Aggression and commensalism in house mouse: a comparative study across Europe and the near east

Species specific differences of house mouse social behavior compared to its closest relatives (aboriginal species Mus macedonicus, Mus spicilegus, and Mus spretus) have recently been suggested. However, substantial variation of behavioral traits between mouse populations has been also evidenced. Agonistic behavior of laboratory‐born house mice from five commensal populations (Mus musculus musculus: central Czech Republic, Mus musculus domesticus: Bulgaria, Greece, Turkey, and natural Mus m. musculus/domesticus hybrids from the Czech part of the hybrid zone) and five non‐commensal populations of M. m. domesticus (C. Syria, E. Syria, Jordan, Iran, Libya) was studied. Dyadic interactions in a neutral cage were performed and the effects of sex and population on time spent by agonistic behavior evaluated. In all studied populations, the male‐male interactions were more agonistic than the female‐female ones. Male‐male behavior gradually increased from the least agonistic population of M. m. musculus from Central Europe to the Near East populations of M. m. domesticus exhibiting the highest scores of agonistic behavior. Between‐population differences were even stronger when female‐female encounters were considered. While females of commensal populations belonging to both M. m. musculus and M. m. domesticus were tolerant of each other, those coming from non‐commensal populations of M. m. domesticus were highly agonistic, reaching even the level of aggression between the females of some aboriginal mouse species. This phenomenon may be attributed to increased competition for food in non‐commensal populations when compared to commensal ones supplied by superabundant resources. Social behavior of house mice, therefore, appears to be pliable rather than rigid and species specific. It can be changed rapidly according to ecological needs and such adaptability allows house mice to colonize various habitats. Aggr. Behav. 31:283–293, 2005. © 2005 Wiley‐Liss, Inc.     

Development of the Social Behavior of Two Mice Species With Contrasting Social Systems

The house mouse (Mus musculus) and the mound‐building mouse (M. spicilegus) differ in their mating and social systems. The M. musculus is polygynous and females tend to breed cooperatively while M. spicilegus is known to be monogamous and famous for its unique cooperative behavior; the communal overwintering. Mus spicilegus is considered as a highly aggressive species in the genus Mus. In the present study, we attempted to analyze the development of aggressive and sociable behavior in these species and to discover how familiarity with the target moderates the development of sociable and aggressive behaviors and moderates the differences between the species. Dyadic social interaction tests in neutral cages were performed on 21‐, 60‐, and 120‐day‐old mice of both genders and both species. Each individual was tested against a sibling and an unfamiliar individual at all three ages. Our results showed that the development of aggressive and sociable behavior with age differed between the species and sexes; however, familiarity with the other mouse moderated the effect of species on aggression. At 21 days, both genders of M. spicilegus were more aggressive against strangers than siblings. This became true of both species at 60 days. When facing a stranger, both sexes of M. spicilegus were more aggressive than M. musculus at 120 days. However, when facing a sibling, neither gender of M. spicilegus was more agonistic than M. musculus, indicating that either kinship or early social experiences elicit tolerance. Aggr. Behav. 38:288‐297, 2012. © 2012 Wiley Periodicals, Inc.     

Selective approach to a male and subsequent receptivity to mounting comprise mate‐choice behavior of female mice1

Abstract: To ensure the effectiveness of the mate‐choice behavior of female house mice (Mus domesticus), we observed them in two different situations that involved restriction of the area of movement of the male mice. In Experiment 1, we observed 12 trios consisting of two male mice and an estrous female placed in a chamber in which none of the animals was restricted during the 6‐h test. It was found that the female was more receptive to the male that had ejaculated with it first. Additionally, when the female initiated the mating event by approaching the male, the lordosis quotient was higher than that when the male initiated the mating event. In Experiment 2, a female was able to visit two males that were prevented from getting out of small boxes. As a result of the 3‐h observation of 10 cases, it was found that the females were more receptive to the dominant male. The intromission ratio of the dominant male was also higher than that of the subordinate male. The behavioral roles of female mice in mating interactions and their adaptive validity are discussed.     

Conflict and postconflict behaviour in two lemur species with different social organizations (Eulemur fulvus and Eulemur macaco): A study on captive groups

Although the brown lemur (Eulemur fulvus) and the black lemur (Eulemur macaco) share many life parameters and are genetically closed, they show considerable difference in social organization. Dominance relationships with no systematic effect of gender characterize the former, whereas the latter is based on female dominance. The present study was done on two captive groups of brown lemurs and one semi–free‐ranging group of black lemurs. To reveal links between the specific pattern of social organization and agonistic behaviors, agonistic interactions were analyzed for each species as for their context of occurrence, symmetry, initiation, and outcome. The effect of gender in the initiation of conflicts appeared as the only notable interspecific difference, aggression being mostly initiated by females in E. macaco and by males in E. fulvus. Conflict outcome was generally in favor of the initiator, regardless of gender in both species. The analysis of postconflict behaviors revealed conciliatory processes in the brown lemur, whereas reconciliation seemed to be absent in the black lemur, a characteristic shared with the ring‐tailed lemur (Lemur catta), another lemur species with female dominance. Aggr. Behav. 28:62–74, 2002. © 2002 Wiley‐Liss, Inc.     

Open-field nidus and pullusindices in Mus Musculus L.

Swiss albino mice ( Mus Musculus L. ) were studied in an open field (OF). The question whether laboratory rodents were more attracted to a nest equipped with familiar odoriferous cues from the home-cage bedding or to signals of an unfamiliar newborn pup inserted in the OF was addressed. The results of the three quantitatively recorded OF behaviors, ambulation, retrieval and radial latency , indicated that in females both ambulation and retrieval were enhanced by the presence of a pup in a nestless field; in males locomotion was suppressed by a nest in a pupless OF. In the case of both sexes radial latency was determined by the OF position of a nest. A comparison between the two qualitative assessments, the nidus and pullus indices, yielded that the sex of the adult and the OF positions of both targets equally impacted attraction towards both nest and pup.     

Short-term contact elicits heterospecific behavioral discrimination of individual odors in mound-building mice (Mus spicilegus)

The authors used a habituation-dishabituation procedure to test the ability of male mound-building mice (Mus spicilegus) to discriminate individual odors from males of another species of mouse. Male mound-building mice failed to spontaneously discriminate individual odors from Mus musculus musculus males, a natural competitor. After 24-hr contact with a male of one of the M. musculus subspecies (M. m. musculus or M. m. domesticus), experienced M. spicilegus males discriminated the individual odors of unfamiliar males of the same subspecies. These results confirm that discrimination of individual chemosignals is not confined to olfactory cues of a single species and provide new information about the effect of short-term contact on discrimination of individual odors across species.     

Social organization predicts nature of infant-adult interactions in two species of wild guinea pigs (Cavia aperea and Galea monasteriensis)

The authors compared interactions of infants with mothers and unfamiliar females in a novel environment in 2 caviomorph rodent species: the harem-living Cavia aperea, the probable progenitor of the domestic guinea pig; and the pair-living Galea monasteriensis. In C. aperea, interactions with mothers and unfamiliar females were largely similar; in G. monasteriensis, interactions with the mother, but not unfamiliar female, were characterized by physical closeness and sociopositive behavior. In G. monasteriensis, plasma cortisol levels were lower when with the mother than when with the unfamiliar female. Results are consistent with the species' social organizations and suggest that behavioral interactions of pups with mothers and other females in domestic guinea pigs reflect primarily the social organization of the progenitor species rather than domestication.     

Cleaner fish Labroides dimidiatus recognise familiar clients

Individual recognition has been attributed a crucial role in the evolution of complex social systems such as helping behaviour and cooperation. A classical example for interspecific cooperation is the mutualism between the cleaner fish Labroides dimidiatus and its client reef fish species. For stable cooperation to evolve, it is generally assumed that partners interact repeatedly and remember each other's past behaviour. Repeated interactions may be achieved by site fidelity or individual recognition. However, as some cleaner fish have more than 2,300 interactions per day with various individuals per species and various species of clients, basic assumptions of cooperation theory might be violated in this mutualism. We tested the cleaner L. dimidiatus and its herbivorous client, the surgeon fish Ctenochaetus striatus, for their ability to distinguish between a familiar and an unfamiliar partner in a choice experiment. Under natural conditions, cleaners and clients have to build up their relationship, which is probably costly for both. We therefore predicted that both clients and cleaners should prefer the familiar partner in our choice experiment. We found that cleaners spent significantly more time near the familiar than the unfamiliar clients in the first 2 minutes of the experiment. This indicates the ability for individual recognition in cleaners. In contrast, the client C. striatus showed no significant preference. This could be due to a sampling artefact, possibly due to a lack of sufficient motivation. Alternatively, clients may not need to recognise their cleaners but instead remember the defined territories of L. dimidiatus to achieve repeated interactions with the same individual. Electronic Publication     

A comparative study of rodent social behavior in a seminatural enclosure

Social behavior, aggression, and copulation were studied in six groups of two males and two females each in seven species of muroid rodents (Clethrionomys gapperi, Microtus montanus, M ochrogaster, M pennsylvanicus, Peromyscus eremicus, P leucopus, and P polionotus) in a seminatural enclosure. Data were compared to those from an earlier study with P maniculatus tested under identical conditions. There were appreciable species differences in levels of both aggressive and sexual behavior; the two were not significantly correlated. Although levels of aggression did not appear well correlated with reports of social structure in the field, patterns of weight loss and litter production during the study did appear correlated. In general, levels of copulatory behavior appeared weakly correlated with factors previously proposed as predictors of polygamous mating systems; levels of aggressive behavior were better correlated with taxonomy.     

The desire for sexual variety as a key to understanding basic human mating strategies

Different authors have proposed competing evolutionary theories of human mating. Some argue that both sexes are designed to pursue a singular long‐term mating strategy. Others contend that both sexes are designed to function as essentially multiple maters. Sexual Strategies Theory (SST; D.M. Buss & D.P. Schmitt, 1993), in contrast, proposes that men and women have evolved short‐term and long‐term mating strategies that are pursued differently by each sex depending on theoretically derived dimensions of context. According to SST, the sexes tend to differ in the nature and prominence of the short‐term component of human mating–particularly the short‐term desire for sexual variety. The current research was designed to test competing empirical predictions from these contrasting theories by focusing on sex differences in the desire for sexual variety. Study 1 (N= 1,049), consisting of five separate samples, found large and consistent sex differences in the desire for short‐term sexual variety, even after employing statistical methods to control for skewed distributions and statistical outliers. Study 2 (N= 192) confirmed the results of Study 1 using an older, more mature sample. Study 3 (N= 50) again replicated these sex differences using an observer‐based method of inquiry. Study 4 (N= 167) found evidence that short‐term mating was unrelated generally to psychological dysfunction and may be related to mentally healthy personality characteristics in men. Discussion focuses on the viability of pluralistic compared with monomorphic evolutionary theories of human mating strategies.     

No postnatal maternal effect on male aggressiveness in wild-derived strains of house mice

Male aggressiveness is a complex behavior influenced by a number of genetic and non-genetic factors. Traditionally, the contribution of each of these factors has been established from experiments using artificially selected strains for high/low aggressive phenotypes. However, little is known about the factors underlying aggressive behavior in natural populations. In this study, we assess the influence of genetic background vs. postnatal maternal environment using a set of cross-fostering experiments between two wild-derived inbred strains, displaying high (STRA, derived from Mus musculus domesticus) and low (BUSNA, derived from Mus musculus musculus) levels of aggressiveness. The role of maternal environment was tested in males with the same genetic background (i.e. strain origin) reared under three different conditions: unfostered (weaned by mother), infostered (weaned by an unfamiliar dam from the same strain), and cross-fostered (weaned by a dam from a different strain). All males were tested against non-aggressive opponents from the A/J inbred strain. Resource-holding potential was assessed through body weight gains and territory ownership. The STRA males were shown to be aggressive in both neutral cage and resident-intruder tests. On the contrary, the BUSNA males were less aggressive in all tests. We did not find a significant effect of postnatal maternal environment; however, we detected significant maternal effect on body weight with differences between the strains, fostering type and interactions between these factors. We conclude that the aggressiveness preserved in the two strains has significant genetic component whose genetic basis can be dissected by quantitative trait loci analysis.     

Analysis of the targets and tactics of conspecific attack and predatory attack in northern grasshopper mice onychomys leucogaster

Comparisons of tactics of fighting between species are often difficult to make since the body targets attacked may differ. Thus it becomes difficult to assess whether differences in fighting tactics are due to species-specific differences in the tactics themselves or due to the different targets attacked. A solution to this problem is to analyse the tactics of a species that attacks different targets under different circumstances. In this way, differences in tactics can be more readily attributed to differences in targets. In this study, resident male northern grasshopper mice (Onychomys leucogaster) were tested against intruding male conspecifics and against laboratory mice (Mus musculus domesticus). Conspecifics were mainly bitten on the lower dorsum, whereas prey were bitten and killed by bites to the nape of the neck. Therefore, it was possible to analyze the tactics of attack by grasshopper mice when attacking different body targets. For example, in order to defend the lower dorsum and the nape, both intruding conspecifics and prey adopted an upright defensive posture. Resident grasshopper mice used the lateral attack tactic to gain access to the lower flanks but not the nape. This illustrates that the lateral attack tactic is not merely a tactic suitable for overcoming the upright defense tactic, but is used in this context only when the target attacked is on the opponent's posterior dorsum. Such withinpecies comparison enables the identification of the contextual rules which govern the use of fighting tactics. © 1992 Wiley-Liss, Inc.     

Intrafemale agonistic interactions in the domestic rabbit (oryctolagus cuniculus L.)

Agonistic interactions between adult domestic rabbit females were observed. Females were housed in groups of four in outdoor enclosures measuring 4 × 4 m. Agonistic patterns included aggression (AG), flight (FL), and submission (SB). Observations focused on 1) initial interactions between unfamiliar females, concomitant with the formation and establishment of a social structure (Phase 1); and 2) interactions between familiar females organized in a stable social structure (Phase 2). AG was frequent between unfamiliar females and appeared related to the acquisition of social dominance. When social organization was settled, there was a dramatic reduction in the number and frequency of aggressive behaviors. Similarly, FL was more frequent when females were unfamiliar, but it did not appear to be merely a response to AG. The decreased frequency of both AG and FL in Phase 2 was paralleled by an increased frequency of SB with respect to FL. Under stable social conditions, subordinate females frequently signalled submission to dominant counterparts. In contrast, the latter did not signal their social status with any consistent behavioral pattern. It follows that SB was not necessarily induced as the appropriate response to aggression given by dominant females. Thus, SB appeared relevant in social communication especially in structured groups, where it conveyed information on the actor's subordination and possibly inhibited the receiver's aggression. A further possibility is that it has an autonomous rather than secondary role in the maintenance of stable dominance/subordination relationships.     

Gender differences in subjective well-being, self-esteem and psychosocial functioning in adolescents with symptoms of anxiety and depression: findings from the Nord-Trøndelag Health Study

Derdikman‐Eiron, R., Indredavik, M. S., Bratberg, G. H., Taraldsen, G., Bakken, I. J. & Colton, M. (2011). Gender differences in subjective well‐being, self‐esteem and psychosocial functioning in adolescents with symptoms of anxiety and depression: Findings from the Nord‐Trøndelag health study. Scandinavian Journal of Psychology52, 261–267. Gender differences in the prevalence of symptoms of anxiety and depression during adolescence are well documented. However, little attention has been given to differences in subjective well‐being, self‐esteem and psychosocial functioning between boys and girls with symptoms of anxiety and depression. The aim of this study was to investigate gender differences in the associations between such symptoms and subjective well‐being, self‐esteem, school functioning and social relations in adolescents. Data were taken from a major population‐based Norwegian study, the Nord‐Trøndelag Health study (HUNT), in which 8984 (91% of all invited) adolescents, aged 13–19 years, completed an extensive self‐report questionnaire. Although prevalence rates of symptoms of anxiety and depression were higher in girls than in boys, a significant interaction between gender and symptoms of anxiety and depression was found in respect of each of the following outcome variables: subjective well‐being, self‐esteem, academic problems, frequency of meeting friends and the feeling of not having enough friends. These interactions indicate that the associations between symptoms of anxiety and depression and lower subjective well‐being and self‐esteem, more academic problems in school and lower social functioning were stronger for boys than for girls. Our findings may contribute to an earlier assessment and more efficient treatment of male adolescent anxiety and depression.     

Assessing volunteer motives: a comparison of an open‐ended probe and Likert rating scales

The purpose of the present study was to compare the motives of volunteers (career, esteem, protective, social, understanding, and value) as assessed by an open‐ended probe and the Volunteer Functions Inventory (VFI) which employs a Likert rating scale. One‐hundred‐and‐twenty‐nine individuals, who volunteered for an organization that focuses on episodic volunteering in the community, completed both measures of volunteer motives and reported their frequency of volunteering for the organization. The Spearman rank correlation between the rankings of the six volunteer motives in the two distributions was 0.71. The maximum variance shared between the same motive as assessed by the two methods was 0.14. Frequency of volunteering for the organization was predicted by the value (positive predictor) and social (negative predictor) VFI scale scores. A post hoc analysis of the data from the open‐ended probe revealed three additional motives for volunteering—enjoyment, religiosity, and team building. Copyright © 2002 John Wiley & Sons, Ltd.     

Exploratory behavior of two species of murid rodents, Acomys cahirinus and Mus musculus: a comparative study

The exploratory behavior of two species of murid rodents, Acomys cahirinus and Mus musculus, was compared in four experiments: In the first, the responses of the two species to a novel arena were studied. Mus was found to take longer to enter the arena, and to spend more time in the relatively familiar or safer start box, than was Acomys. The results suggest that Acomys may persevere longer in exploring particular areas, whereas Mus appear to explore in the open arena by using frequent shifts of attention. The second experiment investigated species differences in response to the addition of a small novel object. Although the species did respond differently, the major species differences seemed to be related more to the open arena than to the object. The third experiment tested the hypothesis that both species would explore more if there was somewhere to hide (e.g., an artificial burrow) than if there was not. It was found that Acomys treated the available artificial burrow as another novel object, while Mus, as predicted, spent more time hiding inside it than did Acomys. The fourth experiment investigated burrow use when a model "predator" was introduced: Both species increased their use of the burrow but some species differences were found. Mus responded to the model more by freezing, or running immediately into the burrow; Acomys responded more by fleeing.     

The dark triad: Facilitating a short‐term mating strategy in men

This survey (N = 224) found that characteristics collectively known as the Dark Triad (i.e. narcissism, psychopathy and Machiavellianism) were correlated with various dimensions of short‐term mating but not long‐term mating. The link between the Dark Triad and short‐term mating was stronger for men than for women. The Dark Triad partially mediated the sex difference in short‐term mating behaviour. Findings are consistent with a view that the Dark Triad facilitates an exploitative, short‐term mating strategy in men. Possible implications, including that Dark Triad traits represent a bundle of individual differences that promote a reproductively adaptive strategy are discussed. Findings are discussed in the broad context of how an evolutionary approach to personality psychology can enhance our understanding of individual differences. Copyright © 2008 John Wiley & Sons, Ltd.     

Characterizing the Linguistic Chameleon: Personal and Social Correlates of Linguistic Style Accommodation

Linguistic style accommodation between conversationalists is associated with positive social outcomes. We examine social power and personality as factors driving the occurrence of linguistic style accommodation, and the social outcomes of accommodation. Social power was manipulated to create 144 face‐to‐face dyadic interactions between individuals of high versus low power and 64 neutral power interactions. Particular configurations of personality traits (high self‐monitoring, Machiavellianism and leadership, and low self‐consciousness, impression management and agreeableness), combined with a low‐power role, led to an increased likelihood of linguistic style accommodation. Further, greater accommodation by low‐power individuals positively influenced perceptions of subjective rapport and attractiveness. We propose individual differences interact with social context to influence the conditions under which nonconscious communication accommodation occurs.     

Differences in affiliative behavior, pair bonding, and vaginal cytology in two species of vole (Microtus ochrogaster and M. montanus)

Prairie voles (Microtus ochrogaster) and montane voles (M. montanus) display marked differences in social organization in the field. Trios of 1 male and 2 females were studied in a large enclosure for a 10-day period. Prairie voles spent 59% of the observation time in side-by-side contact, whereas montane voles spent only 7% of the time in contact. Vaginal smears indicated female-female suppression of estrus in prairie voles; female montane voles appeared to cycle in the presence of males. Male prairie voles preferentially paired and nested with 1 of the females, and vaginal estrus generally followed pair formation by 2 days. Male montane voles did not spend time preferentially with either female, even after mating. These results suggest that the contrasting mating systems of these species result from differences in the propensity for affiliative behavior and social bonding rather than from mate availability or female receptivity.     

Communicative factors,conflict progression,and use of reconciliatory strategies in pre‐school boys‐a series of random events or a sequential process?

Affiliative interactions between former opponents soon after a conflict, in non‐human primates and pre‐school children, have been documented to be followed by a reduction of future aggression and stress reactions, and to promote tolerance between individuals. The phenomenon has, therefore, been called reconciliation. Studies of non‐human primates have shown that the conflict cause can influence the reconciliatory outcome, and whether the aggressor or the victim of the aggression is more likely to take the initiative to reconcile, can differ between species. Few studies in pre‐school children have addressed how factors preceding the post‐conflict period, such as social interactions before the conflict outbreak, or the cause of the conflict, may be related to the likelihood of reconciliation, conflict progression, and conflict outcome in the form of possible continuation or initiation of interactions. Twenty boys were video‐recorded during free‐play at six pre‐schools. The existence of social interaction between the opponents in the upcoming conflict was examined in the pre‐conflict period. The observed causes of conflict were determined and classified into five categories. The affiliative behaviors identified in the post‐conflict period were classified into six categories. Finally, whether or not conflicts were followed by communicative exchanges in the succeeding non‐conflict period was documented. The results revealed that the cause of the conflict is associated with whether opponents had established social interaction prior to conflict in the pre‐conflict period. Acceptance rates (for the various categories of affiliative behaviors) appeared to differ. A non‐random pattern of conflict progression was apparent, suggesting the conflict cause was related to the category of reconciliatory strategy shown by the individuals. The aggressor and the victim initiated reconciliation at similar rates, with the exception of verbal apologies, which were initiated most often by the aggressor. Finally, the data also showed that higher frequencies of social interaction between former opponents in the succeeding non‐conflict period were associated both with whether or not social interaction had occurred in the pre‐conflict period, and whether or not the conflict was reconciled. In conclusion, communicative factors preceding conflicts, and conflict cause, are distinctively correlated with both the use and the outcome of post‐conflict affiliation in pre‐school boys. Aggr. Behav. 00:000–000, 2005. © 2005 Wiley‐Liss, Inc.