No description available.

Det tycks finnas ett starkt samband mellan en organisms kroppsmassa, aktivitetsnivå och metabolism (metabolic rate, MR) där en högre kroppsmassa och aktivitetsnivå korrelerar med ett högre MR. Hur är det då med en organisms personlighet och dess MR; spelar typen av personlighet hos organismen någon roll för dess MR? För att testa hypotesen att en mer aktiv personlighet, så som boldness, skulle uppvisa ett högre värde på MR i jämförelse mot en mer inaktiv personlighet, så som shyness, jämfördes personlighet, standard metabolic rate (SMR), maximal metabolic rate (MMR) och aerobic scope (MMR-SMR) hos den invasiva fiskarten svartmunnad smörbult (Neogobius melanostomus) insamlade från bräckvattenflodmynningen Guldborgsund i västra Östersjön. Totalt fångades ca 400 smörbultar, varav 19 individer genomgick hela studien. Personlighet bedömdes genom två olika försök, scototaxis och boldness, där individerna sedan delades in i personlighetsgrupperna bold och shy. SMR, MMR och aerobic scope analyserades fram genom respirometri. Ett t-test visade att det förekom en signifikant skillnad i SMR mellan de två personlighetstyperna (bold och shy), vilket man även funnit i tidigare studier (Toscano & Monacos, 2015). Ytterligare t-test visade att det dock inte fanns någon signifikant skillnad mellan vare sig MMR, aerobic scope eller vikten hos fiskarna av de två personligheterna. Sammanfattningsvis drogs slutsatsen att den signifikanta skillnaden i SMR mellan bold och shy individer, troligtvis grundade sig i att individer med högre andel boldness hade en högre energiförbrukning som kompensation för fenotypiska fördelar (som exempelvis i form av högre och lättare spridning) i jämförelse med individer med mindre boldness-karaktär. Fler studier på smörbult skulle dock behöva utföras, där man undersöker om det eventuellt finns samband mellan boldness och en högre spridning, för att kunna säkerställa ett sådant samband som vidare kan hjälpa oss i arbetet att minska spridningen av svartmunnad smörbult som invasiv art. / Previous studies have shown that there is a strong correlation between the body mass of an organism, activity level and metabolism (metabolic rate, MR) where a higher body mass and activity level correlate with a higher MR. How is it then with an organism's personality and its MR; does the type of personality of the organism play a part in its MR? To test the prediction that a more active personality, such as boldness, would show a higher value of MR in comparison to a more inactive personality, such as shyness, personality, standard metabolic rate (SMR), maximum metabolic rate (MMR) and aerobic scope (MMR-SMR) were compared for the invasive fish species round goby (Neogobius melanostomus) sampled from Guldborgsund in the Western Baltic. In total, about 400 round goby were captured, of which 19 individuals underwent the entire study. Personality was assessed by two different experiments, scototaxis and boldness, where the individuals then were divided into the personality groups bold and shy. SMR, MMR and aerobic scope were analyzed by respirometry. There was a significant difference in SMR between the two types of personality (bold and shy), which also has been found in previous studies (Toscano & Monacos, 2015). There were no significant differences between either MMR, aerobic scope or weight between bold and shy fish. In conclusion, the significant difference in SMR between bold and shy fishes, was probably based on the fact that individuals with a higher proportion of boldness had a higher energy consumption to compensate for the phenotypic benefits (such as higher and easier dispersibility) compared to individuals with less boldness. However, further studies on round goby would have to be performed to investigate whether there is a connection between boldness and a higher dispersibility.

No description available.

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.