Emergence of Individuality in Genetically Identical Mice

Simple SummaryThe aim of this study was to determine how individual differences in behavior affect disease risk in Holstein dairy cows housed in two different social environments: (1) a predictable and non-competitive social environment and (2) an unpredictable and competitive social environment. Individual differences in feed intake and feeding behavior before calving were associated with cytological endometritis post-calving; however, the direction and magnitude of these effects were dependent on the social environment. These results provide the first evidence that individual differences in feeding behavior affect cytological endometritis risk differently depending on the social environment.Our aim was to determine whether individual differences in feeding and social behavior in different social environments affect health outcomes in dairy cows. We used eight groups of four animals per treatment assigned to either a ‘predictable’ or an ‘unpredictable’ and competitive social environment. Predictable cows were given free access to six feed bins with no change in feed delivery times; whereas, the unpredictable cows were required to share one feed bin with one resident cow and morning feed was delayed 0, 1, 2, or 3 h every other day. On alternate days, the unpredictable cows were also re-assigned to a new bin and a new resident partner. Low daily dry matter intake (DMI) was a risk factor for cytological endometritis in predictable cows (odds ratio (OR) (95% confidence interval): 0.17 (0.02, 0.53)), but low daily DMI was protective for unpredictable cows (OR: 1.93 (1.09, 4.14)). Although low rate of DMI (kg/min) was a risk factor for cytological endometritis for predictable cows (OR: 4.2 × 10−101 (8.6 × 10−206, 4.8 × 10−30)) it was unrelated to disease for unpredictable cows. There were no associations between feed bin visits or percentage of non-nutritive visits with the likelihood of cytological endometritis. This is the first evidence that individual differences in feeding behavior influence cytological endometritis risk in dairy cows, but the direction and magnitude of these effects is dependent on the social environment.

Competition among mammalian carnivores can be particularly intense and can influence population dynamics at lower trophic levels. One strategy employed by carnivores to minimize potentially costly interspecific competition is avoidance of dominant species. Recent research has highlighted the importance of consistent individual differences in behavior (i.e. temperament traits) in understanding behavioral variation during predator–prey interactions and intraspecific interactions. However, the importance of such individual differences to interspecific competition has received little attention. Here, we examined the responses of spotted hyenas (Crocuta crocuta) to their primary competitors, African lions (Panthera leo), to (1) determine whether hyenas avoid lions and (2) evaluate the potential importance of individual differences in behavior during interspecific competition. Spotted hyenas and lions co‐occur throughout much of Africa and are vigorous competitors. Whereas lions sometimes kill hyenas and steal their food, lions also represent a source of food for hyenas via scavenging. Using audio playback experiments, we found that hyenas do not uniformly avoid potential encounters with lions. Indeed, we noted considerable variation among individuals in their responses to lion roars, and this variation reflected consistent individual differences in risk‐taking and vigilance tendencies. Individual differences in vigilance behavior were specific to interactions with lions. We conclude that individual differences in behavior have the potential to play an important role in determining the nature and outcome of interspecific competition.

Individual differences in behavior and heart rate variability across the preweaning period in the domestic horse in response to an ecologically relevant stressor

Do all you can to minimize dangerous behaviors to benefit communities, employees, and organizations!Safety is a “real world” problem that community psychologists, industrial/organizational psychologists, industrial hygenists, human resources professionals, and corporate insurance groups must deal with on a day-to-day basis. In Workplace Safety: Individual Differences in Behavior you will examine safety behavior and discover practical interventions to help increase the safety awareness of the people in your life. This book takes a look at ways of defining and measuring safety as well as a variety of individual differences like gender, job knowledge, conscientiousness, self-efficacy, risk avoidance, and stress tolerance that are important in creating safety interventions and improving the selection and training of employees.Workplace safety is of prime importance in today's increasingly litigious society. It has been estimated that each year in the United States, there are 100,000 work-related accident or disease fatalities, 400,000 workers who become disabled, and 6 million workplace injuries. Of equal importance are driver safety and safety hazards in public spaces such as malls and individual stores. Workplace Safety: Individual Differences in Behavior examines: the importance of measurement in understanding worker abilities and defining safety behaviors the often-neglected issue of gender differences in safety definitions and research the relationship between personality variables, job, knowledge, and accident involvement the five-factor personality model for predicting safety behavior a model of safety consciousness types of safety hazards in public spaces monetary costs of accidents in malls and stores a practitioner's perspective on individual differences in safety behaviorWorkplace Safety: Individual Differences in Behavior takes an incisive look at these issues with a unique focus on the way individual differences in people impact safety behavior in the real world.

Daily rhythms in mammals are controlled by the circadian system, which is a collection of biological clocks regulated by a central pacemaker within the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. Changes in SCN function have pronounced consequences for behaviour and physiology; however, few studies have examined whether individual differences in circadian behaviour reflect changes in SCN function. Here, PERIOD2::LUCIFERASE mice were exposed to a behavioural assay to characterize individual differences in baseline entrainment, rate of re-entrainment and free-running rhythms. SCN slices were then collected for ex vivo bioluminescence imaging to gain insight into how the properties of the SCN clock influence individual differences in behavioural rhythms. First, individual differences in the timing of locomotor activity rhythms were positively correlated with the timing of SCN rhythms. Second, slower adjustment during simulated jetlag was associated with a larger degree of phase heterogeneity among SCN neurons. Collectively, these findings highlight the role of the SCN network in determining individual differences in circadian behaviour. Furthermore, these results reveal novel ways that the network organization of the SCN influences plasticity at the behavioural level, and lend insight into potential interventions designed to modulate the rate of resynchronization during transmeridian travel and shift work.

Strong personalities, not social niches, drive individual differences in social behaviours in sticklebacks

Individuals may vary consistently in their architectural makeup of the constructions they build, which might have tremendous implications for their ecology and fitness. In particular, the relationship between individual differences in architectural constructions and behavior (i.e., animal personalities) is largely unexplored. Individual black widow spiders, Latrodectus hesperus, build a 3D cobweb made up of distinctive components serving to support foraging (gumfooted lines) or antipredator protection (structural lines). To explore the relationship between individual differences in behavior and architectural constructions, we quantified 1) the level of consistent individual variation in several elements of web structure and 2) the level of consistent individual variation in foraging behavior and its relationship with web structure. We controlled for condition-dependent or environmental effects by satiating all spiders prior to assays and maintaining them in standardized conditions. Spiders exhibited consistent differences in the number of gumfooted lines they built for capturing preys and overall web weight, but not in the number of structural lines. Individuals also varied consistently in their tendency to attack a prey cue, despite all spiders being satiated. Finally, spiders producing more gumfooted lines exhibited a higher tendency to attack the prey cue. Our results suggest that the architectural constructions may impact the expression of individual behavioral differences (or animal personalities) and suggest that individual behavior and extended phenotype may be part of alternative foraging strategies in L. hesperus.

Animal personality

Virtually all aspects of human development are subject to both genetic (i.e., heritable) and environmental influences that conjointly shape developmental outcomes through various mechanisms of gene-environment interplay. This special issue presents new research examining how the peer environment works together with genetic factors to influence children's and adolescents' social development. To this end, three studies utilize a quantitative genetic approach, whereas two others use molecular genetic methodologies. Covering a wide age range from early childhood to early adulthood, the studies examine different processes of gene-environment correlation and gene-environment interaction while focusing on dyadic and group-based peer experiences (e.g., friendships, peer acceptance, and peer victimization) as well as on positive and negative aspects of social development (e.g., prosocial leadership and aggression). Overall, the findings from the studies in this special issue clearly illustrate that we need to consider how genetics and the peer environment effects work together if we are to gain a more complete picture of children's and adolescents' social development.It is with great pleasure that I present this special issue: 'The Interplay Between Genetic Factors and the Peer Environment in Explaining Children's Social Adjustment. While the study of human development was long dominated by a mainly environment-focused behavioral perspective, there is now a wide consensus that virtually all aspects of human development are subject to both genetic (i.e., heritable) and environmental influences. However, the scientific study of heritability in individual differences in human behavior is not a recent phenomenon but began more than a hundred years ago. First evidence that individual differences in intelligence and behavior are heritable was provided by Charles Darwin's cousin, Sir Francis Galton (1822-1911), in his article Hereditary Talents and Character (Rushton, 1990). Galton was also the first to use a twin design to disentangle the effects of heritable and environmental factors on individual differences in behavior. The term genetics emerged only in 1909 with the rediscovery of Mendel's laws.Quantitative genetic studies based on twin, family, or adoption designs were the main tool of research into human behavioral genetics for several decades. In contrast to molecular genetic studies, quantitative genetic studies do not measure specific genes and often do not even include any specific measure of the environment. Instead, the relative strength of genetic and environmental effects is statistically inferred by examining the similarity of family members with varying degrees of genetic relatedness, such as identical and fraternal twins (Falconer, 1996). Findings from such studies have shown that basically all facets of human development, including social behavior such as aggression or withdrawal, are influenced by both genetic and environmental factors (Turkheimer, 2000). Now, advances in molecular genetics and the completion of the DNA sequencing of the human genome (Collins, Morgan, & Patrinos, 2004) make it possible to identify specific genes implicated in interindividual differences in social behavior. Many scholars initially expected that genetic and environmental influences on human development work independently of each other (Kidd, 1991). Others have argued, however, that genes and environments are likely to interact as well as to influence each other reciprocally (Allen, Knobloch, & Pasamanick, 1961; Plomin, DeFries, & Loehlin, 1977; Scarr & McCartney, 1983). In line with this notion, there is now a growing body of research showing that genetic and environmental effects work together to shape behavioral development through various mechanisms of gene-environment interplay.Most studies on the interplay of genetic factors with the social environment have focused on the family environment such as parenting behavior or child maltreatment (Bellani, Nobile, Bianchi, Van Os, & Brambilla, 2012; Burt, Klahr, Neale, & Klump, 2013; Thapar, Harold, Rice, Langley, & O'Donovan, 2007). …

In recent years, many studies have investigated the potential state dependence of individual differences in behaviour, with the aim to understand the proximate and ultimate causes and consequences of animal personality. Among the potential state variables that could affect behavioural expression is size and mass, but few studies have found associations at the among-individual levels. Insufficient sampling and incorrect analysis of data are cited as impediments to detecting correlations, if they exist. Here, we conducted a study using 100 pillbugs (Armadillidium vulgare) and assayed their defensive behaviour 24 times each over time and across familiarity contexts, to test the asset protection hypothesis that predicts a negative correlation between boldness and mass, and with increases in mass over time. Multivariate mixed models revealed that despite mostly consistent individual behavioural differences over time (modest slope variance) and across contexts (near-parallel reaction norms), and 18-fold range in starting mass, there was no correlation between individual mean mass and boldness. However, individuals that gained more mass over time may have been more ‘shy’ compared to those gaining less mass, but the correlation was weak and observed variation in mass gain was small. There was also a mean level trend of increasing shyness over time that was coincident with mean level mass increases over time. Together, our study provides weak evidence for the asset protection hypothesis, whereby individuals that accumulate more resources are thought to protect them through risk averse behaviour.Significance statementIndividual variation in ‘state’, such as mass or energy reserves, is thought to be a predictor of individual differences in behaviour that are consistent over time. However, few studies reveal such links, and several studies suggest insufficient sampling may explain null results in most studies. We studied 100 animals sampled 24 times each in a controlled setting to reveal stable individual differences in mean behaviour over time and across contexts; however, individual behaviour was unrelated to large differences in individual mass but weakly related to increases in mass through time whereby individuals became more shy and those growing faster were somewhat more shy. Our results provide little evidence for the asset protection hypothesis.

Individual differences in the attack behavior of male mice: A function of attack stimulus and hormonal state

Although most mammals grow up in the company of same or different age sibs (or half sibs), surprisingly little attention has been given to how relations among them might influence the development of individual differences in morphology, physiology, and behavior. Here we review evidence from our work on domestic and wild European rabbits, and more recently on laboratory rats, mice, and domestic cats, supporting the proposition that in mammals early sibling relations contribute to the development of individual differences in these three domains and thereby to long-term behavioral differences of the kind we might consider part of an animal's behavioral style or personality. First we report a consistent and marked negative relation between litter size and individuals' body mass at birth and weaning, as well as marked within-litter differences in prenatal body mass and placental efficiency. We then report individual differences in preweaning behaviors associated with these morphological variables such as position occupied in the litter huddle and development of motor ability, as well as physiological differences in thermoregulation, immune parameters, and endocrine indicators of stress. Finally, we report first evidence from wild rabbits that early relations among littermates may have long-term consequences for individual differences in behavioral style. We conclude that in mammals, individual differences in early growth, physiology and behavior potentially important for the development of animal personality, are shaped to an appreciable extent by early sibling relations and that this little-researched field deserves closer attention.

The understanding of consistent individual differences in behavior, often termed “personality,” for adapting and coping with threats and novel environmental conditions has advanced considerably during the last decade. However, advancements are almost exclusively associated with higher‐order animals, whereas studies focusing on smaller aquatic organisms are still rare. Here, we show individual differences in the swimming behavior of Daphnia magna, a clonal freshwater invertebrate, before, during, and after being exposed to a lethal threat, ultraviolet radiation (UVR). We show consistency in swimming velocity among both mothers and daughters of D. magna in a neutral environment, whereas this pattern breaks down when exposed to UVR. Our study also, for the first time, illustrates how the ontogenetic development in swimming and refuge‐seeking behavior of young individuals eventually approaches that of adults. Overall, we show that aquatic invertebrates are far from being identical robots, but instead they show considerable individual differences in behavior that can be attributed to both ontogenetic development and individual consistency. Our study also demonstrates, for the first time, that behavioral consistency and repeatability, that is, something resembling “personality,” is context and state dependent in this zooplankter taxa.

Individual differences in the behaviour of sows at the nest-site and the crushing of piglets

Simple SummaryAn important activity of modern animal shelters is the development of successful adoption programmes. In this regard, there is a need for reliable tests of individual differences in behaviour to help match the “personality” of potential adoptees with the lifestyle and needs of prospective owners; a companion animal for an elderly person remaining at home requires a different match than a pet for someone who will be away most of the day; a pet kept exclusively indoors in a small apartment requires a different match than an indoor/outdoor pet. In the present study, we repeatedly tested 31 mixed-breed adult cats of both sexes and a wide range of ages in five behavioural tests at a shelter in Mexico City, Mexico. The tests were designed to be easily implemented by shelter staff, and were short and low cost and intended to simulate common situations in a pet cat’s everyday life. We found consistent (stable) individual differences in the cats’ behaviour on all five tests, as well as correlations between their behaviour across tests. This suggests that such tests may contribute to reliably characterizing the “personality” of individual cats and so help increase the rate of successful adoptions. Consistent inter-individual differences in behaviour have been previously reported in adult shelter cats. In this study, we aimed to assess whether repeatable individual differences in behaviours exhibited by shelter cats in different situations were interrelated, forming behavioural syndromes. We tested 31 adult cats in five different behavioural tests, repeated three times each: a struggle test where an experimenter restrained the cat, a separation/confinement test where the cat spent 2 min in a pet carrier, a mouse test where the cat was presented with a live mouse in a jar, and two tests where the cat reacted to an unfamiliar human who remained either passive or actively approached the cat. Individual differences in behaviour were consistent (repeatable) across repeated trials for each of the tests. We also found associations between some of the behaviours shown in the different tests, several of which appeared to be due to differences in human-oriented behaviours. This study is the first to assess the presence of behavioural syndromes using repeated behavioural tests in different situations common in the daily life of a cat, and which may prove useful in improving the match between prospective owner and cat in shelter adoption programmes.