Karen de Jong

Welcome to my home page.
I am a behavioural ecologist working mainly on reproductive behaviour in fish, but I have also worked with other model systems such as birds and plants. I am interested in how changing environments, and in particular the increasing noise-levels in our oceans and rivers, affect sexual selection and reproductive potential. My favourite model systems are gobies: small bottom dwelling fish that can live under extreme circumstances. Gobies live basically everywhere in the world, from pools in the desert of Australia to anoxic deep seas in Africa. I have studied them in slightly less exotic places, such as Sweden, Germany, Scotland and Portugal.
I currently work at the Institute for Marine Research in Bergen, Norway.


Aquatic noise, reproductive behaviour and sexual selection

Noise level in the seas are rising due to increased boat traffic, the establishment of wind farms and seismic exploration of the sea floor. Because any fish species use sound in communication, anthropogenic noise could hamper the transfer of information between individuals. Males of several goby species use visual and acoustic courtship to attract females and convince them to lay eggs in his nest. In several projects, we test wether increased noise levels affect fish reproduction, male behaviour, female choice and sexual selection.
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Collaborators: Katja Heubel, Clara Amorim, Paulo Fonseca, Clive Fox, Adrian Klein, Gregor Schulte, Ola Svensson, Charlotta Kvarnemo, Eva-Lotta Blom, Sarah Schroeder, Karen Bussmann, Anne Christine Utne Palm, Lise Doksæter Sivle, Tonje Nesse Forland, Guilleaume Rieucau, Hans Slabbekoorn

Reproductive behaviour of invasive gobies in the Rhine

Since the beginning of this century, five species of invasive gobies have entered the Netherlands via the rivers. They are now among the most abundant freshwater species in the Dutch rivers. In this project, we assess what characteristics make them so successful at reproduction in their new habitat.
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Collaborators: Katinka Bleeker, Nils van Kessel, Leo Nagelkerke, Camilla Hinde, Katja Heubel, Jost Borcherding

Sex roles and reproductive behaviour

In a small marine fish, the two-spotted goby (Gobiusculus flavescens), sex roles change over the season. Males compete for females early in the mating season when males are abundant, but later, when males become scarce, females compete for males. This is in line with sexual selection theory, that predicts that the more abundant sex competes for the limiting sex. In my PhD project, we tested if competitive behaviour is indeed affected by the sex ratio or density. We found that the propensity to court is indeed affected as expected; males are more likely to court each female when females are scarce. However, because males get less opportunities to court when females are scarce, courtship frequency decreases.
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Collaborators: Sebastian Wacker, Lise Cats Myhre, Elisabet Forsgren, Trond Amundsen

Seasonal changes in maternal effects

Offspring quality has a direct effect on the fitness of the parents. In animals that breed more than once in a life time (iteroparous animals), there may often be a trade-off between investment in current offspring and investment future offspring. For the mother, it would then be advantageous to invest most at a time when her offspring is likely to benefit the most. However, what she is able to invest could also change over time, depending on factors such as food availability, age and condition of the mother. In this project, we aim to disentangle these effects and get an overview of both possible and actual investment in different parts of the reproductive season in a small marine fish, the two-spotted goby.

Collaborators: Laura Rodigues-Grana, Irja Ida Ratikainen, Helen Skjöld, Geraldine Fauville, Elisabet Forsgren, Trond Amundsen