Personality-dependent Dispersal Research Articles

Sociability interacts with temporal environmental variation to spatially structure metapopulations: A fish dispersal simulation in an ephemeral landscape

Metapopulation structure emerges from the dispersal of individuals among spatially distinct patches across a low-quality matrix. While dispersing agents are typically modeled as functionally identical with limited, linear and non-directional dispersal, field studies argue for the incorporation of intraspecific trait variation, such as behavioral, into the modeling of dispersal. Individual personality is of growing interest as a trait that affects dispersal metrics yet remains understudied at large, field-relevant spatial scales. Here, we used an individual-based model to investigate the influence of sociability, a personality-type known to be linked to density-dependent dispersal decisions, on a metapopulation at the individual, local and regional scales. As personality dependent dispersal is temporally dependent, we also examined how emergent properties of the metapopulation varied across two dispersal scenarios: long and short dispersal windows. Overall, our results support the growing evidence that individual personalities can significantly structure metapopulations in both space and time, through negative relationships between sociability and dispersal distance and positive relationships between sociability and patch density. However, we also demonstrate the effects of personality are limited by environmental factors. At the larger spatial scales of our model, patch density as a function of distance from source, and proportion of the landscape occupied were more strongly influenced by the dispersal window than by the personality. Using these results, we derive hypotheses to be examined in future empirical research. As the climate continues to shift, and dispersal models are updated to reflect ever changing conditions, these results suggest individual personality types and the personality type by environment interaction should be considered to accurately reflect dispersal and manage valuable metasystems.

Aggression mediates dispersal tendency in an invasive lizard

Personality-dependent dispersal is a key ecological and evolutionary process that is likely to facilitate the successful movement and colonization/invasion success of species. This dispersal syndrome suggests that dispersers should possess a suite of behavioural tendencies that differ from those of nondispersers, thus influencing the composition of populations in the new range and, ultimately, colonization success. However, dispersal is also often condition dependent, and is probably mediated by the interaction between an individual's personality and environmental and social factors such as competition. Accordingly, we investigated whether dispersal tendency was linked to an activity, exploration and social syndrome and/or aggression in a reptile, the delicate skink, Lampropholis delicata, which has had a successful invasion history via accidental introductions. Contrary to our prediction, we found that dispersal was not related to activity, exploration or social personality traits. Instead, dispersal tendency was associated with aggression: the most aggressive individuals dispersed further and faster than less aggressive individuals. The presence of aggression-dependent dispersal could be due to either (1) dispersers generally being more aggressive than nondispersers or (2) aggressive individuals forcing nonaggressive individuals into hiding, thus impinging on the ability of subordinates to disperse regardless of their personality. Our study highlights the need to consider the ecological context when examining personality-dependent dispersal and suggests that aggression and the social environment can play an important role in dispersal decisions.

Investigating movement behavior of invasive Burmese pythons on a shy–bold continuum using individual-based modeling

Burmese pythons are established in the Everglades and are expanding their population in Florida to more urbanized and fragmented habitats. Understanding movement and dispersal behavior contributes to our knowledge of how landscape factors influence the persistence of pythons in Florida's habitat. Our goal was to examine personality-dependent dispersal in juvenile Burmese pythons by creating behavioral scenarios of risk-taking behavior on a shy–bold continuum using an individual-based model. We observed that a behaviorally plastic strategy best resembled empirically derived patterns of the Burmese python's expansion from the Everglades into the increasingly urbanized landscapes of Homestead and Miami, Florida. This result is consistent with the notion that animal personalities can be flexible in different situations and that animals must make decisions based on trade-offs while dispersing.

What's your move? Movement as a link between personality and spatial dynamics in animal populations.

Recent studies have established the ecological and evolutionary importance of animal personalities. Individual differences in movement and space-use, fundamental to many personality traits (e.g. activity, boldness and exploratory behaviour) have been documented across many species and contexts, for instance personality-dependent dispersal syndromes. Yet, insights from the concurrently developing movement ecology paradigm are rarely considered and recent evidence for other personality-dependent movements and space-use lack a general unifying framework. We propose a conceptual framework for personality-dependent spatial ecology. We link expectations derived from the movement ecology paradigm with behavioural reaction-norms to offer specific predictions on the interactions between environmental factors, such as resource distribution or landscape structure, and intrinsic behavioural variation. We consider how environmental heterogeneity and individual consistency in movements that carry-over across spatial scales can lead to personality-dependent: (1) foraging search performance; (2) habitat preference; (3) home range utilization patterns; (4) social network structure and (5) emergence of assortative population structure with spatial clusters of personalities. We support our conceptual model with spatially explicit simulations of behavioural variation in space-use, demonstrating the emergence of complex population-level patterns from differences in simple individual-level behaviours. Consideration of consistent individual variation in space-use will facilitate mechanistic understanding of processes that drive social, spatial, ecological and evolutionary dynamics in heterogeneous environments.

Personality-dependent dispersal cancelled under predation risk

Dispersal is a fundamental life-history trait for many ecological processes. Recent studies suggest that dispersers, in comparison to residents, display various phenotypic specializations increasing their dispersal inclination or success. Among them, dispersers are believed to be consistently more bold, exploratory, asocial or aggressive than residents. These links between behavioural types and dispersal should vary with the cause of dispersal. However, with the exception of one study, personality-dependent dispersal has not been studied in contrasting environments. Here, we used mosquitofish (Gambusia affinis) to test whether personality-dependent dispersal varies with predation risk, a factor that should induce boldness or sociability-dependent dispersal. Corroborating previous studies, we found that dispersing mosquitofish are less social than non-dispersing fish when there was no predation risk. However, personality-dependent dispersal is negated under predation risk, dispersers having similar personality types to residents. Our results suggest that adaptive dispersal decisions could commonly depend on interactions between phenotypes and ecological contexts.

Seasonal- and sex-specific correlations between dispersal and exploratory behaviour in the great tit

While the importance of personality in explaining individual dispersal strategies is increasingly recognized, limited information is still available on how patterns of personality-dependent dispersal may develop, hampering our understanding of the ecological significance of behavioural dispersal syndromes. Here, we examine the relative importance of personality at different stages of dispersal in the great tit, by analysing the sex-specific relationship between exploratory behaviour (EB; quantified in a novel environment) and dispersal distances in different seasons over the course of the first year of life (summer, autumn, winter, and until the first breeding attempt). In females, we found that EB was an important predictor of dispersal distances in summer and autumn, but only a weak to moderate correlation remained for females captured in winter or for natal dispersal distances based on first breeding records. We obtained a contrasting pattern at the population level, whereby male (but not female) immigrants captured in summer and autumn had higher EB scores than locally born birds, while this was not the case in birds captured in winter and those recruited as breeders into the population. In addition to providing further evidence for the existence of a behaviour dispersal syndrome in birds, our results show that correlations between EB and dispersal appear strongest at the early stages of the dispersal process, rather than being developed gradually. These findings show the importance of analysing the effect of phenotypic attributes on dispersal across different stages of the dispersal phenomenon and in each sex separately.

Individual sociability and choosiness between shoal types

In social species, individual and group fitness and social dynamics in groups often depend on group size and on the group's social composition (e.g. the mix of personality types within groups). In turn, the size and social composition of groups is an emergent outcome of the grouping tendencies of individuals. While grouping behaviour has often been studied at a species level, within-species variation in grouping tendency has rarely been studied. We examined the role of personality type in shoaling preferences in a social fish, the western mosquitofish, Gambusia affinis. After scoring individuals for their social personality types (sociability), we gave individuals the choice to associate with shoals that differed in size and in the average sociability of individuals in the shoal. Shoal preferences depended on both the individual's sociability and on shoal size and composition in sociability types, and on the interaction between the individual's sociability and shoal size and composition. On average, fish preferred large to small shoals and groups made up of social individuals to groups made of asocial individuals at least when shoal size was small. Individual sociability types were linked to the time individuals spent far from any shoal and to consistent differences in choosiness about social contexts. Asocial individuals shoaled less and swam more between shoals than social ones, but preferred large shoals during the short time that they shoaled. These results can help explain patterns of group size and composition and individual and population-level personality-dependent dispersal.

Personality-dependent dispersal: characterization, ontogeny and consequences for spatially structured populations.

Dispersal is one of the most fundamental components of ecology, and affects processes as diverse as population growth, metapopulation dynamics, gene flow and adaptation. Although the act of moving from one habitat to another entails major costs to the disperser, empirical and theoretical studies suggest that these costs can be reduced by having morphological, physiological or behavioural specializations for dispersal. A few recent studies on different systems showed that individuals exhibit personality-dependent dispersal, meaning that dispersal tendency is associated with boldness, sociability or aggressiveness. Indeed, in several species, dispersers not only develop behavioural differences at the onset of dispersal, but display these behavioural characteristics through their life cycle. While personality-dependent dispersal has been demonstrated in only a few species, we believe that it is a widespread phenomenon with important ecological consequences. Here, we review the evidence for behavioural differences between dispersers and residents, to what extent they constitute personalities. We also examine how a link between personality traits and dispersal behaviours can be produced and how personality-dependent dispersal affects the dynamics of metapopulations and biological invasions. Finally, we suggest future research directions for population biologists, behavioural ecologists and conservation biologists such as how the direction and the strength of the relationship between personality traits and dispersal vary with ecological contexts.

Personality-dependent dispersal in the invasive mosquitofish: group composition matters.

Understanding/predicting ecological invasions is an important challenge in modern ecology because of their immense economical and ecological costs. Recent studies have revealed that within-species variation in behaviour (i.e. animal personality) can shed light on the invasion process. The general hypothesis is that individuals' personality type may affect their colonization success, suggesting that some individuals might be better invaders than others. We have recently shown that, in the invasive mosquitofish (Gambusia affinis), social personality trait was an important indicator of dispersal distance, with more asocial individuals dispersing further. Here, we tested how mean personality within a population, in addition to individual personality type, affect dispersal and settlement decisions in the mosquitofish. We found that individual dispersal tendencies were influenced by the population's mean boldness and sociability score. For example, individuals from populations with more asocial individuals or with more bold individuals are more likely to disperse regardless of their own personality type. We suggest that identifying behavioural traits facilitating invasions, even at the group level, can thus have direct applications in pest management.

Personality traits and dispersal tendency in the invasive mosquitofish (Gambusia affinis)

Ecological invasions, where non-native species spread to new areas, grow to high densities and have large, negative impacts on ecological communities, are a major worldwide problem. Recent studies suggest that one of the key mechanisms influencing invasion dynamics is personality-dependent dispersal: the tendency for dispersers to have a different personality type than the average from a source population. We examined this possibility in the invasive mosquitofish (Gambusia affinis). We measured individual tendencies to disperse in experimental streams and several personality traits: sociability, boldness, activity and exploration tendency before and three weeks after dispersal. We found that mosquitofish display consistent behavioural tendencies over time, and significant positive correlations between all personality traits. Most notably, sociability was an important indicator of dispersal distance, with more asocial individuals dispersing further, suggesting personality-biased dispersal on an invasion front. These results could have important ecological implications, as invasion by a biased subset of individuals is likely to have different ecological impacts than invasion by a random group of colonists.