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Stress coping styles in response to high densities in invasive populations of the round goby (Neogobius melanostomus) in the Baltic Sea
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.ORCID iD: 0000-0002-5050-2880
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Over the past decade, individual differences in behavior have gained much interest in the context of species invasions. Certain behavioral traits, such as e.g. aggression, have been suggested to facilitate invasion success and a number of studies have found founding populations at invasion fronts to be a non-random sample of behavioral types from their source populations. In many animals, behavioral and physiological responses to challenge are connected, forming stress coping styles. However, there is a lack of studies considering the role of physiological stress response or coping styles during species invasions. Therefore we investigated the connection between aggression and stress response to high densities, in four invasive round goby (Neogobius melanostomus) populations of different age. We found the

first evidence for stress coping styles in round gobies, as individuals with a low stress response to high densities are also more aggressive. We did not find an effect of population age, likely because the youngest populations used were already too old, meaning that traits selected for at invasion fronts had started to fade out. Given that individual levels of aggression and stress tolerance are dependent on one another, and aggression has previously been identified as an important facilitator of dispersal and invasion success, stress coping styles should be an important factor during species invasions. 

Keyword [en]
round goby, Neogobius melanostomus, aggression, plasma cortisol, species invasions, stress-tolerance
National Category
URN: urn:nbn:se:umu:diva-111909OAI: diva2:873982
Available from: 2015-11-25 Created: 2015-11-25 Last updated: 2015-11-26
In thesis
1. Round goby invasion of the Baltic Sea: the role of phenotypic variation
Open this publication in new window or tab >>Round goby invasion of the Baltic Sea: the role of phenotypic variation
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Biological invasions are a major threat to biodiversity world wide with annual economic costs up to 1.4 trillion dollars. The round goby (Neogobius melanostomus) is a particularly fierce invader that threatens ecological function of the Baltic Sea. Individual variation in behavioral traits that remain constant through time and context have been identified as crucial factors for explaining different parts of the invasion process. For example, asocial behavior facilitates dispersal from high density populations and comes with fitness benefits in low conspecific density. The latter is especially relevant, in an invasion context, following the initial colonization of a novel environment when population density usually is low.

This thesis investigates the role of individual variation in phenotypic traits on species invasions. The main focus is on the effects of sociability, activity and boldness, but also including aggression and physiological stress tolerance, on dispersal tendency and selection at invasion fronts. To do this, we studied four round goby populations in the Baltic Sea, two of the most recently established and two of the oldest populations.

In 2012 we demonstrated that asocial, active and bold round gobies are overrepresented at invasion fronts. Two years later we showed that dispersal from the new populations was led by individuals with high activity levels, while in all populations larger individuals dispersed. We also determined the length of the socalled lag-phase, between colonization and spread, in both newly established populations. The end of the lag-phase is hypothesized being triggered by high population density in the harbors leading to dispersal and subsequen colonization of the surrounding areas by small asocial individuals. In our final experiment, we present evidence of stress coping styles in round gobies, in which more aggressive individuals are also more stress tolerant and vice versa. Though we found no connection between stress coping and population age, we found that mortality was unaffected by population density and that the gobies became more aggressive and stress tolerant when kept in high density.

To conclude, we have shown that: 1) individuals with high levels of activity, boldness and asociality are common at invasion fronts; 2) a lag phase occurs between colonization and spread in round goby invasions; 3) asocial individuals drive the spread from high density populations at the invasion front and; 4) round gobies adapt to high densities with high aggression and stress tolerance. 

Place, publisher, year, edition, pages
Umeå: Umeå University, 2015. 40 p.
Round goby (Neogobius melanostomus), behaviour, animal personality, dispersal, species invasions, colonisation, spread, sociability, activity, boldness, aggression, cortisol coping-styles
National Category
Research subject
urn:nbn:se:umu:diva-111910 (URN)978-91-7601-328-1 (ISBN)
Public defence
2015-12-18, KB3B1, Linnaeus väg 6, Umeå, 09:00 (English)
Available from: 2015-11-27 Created: 2015-11-25 Last updated: 2015-11-26Bibliographically approved

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