania State University will talk about drug resistance, evolving pathogens, and evolutionary medicine. At 12:00 he will give a talk at Haukeland University Hospital, and at 18:00 a lecture at the Student Centre. The evening lecture is arranged in collaboration with the Horizons seminar series by the Faculty of Mathematics and Natural Sciences at UiB, and the lunch lecture in collaboration with Centre for International Health and Haukeland University Hospital.

The web pages of the Darwin Day in Bergen.
The web pages of his research group.

[9 Jan 2013]


Evolution of Mating Systems Featured in National Newspaper

Project leader Sigrunn Eliassen and researcher Christian Jørgensen recently received news that a new four-year project on the evolution of mating systems received funding by the Research Council of Norway. The Norwegian national newspaper Aftenposten highlighted this as the type of innovative science that the national funding body would like to support more strongly in the coming years. A post-doc will be recruited to the project, and work in collaboration with the University of Bergen's Center for Women's and Gender Research.

Read the article in Aftenposten here [In Norwegian].

Read story at The Research Council of Norway webpages here [In Norwegian].

[3 Jan 2013]



Trait-Based Ecosystem Models

Trait-based ecosystem models are becoming more popular and taken into use in a wide range of applications and questions in oceanography. Øyvind Fiksen has been on a one-year sabbatical at Massachusetts Institute of Technology (MIT) in Boston, USA, working with Mick Follows and his group The Darwin Project. Read more about what they think about the future for Trait-based ecosystem models here:
Dutkiewicz S, Follows M, Fiksen Ø, Kiørboe T. 2012.
Trait-based ecosystem models
International Innovation. 2012 June: 120-122. [ pdf ]
[6 Sep 2012]


Featured Article in MEPS: Internal Waves and Vertical Migrations

A figure from the article, illustrating the effect of the internal wave on fish distributions. Each wace cycle is about 30 minutes. (Illustration by Hege Vestheim.)
The major upwelling systems of the oceans sustain a large part of the world fisheries. The high productivity of these systems has been attributed to high primary production, short food chains, and high trophic transfer efficiency. The study Internal wave-mediated shading causes frequent vertical migrations in fishes suggests that frequent vertical migration (FVM) in fish might contribute to increased prey encounters and the time available for safe visual foraging, thus improving fish growth and survival and trophic transfer efficiency in the Benguela upwelling system. The observed FVM appears to be facilitated by the periodic shading of downwelling irradiance due to the action of internal waves. The thickness of a turbid surface layer varies with the wave and causes a fluctuation in light intensity of 3 to 4 orders of magnitude. Like diel vertical migration, the fish respond by vertical migration, but now with a period of 30 min instead of 1 day. Thus it is hypothesized that fish feeding is enhanced due to an increase in the daily number of antipredation windows for feeding in the water column.
[26 Apr 2012]


Special Issue on Fish-Zooplankton Interactions in the Norwegian Sea

Effects of interactions between fish populations on ecosystem dynamics in the Norwegian Sea - results of the INFERNO project is the title of a special issue of Marine Biology Research published today. Geir Huse, Jens Christian Holst, Kjell Rong Utne, Leif Nøttestad, Webjørn Melle, Aril Slotte, and Geir Ottersen are guest editors. The volume includes several articles using the Norwecom end-to-end model, with contributions from Geir Huse, Solfrid Stre Hjllo, Morten D. Skogen, and Kjell Rong Utne, among others. The Special Issue is found online at
[25 Apr 2012]


Seminar Series in Marine Ecosystem Modelling

Starting April 2012, the Theoretical Ecology Group arranges a weekly seminar series on marine ecological modelling, with a special focus on issues of relevance for development of the NORWECOM end-to-end ecosystem model. Talks may include a wide variety of topics in quantitative ecology. The seminar series is a meeting point for ecologists, geophysicists, mathematicians, and computer scientists from UiB (Dept. of Biology, Geophysical Institute, Dept. of Mathematics), Uni Research, Institute of Marine Research, and other research institutes, and is open to all interested. Check here for location and upcoming program.
[21 Apr 2012]


PhD Position: 45 Applications Received

A total of 45 applications was received for the 3-year PhD position connected to the Nordic Centre of Excellence NorMER. The successful candidate will model responses in cod larvae to climate change, and work with Øyvind Fiksen, Christian Jørgensen, and Anders F. Opdal.
[11 Apr 2012]


Open PhD Position: Cod Larvae and Climate Change

A 3-year PhD position connected to the Nordic Centre of Excellence NorMER is now announced.

The successful applicant will perform theoretical modelling studies on larval cod growth and survival in scenarios of future oceanographic conditions. The research question is how recruitment success of larval cod will depend on changes in environmental and ecological conditions such as ocean temperature, acidity, primary production, optics and prey availability. The candidate will apply optimality modelling and individual-based models to integrate from physiological processes to ecological and evolutionary mechanisms involved in long-term changes of the environment.

We are seeking a highly motivated candidate with background in one or more of the following disciplines: biological oceanography, ecology, evolution, behavioural ecology, larval fish biology, life history theory, physiology and theoretical biology. Candidates with backgrounds from related disciplines will also be considered. Good communication and writing skills in English and a desire to engage in collaborative research are essential.

For further information and to apply, please visit
(you may need to click 'English' in the top menu to change language). The application deadline is 30 March 2012.

[23 Feb 2012]



Visitor from the Red Sea Research Center

Perdana Karim Prihartato is an Indonesian PhD student of professor Stein Kaartvedt at the Red Sea Research Center at KAUST in Saudi Arabia. He visits TEG in October 2011 to learn Dynamic Programming and to start modeling the life history and behavior of Red Sea mesopelagic fish by this method. He is cooperating here with Rune Rosland (who studied Norwegian mesopelagic fish by the same modeling tools in his PhD) and Jarl Giske, who is also his co-supervisor at KAUST.
[4 Oct 2011]


Group Meeting at Herdla

Jarl blended in perfectly as he gave a talk on modelling proximate mechanisms for decision-making in fish.
The Theoretical Ecology Group met for two days at Herdlevågen Gjestehus. The hotel used to be the marine biological station of Bergen, but was abandoned to avoid noise and pollution as the city's airport was planned at Herdla. As the institute moved to Espegrend, so did the airport plans, and Espegrend is ironically now the closest neighbour to Flesland.

In addition to members from the Department of Biology, researchers from Institute of Marine Research (IMR) and Uni Research (Uni) were also present. Part of the discussions revolved around plans for how to establish a research centre with all three research institutions involved.

Two new faces also joined the meeting and presented their science. Rebecca Holt is beginnig a PhD on cod and climate change in September. Leo Zijerveld is a long-term visitor from the Sottish Agricultural College in Edinburgh, and is completing a PhD on the dynamics of disease outbreaks.

Since Øyvind Fiksen will be on sabbatical at the Massachusetts Institute of Technology the upcoming academic year, Dag L. Aksnes was elected new group leader from 1 August 2011.

The extended Theoretical Ecology Group at Herdla. Back row (from left): Jarl Giske, Nicolas Dupont, Rune Rosland, Rebecca Holt, Frode Vikebø (IMR), Geir Huse (IMR), Kjell Utne (IMR), Christian Jørgensen (Uni). Front row: Agurtzane Urtizberea, Dag Aksnes, Sigrunn Eliassen, Øyvind Fiksen, Anders Frugård Opdal (Uni), Leo Zijerveld (visitor). In front: Marco Castellani.

[14 Jun 2011]


New PhD Student: Rebecca Holt

Rebecca Holt from Plymouth, United Kingdom, has been offered the position as PhD Student in connection with the Nordic Centre of Excellence NorMER (The Nordic Centre for Research on Marine Ecosystems and Resources under Climate Change). She plans to begin in September, and her thesis will study temperature adaptations in cod. Supervisors will be Christian Jørgensen and Øyvind Fiksen.

There were a total of 52 applicants, ten were interviewed, and Rebecca was ranked first by the committee.

[13 Jun 2011]


Long-Term Visitor: Leo Zijerveld

Leo Zijerveld is a visiting PhD Student from Biomathematics & Statistics Scotland, Sottish Agricultural College. His interests are stochastic models for the spread of disease in heterogeneous wildlife populations. To derive parameter estimates for such models, he uses time series data and Markov Chain Monte Carlo inference techniques.
[12 Jun 2011]


Many PhD Applicants

A stunning fifty-two applications were received for the recently announced PhD position as part of the Nordic Centre of Excellence NorMER (The Nordic Centre for Research on Marine Ecosystems and Resources under Climate Change). Several of the candidates are excellent, and interviewing will begin soon. But first one has to get throughly through the nearly 2000 pages of letters and documentation to make sure everyone has been evaluated fairly.
[27 Apr 2011]


Open Position: 4-year PhD Scholarship

We currently have a four-year PhD scholarship open. The position is part of The Nordic Centre for Research on Marine Ecosystems and Resources under Climate Change, and will involve evolutionary modelling of adaptations to climate change in the Atlantic cod. The application deadline is 30 March 2011. Follow this link to find out more.
[17 Feb 2011]


Anders Frugård Opdal Hired as Researcher

Anders F. Opdal defended his PhD thesis in November 2010 and has now been hired as researcher in Uni Computing. His focus will be to combine models of fish larval survival and drift from oceanography models, with life history models for the adult phase in a fish's life. The aim is to close the life cycle in a broad perspective by coupling these modelling tools. The research is funded by the Research Council of Norway through the Havet and Kysten thematic programme.
[10 Feb 2011]


Marc Mangel Becomes Adjunct Professor

Professor Marc Mangel at University of California Santa Cruz joined TEC in November 2010 as Adjunct Professor at Department of Biology.
    His relationships with TEC date back to the early 1990s. He has been guest lecturer on several UiB PhD courses, co-supervisor for UiB PhD students, host for TEC researchers at sabbaticals, and co-authors in several of our journal articles. In his adjunct professorship he will participate in three TEC core activities, namely Evolution of mating systems, Evolution in Fisheries Science, and Animal Decision Making.
    More information about Marc can be found at his web page:
[1 Feb 2011]


Nordic Center of Excellence Launched

The Nordic Center of Excellence NorMER (The Nordic Centre for Research on Marine Ecosystems and Resources under Climate Change) was granted funding November 2010 and is now launching its activities.
    The center is led from the Univesity of Oslo (chaired by Professor Nils Christian Stenseth) in conjunction with the Stockholm Resilience Center (Professor Carl Folke is co-chair). Department of Biology, University of Bergen, is one of nine nodes across the Nordic countries. Øyvind Fiksen leads the UiB involvement. You can read more about the network and its organisation at
    The network will research climate change effects on Atlantic cod, a species with a wide distribution in Nordic waters and of great regional economic importance. The main activity of the centre will be to fund 16 PhD students and 4 postdocs that will visit several of the nodes. The first positions will be announced 18 February 2011 with application deadline 30 March 2011.
[21 Jan 2011]



Dag L. Aksnes
Sergey Budaev
PhD Student
Ryan J. Dillon
Associate Professor
Sigrunn Eliassen
PhD student
Johanna Fall
Øyvind Fiksen
Jarl Giske
PhD Student
Laura Hildesheim
PhD Student
Camilla Håkonsrud Jensen
Group Leader, Professor
Christian Jørgensen
Tom J. Langbehn
Christian Lindemann
PhD Student
Gabriella Ljungström
Adjunct Professor
Marc Mangel
Adéle Mennerat
Anders F. Opdal
PhD student
Nicolas J. I. Rodriguez
PhD Student
Jacqueline Weidner