Researcher, PhD Christian Jørgensen
My research focuses on four topics that all use evolutionary biology:
Fishing-Induced Evolution
One dominant selective agent nowadays is fishing. Both industrial and recreational
fishing can induce mortality rates so high that evolutionary responses in the
harvested species are bound to happen. But, in what direction and towards what
endpoint will the fish species evolve?
I use evolutionary models to investigate evolving traits. So far I have, together
with several co-authors, shown that fishing can induce evolution towards earlier
sexual maturation at smaller size, breakdown of mating systems in hermaphrodites,
altered migration patterns and geographical distribution, increased natural
mortality, and less skipped spawning. I am also interested in how fisheries
management can use this type of knowledge to achieve sustainable fisheries.
You can read more about this research here.
Evolutionary Marine Ecology
What can fisheries science learn from life history theory and behavioural
ecology? Theories and methodologies developed in these central disciplines of
evolutionary ecology have the potential to shed new light on many aspects of
marine ecology. Most population level phenomena arise from individual processes.
One fruitful approach is therefore to incorporate ecological and physiological
mechanisms at the individual level, and investigate their effects on populations.
Using state-dependent energy allocation models for fish, I have investigated the life
history trade-offs that underlie phenomena such as reproductive investment,
skipped spawning, and evolution of spawning migrations.
Together with Øyvind Fiksen and other coauthors I have also studied what happens
to fish larvae after they have been spawned -
during their pelagic drift phase. Their challenge is not only to eat and to survive,
but also to drift towards benevolent settlement habitat. Surprisingly many aspects
of a larva's future life can be modified by vertical migrations, and the trade-offs
are almost piled on top of each other. By incorporating mechanistic representations
of predation and feeding, physiological growth models, and simple rules that govern
risk-sensitive behaviour, these trade-offs can be studied in physical ocean models.
Experimenting with these virtual large-scale laboratories is thrilling.
You can read more about this here.
Evolution of Mating Systems
The strategig games between males and females is an important basis for the evolution of
mating systems. Using evolutionary models, I work with Sigrunn Eliassen to describe
how some of the variation in mating systems may have originated and is maintained.
Methodologies for Evolutionary Modelling
I am intrigued by how the rich mechanisms of physiology and behaviour cause
constraints and opportunities for life history evolution. To be able to construct
evolutionary models that incorporate more complex individuals, I work on
developing new methodologies. The different modelling methodologies have different
strengths and weaknesses, and I believe a varied toolbox is necessary to reach
generalisable conclusions.
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