Individual variation and limited plasticity in behavior are factors that have been shown to shape populations and determine how well individuals are doing in different stages of life. When salmon transform from parr to smolt and start the migration out to sea many factors together make an individual successful. The hypothesis of this study was that the boldness of individual smolt (1 and 2 year olds) is correlated to their inclination to migrate downstream. The study also investigated difference in boldness and migration tendency between 1- and two year old smolt. Today, some hatcheries release smolt as both one and two year old and it is important to know whether there is any difference in behavior and migration intensity between age classes in order to make stocking programs more effective. To determine if the individuals differed in boldness, and/or displayed a bold behavioral type, two assays were performed in different contexts (novel environment and simulated predatory attack). Downstream migratory intensity was, after behavior assays, quantified in an artificial stream. I found that: i) the one year old smolts tended to be bolder in a predatory response assay than two year old smolt, ii) one year old smolts migrated less in the artificial stream compared to two year old smolt. Being bolder can have an effect on several aspects connected to fitness in the salmon life cycle and could affect the survival of a smolt migrating out to sea, even though no correlations to inclination to downstream migration were found in this study.

Observations of consistency in behavioural responses in animals suggest that animals have personality, a term previously mainly used when describing humans. The expression of differences in personality, similar to expression of variation in behaviour, is in principle dependent on genetic background, environmental factors and experiences. Therefore, by estimating heritability one can determine to which extent the genes affect the phenotypic expression of behaviour. This has rarely been done for variation in animal personality. The aim of the present study was therefore to estimate the consistency and heritability of personality traits in red junglefowl chicks (Gallus gallus). Consistency of behaviours within individuals (n=100) was determined from their responses to repeated novel arena tests, novel object tests and tonic immobility tests. A comparison between the offspring and the parent generation, both with known personalities, through a linear regression enabled me to estimate heritability of behavioural responses in these birds. The results showed a consistency in exploratory, boldness, risk-taking behaviour, and fearfulness in red junglefowl. Additionally, heritability estimates for exploratory, risk-taking and foraging behaviours were found. Taken together, this shows that in the red junglefowl, similar to in other species, personality have both a heritable and an environmental component. An important aim in biology education is the scientific approach, where hypothesis, experimentation, processing results and discussing the results are in focus. Learning and gaining knowledge through the process is a key factor, and will hopefully increase the interest in science among Swedish pupils.

Urbanization is one of the major causes of the global biodiversity crisis with reptiles being particularly vulnerable, due to factors such as habitat loss and road mortality. Behaviour plays a crucial role in determining the success of urban animals, but behavioural responses to urbanization are rarely studied in reptiles. I studied the differences in aggression, boldness, and exploration in painted turtles (Chrysemys picta) living in urban and undisturbed areas. I hypothesized that aggression, boldness, and exploration would increase in urban painted turtles. I studied painted turtles from 24 sites across an urban to undisturbed gradient in Ottawa, Ontario, Canada over the summers of 2021 and 2022. I captured turtles with hoop nets and tested their behaviour in the field, and the repeatability of their behaviour in the laboratory. I found that urbanization had a statistically significant, positive effect on painted turtle aggression and boldness, and no effect on exploration. Overall, I determined that urbanization is affecting painted turtle behaviour, but further research is required to better understand the factors behind this.

No description available.

Investigators have shown that elephants exhibit consistent individual differences in behavior by rating elephants using personality adjectives. These adjectives, however, are not based on pre-defined measurements of the behaviors performed. Instead, they are based on the observers’ interpretations of an animal’s behavioral patterns, therefore making them subject to observer bias. Furthermore, elephants have a capacity for learning; thus, they may alter their behavioral patterns over time. This behavioral plasticity in itself might be a way of measuring consistent behavioral differences among individuals. With this in mind, I approached elephant personality as a multivariate problem. I used behavioral observations collected from female elephants in Addo Elephant National Park, South Africa. Instead of grouping behaviors into subjective categories prior to analysis (as is often done in studies of elephant behavior), I used ordination methods to determine which correlations among behaviors were important for defining personality. Ordination methods were performed on matrices of the behavior data set and on subsets of behaviors for each age class. I calculated the angular differences among major axes of covariation from the ordinations of subsets to determine if the behaviors that defined personalities differed by age class. I also defined personalities by centroids (in multidimensional space) for non-metric multidimensional scaling (NMDS) scores of each individual and dispersion of NMDS scores for each individual as a measure of behavioral plasticity. I analyzed the effects of plasticity and age on personality of individual elephants using a non-parametric multivariate analysis of variance. Major axes of covariation were not well defined and therefore not useful in describing differences among groups. The interaction of age and behavioral plasticity did have a significant effect on the personalities of individuals as defined by ordination centroid scores. This suggests that incorporating plasticity may be a helpful measurement in quantifying consistent behavioral differences among individuals.

Behavioural syndromes, defined as suites of correlated behaviours across different contexts, are used to characterize individual variability in behaviours. Males of the weakly electric fish species, Apteronotus leptorhynchus, produce electro-communication signals called chirps. Chirps are thought to be involved in agonistic signalling, as their relative incidence increases during agonistic conspecific interactions. However, high levels of individual variability in aggression obscure the role of chirps in mediating aggression. Here, I tested the presence of an aggression-boldness behavioural syndrome, and then considered the implications such a syndrome would have on chirping behaviours. Behavioural tests in anti-predation, object novelty, feeding, conspecific intrusion and novel environment exploration contexts revealed a syndrome involving only object novelty and feeding. We found no correlation between chirping behaviour and the assessed behaviours. Our results demonstrate that chirps represent a more complex communication system than previously suggested.

Behavioural syndromes, defined as suites of correlated behaviours across different contexts, are used to characterize individual variability in behaviours. Males of the weakly electric fish species, Apteronotus leptorhynchus, produce electro-communication signals called chirps. Chirps are thought to be involved in agonistic signalling, as their relative incidence increases during agonistic conspecific interactions. However, high levels of individual variability in aggression obscure the role of chirps in mediating aggression. Here, I tested the presence of an aggression-boldness behavioural syndrome, and then considered the implications such a syndrome would have on chirping behaviours. Behavioural tests in anti-predation, object novelty, feeding, conspecific intrusion and novel environment exploration contexts revealed a syndrome involving only object novelty and feeding. We found no correlation between chirping behaviour and the assessed behaviours. Our results demonstrate that chirps represent a more complex communication system than previously suggested.

Animal personality can be defined as a set of physiological and behavioral characteristics that differ between individuals, but are consistent over time and across situations. The evolution of individual differences in behavior that are consistent over time and situations is still not clear. Our understanding of why animals have personality can be improved by investigating the underlying physiological mechanisms of animal behavior. Serotonin is a key monoamine that serves as a physiological modulator of animal behavior. Selective serotonin reuptake inhibitors are a group of chemicals that increase levels of serotonin in the brain. Fluoxetine is one such chemical and is used to treat depression in humans. In the field cricket (Gryllus bimaculatus), increased levels of serotonin have been linked to higher activity and boldness, which are both personality traits. In the current study, the effects of induced serotonin on activity, exploration, boldness and aggression was investigated. My results show that injecting fluoxetine causes substantial changes in behavioral traits used to describe personality in field crickets. This result is opposite to previous studies, as serotonin induced individuals were less active, less explorative, and won less fights, compared to control individuals. This could be due to serotonin existing naturally within the circulatory system of the field cricket, whereas fluoxetine is a manufactured chemical intended for human receptors, or that fluoxetine has a similar effect in modulating personality in field crickets as in humans. Since fluoxetine acts similarly in field crickets as in humans, an increased understanding of the effects of induced serotonin on different behaviors in field crickets could be beneficial for treating psychological illnesses.

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.