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Contest behaviour, and in particular the propensity to attack an unfamiliar conspecific, is influenced by an individual's aggressiveness, as well as by experience of winning and losing (so called 'winner–loser effects'). Individuals vary in aggressiveness and susceptibility to winner–loser effects but the relationship between these drivers of contest behaviour has been poorly investigated. Here we hypothesise that the winner–loser effect on initiation of agonistic behaviour (display, non-damaging aggression, biting and mutual fighting) is influenced by aggressiveness. Pigs (n = 255) were assayed for aggressiveness (tendency to attack in resident−intruder tests) and then experienced two dyadic contests (age 10 and 13 weeks). Agonistic behaviour, up to reciprocal fighting, in contest 2 was compared between individuals of different aggressiveness in the RI test and experiences of victory or defeat in contest 1. Winner–loser effects were more influential than aggressiveness in determining initiation of agonistic behaviour. After accruing more skin lesions in contest 1, individuals were less likely to engage in escalated aggression in contest 2. The interaction between aggressiveness and winner–loser experience did not influence contest behaviour. The results suggest that aggressiveness does not compromise learning from recent contest experience and that reducing aggressiveness is unlikely to affect how animals experience winning and losing. [ABSTRACT FROM AUTHOR]

Social calls have the function to coordinate the behavior of animals. In the presence of conspecifics foraging Common pipistrelle bats (P. pipistrellus) emitted, in addition to typical echolocation signals, two types of social calls: complex social calls and an as-of-yet undescribed, short, frequency-modulated call type with high terminal frequency, which we term "high frequency social call". By recording the flight and acoustic behavior of free flying pairs of foraging P. pipistrellus with an array of four microphones we were able to determine their three-dimensional flight paths and attribute emitted calls to particular behavioral situations. Complex social calls were emitted at further inter-individual distances and at large bearing angles to conspecifics, whereas high frequency social calls were produced at significantly shorter distances and at smaller bearing angles. These calls were associated with chasings and the eviction of the intruder. We assume that the emission of both types of social calls by foraging bats reflects a two-stage-process of the occupation and defense of a food patch. Common pipistrelle bats use complex social calls to claim a food patch and switch to agonistic behaviors, including chasings and high frequency social call emissions, when they defend their foraging territory against an intruder. [ABSTRACT FROM AUTHOR]

Background: Social tolerance strongly influences the patterns of affiliation and aggression in animal societies. However, not much is known about the variation of social tolerance in species living in dispersed social systems that combine solitary foraging activities with the need of coordinating social interactions with conspecifics on a regular basis. This study aims to investigate the sources of variation in social tolerance within a Malagasy primate radiation with dispersed social systems, the mouse lemurs (Microcebus spp.). Six mouse lemur species were selected as model species that belong to three different taxonomic clades, live in two types of forest environments (dry and humid), and differed in this study with respect to their reproductive activity. Six male–female and six male–male dyads of each species were tested temporarily in a standardized social encounter paradigm in Madagascar to collect data on joint use of space, non-agonistic body contacts, aggression rates, the number of conflicts and the establishment of intra- and intersexual dominance. Results: Male–female dyads of the six species differed significantly in the frequency of affiliative and agonistic behaviors. In contrast, the variations between male–male dyads could not be explained by one parameter only, but clade membership, forest type, reproductive state as well as species were all suggested to be partially influential. Only one species (Microcebus mamiratra) showed signals of unambiguous female dominance in all male–female dyads, whereas the others had no or only a few dyads with female dominance. Conclusions: Variations in social tolerance and its consequences are most likely influenced by two factors, ecology (via forest type) and physiology (via reproductive activity), and only to a lesser extent by clade membership. The study suggests that mouse lemur females have higher aggression rates and more agonistic conflicts with males when females in the population are reproducing, at least in resource-rich humid forests. The study confirms a high degree of social plasticity between species in these small solitary foragers that supports their taxonomic distinctiveness and requires further scientific attention. [ABSTRACT FROM AUTHOR]

Animal signals of competitive ability allow contests for limited resources to be settled without costly physical fights. Traits indicating competitive ability are diverse and span visual, acoustic or chemical modalities. Although animal signalling has been intensively studied, research has focused mainly on male traits. Little is known about the extent and functionality of competitive signals in females and whether there are sex differences in signal function. We studied whether plumage colour signals competitive ability in female and male lovely fairy-wrens, Malurus amabilis. In this species, both sexes sport elaborate but sexually dichromatic ornamental plumage. Using a mirror image stimulation test, we first assessed the relationship between male and female colour and agonistic behaviour, controlling for other physical, social and ecological variables. We then tested whether colourful plumage influenced aggressive response in both sexes by experimentally manipulating plumage colour and measuring individual responses to their mirror image. Females and males were more aggressive towards naturally less colourful reflections of the cheek patch in the mirror. However, when we manipulated plumage colour, both females and males responded more aggressively to experimentally increased cheek colour reflection in the mirror. Our findings suggest that plumage colour signals competitive ability in an aggressive context in both sexes and raises the possibility that signal reliability may be maintained by social interactions where individuals police and punish dishonest signals. Highlights • Our understanding of female signals and sex differences is still limited. • We used a mirror image test to study whether plumage colour signals aggression. • Both sexes were more aggressive to natural, less colourful mirror reflections. • Manipulated birds were more aggressive to increased colour reflections. • Plumage colour of females and males appears to be used as a competitive signal. [ABSTRACT FROM AUTHOR]

The article examines the science of self-annihilation. In this report, the author presents a problem of considerable importance, the relationship of the armature of a species and the inhibitions needed to prevent killing members of the species. Some of these mechanisms that inhibit intraspecific killing include the thickness of the animal's skin and the so-called submission or appeasant gestures. Furthermore, the author indicated that these mechanisms are developed under pressure of natural selection.

Highlights • Straw provision reduces the appearance of poor welfare indicators in pigs. • Straw provision does not modify putative indicators of positive emotions and welfare in pigs. • Straw provision decreases ear movement frequency in pigs. • Tail and ear movements as indicators of emotions and welfare in pigs. Abstract The present study aimed to investigate whether straw provision in pigs increases positive emotions, indicated by tail movement, and reduces poor welfare indicators (agonistic and displacement behaviours), including indicators of negative emotions (ear movement). Comparisons between Straw and Control sessions were analysed from video recording for all parameters. 15 mini-pigs participated in a three-week study. Depending on the week, animals were included in Straw or Control sessions. During Straw sessions, pigs were placed in their own pens where straw was introduced and continuously provided for one week. During Control sessions, pigs remained in their pens with no additional stimulus. Pig behaviours were video-recorded four times during each session and scored. Results showed that ear movement frequency was significantly lower in the Straw than in Control session (p = 0.005); agonistic behaviour frequency and duration were significantly lower in the Straw than in Control session (p = 0.013 and p = 0.0004, respectively), and displacement behaviour frequency and duration were significantly lower in the Straw than in Control session (p < 0.001 and p = 0.01, respectively). Results suggest that straw provision reduces poor welfare but does not modify indicators of positive emotions selected for this study (tail movement frequency and duration). Our study also provides information about potential indicators of welfare, and more precisely, about emotions, which could also be useful to improve animal welfare assessment in pigs, obtaining more information about feasible behavioural indicators which could show the emotional state of the animals. [ABSTRACT FROM AUTHOR]

Machado-Joseph disease (MJD, also known as spinocerebellar ataxia 3 or SCA3) is the most common dominant ataxia worldwide, with an overall average prevalence of 1–5/100,000. To this date, two major ancestral lineages have been found throughout the world. In China, the relative frequency of MJD among the SCAs reaches as high as 63%, however, little is known about its mutational origin in this country. We analyzed 50 families with MJD patients in two or more generations to study the hypothesis that new mutational events have occurred in this population. Haplotypes based on 20 SNPs have shown new genetic backgrounds segregating with MJD mutations in our cohort from China. We found the "Joseph-derived" lineage (Joseph lineage with a G variant in rs56268847) to be very common among Chinese MJD patients. Moreover, we estimated the time for the origin of this MJD SNP background based on STR diversity flanking the (CAG)n of ATXN3. It was surprising to find that the Chinese MJD population originated from 8,000 to 17,000 years ago, far earlier than the previous literature reports, which will be an important evidence to explain the origin, spread and founder effects of MJD. [ABSTRACT FROM AUTHOR]

Bats rely heavily on acoustic signals in order to communicate with each other in a variety of social contexts. Among those, agonistic interactions and accompanying vocalizations have received comparatively little study. Here, we studied the communicational behaviour between male greater mouse-eared bats (Myotis myotis) during agonistic encounters. Two randomly paired adult males were placed in a box that allowed us to record video and sound synchronously. We describe their vocal repertoire and compare the acoustic structure of vocalizations between two aggression levels, which we quantified via the bats’ behaviour. By inspecting thirty, one-minute long encounters, we identified a rich variety of social calls that can be described as two basic call types: echolocation-like, low-frequency sweeps and long, broadband squawks. Squawks, the most common vocalization, were often noisy, i.e. exhibited a chaotic spectral structure. We further provide evidence for individual signatures and the presence of nonlinear phenomena in this species’ vocal repertoire. As the usage and acoustic structure of vocalizations is known to encode the internal state of the caller, we had predicted that the spectral structure of squawks would be affected by the caller’s aggression level. Confirming our hypothesis, we found that increased aggression positively correlated with an increase in call frequency and tonality. We hypothesize that the extreme spectral variability between and within squawks can be explained by small fluctuations in vocal control parameters (e.g. subglottal pressure) that are caused by the elevated arousal, which is in turn influenced by the aggression level. [ABSTRACT FROM AUTHOR]

Aggressive behavior may increase or decrease in troglobitic fishes, compared to epigean ones. Herein, we present the agonistic behavior repertoire and the causes that determine the dominance of two Brazilian cave catfishes: Glaphyropoma spinosum and putative undescribed Copionodon species. Both belong to Copionodontinae group, a small basal Trichomycteridae subfamily, and coexist in sandstone caves from Chapada Diamantina, northeastern Brazil. The results were compared with those exhibited by an epigean and syntopic species, Copionodon pecten. The fishes were paired and filmed until dominance was established; frequency of attacks was quantified and statistically analyzed. Cave copionodontine is one of the most hostile among subterranean fishes, with high frequency and complexity of aggressive components, including five new behavior components. Determinant factors for establishing dominance are body size, physical strength, and territoriality. Dominance is probably maintained by avoidance behavior by the subordinate and continuous attacks by the dominant. They are highly intolerant to conspecific, which may be a consequence of territoriality or feeding context. Two hypotheses may explain the agonistic behavior of cave species: (1) It is the maintenance of their ancestral behavior, being plesiomorphic in relation to the remaining Trichomycteridae subfamilies, corroborated by phototactic and spontaneous behavior; (2) It is an autapomorphy for Copionodontinae, due to new evolutionary acquisitions. The epigean C. pecten, in contrast, is much less aggressive, and the high tolerance to conspecific and the absence of accentuated territoriality may be explained by the food and/or space abundance in its natural habitats. [ABSTRACT FROM AUTHOR]

We propose a practical concept that distinguishes the particular kind of weaponry that has evolved to be used in combat between individuals of the same species and sex, which we term intrasexually selected weapons (ISWs). We present a treatise of ISWs in nature, aiming to understand their distinction and evolution from other secondary sex traits, including from 'sexually selected weapons', and from sexually dimorphic and monomorphic weaponry. We focus on the subset of secondary sex traits that are the result of same‐sex combat, defined here as ISWs, provide not previously reported evolutionary patterns, and offer hypotheses to answer questions such as: why have only some species evolved weapons to fight for the opposite sex or breeding resources? We examined traits that seem to have evolved as ISWs in the entire animal phylogeny, restricting the classification of ISW to traits that are only present or enlarged in adults of one of the sexes, and are used as weapons during intrasexual fights. Because of the absence of behavioural data and, in many cases, lack of sexually discriminated series from juveniles to adults, we exclude the fossil record from this review. We merge morphological, ontogenetic, and behavioural information, and for the first time thoroughly review the tree of life to identify separate evolution of ISWs. We found that ISWs are only found in bilateral animals, appearing independently in nematodes, various groups of arthropods, and vertebrates. Our review sets a reference point to explore other taxa that we identify with potential ISWs for which behavioural or morphological studies are warranted. We establish that most ISWs come in pairs, are located in or near the head, are endo‐ or exoskeletal modifications, are overdeveloped structures compared with those found in females, are modified feeding structures and/or locomotor appendages, are most common in terrestrial taxa, are frequently used to guard females, territories, or both, and are also used in signalling displays to deter rivals and/or attract females. We also found that most taxa lack ISWs, that females of only a few species possess better‐developed weapons than males, that the cases of independent evolution of ISWs are not evenly distributed across the phylogeny, and that animals possessing the most developed ISWs have non‐hunting habits (e.g. herbivores) or are faunivores that prey on very small prey relative to their body size (e.g. insectivores). Bringing together perspectives from studies on a variety of taxa, we conceptualize that there are five ways in which a sexually dimorphic trait, apart from the primary sex traits, can be fixed: sexual selection, fecundity selection, parental role division, differential niche occupation between the sexes, and interference competition. We discuss these trends and the factors involved in the evolution of intrasexually selected weaponry in nature. [ABSTRACT FROM AUTHOR]

Agonistic behaviour is an important component of intraspecific competition because outcomes of agonistic contests can serve as indicators of fitness, helping the victors secure critical resources. Although several factors affecting aggression, including age and body size, have been well documented, few studies have examined the effects of abiotic factors on aggression and outcomes of agonistic contests. Abiotic factors affect a broad range of behaviours and can naturally covary, but some factors are becoming increasingly uncoupled. For example, ongoing climate change continues to shift temperature, but not light:dark, cycles. Thus, we employed a 2 × 2 factorial design in sand field crickets, Gryllus firmus , to disentangle the naturally covarying effects of temperature and circadian rhythms. During early adulthood, virgin males were maintained in either a typical or inverted diel temperature cycle (i.e. cool in the morning and warm in the afternoon, or warm in the morning and cool in the afternoon, respectively) reflecting field conditions (20.5–32 °C). Agonistic contests occurred at either cool (22 °C) or warm (31 °C) periods in the temperature cycle. Morphological traits, such as head width, femur length and testes mass, positively covaried and influenced the outcome of contests where relatively large crickets won most contests. However, temperature and time of day had additive, interactive effects on the level of aggression and the duration of contests. Contests occurring in cool, morning conditions were relatively long and aggressive. Although crickets appeared to use a mutual assessment strategy (contests between males of mismatched body size took longer to initiate), there may have been a context-dependent shift to a self-assessment strategy during warm evenings. Thus, plasticity in agonistic behaviour occurred due to the interactive, additive effects of temperature and circadian dynamics. We encourage continued investigation into studies that disentangle the effects of temperature and circadian effects on other fitness-related behaviours, such as mate choice or foraging. Highlights • Temperature and time of day interactively affected fighting dynamics in male crickets. • Fights were longer and more aggressive in cool, morning conditions. • Larger crickets were more likely to win fights. • Fights between crickets of mismatched size took longer to initiate. [ABSTRACT FROM AUTHOR]

The Chinese mitten crab Eriocheir sinensis is an invasive species outside native range and represents a substantial threat to recipient ecosystems. It is regarded as an invasive species in Japan and has recently been found in Tokyo Bay, but little is known about its possible impacts on native species, especially on the congener Japanese mitten crab Eriocheir japonica. This study examined shelter competition between E. sinensis and E. japonica under laboratory conditions. Shelter competition trials were conducted in pairs of native and invasive males in different size combinations. Our results indicated that competition between two species was size-dependent: E. japonica always successfully defended shelter when competing with size-matched or slightly larger E. sinensis; E. sinensis always won shelter when its carapace or chela were at least 10 or 7% larger, respectively, than those of E. japonica. The two species exhibited different behavioural patterns: compared with E. sinensis, E. japonica frequently displayed positive behaviour (approach, walking leg contact, chela contact) and seldomly displayed negative behaviour (retreat). Our results highlight the important role of strong native competitors in controlling invasion success and suggest E. sinensis may be unlikely to exclude native E. japonica from its habitat by direct competition for shelter. [ABSTRACT FROM AUTHOR]

The convict cichlid fish Amatitlania nigrofasciata, an aggressive fish species, was introduced in 1987 into the Balsas River basin in central Mexico, which is home to the native cichlid Mexican mojarra, Cichlasoma istlanum. Local populations of the Mexican mojarra have been hypothesized to be negatively affected by the introduction of the non-native convict cichlid fish, and the two species have been observed engaging in aggressive behaviours over resources such as food and shelter along this basin. Thus, we evaluated agonistic interactions between the native Mexican mojarra and the non-native convict cichlid fish. In experimental contests between the species, chases, bites, refuge use and defence, and food consumed were recorded and analysed. Contrary to expectation, the Mexican mojarra engaged in a greater number of chases and bites than the convict cichlid fish and was more successful in obtaining the resource under dispute (a refuge and food). [ABSTRACT FROM AUTHOR]

Highlights • Deep straw bedding increase lying bout frequency compared to cubicle housing. • Deep straw bedding facilitates getting-up behaviour. • Housing dairy cattle on deep straw bedding during the dry period may increase agonistic behaviours. • Feeding behaviour is unaffected by deep straw housing during the dry period. Abstract The present observational study assessed the effect of deep straw bedding compared to cubicles during the dry period on lying-, feeding- and agonistic behaviour in Holstein cows. A total of 74 primi- (heifers) and multiparous cows were moved either onto deep straw bedding (DS) or into cubicle housing (CS) 4 wk before the expected calving date and were observed for 21 consecutive days. Throughout the 21 d lying time and the number of lying bouts were recorded using automated accelerometers while feeding time, the number of feeder visits and feed intake was recorded using automatic feed bins. All variables were averaged by week. The transition time from lying to standing was obtained by averaging five randomly selected standing up events on d 7 prior to the actual calving date while the number of failed standing attempts was obtained by following the cows standing up bouts throughout all of d 7 prior to the actual calving date. The frequency of agonistic behaviour was obtained from 7 h of continuous video recordings on d 21 and 7 (or 8) before the actual calving date. Lying time was not affected by treatment but DS cows had a higher number of lying bouts and a shorter transition time between lying and standing compared to CS cows. Primiparous cows had a higher number of lying bouts compared to multiparous cows. There were no treatment differences in feeding behaviour but multiparous cows spent more time feeding and increased their feed intake more across weeks compared to primiparous cows. Cows housed in DS initiated more agonistic behaviour compared to CS cows at d 7 (or 8) before calving while no difference between treatments was seen at 21 d before calving. These results suggest that deep straw bedding facilitates the transition between lying and standing but may increase agonistic behaviour. [ABSTRACT FROM AUTHOR]

Highlights • Young Finnraccoon females choose allohuddling and nesting while resting in winter. • Social housing in winter does not compromise welfare of young Finnraccoon females. • Winter nest is used considerably, and it does not cause soiling of the fur. • Level of stereotypic behaviour is low and it peaks in the evening. • Physiological welfare variables do not show difference between wintering conditions. Abstract Raccoon dog ( Nyctereutes procyonoides ussuriensis ) is the only canid species using facultative passive wintering strategy. The aim of the present study is to document the behaviour and welfare of the farmed variant of the species, i.e. Finnraccoon, housed in various conditions in winter. Young Finnraccoon females were housed in four different housing conditions; alone in a small cage (0.8 m2), alone in a larger cage (1.2 m2), alone in the large cage with access to a winter nest and in pair in the large cage, through their first winter. In order to control the body mass, the animals were weighed at the start of the housing treatment. The behaviour of the females was analysed by using instantaneous sampling with a sampling interval of 5 min for 24 h in one day, both in January and February. The animals were euthanized in March. The body size and mass of some organs related to the physiological state of the animals were measured. The Finnraccoons rested for 69–74% of their time, without difference between groups or months. The Finnraccoons with access to the nest box spent over 90% of their resting time inside the nest box, whereas the pair housed Finnraccoons allohuddled over 90% of their resting time. The Finnraccoons without these options rested mainly on the cage floor (74–85% of resting) and to a lesser extent on the platform (15–26 % of resting). The Finnraccoons with access to a nest box were less active and performed less nutritive behaviours than those housed alone, and without access to a nest box. This indicates passive wintering strategy, although no true hibernation was observed. The stereotypic behaviour occupied <1–2% of the observations, without difference between groups. The heavier animals had heavier organs, and no differences between groups were found in the mass of any organ. The furs remained clean in the Finnraccoons with access to the nest box. Number of scars, indicating agonistic interactions, was low in the pair housed Finnraccoons. Although no difference between groups is found in the physiological welfare measurements and in the occurrence of stereotypic behaviour, the results suggest that young Finnraccoon females should be housed in pairs until the onset of the mating season, and if housed singly, they should be provided with a winter nest to secure comfortable resting behaviour. [ABSTRACT FROM AUTHOR]

Group housing of lactating rabbit does is desirable from a welfare standpoint, but agonistic behaviour can cause severe skin injuries, which are undesired for animal welfare. Park layout, creating hiding places and escape possibilities, may help redirect attention away from fighting, which could in turn help prevent skin damage. An experiment was performed to test whether more damaging behaviour would occur in a combi park (with nest box panels) after mixing, compared to a regular park for fatteners, as nest box panels would obstruct does when escaping aggressive interactions. In addition, the position of the PVC pipe underneath the platform differed between parks (longitudinal or transversal), resulting in different escape routes. Twentytwo parks were used, in which 5 does per park were grouped at 23 d of lactation until weaning at 36 d of lactation. Skin injuries were scored at 4 d after grouping and on the day before weaning. The presence of nest box panels in a combi park and the position of the PVC pipe underneath the platform did not affect the level of skin damage. Moderate to severe injuries were observed, mostly at the hind quarters, ears and head. Five to 6% of the does were severely injured (wounds). There was a positive relationship between the average skin injury per park at 4 d after grouping and at weaning. On average, average injury score per park increased from grouping to weaning, but there are differences between individual parks. From this experiment it can be concluded that group housing of lactating rabbit does involves animals getting injured. In fact, 5 to 6% of the does were severely injured (wounds). Social dynamics of group housed does are insufficiently understood and might be important to reduce damaging behaviour in group housing. [ABSTRACT FROM AUTHOR]

Many studies have been carried out into both motor and sensory laterality of horses in agonistic and stressful situations. Here we examine sensory laterality in affiliative interactions within four groups of domestic horses and ponies (N = 31), living in stable social groups, housed at a single complex close to Vienna, Austria, and demonstrate for the first time a significant population preference for the left side in affiliative approaches and interactions. No effects were observed for gender, rank, sociability, phenotype, group, or age. Our results suggest that right hemisphere specialization in horses is not limited to the processing of stressful or agonistic situations, but rather appears to be the norm for processing in all social interactions, as has been demonstrated in other species including chicks and a range of vertebrates. In domestic horses, hemispheric specialization for sensory input appears not to be based on a designation of positive versus negative, but more on the perceived need to respond quickly and appropriately in any given situation. [ABSTRACT FROM AUTHOR]

Animals in social aggregations use signals of quality or motivation to attract mates and intimidate rivals. Theory indicates that honesty can be maintained in these signals if the costs of signalling affect low-quality individuals more than they affect high-quality individuals. Considerable research has focused on identifying the nature of those costs and their ability to maintain honest signals. Much of this research, particularly in recent years, has focused on receiver-independent physiological costs of signal production. Less research attention has been paid to receiver-dependent costs that might arise from conspecific responses to signals. Here we survey the literature on these different types of costs, focusing in particular on case studies from a diversity of taxa. We find that signals often do carry significant physiological production costs, but this is not universal, as many signals appear to be physiologically inexpensive to produce. More importantly, very few studies have tested the key prediction that physiological production costs differentially affect low-quality individuals over high-quality individuals. In contrast, research from a diversity of taxa indicates that signals such as coloration and vocalizations often affect agonistic interactions, which in turn affect the production of signals, and that deceptive signallers receive more aggression than do honest signallers in at least some systems. Social costs are a plausible but understudied mechanism for maintaining honest signalling. Highlights • We review hypotheses for honest signalling and physiological/social cost models. • We review key empirical studies to determine support for these hypotheses. • Social cost models are plausible and may be taxonomically widespread. • Research should focus on social costs as key factors maintaining signal honesty. [ABSTRACT FROM AUTHOR]

Agonistic character displacement (ACD) occurs when selection to avoid maladaptive interspecific aggression leads to the evolution of agonistic signals and/or associated behavioural biases in sympatry. Here, we test for a pattern consistent with ACD in male colour pattern in darters (Percidae: Etheostoma). Male colour pattern has been shown to function in male–male competition rather than female mating preferences in several darter species. Additionally, males bias their aggression towards conspecific over heterospecific males in sympatry but not in allopatry, consistent with divergent ACD in male behavioural biases. We use a common garden approach to show that differences in male colour pattern among four closely related darter species are genetically based. Additionally, we demonstrate that some aspects of male colour pattern exhibit enhanced differences in sympatric compared to allopatric populations of two darter species, consistent with ACD. However, other male colour traits are more similar between species in sympatry compared with allopatry, indicating that not all signal components are under strong divergent selection in sympatry. This study provides evidence that interspecific male–male aggressive interactions alone can promote elaborate male signal evolution both between and within species. We discuss the implications this has for male-driven ACD and cascade ACD. [ABSTRACT FROM AUTHOR]

Post-weaning social isolation (PSI) has been shown to increase aggressive behavior and alter medial prefrontal cortex (mPFC) function in rats. The present study sought to determine whether this phenotype would be normalized by increasing levels of the endocannabinoid 2-arachidonoylglycerol (2-AG) using pharmacological inhibition of monoacylglycerol lipase (MAGL). Male and female Sprague-Dawley rats were exposed to either 4 weeks of PSI or social rearing (SR) starting on postnatal day 21, then underwent a 15 min trial of social interaction with a novel, same-sex juvenile rat. Rats were administered an acute injection of the MAGL inhibitor MJN110 or vehicle prior to the social interaction. Rats received either 0 mg/kg (vehicle), 1 mg/kg, or 5 mg/kg of MJN110. Both doses of MJN110 decreased aggressive grooming, a measure of agonistic behavior, in both males and females, largely driven by decreased aggressive grooming in PSI rats. There were no effects of MJN110 on overall social behavior or play behavior, while modest effects were observed on locomotor activity in SR rats only. While social interaction increased c-Fos expression in the mPFC of both males and females, MJN110 reduced c-Fos preferentially in females. These results suggest that 2-AG can modulate specific social behaviors during adolescence, and may affect mPFC function differentially in males and females. [ABSTRACT FROM AUTHOR]

Humans are the only species capable of powerful and accurate overhand throwing. However, the evolution of this ability remains underexplored. Here we draw on several lines of evidence—anatomical, archeological, cross-species comparisons, and ethnographic—to develop a scenario for the evolution of throwing. Throwing has deep roots in the primate lineage. Nonhuman primates throw projectiles during agonistic interactions but rarely to subdue prey. Thus, we argue that throwing first arose during agonistic interactions and was later incorporated into hunting by human ancestors. The fossil record indicates that anatomical adaptations for high-speed throwing in Homo first appeared about two million years ago. Once the effective use of projectile weapons became critical to success in combat and hunting, the importance of the ability to throw, intercept, and dodge projectiles would have resulted in stronger selection on males than females to become proficient at these skills because males throw projectiles more often than females in both combat and hunting. [ABSTRACT FROM AUTHOR]

Abstract: Resource competition is frequently strong among parasites that feed within small discrete resource patches, such as seeds or fruits. The properties of a host can influence the behavioural, morphological and life‐history traits of associated parasites, including traits that mediate competition within the host. For seed parasites, host size may be an especially important determinant of competitive ability. Using the seed beetle, Callosobruchus maculatus, we performed replicated, reciprocal host shifts to examine the role of seed size in determining larval competitiveness and associated traits. Populations ancestrally associated with either a small host (mung bean) or a large one (cowpea) were switched to each other's host for 36 generations. Compared to control lines (those remaining on the ancestral host), lines switched from the small host to the large host evolved greater tolerance of co‐occurring larvae within seeds (indicated by an increase in the frequency of small seeds yielding two adults), smaller egg size and higher fecundity. Each change occurred in the direction predicted by the traits of populations already adapted to cowpea. However, we did not observe the expected decline in adult mass following the shift to the larger host. Moreover, lines switched from the large host (cowpea) to the small host (mung bean) did not evolve the predicted increase in larval competitiveness or egg size, but did exhibit the predicted increase in body mass. Our results thus provide mixed support for the hypothesis that host size determines the evolution of competition‐related traits of seed beetles. Evolutionary responses to the two host shifts were consistent among replicate lines, but the evolution of larval competition was asymmetric, with larval competitiveness evolving as predicted in one direction of host shift, but not the reverse. Nevertheless, our results indicate that switching hosts is sufficient to produce repeatable and rapid changes in the competition strategy and fitness‐related traits of insect populations. [ABSTRACT FROM AUTHOR]

Aggression is an extremely complex behaviour and female aggression is understudied when compared to males. Despite the fact that it has been suggested that conflict among females may be more frequently resolved peacefully, in many species females show high levels of aggression. We used Cichlasoma dimerus to describe dynamics and conflict outcome in intrasexual agonistic encounters. We performed encounters of two sex-matched animals in a neutral arena and we recorded agonistic interactions during one hour. All aggressive and submissive behaviours were described and quantified to perform the ethogram. Encounters followed three phases: pre-contest, contest and post-resolution. Latency, time of resolution and frequency of aggressive displays did not differ between sexes. Relative variations in size between female opponents better explained aggression outcome in each contest, since higher levels of aggression occurred in dyads of more similar fish. However, this was not observed in males, suggesting that probably morphological characteristics could be less relevant in male conflict resolution. Altogether these results suggest that in this ethological context, C. dimerus females are as aggressive as males and that they have similar motivation towards territorial aggression, emphasizing the need of deepening the study of aggression in females and not only in males. [ABSTRACT FROM AUTHOR]

Background: Acoustic properties of vocalizations can vary with the internal state of the caller, and may serve as reliable indicators for a caller's emotional state, for example to prevent conflicts. Thus, individuals may associate distinct characteristics in acoustic signals of conspecifics with specific social contexts, and adjust their behaviour accordingly to prevent escalation of conflicts. Common ravens (Corvus corax) crowd-forage with individuals of different age classes, sex, and rank, assemble at feeding sites, and engage in agonistic interactions of varying intensity. Attacked individuals frequently utter defensive calls in order to appease the aggressor. Here, we investigated if acoustic properties of defensive calls change with varying levels of aggression, and if bystanders respond to these changes. Results: Individuals were more likely to utter defensive calls when the attack involved contact aggression, and when the attacker was higher in rank than the victim. Defensive calls produced during intense conflicts were longer and uttered at higher rates, and showed higher fundamental frequency- and amplitude-related measures than calls uttered during low-intensity aggression, indicating arousal-based changes in defensive calls. Playback experiments showed that ravens were more likely to react in response to defensive calls with higher fundamental frequency by orientating towards the speakers as compared to original calls and calls manipulated in duration. Conclusions: Arousal-based changes are encoded in acoustic parameters of defensive calls in attacked ravens, and bystanders in the audience pay attention to the degree of arousal in attacked conspecifics. Our findings imply that common ravens can regulate conflicts with conspecifics by means of vocalizations, and are able to gather social knowledge from conspecific calls. [ABSTRACT FROM AUTHOR]

Chicken agonistic behavior, a type of social behavior related to threatening and fighting, is among the most serious problems in the poultry industry. However, due to luck of effective models for investigating the brain mechanisms of the behavior, no effective measures have been taken. This study, therefore, aimed to select the behavioral tests available for monitoring chicken agonistic behavior. Two behavioral tests, resident-intruder (R-I) test and social interaction (SI) test, were performed for 10 minutes in 10 pairs of male layer chicks at 8, 12, 16, 20, and 24 days of age, and total agonistic frequencies (TAF: Sum of the frequencies of agonistic displays like pecking, biting, kicking, threatening, and leaping) and latency (the period of time from the beginning of the behavioral test to the occurrence of the first agonistic behavior) were measured as indices of agonistic behavior. Two-way repeated measures ANOVA revealed significant differences in TAF and latency between aggressors and opponents in both the behavioral tests. In the R-I test, the TAF of aggressors significantly increased from 8 to 20 days of age, and the latency significantly decreased from 8 to 24 days of age. In the SI test, however, the TAF of aggressors significantly increased and the latency significantly decreased only from 16 to 20 days of age. When the criterion of high agonistic behavior was defined as the TAF, where aggressors showed more than 30 times of TAF and the opponents did less than one-third TAF of aggressors, the aggression establishment rate (AER), which is equal to the number of aggressors showing high agonistic behavior per total behavioral trials, was significantly higher in the R-I test than in the SI test. These results suggest that the R-I test, rather than the SI test, is an effective tool for monitoring agonistic behavior of layer chicks. [ABSTRACT FROM AUTHOR]

This short communication reports an observation of unusual non-agonistic interactions between a juvenile harbour porpoise (Phocoena phocoena) and a group of bottlenose dolphins (Tursiops truncatus) in the Marmara Sea on 25 April 2015. [ABSTRACT FROM AUTHOR]

Recent studies of animal personality have focused on its proximate causation and ecological and evolutionary significance in particular, but the question of its development was largely overlooked. The attributes of personality are defined as between-individual differences in behaviour, which are consistent over time (differential consistency) and contexts (contextual generality) and both can be affected by development. We assessed several candidates for personality variables measured in various tests with different contexts over several life-stages (juveniles, older juveniles, subadults and adults) in the Northern common boa. Variables describing foraging/feeding decision and some of the defensive behaviours expressed as individual average values are highly repeatable and consistent. We found two main personality axes—one associated with foraging/feeding and the speed of decision, the other reflecting agonistic behaviour. Intensity of behaviour in the feeding context changes during development, but the level of agonistic behaviour remains the same. The juveniles and adults have a similar personality structure, but there is a period of structural change of behaviour during the second year of life (subadults). These results require a new theoretical model to explain the selection pressures resulting in this developmental pattern of personality. We also studied the proximate factors and their relationship to behavioural characteristics. Physiological parameters (heart and breath rate stress response) measured in adults clustered with variables concerning the agonistic behavioural profile, while no relationship between the juvenile/adult body size and personality concerning feeding/foraging and the agonistic behavioural profile was found. Our study suggests that it is important for studies of personality development to focus on both the structural and differential consistency, because even though behaviour is differentially consistent, the structure can change. [ABSTRACT FROM AUTHOR]

Social species in captivity may face allostatic overload due to artificial grouping and other social constraints. In rescue centres, groups of psittacines are constantly mixed due to the arrival and/or release of individuals; this procedure is potentially harmful to animal welfare. This study aimed at evaluating the possible impacts of mate replacement on the stress levels of captive blue-fronted amazon parrots ( Amazona aestiva). During five weeks, we recorded agonistic interactions and dropping-glucocorticoid metabolites (GCM) concentrations of individuals allocated in a group whose members were kept constant and in a group subjected to frequent member replacement. In both groups, non-linear hierarchies developed, without sex differences regarding aggression or hierarchical positions. The replacement of individuals had no effect on the number of agonistic interactions or on the animals’ stress levels. In both groups, higher-ranking individuals had higher stress loads than subordinates. Our study, the first to investigate the social dynamics of A. aestiva, indicated that introducing or removing individuals in captive groups does not seem to affect the welfare of the birds in the short term. This information favours release and reintroduction programs and is relevant for conservation management of this, and possibly other parrot species with similar environmental requirements. [ABSTRACT FROM AUTHOR]

Introduction: Agonistic behaviors help to ensure survival, provide advantage in competition, and communicate social status. The resident-intruder paradigm, an animal model based on male intraspecific confrontations, can be an ethologically relevant tool to investigate the neurobiology of aggressive behavior. Objectives: To examine behavioral and neurobiological mechanisms of aggressive behavior in male Swiss mice exposed to repeated confrontations in the resident intruder paradigm. Methods: Behavioral analysis was performed in association with measurements of plasma corticosterone of mice repeatedly exposed to a potential rival nearby, but inaccessible (social instigation), or to 10 sessions of social instigation followed by direct aggressive encounters. Moreover, corticotropin-releasing factor (CRF) and brain-derived neurotrophic factor (BNDF) were measured in the brain of these animals. Control mice were exposed to neither social instigation nor aggressive confrontations. Results: Mice exposed to aggressive confrontations exhibited a similar pattern of species-typical aggressive and non-aggressive behaviors on the first and the last session. Moreover, in contrast to social instigation only, repeated aggressive confrontations promoted an increase in plasma corticosterone. After 10 aggressive confrontation sessions, mice presented a nonsignificant trend toward reducing hippocampal levels of CRF, which inversely correlated with plasma corticosterone levels. Conversely, repeated sessions of social instigation or aggressive confrontation did not alter BDNF concentrations at the prefrontal cortex and hippocampus. Conclusion: Exposure to repeated episodes of aggressive encounters did not promote habituation over time. Additionally, CRF seems to be involved in physiological responses to social stressors. [ABSTRACT FROM AUTHOR]

Photographs of a ‘spy raptor’ killed while flying over the India-Pakistan border in Rajasthan were disseminated over the social media. The ‘raptor’ was a Macqueen’s Bustard,Chlamydotis macqueeniicarrying a satellite transmitter assembly and a red leg ring with an inscription K34. The National Avian Research Centre (NARC), Abu Dhabi, has extensively studied the biology ofC. macqueenii.The killed bustard was one of the captive-bred bustards participating in NARC’s monitoring of their migration. Inquiry showed that this bustard was shot in Afghanistan in 2014 and not in India in 2016 as reported. The report from Afghanistan described this bird as a Taliban drone fitted with a bomb vest. The Indian television channel broadcast this news and misinformed its viewers by calling this bird a spy sent over by Pakistan. The Afghanistan report misdirected this incident to blame the Taliban. The Indian television did the same to incriminate Pakistan. The misconceived labelling of a bird participating in a scientific study as a spy has led to misinformation and misdirection that can provoke international aggression. This paper argues that a Macqueen’s bustard contributing to scientific knowledge for conservation has been killed unnecessarily and appeals for an improvement in the knowledge of security agencies about birds carrying identification tags and tracking devices. [ABSTRACT FROM PUBLISHER]

Aggressive behavioural interactions between animals are widespread in nature, with ecological and evolutionary consequences of such interactions reported for both individuals giving and receiving aggression. Yet despite the importance of aggressive interactions in determining social dominance and conferring fitness benefits to successful individuals, we lack a general understanding of the conditions that influence the variation in agonistic behaviours among individuals and species. We conducted a global meta-analysis of published time–activity budgets, using a data set comprising 555 values from 88 studies, to determine variation in the time that waterbirds engaged in aggressive interactions. The mean ± SD percentage of time devoted to aggression was 2.0 ± 3.6%, with a range of 0.0–35.0%. We used our data set to test four predictions regarding avian aggression, based on the findings of earlier site-based studies. We predicted that the time spent on aggression would be influenced by four factors: (1) age class, (2) sex, (3) seasonal timing and (4) functional feeding group. A comparison of linear mixed-effects models using an information theoretic approach indicated that the proportion of time waterbirds spent engaged in aggressive interactions was best explained by the age class and sex of the focal waterbird species. More time was spent on aggression by males than females, and by adults than juveniles. We found no evidence that the time spent on aggressive behaviours varied across latitudes or body mass, with seasonal timing, sexual dimorphism, migration or breeding strategies, or between different functional feeding groups. Our findings highlight the high levels of variation in the time devoted to aggression across species, feeding groups, latitudes and seasons. Furthermore, our study demonstrates the utility of the numerous published time–activity budget studies that are available as a valuable source of data that can be used to answer broad-scale questions regarding animal behaviour. [ABSTRACT FROM AUTHOR]

The enzyme aromatase, responsible for the conversion of C19 androgens to C18 estrogens, exists as two paralogue copies in teleost fish: Cyp19a1a mostly expressed in the gonads, referred as gonadal aromatase, and Cyp19a1b, mostly expressed in the brain, accordingly known as brain aromatase. The neural localization of Cyp19a1b is greatly contained within the social behavior network and mesolimbic reward system in fish, suggesting a strong role of estrogen synthesis in the regulation of social behavior. In this work we aimed to analyze the variation in cyp19a1b expression in brain and pituitary of males of a highly social cichlid, Cichlasoma dimerus (locally known as chanchita ), and its relation with inter-individual variability in agonistic behavior in a communal social environment. We first characterized chanchita 's cyp19a1b mRNA and deduced amino acid sequence, which showed a high degree of conservation when compared to other teleost brain aromatase sequences, and its tissue expression patterns. Within the brain, Cyp19a1b was solely detected at putative radial glial cells of the forebrain, close to the brain ventricles. We then studied the relative expression levels of cyp19a1b by Real Time PCR in the brain and pituitary of males of different social status, territorial vs. non-territorial, and its relationship with an index of agonistic behavior. We found that even though, brain aromatase expression did not differ between types of males, pituitary cyp19a1b expression levels positively correlated with the index of agonistic behavior. This suggests a novel role of the pituitary in the regulation of social behavior by local estrogen synthesis. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the body weight (BW) and size, metabolic status, and reproductive development of dominant and subordinate prepubertal dairy heifers allocated in competitive dyads. Sixteen Holstein and Jersey × Holstein prepubertal heifers (means ± SEM; 250.8 ± 9.8 d; 208.5 ± 13.9 kg of BW) were assigned to 8 homogeneous dyads according to breed, age, and BW. Dyads were housed in pens separated 1 m from each other during 120 d, receiving a total mixed ration on a 5% restriction of their potential dry matter intake, and had access to the same feeder (60 cm) throughout the experiment. Dominant and subordinate heifers were defined based on the winning agonistic interactions in each dyad. Body development was recorded every 20 d in all heifers, and blood samples were collected on the same days to determine endocrine and metabolic status. The maximum follicle diameter, number of follicles >6 mm, and the presence of corpus luteum were observed weekly by ultrasound. Heifer BW (269.3 vs. 265.3 ± 1.5 kg) and average daily gains (0.858 vs. 0.770 ± 0.02 kg/d) were greater in dominant than subordinate heifers. On d 30, 37, and 53, dominant heifers had more follicles than subordinate heifers, and maximum follicle diameter was greater in dominant than in subordinate heifers (10.0 vs. 9.0 ± 0.3 mm). Dominant heifers achieved puberty earlier than subordinate heifers (313.9 ± 4.9 vs. 329.6 ± 5.7 d) with similar BW (279.4 ± 2.6 vs. 277.4 ± 5.8 kg). Glucose concentrations were greater in dominant than subordinate heifers (89.2 vs. 86.8 ± 1.2 mg/dL), but cholesterol concentrations were greater in subordinate than dominant heifers (86.1 vs. 90.2 ± 2.6 mg/dL). We concluded that, under continuous competitive situations, dominant heifers were more precocious than subordinate ones, achieving an earlier puberty. Dominant heifers had greater body growth and glucose concentrations than subordinate heifers, which may be responsible, at least in part, for the differences on reproductive development between heifers of different social status. [ABSTRACT FROM AUTHOR]

The aim of the present study was to describe the type of interaction between swimmers and sea lions, during tourist trips, at a small colony in Northern Patagonia, Argentina. Particularly we explored if sea lions would show agonistic behaviors towards people, or behaviors that potentially poses a danger, and to detect which interaction may produce such behavior. Underwater sea lions behavior was recorded by videotapes, and significant behavioral sequences were determined by two-event sequences analysis. During the resting period, sea lions swim around and look at the swimmer most of the time, and vice versa. During the pupping period, sea lions breathe more frequently during these behavioral sequences. During both seasons, the sequences including bites as the target behavior were significant (Adjusted residuals z-scores larger than 1.96 at the p < 0.05 level). These sequences consisted mainly in a sea lion allowing a swimmer to touch it and then biting him/her and a sea lion allowing a swimmer to touch it and then going away. Although these bites did not finished in cutting wounds, they represent potential risk of injuries. These results support the recommendation of no allowance of physical contact, or at least no looking for physical contact actively. [ABSTRACT FROM AUTHOR]

Some evidence indicates that in anuran amphibians, visual signalling can be important during social interactions such as territorial disputes among males, especially in diurnal species. The correct identification of a signal is not a trivial matter. A visual signal provides a visual cue during a social interaction, and to be effective it must elicit an immediate response in the receiver. We tested the hypothesis that visual displays in an agonistic context constitute aggressive signals, in three nocturnal species of Hylidae. We predicted that the production of visual displays would increase in the presence of a conspecific intruder male. Males ofHypsiboas raniceps,Dendropsophus nanusandLysapsus limellumwere submitted to two treatments: (1) Self Image, a reflection in a mirror, simulating the presence of an intruder; and (2) Control, a black rectangle covering the mirror. We observed three visual displays: vocal-sac display (inflate the vocal sac and maintain it inflated for some time), limb lifting (rapid up-and-down movements of one or more limbs), and toe/finger trembling (rapid up-and-down movements of one or more toes and/or fingers). This last display was observed only inH. ranicepsmales. Contrary to our hypothesis, the emission rates of all visual displays of the focal animals did not differ between treatments; and the behavioural response did not differ among species. Therefore, we suggest that these behaviours could not be used directly for communication in agonistic contexts, and may represent displacement activities (involuntary responses). Alternatively, an aggressive bimodal stimulus may be necessary to trigger a behavioural response by using visual signals during territory defence in these three species. [ABSTRACT FROM PUBLISHER]

This study tested the efficacy of mirror trials in studying aggressiveness in the matrinxã fish, Brycon amazonicus. The hypothesis was that a mirror would elicit an aggressive response in B. amazonicus juveniles, but show different behavioral and physiological profiles than those observed in trials with real opponents. Fish were tested using either a mirror trial ( n = 7) or a real trial ( n = 7), that is, placed alone with a mirror or paired with a same-sized opponent, respectively. All trials lasted for 20 min and took place in 96-L aquaria with water temperatures of 28°C. Fish in mirror trials exhibited less locomotion (mirror: 423.3 ± 39.1; real trial: 735.1 ± 31.9; p < .001), rushed less against the opponent (mirror: 3.1 ± 2.3; real trial: 39.6 ± 5.1; p < .001) and showed less escalation of aggressive behavior compared to the winner of a real trial. Regarding the physiological parameters, despite similar cortisol responses (mirror: 84.2 ± 13.8 ng/ml; real trial: 77.2 ± 16.9 ng/ml; p = .757), the fish that fought against a mirror had lower levels of plasma glucose than those of fish that fought against a real opponent (mirror: 76.8 ± 3.6 ng/dl; real trial: 103.8 ± 10.1 ng/ml; p = .037). This lower energy mobilization might be due to a lower cost of the fight in the absence of an opponent that flees from attacks, as the locomotion and number of rush totals were also lower in the mirror trials. This pattern of less locomotion is probably common in mirror trials because the opponent is always limited to one side of the arena. If the energetic cost is one of the factors that can determine the outcome of a fight, and if mirror trials do not evoke the physiological response observed in a real fight, the use of mirror trials must be reviewed in studies that consider the physiological responses. [ABSTRACT FROM AUTHOR]

Despite their prevalent use amongst avian species, particularly in Budgerigars, the relationship between mirror use and social behaviors is in need of elucidation. After establishing social behavior measures (e.g., agonistic and pair-bond data) in a colony of Budgerigars, mirrors were introduced and subsequent use was documented. Results illustrated a significant relationship between mirror use and pair-bonds, such that mirror use increased with increasing pair-bond strength. The authors posit that individual differences in gregariousness may best account for the obtained results, with certain birds seeking more social stimulation than others, whether it be from a pair-bond or from its own reflected mirror image. Additionally, the trends observed within agonistic behaviors were consistent with previous avian literature such that those who initiated more encounters also won more encounters and that there was a preference to be closer to birds that win more encounters. [ABSTRACT FROM AUTHOR]

Little is known about the specific behavioral exchanges that occur on a day-to-day basis between dyads of common bottlenose dolphins ( Tursiops truncatus ). This study assesses the proportion of time dyads spend in proximity (within ∼2 m) and the proportion of time spent in affiliative, agonistic, or socio-sexual contexts within and between age/sex dolphin pairings to better understand their social relationships. Observations of bottlenose dolphins housed at the Roatan Institute of Marine Sciences provided 10.5 h of underwater footage from which to examine association coefficients and inter-individual interactions. These data suggest similar patterns to previous studies on bottlenose dolphins: mother-calf dyads shared the highest coefficients of association, followed by male-male, female-female, and male-female dyads. Four classes of association coefficients were defined for the population including low, medium, medium-high and high. This study is the first to quantitatively assess association patterns concurrently with affiliative, agonistic, and socio-sexual behaviors for bottlenose dolphins. The predominant relationships were affiliative. [ABSTRACT FROM AUTHOR]

Objectives Primate social systems are remarkably diverse, and thus play a central role in understanding social evolution, including the biological origin of human societies. Although baboons have been prominently featured in this context, historically little was known about the westernmost member of the genus, the Guinea baboon ( Papio papio). Material and Methods Here, we summarize the findings from the first years of observations at the field site CRP Simenti in the Niokolo Koba National Park in Senegal. Results Guinea baboons reveal a nested multi-level social organization, with reproductive units comprising one 'primary' male, one to several females, young, and occasionally 'secondary' males at the base of the society. Three to five units form 'parties,' which team up with other parties to form a 'gang.' Different gangs have largely overlapping home ranges and agonistic interactions between different parties or gangs are rare. Some but not all strongly socially bonded males are highly related, and population genetic and behavioral evidence indicate female-biased dispersal. Females play an important role in intersexual bond formation and maintenance, and female tenure length varies between a few weeks to several years. Discussion While the social organization resembles that of hamadryas baboons ( P. hamadryas), the social structure differs considerably, specifically in terms of low male aggressiveness and female freedom. Despite substantial differences in social organization and social structure, the acoustic structure of Guinea baboon vocalizations does not differ substantially from that of other baboon taxa. With its multi-level organization, stable bonds between males and females, as well as a high-degree of male-male cooperation and tolerance, Guinea baboons constitute an intriguing model for reconstructing human social evolution. [ABSTRACT FROM AUTHOR]

The co-inhibitory molecule PD-1 suppresses T cell responses and has been targeted in the treatment of cancer. Here, we examined the role of PD-1 in regulating the balance between regulatory and effector T cells and whether blocking PD-1 could enhance tumour vaccine-induced protective immunity. A significantly higher proportion of tumour-resident T cells expressed PD-1 and Foxp3 compared with T cells in the tumour circulation or draining lymph nodes, and this correlated with a lower frequency of IFN-γ- and TNF-secreting CD8 T cells. Blocking PD-1 with a specific antibody reduced Foxp3 regulatory T (Treg) cell induction and enhanced proliferation, cytokine production, and tumour killing by CD8 T cells. Treatment of CT26 tumour-bearing mice with anti-PD-1 in combination with a vaccine, comprising heat-shocked irradiated tumour cells and a TLR 7/8 agonist, significantly reduced tumour growth and enhanced survival. Furthermore, surviving mice resisted tumour re-challenge. The rejection of tumours in mice treated with the anti-PD-1 vaccine combination was associated with a reduction in tumour-infiltrating Treg cells and enhancement of IFN-γ-secreting CD8 T cells. Our findings demonstrate that high PD-1 expression correlates with increased tumour-infiltrating Treg cells and reduced effector T cells and that when combined with a potent antigen-adjuvant combination, blocking PD-1 effectively enhances anti-tumour immunity. [ABSTRACT FROM AUTHOR]

Dominance and high status are directly associated with perception of angry expressions. However, studies that have sought to empirically assess the causal mechanisms between these construct are still relatively scarce. Moreover, several variables can influence and be influenced by both anger and dominance, increasing the complexity of synthesizing the findings related to the association between these agonistic behaviors. We conducted a systematic review in five electronic databases. A total of 207 potentially relevant publications were identified and screened. Of those, 20 articles were found eligible for detailed review, with 26 empirical studies. All reviewed studies reported an association between dominance and anger. Social status and dominance have a direct effect on the perception of anger. In turn, the perception of anger has a consistent effect on attributions of dominance for those who express this emotion. There are mutual effects between dominance and anger, which, if recurring and positively feedback-regulated, at least in perceptual terms, can lead to the establishment and maintenance of dominance hierarchies in social groups. [ABSTRACT FROM AUTHOR]

Aggressiveness is directly related to testosterone concentration, which varies with seasons and in response to female stimulation. The aim was to determine if the frequency and pattern of agonistic interactions between bucks varies seasonally and in response to oestrous female stimulation. In the first study we characterized the pattern of agonistic interactions during feeding throughout a whole year in groups of Iberian ibex bucks; and in the second study, we determined the influence of oestrous does on the frequencies of agonistic behaviours between Gabon bucks in different seasons. In Iberian ibex bucks, the frequency of agonistic behaviours was maximum in summer and testosterone concentration in late autumn. In Gabon bucks, total agonistic interactions increased in bucks stimulated by females in late summer and autumn. In late autumn there were more interactions without physical contact in stimulated than in isolated bucks. Aggressiveness in bucks varied along the year, but the seasonal pattern was related to the context in which behaviours were recorded. Stimulation with oestrous females induced an increase of aggressiveness during the breeding season. At least in the conditions of these studies, testosterone concentrations seemed not to be the main influence on the frequency in which aggressive behaviour was displayed. [ABSTRACT FROM AUTHOR]

As a highly motivated social behavior, maternal behavior in rats has been routinely used to study psychoactive drugs for clinical, neuroscience and pharmacological purposes. Recent evidence indicates that acute activation of serotonin 2C (5-HT 2C ) receptors causes a disruption of rat maternal behavior. The present study was designed to elucidate the behavioral, pharmacological mechanisms and neuroanatomical basis of this 5-HT 2C effect. First, we replicated the finding that acute MK212 injection (2.0 mg/kg, a highly selective 5-HT 2C agonist) disrupts maternal behavior, especially on pup retrieval. Interestingly, this disruption was significantly attenuated by 4-h pup separation (a procedure putatively increased maternal motivation). MK212 also suppressed food retrieval, indicating that it has a general effect on motivated behaviors. Second, we showed that MK212 disrupts maternal behavior by specifically activating 5-HT 2C receptor, as pretreatment with a 5-HT 2C receptor antagonist SB242084 (0.6 and 1.0 mg/kg) alleviated MK212-induced disruption on pup retrieval. Third, we microinjected MK212 into various brain regions implicated in the regulation of maternal behavior: nucleus accumbens shell (25, 75, 250 ng/0.5 μl/side), medial prefrontal cortex (25 and 250 ng, 1, 2 and 5 μg/0.5 μl/side), and medial preoptic area (MPOA, 75 ng, 1 and 5 μg/0.5 μl/side). Pup retrieval and other maternal responses were not affected by any of these manipulations. Finally, we used c-Fos immunohistochemistry to identify the central mechanisms of the acute and repeated MK212 effects on maternal behavior. Acute MK212 (2.0 mg/kg) disrupted pup retrieval and concurrently decreased c-Fos expression in the ventral part of lateral septal nucleus (LSv), MPOA, dentate gyrus (DG) and dorsal raphe (DR), but increased it in the central amygdala (CeA). Five days of repeated MK212 (2.0 mg/kg) treatment produced a persistent disruption of pup retrieval and only decreased c-Fos expression in the DR. These findings not only confirm a role of 5-HT 2C receptor in rat maternal behavior, but also suggest that the coordinated 5-HT 2C activity in various limbic (e.g., LSv, DG, CeA), hypothalamic regions (e.g., MPOA) and brainstem areas (e.g. DR), is likely involved in the mediation of important psychological processes (e.g. motor function, motivation) necessary for the normal expression of maternal behavior. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the effect of density on growth rate, agonistic behaviour, activity and use of space by hatchling C. porosus in captivity. Hatchling C. porosus were raised in identical enclosures (1.5 m 2 ) at different densities (3.3, 6.7, 13.3 and 20.0 hatchlings/m 2 ; or 0.30, 0.15, 0.08 and 0.05 m 2 /hatchling respectively). Hatchlings came from 5 different clutches, hatched on the same day, spread evenly between density treatments (2 replicates per treatment). Growth rate (grams per day) was assessed between 4 and 25 days of age, which is a reliable indicator of post-hatching growth trajectories for this species. Clutch and initial body mass (BM) had a strong influence on growth rate, with a lower growth rate among the largest hatchlings born. The highest mean growth rate in body mass occurred at 6.7/m 2 (6.12 ± 1.24 g/d) and was lowest at the highest density (20.0/m 2 : −2.33 ± 0.63 g/d). Behavioural observations taken every 10 min on day 19 (24 h period) confirmed that hatchlings remained relatively inactive and hidden under cover for most of the day, and were more active at night, with peaks at dusk and dawn. However, the level of hourly activity (mean movements per individual per hour) was highest at densities of 13.3/m 2 and 20.0/m 2 , compared with densities of 3.3/m 2 and 6.7/m 2 . Behavioural observations at 17:00–8:00 h over 3 days (days 17–19) revealed that the frequency of agonistic interactions (mean per animal per night) was highest at the lower densities (3.3/m 2 ; 6.7/m 2 ) and decreased with increased density (13.3/m 2 ; 20.0/m 2 ). The results suggest that as density increases above 6.7/m 2 , growth rate in hatchling C. porosus during the first 3 weeks begins to decline as activity increases. However, at the lowest density (and group size: 5), 1 or 2 individuals become dominant and grow large at the expense of the remaining hatchlings. Based on these results, it appears that the high and low densities tested may have an adverse effect on hatchling C. porosus growth rate and behaviour in captivity. [ABSTRACT FROM AUTHOR]

Animals establish social hierarchies through agonistic behavior. The recognition of the own and others social ranks is crucial for animals that live in groups to avoid costly constant conflicts. Weakly electric fish are valuable model systems for the study of agonistic behavior and its neuromodulation, given that they display conspicuous electrocommunication signals that are generated by a very well-known electromotor circuit. Brachyhypopomus gauderio is a gregarious electric fish, presents a polygynous breeding system, morphological and electrophysiological sexual dimorphism during the breeding season, and displays a typical intrasexual reproduction-related aggression. Dominants signal their social status by increasing their electric organ discharge (EOD) rate after an agonistic encounter (electric dominance). Subordinates only occasionally produce transient electric signals (chirps and offs). The hypothalamic neuropeptide arginine-vasotocin (AVT) and its mammalian homologue, arginine- vasopressin (AVP) are key modulators of social behavior across vertebrates. In this study, we focus on the role of AVT on dominance establishment in Brachyhypopomus gauderio by analyzing the effects of pharmacological manipulations of the AVT system in potential dominants. AVT exerts a very specific direct effect restricted only to EOD rate, and is responsible for the electric dominance. Unexpectedly, AVT did not affect the intensity of aggression in either contender. Nor was the time structure affected by AVT administration. We also present two interesting examples of the interplay between contenders by evaluating how AVT modulations, even when directed to one individual, affect the behavior of the dyad as a unit. First, we found that V1a AVT receptor antagonist Manning Compound (MC) induces a reversion in the positive correlation between dominants’ and subordinates’ attack rates, observed in both control and AVT treated dyads, suggesting that an endogenous AVT tone modulates aggressive interactions. Second, we confirmed that AVT administered to dominants induces an increase in the submissive transient electric signals in subordinates. [ABSTRACT FROM AUTHOR]