Freshwater pearl mussels show plasticity of responses to different predation risks but also show consistent individual differences in responsiveness

Animals often show behavioural plasticity with respect to predation risk but also show behavioural syndromes in terms of consistency of responses to different stimuli. We examine these features in the freshwater pearl mussel. These bivalves often aggregate presumably to reduce predation risk to each individual. Predation risk, however, will be higher in the presence of predator cues. Here we use dimming light, vibration and touch as novel stimuli to examine the trade-off between motivation to feed and motivation to avoid predation. We present two experiments that each use three sequential novel stimuli to cause the mussels to close their valves and hence cease feeding. We find that mussels within a group showed shorter closure times than solitary mussels, consistent with decreased vulnerability to predation in group-living individuals. Mussels exposed to the odour of a predatory crayfish showed longer closures than control mussels, highlighting the predator assessment abilities of this species. However, individuals showed significant consistency in their closure responses across the trial series, in line with behavioural syndrome theory. Our results show that bivalves trade-off feeding and predator avoidance according to predation risk but the degree to which this is achieved is constrained by behavioural consistency. © 2011 Elsevier B.V.

Do consistent individual differences in metabolic rate promote consistent individual differences in behavior?

Consistent individual differences (CIDs) in behavior are a widespread phenomenon in animals, but the proximate reasons for them are unresolved. We discuss evidence for the hypothesis that CIDs in energy metabolism, as reflected by resting metabolic rate (RMR), promote CIDs in behavior patterns that either provide net energy (e.g. foraging activity), and/or consume energy (e.g. courtship activity). In doing so, we provide a framework for linking together RMR, behavior, and life-history productivity. Empirical studies suggest that RMR is (a) related to the capacity to generate energy, (b) repeatable, and (c) correlated with behavioral output (e.g. aggressiveness) and productivity (e.g. growth). We conclude by discussing future research directions to clarify linkages between behavior and energy metabolism in this emerging research area.

Individual and sex-specific differences in intrinsic growth rate covary with consistent individual differences in behaviour

1.The evolutionary causes of consistent individual differences in behavior are currently a source of debate. A recent hypothesis suggests that consistent individual differences in life-history productivity (growth and/or fecundity) may covary with behavioral traits that contribute to growth-mortality trade-offs, such as risk-proneness (boldness) and foraging activity (voraciousness). It remains unclear, however, to what extent individual behavioral and life-history profiles are set early in life, or are a more flexible result of specific environmental or developmental contexts that allow bold and active individuals to acquire more resources. 2.Longitudinal studies of individually housed animals under controlled conditions can shed light on this question. Since growth and behaviour can both vary within individuals (they are labile), studying between-individual correlations in behaviour and growth rate requires repeated scoring for both variables over an extended period of time. However, such a study has not yet been done. 3.Here, we repeatedly measured individual mass 7-times each, boldness 40-times each, and voracity 8-times each during the first four months of life on 90 individually-housed crayfish (Cherax destructor). Animals were fed ad-libitum, generating a context where individuals can express their intrinsic growth rate (i.e. growth capacity), but in which bold and voracious behaviour is not necessary for high resource acquisition (crayfish can and do hoard food back to their burrow). 4.We show that individuals that were consistently bold over time during the day were also bolder at night, were more voracious, and maintained higher growth rates over time than shy individuals. Independent of individual differences, we also observed that males were faster growing, bolder, and more voracious than females. 5.Our findings imply that associations between bold behaviour and fast growth can occur in unlimited food contexts where there is no necessary link between bold behaviour and resource acquisition - offering support for the 'personality- productivity' hypothesis. We suggest future research should study links between consistent individual differences in behaviour and life-history under a wider range of contexts, in order to shed light on the role of biotic and abiotic conditions in the strength, direction and stability of their covariance. This article is protected by copyright. All rights reserved.

To boldly go: individual differences in boldness influence migratory tendency

Partial migration, whereby only a fraction of the population migrates, is thought to be the most common type of migration in the animal kingdom, and can have important ecological and evolutionary consequences. Despite this, the factors that influence which individuals migrate and which remain resident are poorly understood. Recent work has shown that consistent individual differences in personality traits in animals can be ecologically important, but field studies integrating personality traits with migratory behaviour are extremely rare. In this study, we investigate the influence of individual boldness, an important personality trait, upon the migratory propensity of roach, a freshwater fish, over two consecutive migration seasons. We assay and individually tag 460 roach and show that boldness influences migratory propensity, with bold individuals being more likely to migrate than shy fish. Our data suggest that an extremely widespread personality trait in animals can have significant ecological consequences via influencing individual-level migratory behaviour.

Are most samples of animals systematically biased? Consistent individual trait differences bias samples despite random sampling

Sampling animals from the wild for study is something nearly every biologist has done, but despite our best efforts to obtain random samples of animals, ‘hidden’ trait biases may still exist. For example, consistent behavioral traits can affect trappability/catchability, independent of obvious factors such as size and gender, and these traits are often correlated with other repeatable physiological and/or life history traits. If so, systematic sampling bias may exist for any of these traits. The extent to which this is a problem, of course, depends on the magnitude of bias, which is presently unknown because the underlying trait distributions in populations are usually unknown, or unknowable. Indeed, our present knowledge about sampling bias comes from samples (not complete population censuses), which can possess bias to begin with. I had the unique opportunity to create naturalized populations of fish by seeding each of four small fishless lakes with equal densities of slow-, intermediate-, and fast-growing fish. Using sampling methods that are not size-selective, I observed that fast-growing fish were up to two-times more likely to be sampled than slower-growing fish. This indicates substantial and systematic bias with respect to an important life history trait (growth rate). If correlations between behavioral, physiological and life-history traits are as widespread as the literature suggests, then many animal samples may be systematically biased with respect to these traits (e.g., when collecting animals for laboratory use), and affect our inferences about population structure and abundance. I conclude with a discussion on ways to minimize sampling bias for particular physiological/behavioral/life-history types within animal populations.

Individual differences in learning from worked examples by senior secondary mathematics students

The primary purpose of this research was to examine individual differences in learning from worked examples. By integrating cognitive style theory and cognitive load theory, it was hypothesised that an interaction existed between individual cognitive style and the structure and presentation of worked examples in their effect upon subsequent student problem solving. In particular, it was hypothesised that Analytic-Verbalisers, Analytic-Imagers, and Wholist-lmagers would perform better on a posttest after learning from structured-pictorial worked examples than after learning from unstructured worked examples. For Analytic-Verbalisers it was reasoned that the cognitive effort required to impose structure on unstructured worked examples would hinder learning. Alternatively, it was expected that Wholist-Verbalisers would display superior performances after learning from unstructured worked examples than after learning from structured-pictorial worked examples. The images of the structured-pictorial format, incongruent with the Wholist-Verbaliser style, would be expected to split attention between the text and the diagrams. The information contained in the images would also be a source of redundancy and not easily ignored in the integrated structured-pictorial format. Despite a number of authors having emphasised the need to include individual differences as a fundamental component of problem solving within domainspecific subjects such as mathematics, few studies have attempted to investigate a relationship between mathematical or science instructional method, cognitive style, and problem solving. Cognitive style theory proposes that the structure and presentation of learning material is likely to affect each of the four cognitive styles differently. No study could be found which has used Riding's (1997) model of cognitive style as a framework for examining the interaction between the structural presentation of worked examples and an individual's cognitive style. 269 Year 12 Mathematics B students from five urban and rural secondary schools in Queensland, Australia participated in the main study. A factorial (three treatments by four cognitive styles) between-subjects multivariate analysis of variance indicated a statistically significant interaction. As the difficulty of the posttest components increased, the empirical evidence supporting the research hypotheses became more pronounced. The rigour of the study's theoretical framework was further tested by the construction of a measure of instructional efficiency, based on an index of cognitive load, and the construction of a measure of problem-solving efficiency, based on problem-solving time. The consistent empirical evidence within this study that learning from worked examples is affected by an interaction of cognitive style and the structure and presentation of the worked examples emphasises the need to consider individual differences among senior secondary mathematics students to enhance educational opportunities. Implications for teaching and learning are discussed and recommendations for further research are outlined.

Coping strategies used by ballet dancers : effects of individual differences in competitive trait anxiety

The world of classical ballet exerts considerable physical and psychological stress upon those who participate, and yet the process of coping with such stressors is not well understood. The purpose of the present investigation was to examine relationships between coping strategies and competitive trait anxiety among ballet dancers. Participants were 104 classical dancers (81 females and 23 males) ranging in age from 15 to 35 years (M = 19.4 yr., SD = 3.8 yr.) from three professional ballet companies, two private dance schools, and two full-time, university dance courses in Australia. Participants had a mean of 11.5 years of classical dance training (SD = 5.2 yr.), having started dance training at 6.6 years of age (SD = 3.4 yr.). Coping strategies were assessed using the Modified COPE scale (MCOPE: Crocker & Graham, 1995), a 48-item measure comprising 12 coping subscales (Seeking Social Support for Instrumental Reasons, Seeking Social Support for Emotional Reasons, Behavioral Disengagement, Planning, Suppression of Competing Activities, Venting of Emotions, Humor, Active Coping, Denial, Self-Blame, Effort, and Wishful Thinking). Competitive trait anxiety was assessed using the Sport Anxiety Scale (SAS: Smith, Smoll, & Schutz, 1990), a 21-item measure comprising three anxiety subscales (Somatic Anxiety, Worry, Concentration Disruption). Standard multiple regression analyses showed that trait anxiety scores, in particular for Somatic Anxiety and Worry, were significant predictors of seven of the 12 coping strategies (Suppression of Competing Activities: R2 = 27.1%; Venting of Emotions: R2 = 23.2%; Active Coping: R2 = 14.3%; Denial: R2 = 17.7%; Self-Blame: R2 = 35.7%; Effort: R2 = 16.6%; Wishful Thinking: R2 = 42.3%). High trait anxious dancers reported more frequent use of all categories of coping strategies. A separate two-way MANOVA showed no significant main effect for gender nor status (professional versus students) and no significant interaction effect. The present findings are generally consistent with previous research in the sport psychology domain (Crocker & Graham, 1995; Giacobbi & Weinberg, 2000) which has shown that high trait anxious athletes tend, in particular, to use more maladaptive, emotion-focused coping strategies when compared to low trait anxious athletes; a tendency which has been proposed to lead to negative performance effects. The present results emphasize the need for the effectiveness of specific coping strategies to be considered during the process of preparing young classical dancers for a career in professional ballet. In particular, the results suggest that dancers who are, by nature, anxious about performance may need special attention to help them to learn to cope with performance-related stress. Given the absence of differences in coping strategies between student and professional dancers and between males and females, it appears that such educational efforts should begin at an early career stage for all dancers.

Validating the use of intrinsic markers in body feathers to identify inter‑individual differences in non‑breeding areas of northern fulmars

Many wildlife studies use chemical analyses to explore spatio-temporal variation in diet, migratory patterns and contaminant exposure. Intrinsic markers are particularly valuable for studying non-breeding marine predators, when direct methods of investigation are rarely feasible. However, any inferences regarding foraging ecology are dependent upon the time scale over which tissues such as feathers are formed. In this study, we validate the use of body feathers for studying non-breeding foraging patterns in a pelagic seabird, the northern fulmar. Analysis of carcasses of successfully breeding adult fulmars indicated that body feathers moulted between September and March, whereas analyses of carcasses and activity patterns suggested that wing feather and tail feather moult occurred during more restricted periods (September to October and September to January, respectively). By randomly sampling relevant body feathers, average values for individual birds were shown to be consistent. We also integrated chemical analyses of body feather with geolocation tracking data to demonstrate that analyses of δ13C and δ15N values successfully assigned 88 % of birds to one of two broad wintering regions used by breeding adult fulmars from a Scottish study colony. These data provide strong support for the use of body feathers as a tool for exploring non-breeding foraging patterns and diet in wide-ranging, pelagic seabirds.

Are individual differences in temperament of relevance to Gibson's theory of affordances?

The ambitious scope, complexity, and difficulty of Gibson’s project in proposing the theory of affordances are captured nicely by the words of Gibson’s biographer, Ed Reed:
“Gibson was convinced that the theory of affordances, in
conjunction with the concepts of information, persistence, and
change, would enable him to transcend the ancient debate between
subjectivity and objectivity and to resolve the mind-body problem. …
[H]e was offering a new approach to problems of psychology, one
that he believed would not sink in the morass that have engulfed
previous psychologies.” (Reed, 1988, p. 280).
These characteristics of the theory of affordances are further evidenced in the debates about the nature of affordances presented in the suite of papers in Ecological Psychology, Volume 12(1). In this paper we propose an elaboration of the notion of affordance by suggesting that those persisting individual differences in behaviour described as temperamental differences (e.g., differences on a dimension of temperament anchored at one end by behaviour described as ‘outgoingness’ and at the other by behaviour described as ‘avoidance’) can be integrated into the theory of affordances. We argue that such integration is consistent with Gibson’s project as reflected in Reed’s words, and as part of our argument, draw parallels between the integration of temperament with the theory of affordances and the way in which individual differences in body dimensions are incorporated in the theory. We also outline some empirical tests of our proposition.

Testing dynamic variance-sensitive foraging using individual differences in basal metabolic rates of zebra finches

Social foragers can alternate between searching for food (producer tactic), and searching for other individuals that have located food in order to join them (scrounger tactic). Both tactics yield equal rewards on average, but the rewards generated by producer are more variable. A dynamic variance-sensitive foraging model predicts that social foragers should increase their use of scrounger with increasing energy requirements and/or decreased food availability early in the foraging period. We tested whether natural variation in minimum energy requirements (basal metabolic rate or BMR) is associated with differences in the use of producer–scrounger foraging tactics in female zebra finches Taeniopygia guttata. As predicted by the dynamic variance-sensitive model, high BMR individuals had significantly greater use of the scrounger tactic compared with low BMR individuals. However, we observed no effect of food availability on tactic use, indicating that female zebra finches were not variance-sensitive foragers under our experimental conditions. This study is the first to report that variation in BMR within a species is associated with differences in foraging behaviour. BMR-related differences in scrounger tactic use are consistent with phenotype-dependent tactic use decisions. We suggest that BMR is correlated with another phenotypic trait which itself influences tactic use decisions.

Individual Differences in First and Fourth Year College Women’s Short Term Mating Strategy Preferences and Perceptions

Using survey methodology, a cross sectional study was undertaken to ascertain whether first and fourth year college women have different perceptions and behavior associated with short term mating preferences. It was hypothesized that after incurring significant negative or costly experiences associated with hooking up, fourth year women would prefer men who had qualities associated with a desired long term partner as opposed to characteristics associated with short term mating partners. The results were partially consistent with the hypothesis. Reported preferences in a desired partner and perspective on hooking up differ between first and fourth year groups. No difference was found between frequency and willingness to hookup between the two groups. The findings are explained in terms of evolutionary theory, social exchange theory, and sexual script concepts.

Individual differences in first and fourth year college women’s short term mating strategy preferences and perceptions

Using survey methodology, a cross sectional study was undertaken to ascertain whether first and fourth year college women have different perceptions and behavior associated with short term mating preferences. It was hypothesized that after incurring significant negative or costly experiences associated with hooking up, fourth year women would prefer men who had qualities associated with a desired long term partner as opposed to characteristics associated with short term mating partners. The results were partially consistent with the hypothesis. Reported preferences in a desired partner and perspective on hooking up differ between first and fourth year groups. No difference was found between frequency and willingness to hookup between the two groups. The findings are explained in terms of evolutionary theory, social exchange theory, and sexual script concepts.

Neuroanatomy of intergroup bias: A white matter microstructure study of individual differences

Intergroup bias - the tendency to behave more positively towards an ingroup member than an outgroup member - is a powerful social force, for good and ill. And though it is widely demonstrated, intergroup bias is not universal, as it is characterized by significant individual differences. Recently, attention has begun to turn to whether neuroanatomy might explain these individual differences in intergroup bias. However, no research to date has examined whether white matter microstructure could help determine differences in behavior towards ingroup and outgroup members. In the current research, we examine intergroup bias with the third-party punishment paradigm and white matter integrity and connectivity strength as determined by diffusion tensor imaging (DTI). We found that both increased white matter integrity at the right temporal-parietal junction (TPJ) and connectivity strength between the right TPJ and the dorsomedial prefrontal cortex (DMPFC) were associated with increased impartiality in the third-party punishment paradigm, i.e., reduced intergroup bias. Further, consistent with the role that these brain regions play in the mentalizing network, we found that these effects were mediated by mentalizing processes. Participants with greater white matter integrity at the right TPJ and connectivity strength between the right TPJ and the DMPFC employed mentalizing processes more equally for ingroup and outgroup members, and this non-biased use of mentalizing was associated with increased impartiality. The current results help shed light on the mechanisms of bias and, potentially, on interventions that promote impartiality over intergroup bias.

Individual differences in activity and habitat selection of juvenile queen conch evaluated using acceleration biologgers

Fine-scale differences in behaviour and habitat use have important ecological implications, but have rarely been examined in marine gastropods. We used tri-axial accelerometer loggers to estimate activity levels and movement patterns of the juvenile queen conch Lobatus gigas (n = 11) in 2 habitat types in Eleuthera, The Bahamas. In 2 manipulations in nearshore areas, queen conchs were equipped with accelerometers and released in adjacent coral rubble or seagrass habitats. Queen conchs were located approximately every 6 h during daylight by snorkeling, to measure individual differences in linear distance moved, and after 24 h they were relocated to an alternate habitat (24 h in each habitat). We found significant inter-individual variability in activity levels, but more consistent levels of activity between the 2 habitat types within individual queen conchs. Four (36%) of the individuals placed in seagrass moved back to the adjacent coral rubble habitat, suggesting selectivity for coral rubble. Individuals showed variable behavioural responses when relocated to the less preferable seagrass habitat, which may be related to differing stress-coping styles. Our results suggest that behavioural variability between individuals may be an important factor driving movement and habitat use in queen conch and, potentially, their susceptibility to human stressors. This study provides evidence of diverse behavioural (activity) patterns and habitat selectivity in a marine gastropod and highlights the utility of accelero meter biologgers for continuously monitoring animal behaviour in the wild.