Dynamics of sex roles and sexual selection in males and females

– Amundsen Lab
 

Amundsen’s research lab is focused on the behavioural and evolutionary dynamics of sexual selection in animals. We work to understand how mating competition and mate choice in both sexes shape the way animals behave to successfully reproduce, and how mating competition and mate choice shapes what the animals look like: their body size, their colours and their many other extravagant traits hard to explain if not being useful for gaining mates. We are particularly interested in how sexual selection in both sexes varies in space and time, and how the two sexes interact in shaping animal mating dynamics.

 

Field work in the Hitra archipelago. Photo: Per Harald Olsen

 

Sexual selection - two model systems

We currently work with two main model systems. We call them model systems because we mainly work with these species to understand things that have relevance across a lot of animal species – principles that can help us understand the broad picture of mating dynamics in animals. The model species are chosen because they are easy to work with both in the lab and in the field, not hard to find, and have interesting mating dynamics. Both current model systems are fishes but the lab leader has extensive experience from similar work on birds.

Coral reef fishes – an understudied world of colour and splendour

Coral reef fishes are renowned for their amazing colours. Surprisingly, it is not well known why they are so colourful. Sexual selection, which is an obvious candidate explanation, has been little tested. Based on field and lab work at Lizard Island Research Station on the Great Barrier Reef, we analyse the function of coloration in explaining in competition and mate attraction. We also study the dynamics of colour signalling, as colours can be turned on and off very quickly in some fishes, and how the social structuring of populations affect mating dynamics. We work primarily with two small damselfishes: the sapphire devil Chrysiptera cyanea and the black-and-gold chromis Neoglyphidodon nigroris.

 
  • Studying reef fish behaviour. Photo: Trond Amundsen

     

     

  • Sapphire devil damselfish by its nest in a coral. Photo: Trond Amundsen

     

     

  • Flirting two-spotted gobies. Photo: Nils Aukan

     

     

The two-spotted goby – a small fish with a uniquely dynamic sex life

Our main model system during many years has been the two-spotted goby Gobiusculus flavescens. This fish is extremely abundant in shallow-water kelp forests in Scandinavia (and other W European coastlines). It is staple food for juvenile codfish and there have a central role in rocky-coast ecosystems. We have made the two-spotted goby “famous” by showing that it has exceptionally dynamic sex roles: early in the breeding season males compete amongst themselves and to attract females whereas in high summer it is suddenly the females that vigorously compete for the few males still alive. This uniquely dynamic system has set the stage for range of exciting studies conducted both in the lab and in the field. It is a hallmark of our lab to combine controlled lab experiments with extensive field studies to understand and analyse behaviours, their ecological context, and their evolutionary consequences.

The Hitra study system

We have previously mostly studied populations of two-spotted gobies on the Swedish west coast, from a base at a marine research station there. In addition, we have done collaborative studies together with other labs using various goby species as model organisms. In the last few years, we have established a study system on the coast outside Trondheim, in the archipelago NW of the island Hitra. There, we focus particularly on micro-geographic and within-season dynamics of breeding, and how these dynamics are linked to variation in ecology including exposure and vegetation. Interestingly, we find major differences between this system and our previously studied populations of the species, which opens up for exciting comparative research. We aim to combine field studies at Hitra with experimental lab studies at the NTNU Sealab facility. We also hope to extend the project to include populations further south and north, in order to analyse large-scale effects of climate and ecology.

 

Collaborations

 

We collaborate with a range of scientists with complementary competence nationally and internationally (currently Sweden, Finland, Denmark, UK, Germany, USA, Australia, Argentine)