The role of hair in swimming of laboratory mice: implications for behavioural studies in animals with abnormal hair

Animal swimming tests, such as the forced swim test, are extensively used in biomedical research to study rodent behaviour. Hair and skin exposed to water may be an important factor affecting the performance in this test. Since various hair and skin abnormalities are not uncommon in genetically modified or drug-treated laboratory animals, this test may be inappropriate for these animals. Because on occasions it is necessary to screen their swimming behaviour, in the present study we aimed to assess the role of hair in swimming of laboratory rodents in the forced swim test, widely used in behavioural research. For this, we shaved laboratory mice (129S1 strain) and compared their swimming patterns with those of unshaven controls. Overall, shaving mice did not affect their swimming behaviours in the 5 min forced swim test. Our results indicate that hair condition is not an important factor in the forced swim test for this mouse strain, and suggest that this test may have wider utility for behavioural analyses of mice with abnormal hair.     

The role of behavioral hyperactivation in the formation of anxiety in rodents]

Rodents are a useful tool for studying various stress behaviours, including anxious. Physiological arousal is traditionally thought to accompany anxiety in human and animals. The paper reviews behavioural and pharmacological data on effects of anxiety observed in rodents at different arousal levels. The results indicate that mild arousal might have "paradox" anti-anxiety effects on rodent behaviour while higher arousal level is a pro-anxiety factor. The concept of "pleasurable emotion" produced in rodents by mild arousal is supported.     

Ecological validity of social interaction tests in rats and mice

Different rat and mouse models are used in studies of social interactions. Simple behavioral measures, which are commonly used in the laboratory, allow to perform relatively short experiments and to use multiple brain manipulation techniques. However, too much focus on the simplest behavioral models generates a serious risk of reducing ecological validity or even studying phenomena which would never happen outside of the laboratory. In this review, we discuss the suitability of mice and rats as model organisms for studying social behaviors, with focus on social transmission of fear paradigms. First, we briefly introduce the concept of domestication and what impact it had on laboratory rodents. Then, we present two aspects of social behaviors, sociability and dominance, which are crucial for social organization in these species. Finally, we present experimental models used for studying how animals transmit information about danger between each other, and how these models may reflect what happens in the natural environment. We discuss the difficulties that arise from our limited knowledge of rat and mouse ecology, especially their social life. We also explore the subject of balancing ecological validity and controllability in rodent models of social behaviors, the latter being particularly important for studying brain activity. Although it is very challenging, an efficient program for social neuroscience research should, in our opinion, aim at bridging the gap between laboratory and field studies.     

The evolution of social behaviour in Blaberid cockroaches with diverse habitats and social systems: phylogenetic analysis of behavioural sequences

The adequacy and utility of behavioural characters in phylogenetics is widely acknowledged, especially for stereotyped behaviours. However, the most common behaviours are not stereotyped, and these are usually seen as inappropriate or more difficult to analyze in a phylogenetic context. A few methods have been proposed to deal with such data, although they have never been tested on samples larger than six species, which limits their evolutionary interest. In the present study, we perform behavioural observations on 13 cockroach species and derive behavioural phylogenetic characters with the successive event‐pairing method. We combine these characters with morphological and molecular data (approximately 6800 bp) in a phylogenetic study of 41 species. We then reconstruct ancestral states of the behavioural data to study evolution of social behaviour in these insects with regard to their social systems (i.e. solitary, gregarious, and subsocial) and diversity of habitat choice. We report for the first time that nonstereotyped behavioural data are adequate for phylogenetic analyses: they are no more homoplastic than traditional data, and support several phylogenetic relationships that we discuss. From an evolutionary perspective, we show that the solitary species Thanatophyllum akinetum does not display original behavioural interactions, suggesting phylogenetic inertia of interactive behaviours despite a radical change in social structure. Conversely, the subsocial species Parasphaeria boleiriana shows original behavioural interactions, which could result from its peculiar social system or habitat. We conclude that phylogenetic approaches in studies of behaviour are useful for deciphering evolution of behaviour and discriminating between its different modalities, even for nonstereotyped characters. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 58–77.     

Correlational selection does not explain the evolution of a behavioural syndrome

Correlated suites of behaviours, or behavioural syndromes, appear to be widespread, and yet few studies have explored how they arise and are maintained. One possibility holds that correlational selection can generate and maintain behavioural syndrome if certain behavioural combinations enjoy greater fitness than other combinations. Here we test this correlational selection hypothesis by comparing behavioural syndrome structure with a multivariate fitness surface based on reproductive success of male water striders. We measured the structure of a behavioural syndrome including dispersal ability, exploration behaviour, latency to remount and sex recognition sensitivity in males. We then measured the relationship between these behaviours and mating success in a range of sex ratio environments. Despite the presence of some significant correlational selection, behavioural syndrome structure was not associated with correlational selection on behaviours. Although we cannot conclusively reject the correlational selection hypothesis, our evidence suggests that correlational selection and resulting linkage disequilibrium might not be responsible for maintaining the strong correlations between behaviours. Instead, we suggest alternative ways in which this behavioural syndrome may have arisen and outline the need for physiological and quantitative genetic tests of these suggestions.     

鸟类社会行为中的嗅觉通讯研究进展

长期以来, 学者普遍认为大多数鸟类的嗅觉能力较弱或丧失。早期实验未能得到统一而清晰的结果, 进一步扩大了这一认知误区。随着研究手段和技术的发展, 解剖学、电生理学、分子生物学和行为生态学等学科提供了鸟类嗅觉存在的证据。目前, 相关研究在鸟类14目33科中发现了嗅觉通讯的证据。与视觉和听觉一样, 这一感觉通路可能在鸟类的觅食、导航、防御、隐蔽、警戒和交流等社会行为中发挥着重要作用。本文着重于嗅觉通讯在鸟类社会行为中的功能, 通过回顾近十年的相关研究, 综述鸟类嗅觉在物种和个体识别、繁殖行为、亲缘识别、配偶选择与竞争等方面发挥的作用。我们也指出: 研究手段的创新将揭示更多鸟类物种在社会行为中对于嗅觉通讯的运用。此外, 当前研究多聚焦于少数物种和单一层面(如生理、生态和环境等), 使用分子生物学、解剖与生理学、行为学和神经生物学手段的整合研究较为缺乏; 而后者更有可能全面地揭示鸟类嗅觉通讯的复杂机理及其在社会行为中发挥的多种功能。     

Evidence of social niche construction: persistent and repeated social interactions generate stronger personalities in a social spider

While there are now a number of theoretical models predicting how consistent individual differences in behaviour may be generated and maintained, so far, there are few empirical tests. The social niche specialization hypothesis predicts that repeated social interactions among individuals may generate among-individual differences and reinforce within-individual consistency through positive feedback mechanisms. Here, we test this hypothesis using groups of the social spider Stegodyphus mimosarum that differ in their level of familiarity. In support of the social niche specialization hypothesis, individuals in groups of spiders that were more familiar with each other showed greater repeatable among-individual variation in behaviour. Additionally, individuals that were more familiar with each other exhibited lower within-individual variation in behaviour, providing one of the first examples of how the social environment can influence behavioural consistency. Our study demonstrates the potential for the social environment to generate and reinforce consistent individual differences in behaviour and provides a potentially general mechanism to explain this type of behavioural variation in animals with stable social groups.     

Validating standardised personality tests under semi‐natural conditions in wild house mice (Mus musculus domesticus)

Personality traits in animals are often measured using standardised behavioural tests for activity, boldness/shyness, sociability, aggression and exploration. These tests are quick and convenient, as well as easy to repeat. As the interest in studying the impact of animal personality on ecological and evolutionary consequences has been growing rapidly, there is increasing focus on cross‐validating measurements taken during these tests with behaviours shown under natural situations. In our experiment, we aimed to study the relationship between standardised measurements for activity, exploration and anxiety‐like behaviour measured in Open Field, Novel Object and Elevated Plus Maze tests with exploration and colonisation in semi‐natural conditions. We carried out a semi‐natural enclosure experiment in parallel with standardised behavioural tests, creating a scenario similar to an invasion or dispersal event. We compared behaviours in standardised tests and in enclosures for animals of two populations of wild house mice (Mus musculus domesticus). Several behavioural variables taken during the standardised tests, such as distance moved and time spent with novel object, were negatively correlated with space‐use in the enclosure while being highly positively correlated among each other. Based on their relationship with space use, we refer to behavioural measurements from standardised tests as activity/exploration. The time spent near the walls in an open field, probably reflecting anxiety, was not correlated to any other variable or the behaviour in the enclosure. In addition, we found differences in activity/exploration behaviour between the two populations in the standardised tests, but not during the colonisation of the novel environment. These results emphasise that researchers have to be careful when trying to extrapolate behaviour shown in standardised laboratory test setups to more natural, ecologically relevant situations. This has to be taken into account in distantly related species but even when studying the wild relative of laboratory rodents, for which these standardised tests have originally been developed.     

Experimental study of the behavioural mechanisms underlying self-organization in human crowds

In animal societies as well as in human crowds, many observed collective behaviours result from self-organized processes based on local interactions among individuals. However, models of crowd dynamics are still lacking a systematic individual-level experimental verification, and the local mechanisms underlying the formation of collective patterns are not yet known in detail. We have conducted a set of well-controlled experiments with pedestrians performing simple avoidance tasks in order to determine the laws ruling their behaviour during interactions. The analysis of the large trajectory dataset was used to compute a behavioural map that describes the average change of the direction and speed of a pedestrian for various interaction distances and angles. The experimental results reveal features of the decision process when pedestrians choose the side on which they evade, and show a side preference that is amplified by mutual interactions. The predictions of a binary interaction model based on the above findings were then compared with bidirectional flows of people recorded in a crowded street. Simulations generate two asymmetric lanes with opposite directions of motion, in quantitative agreement with our empirical observations. The knowledge of pedestrian behavioural laws is an important step ahead in the understanding of the underlying dynamics of crowd behaviour and allows for reliable predictions of collective pedestrian movements under natural conditions.     

Economic behaviours among non-human primates

Do we have any valid reasons to affirm that non-human primates display economic behaviour in a sufficiently rich and precise sense of the phrase? To address this question, we have to develop a set of criteria to assess the vast array of experimental studies and field observations on individual cognitive and behavioural competences as well as the collective organization of non-human primates. We review a sample of these studies and assess how they answer to the following four main challenges. (i) Do we see any economic organization or institutions emerge among groups of non-human primates? (ii) Are the cognitive abilities, and often biases, that have been evidenced as underlying typical economic decision-making among humans, also present among non-human primates? (iii) Can we draw positive lessons from performance comparisons among primate species, humans and non-humans but also across non-human primate species, as elicited by canonical game-theoretical experimental paradigms, especially as far as economic cooperation and coordination are concerned? And (iv) in which way should we improve models and paradigms to obtain more ecological data and conclusions? Articles discussed in this paper most often bring about positive answers and promising perspectives to support the existence and prevalence of economic behaviours among non-human primates.This article is part of the theme issue ‘Existence and prevalence of economic behaviours among non-human primates’.     

Social ontogeny and behavioural diversity: consequences for Bighorn sheep Oris canadensis inhabiting desert and mountain environments

The development of social behaviour was studied in three natural populations of Bighorn sheep ( Ovis canadensis ). Individuals in all populations exhibited the same behavioural repertoires, but the utilization of specific behaviours among both infants and adults differed between populations. It was suggested that differences in the adult utilization of behaviour patterns result in part from behaviours used during infancy. In turn, the social and physical environments affected the development of subsequent behaviour patterns in sheep older than lambs.
Desert sheep (in southern California) used mounting behaviours often, presumably because they matured sexually at an early age. Sheep in a more northern environment (British Columbia) used different behaviour patterns more frequently perhaps as a consequence of interactions experienced in larger bands. Additionally, playful interactions were reduced due to physical hazards in the desert, but they were at least nine times as frequent in the northern study population. Play in large groups resulted in the utilization of more different kinds of behaviour patterns. These behavioural findings are interpreted ecologically as consequences of inhabiting environments that differ socially and physically.     

Taste aversion induced by confinement in a running wheel

Behavioural lateralisation, which has been postulated to be an individual personality trait, is related to the activity of various physiological systems including the immune system. As lateralisation has been related to anxiety, which is known to influence immune reactivity, it can be hypothesized that the relation between lateralisation and immune reactivity involves individual behavioural patterns as they appear in exploratory-based anxiety models. In order to answer this question, a behavioural investigation focussing on exploratory activity was undertaken in male and female C3H mice previously selected for their paw preference. The observations were performed using two generic paradigms: elevated plus-maze and open field. Exploratory behaviour in the open field, but not in the plus-maze, was influenced by the interactive effect of gender and behavioural lateralisation. A significant difference between male and female mice was found in left-pawed but not in right-pawed nor ambidextrous animals, left-pawed female mice displaying the less exploratory behaviours. These results provide a first evidence of inter-individual variations in exploratory behaviours involving interaction between gender and lateralisation.     

Enriched environments, experience-dependent plasticity and disorders of the nervous system

Behavioural, cellular and molecular studies have revealed significant effects of enriched environments on rodents and other species, and provided new insights into mechanisms of experience-dependent plasticity, including adult neurogenesis and synaptic plasticity. The demonstration that the onset and progression of Huntington's disease in transgenic mice is delayed by environmental enrichment has emphasized the importance of understanding both genetic and environmental factors in nervous system disorders, including those with Mendelian inheritance patterns. A range of rodent models of other brain disorders, including Alzheimer's disease and Parkinson's disease, fragile X and Down syndrome, as well as various forms of brain injury, have now been compared under enriched and standard housing conditions. Here, we review these findings on the environmental modulators of pathogenesis and gene-environment interactions in CNS disorders, and discuss their therapeutic implications.     

Social Interactions of Yearling Male Fallow Deer during Rut

Despite a low probability of achieving copulations, yearling male (1.5-year-old) fallow deer Dama dama display behavioural changes during rut, interacting with both females and older males. Juvenile interactions in polygynous ungulates may affect further reproductive success through both motor training for future interactions and/or competition for current resources that affect growth. To test this hypothesis, we intensively studied the behaviour of 12 yearling males in two captive populations during a rutting season. Interactions with females were interpreted as motor training aimed at learning to recognize oestrous females, because yearling males rarely interacted with their mother and because interactions essentially consisted of olfactory investigations focused on oestrous females. Because agonistic interactions with older males never involved physical contact and were mainly initiated by the most dominant buck in each population, we concluded that these interactions resulted from the presence of the yearlings close to oestrous females defended by rutting males. Heavier yearlings tended to be dominant over lighter ones and tended to interact more frequently with other animals, suggesting that early growth may influence the ontogeny of social behaviours.     

Early Olfactory Environment Influences Social Behaviour in Adult Octodon degus

We evaluated the extent to which manipulation of early olfactory environment can influence social behaviours in the South American Hystricognath rodent Octodon degus. The early olfactory environment of newborn degus was manipulated by scenting all litter members with eucalyptol during the first month of life. The social behaviour of sexually mature animals (5–7 months old) towards conspecifics was then assessed using a y-maze to compare the response of control (naïve) and treated animals to two different olfactory configurations (experiment 1): (i) a non-familiarized conspecific impregnated with eucalyptol (eucalyptol arm) presented against (ii) a non-familiarized unscented conspecific (control arm). In addition, in dyadic encounters, we assessed the behaviour of control and eucalyptol treated animals towards a non-familiarized conspecific scented with eucalyptol (experiment 2). We found that control subjects explored and spent significantly less time in the eucalyptol arm, indicating neophobic behaviours towards the artificially scented conspecific. Treated subjects explored and spent similar time in both arms of the maze, showing the same interest for both olfactory stimuli presented. During dyadic encounters in experiment 2, an interaction effect between early experience and sex was observed. Control males escaped and avoided their scented partner more frequently than eucalyptol treated male subjects and than females. Both groups did not differ in the exploration of their scented partners, suggesting that avoidance within agonistic context does not relate to neophobic behaviours. Our results suggest that the exposure to eucalyptol during early ontogeny decreases evasive behaviours within an agonistic context as a result of olfactory learning. Altogether, these results indicate that olfactory cues learned in early ontogeny can influence olfactory-guided behaviours in adult degus.     

啮齿动物的嗅觉通讯研究进展

通过对近40 年来啮齿动物嗅觉通讯的研究综述, 主要介绍嗅觉信号的来源、组成及其对啮齿动物行为生理所产生的作用。啮齿动物嗅觉通讯的信号来源主要是粪便、尿液和特化皮肤腺等, 对这些化学信号的成分分析主要集中在各种信息素(Pheromone) 的结构、来源及其引起的行为反应。目前, 在对啮齿动物嗅觉通讯神经通路的研究中, 对主嗅觉系统和犁鼻器系统在动物嗅觉通讯中的作用仍将是人们研究的重点; 而通过信息素作用所产生的各种行为反应的神经内分泌机制也是动物嗅觉通讯领域研究的热点之一。研究气味信号对动物行为和生理等方面所产生的作用, 将有助于揭示啮齿动物嗅觉通讯在其社会行为中的重要作用。     

A screen for genes expressed in the olfactory organs of Drosophila melanogaster identifies genes involved in olfactory behaviour

Background

For insects the sense of smell and associated olfactory-driven behaviours are essential for survival. Insects detect odorants with families of olfactory receptor proteins that are very different to those of mammals, and there are likely to be other unique genes and genetic pathways involved in the function and development of the insect olfactory system.

Methodology/Principal Findings

We have performed a genetic screen of a set of 505 Drosophila melanogaster gene trap insertion lines to identify novel genes expressed in the adult olfactory organs. We identified 16 lines with expression in the olfactory organs, many of which exhibited expression of the trapped genes in olfactory receptor neurons. Phenotypic analysis showed that six of the lines have decreased olfactory responses in a behavioural assay, and for one of these we showed that precise excision of the P element reverts the phenotype to wild type, confirming a role for the trapped gene in olfaction. To confirm the identity of the genes trapped in the lines we performed molecular analysis of some of the insertion sites. While for many lines the reported insertion sites were correct, we also demonstrated that for a number of lines the reported location of the element was incorrect, and in three lines there were in fact two pGT element insertions.

Conclusions/Significance

We identified 16 new genes expressed in the Drosophila olfactory organs, the majority in neurons, and for several of the gene trap lines demonstrated a defect in olfactory-driven behaviour. Further characterisation of these genes and their roles in olfactory system function and development will increase our understanding of how the insect olfactory system has evolved to perform the same essential function to that of mammals, but using very different molecular genetic mechanisms.     

Recognizing odd smells and ejection of brood parasitic eggs. An experimental test in magpies of a novel defensive trait against brood parasitism

One of the most important defensive host traits against brood parasitism is the detection and ejection of parasitic eggs from their nests. Here, we explore the possible role of olfaction in this defensive behaviour. We performed egg‐recognition tests in magpie Pica pica nests with model eggs resembling those of parasitic great spotted cuckoos Clamator glandarius. In one of the experiment, experimental model eggs were exposed to strong or moderate smell of tobacco smoke, whereas those of a third group (control) were cleaned with disinfecting wipes and kept in boxes containing odourless cotton. Results showed that model eggs with strong tobacco scent were more frequently ejected compared with control ones. In another experiment, models were smeared with scents from cloacal wash from magpies (control), cloacal wash or uropygial secretions from cuckoos, or human scents. This experiment resulted in a statistically significant effect of treatment in unparasitized magpie nests in which control model eggs handled by humans were more often rejected. These results provide the first evidence that hosts of brood parasites use their olfactory ability to detect and eject foreign eggs from their nests. These findings may have important consequences for handling procedures of experimental eggs used in egg‐recognition tests, in addition to our understanding of interactions between brood parasites and their hosts.     

Plasticity of olfactory-guided behaviour and its neurobiological basis: lessons from moths and locusts

The sense of smell plays an important role in guiding the behaviour of many animals including insects. The attractiveness of a volatile is not only dependent on the nature of the chemical, but might change with the physiological status (e.g., age/hormone or mating status) or environmental conditions (e.g., photoperiod or temperature) of the individual. Here we summarize our studies focused on the plasticity of olfactory-guided behaviour and its neurobiological basis linked with the physiological status in Lepidoptera and migratory locusts. In moths and locusts, age and juvenile hormone changed the behavioural responses to pheromones. In moths, mating had an effect on pheromone responses in males and plant odour responses in females. In all cases of behavioural plasticity studied, we found changes in the sensitivity of olfactory interneurons in the antennal lobe, whereas the peripheral system does not seem to show any plasticity in that context. Changes in the central nervous system were slow under the influence of juvenile hormone (days) or fast after mating (minutes). The olfactory system seems thus to adapt to the physiological or environmental situation of an animal to avoid a waste of energy. We discuss possible mechanisms underlying the observed plasticity.     

Parent-offspring conflict and co-adaptation: behavioural ecology meets quantitative genetics

The evolution of the complex and dynamic behavioural interactions between caring parents and their dependent offspring is a major area of research in behavioural ecology and quantitative genetics. While behavioural ecologists examine the evolution of interactions between parents and offspring in the light of parent-offspring conflict and its resolution, quantitative geneticists explore the evolution of such interactions in the light of parent-offspring co-adaptation due to combined effects of parental and offspring behaviours on fitness. To date, there is little interaction or integration between these two fields. Here, we first review the merits and limitations of each of these two approaches and show that they provide important complementary insights into the evolution of strategies for offspring begging and parental resource provisioning. We then outline how central ideas from behavioural ecology and quantitative genetics can be combined within a framework based on the concept of behavioural reaction norms, which provides a common basis for behavioural ecologists and quantitative geneticists to study the evolution of parent-offspring interactions. Finally, we discuss how the behavioural reaction norm approach can be used to advance our understanding of parent-offspring conflict by combining information about the genetic basis of traits from quantitative genetics with key insights regarding the adaptive function and dynamic nature of parental and offspring behaviours from behavioural ecology.