Sexual behavior and extragroup copulations in a wild population of common marmosets (Callithrix jacchus).

Sexual behavior and mating patterns are described for 3 free-ranging groups of common marmosets living in a coastal forest in northeastern Brazil. Each group contained 2 breeding females. Within groups, sexual behavior was generally restricted to breeding females and a single behaviorally dominant male. Of 101 mounts and copulations, 24 involved pairings of individuals from 2 different groups. Extragroup sexual behavior was performed by both breeding and nonbreeding group members, and 65% of all adults mounted or copulated with an extragroup individual at least once. Sexual behavior occurred throughout the female reproductive cycle but was significantly more frequent during an 11-day 'conception period'. Thus, while female marmosets show no physical signs of estrus, both males and females likely do have some information about the timing of ovulation. Mating patterns in this population included both polygyny and monogamy and varied between groups and over time.     

Does the match between individual and group behavior matter in shoaling sticklebacks?

In animals living in groups, the social environment is fundamental to shaping the behaviors and life histories of an individual. A mismatch between individual and group behavior patterns may have disadvantages if the individual is incapable of flexibly changing its state in response to the social environment that influences its energy gain and expenditure. We used different social groups of juvenile three‐spined sticklebacks (Gasterosteus aculeatus) with experimentally manipulated compositions of individual sociability to study the feedback between individual and group behaviors and to test how the social environment shapes behavior, metabolic rate, and growth. Experimentally created unsociable groups, containing a high proportion of less sociable fish, showed bolder collective behaviors during feeding than did corresponding sociable groups. Fish within groups where the majority of members had a level of sociability similar to their own gained more mass than did those within mismatched groups. Less sociable individuals within sociable groups tended to have a relatively low mass but a high standard metabolic rate. A mismatch between the sociability of an individual and that of the majority of the group in which it is living confers a growth disadvantage probably due to the expression of nonadaptive behaviors that increase energetic costs.     

Seasonal Changes in Male Associative Behavior and Subgrouping of Alouatta palliata on an Island

Howler groups are usually spatially cohesive and stable in composition; however, more flexible grouping patterns occur in some social groups. We analyzed the associative and subgrouping patterns of males living in a group with fission-fusion social organization. Based on information from previous studies on Alouatta palliata and other primates and in the current socioecological models, we established initial predictions on the variations in male behavior according to several socioecological factors. We studied associative behavior via scan sampling at 15-min intervals to register the identity of males in the subgroups and the presence and number of receptive females. We calculated an association index that was then transformed into a measure of association strength. We found individual association trends, as well as important seasonal differences in the subgrouping patterns of males. During the dry season the presence of many receptive females resulted in reduced levels of association, and therefore fewer males per subgroup. The scenario changed during the wet season, when males grouped together significantly more and kinship relationships were a major determinant for individual association preferences.     

Changes in the social structure of two groups of stumptail macaques (Macaca arctoides)

Two previously studied groups of stumptail macaques were restudied to investigate stabilities and instabilities within group structures. Frequency data for nonsocial and dyad behaviors were collected. While there was considerable group stability, several important changes occurred. The most noteworthy group changes were in grooming and playing. Individual changes centered upon females. The first and fourth ranking females of one group switched dominance positions. The roots of this reversal were minimally reflected by aggressive and submissive interactions, and more fully exposed by quiet association patterns such as grooming, huddling, and sitting together. Increased frequencies of huddling, touching, and approaching indicated that the lowest ranking female of each group moved closer to other group members. There was no hint of this change in agonistic interactions.     

Resumption of seasonal breeding patterns in male and female rhesus monkeys transferred from an indoor to an outdoor environment

Seasonal aspects of social behavior and sex steroid levels were observed in two groups of rhesus monkeys from March through December. One group (3 males, 7 females) had lived outdoors for several years. The other group (6 males, 5 females), transferred outdoors in late February, had lived indoors for several years. In March-April, the long-term outdoor residents displayed the expected seasonal pattern of sexual behavior, characterized by absence of complete sequences of copulatory behavior. At this time the indoor-adapted group displayed high levels of copulatory behavior. Thereafter, frequencies of sexual behavior of the two groups were similar. Testosterone in the males was positively correlated with frequency of sexual behavior in each group. Females in the indoor-adapted group displaced menstrual cycles in March and April and 3 of 5 became pregnant at this time. The two remaining indoor-adapted females continued to display ovulatory cycles, but little sexual behavior, throughout the summer. Interestingly, two females in the outdoor-adapted group also displayed summer ovulatory cycles; without concomitant sexual activity. These data show that the disruption of seasonal breeding patterns produced by lengthy indoor housing remains briefly apparent following transfer outdoors, but is substantially overcome within a few months.     

Postparturitional testosterone surge in male offspring of rats stressed and/or fed ethanol during late pregnancy

Male offspring of rats exposed to restraint stress and/or alcohol during late pregnancy show aberrant patterns of sexual behavior masculinization and defeminization that vary as a function of treatment. The impact of these treatments on the postparturitional testosterone (T) surge that contributes to sexual behavior differentiation was investigated. Plasma T was measured using radioimmunoassay in individual males sampled on day 21 of gestation within 10 min of cesarean delivery or 1, 2, or 4 h thereafter. Neonatal T in the group exposed only to stress did not differ from that in the control group. T was lower than control levels at birth in both alcohol groups. The magnitude of the T surge that occurred during the first hour of birth in the control group was diminished by 50% in both alcohol groups, whose T pattern was very similar. There was no common alteration in postparturitional T associated with the increased lordotic behavior potential that males in all three treatment groups typically share, nor were there idiosyncratic endocrine abnormalities linked to the very different male copulatory pattern each exhibits. Exposure to an abnormal T milieu during fetal as well as neonatal ontogeny may underlie the etiology of the different sexual behavior patterns exhibited by males exposed to stress and/or alcohol. Possible unique effects each treatment exerts on perinatal plasma T and it's aromatization to estradiol in hypothalamic targets are discussed.     

How group size affects vigilance dynamics and time allocation patterns: the key role of imitation and tempo

In the context of social foraging, predator detection has been the subject of numerous studies, which acknowledge the adaptive response of the individual to the trade-off between feeding and vigilance. Typically, animals gain energy by increasing their feeding time and decreasing their vigilance effort with increasing group size, without increasing their risk of predation ('group size effect'). Research on the biological utility of vigilance has prevailed over considerations of the mechanistic rules that link individual decisions to group behavior. With sheep as a model species, we identified how the behaviors of conspecifics affect the individual decisions to switch activity. We highlight a simple mechanism whereby the group size effect on collective vigilance dynamics is shaped by two key features: the magnitude of social amplification and intrinsic differences between foraging and scanning bout durations. Our results highlight a positive correlation between the duration of scanning and foraging bouts at the level of the group. This finding reveals the existence of groups with high and low rates of transition between activities, suggesting individual variations in the transition rate, or 'tempo'. We present a mathematical model based on behavioral rules derived from experiments. Our theoretical predictions show that the system is robust in respect to variations in the propensity to imitate scanning and foraging, yet flexible in respect to differences in the duration of activity bouts. The model shows how individual decisions contribute to collective behavior patterns and how the group, in turn, facilitates individual-level adaptive responses.     

Quantitative genetics of natural variation of behavior in Drosophila melanogaster: the possible role of the social environment on creating persistent patterns of group activity

Using a set of nine effectively isogenic lines collected from nature in 1998, we observed unperturbed behaviors of mixed-sex groups of Drosophila melanogaster. We repeatedly scanned replicated groups of genetically identical individuals, five females and five males, and recorded the behavior of each individual (i.e., walking, feeding, grooming, flying, courting, mating, fighting, or resting). From these behaviors, we made a composite variable of activity for our quantitative genetic analysis. Genotypes differed in activity, explaining 14.41% of the variation in activity; 8.60% of the variation was explained by a significant genotype x sex interaction, which signifies genetic variation for sexual dimorphism in behavior. Phenotypic plasticity explained 11.13% of the variation in activity. Different genotypes and sexes within genotypes had different rank orders of the component behaviors that contribute to activity. We found no effect of common rearing environment. Instead, differences between replicate groups within genotype accounted for 19.47% variation in activity, and activity was significantly repeatable across scans. This emergent group behavior is likely caused by differences between groups of interacting individuals, even though individuals were genetically identical across groups. Thus, emergent group behavior explained almost as much variation in activity as the combined sources of genetic variation (23.01%), and this is an additional level on which selection could operate: individuals and groups. We discuss how differences among groups could change patterns of additive genetic variation available for evolution. Furthermore, because the behavior of an individual is influenced by conspecifics, genotype interactions between individuals could contribute to indirect selection. Finally, if we consider activity as a syndrome governing all component behaviors with strong genetic correlations among behaviors within an individual, then these component behaviors cannot evolve independently. These results suggest that reductionist approaches of molecular behavior genetics may be incomplete and/or misleading when considering similar phenotypes at the population level or when trying to understand how behaviors evolve.     

Behavioral effects of changing group membership among captive lowland gorillas

Group membership was modified among 4 gorilla groups at Zoo Atlanta in an attempt to increase compatibility and sexual behavior. The modifications ultimately moved 7 adult females among the groups. The moves were made by individually introducing the new group members to the old members, resulting in 18 total introductions. Several individual and social behaviors differed in the two conditions. The most obvious change was a temporary increase in aggressive display behaviors, as well as an increase in contact and social examination, in the postmovement condition. Additionally, the individual behaviors of travelling and eating increased after the introductions, while resting decreased. Other self-maintenance behaviors did not change. Finally, there was an increase in time mothers and offspring spent closer to one another following the moves. Previous research and anecdotal evidence suggest that gorillas respond to changes in group membership with aggression; these data support and extend those data to different age/sex groups, postmovement trends in behavior, and other aspects of gorilla behavior. © 1996 Wiley-Liss, Inc.     

Effect of landscape heterogeneity on termite tunnel pattern: Simulation study

Although the environment in which termites live is very heterogeneous, most experimental studies on the termite tunnel patterns have been conducted on homogeneous sand substrates. In order to explore how the heterogeneity affects tunnel patterns, I developed an agent-based model to simulate termite tunneling behavior at the individual level. In this model, grid space consists of easy and difficult areas for tunneling. Heterogeneity, H, was defined as the degree of the mixture of the two areas. The tunnel patterns formed by changing the number of termites, N, and H were quantitatively characterized by territory circularity and the territory area. These patterns were categorized into two groups, one with a small territory area and high circularity (group 1) and the other with a large area and low circularity (group 2). Considering the previous study that the termite populations with high N values have high territorial scalability, it can be said that the territories belonging to group 2 have higher foraging abilities and viability than those belonging to group 1. The simulation results showed that the tunnel patterns generated for small N and high H belonged to group 2. This implies that the heterogeneity can make a positive contribution to the expansion of the foraging area by effectively focusing the foraging energy of a termite population. I briefly discussed the mechanism of this positive role and the limitations of this simulation study. In addition, I discussed issues that need to be resolved in the near future to overcome the limitations.     

Effect of management of patients with Anorexia and Bulimia nervosa on symptoms and impulsive behavior

The aim of the study was to provide further and up to date information on the evaluation of the management of Anorexia and Bulimia nervosa at the Eating Disorders Unit (EDU) of the Ljubljana Psychiatric Clinic, based upon detailed assessment of the eating disorders specific and non specific symptoms of impulsive behaviors, highly correlated with these entities. 34 female patients with anorexia (restrictive or purgative type) and 38 female patients with Bulimia nervosa (purgative or non-purgative type) undergoing hospital treatment at the EDU were evaluated upon admission, as well as upon discharge and three and six months after discharge, using the Eating Disorder Questionnaire. Upon discharge a marked decrease in the overall symptoms was noted. The differences in symptoms incidences between the two groups were significantly specific for the individual form of eating disorder, especially upon admission, and were more pronounced in anorexia group. In later measurements, performed during the period of three and six months after discharge, a mild trend of increase in the disorder specific symptoms was detected in both groups, but was not statistically significant. In addition to binging on food, striking, quarreling and spending sprees are characteristics of patients with eating disorders, which in particular apply to the Bulimia nervosa group. Apart from the disorder specific symptoms, impulsive behavior was also reduced during study period, while the difference in its occurrence between the two groups gradually became non-significant. The management of patients with eating disorders at the EDU was successful in both groups, confirmed by an intense reduction of the disorder specific symptoms, impulsive behavior and increased stability recorded three and six months after discharge. The study strongly suggests that the effect of treatment regime for eating disorders can be predicted by careful assessment of the relevant symptoms and impulsive behavioral patterns.     

印度喜马拉雅山区西藏盘羊的警戒行为

在几个动物类群中开展的许多行为研究中发现,个体的警觉水平与群体大小存在着负相关关系。一般认为,这种关系是由于个体在一个较大的群体中被捕杀的概率小。在本研究中,我研究了濒危的印度喜马拉雅地区西藏盘羊(Ovis ammon hodgsoni)的警戒行为与群体大小和逃逸地形的关系。我假设小群体中的、位于悬崖旁的盘羊比那些大群体中的、开阔地带(逃逸地形)中的盘羊的警戒水平高。结果发现随着群体增大,盘羊的警戒水平下降,但是,逃逸地形与盘羊的警戒水平没有关系。盘羊的不同性别、年龄组之间的时间预算存在显著差异。与雄性和亚成年个体比较,雌性用于警觉的时间多,它们比雄性采食时间长,移动少。因此,警戒行为是是盘羊的一种重要反捕食行为     

Reconciliation in three groups of lion-tailed macaques

We studied postconflict behavior in three captive groups of lion-tailed macaques (Macaca silenus). After a conflict, we monitored the aggressee as the focal individual during a 10-min postconflict period and made control observations the following day on the same individual. Selective attraction between former opponents occurred in the first minutes of the postconflict period. The conciliatory tendency was relatively high, about 40%. Although no specific behavior was used to reconcile, postconflict contacts were especially intense and a rich repertoire of affiliative patterns was exihibited. With regard to the rate and form of reconciliation, lion-tailed macaques resemble Sulawesi macaques, which belong to the same phyletic lineage. We also discuss the possible interrelations between conciliatory patterns and other characteristics of social organization.     

Gender-related factors affecting primate social behavior: Grooming,rank, age,and kinship in heterosexual and all-male groups of stumptail macaques

The structure of grooming relations was studied in three captive groups of stumptail macaques, two heterosexual (consisting mainly of females) and one all male. Compared to the heterosexual groups, social hierarchy in the all-male group was less linear, and agonistic and peaceful activity of low-ranking individuals toward high-ranking ones was higher. In addition, in the all-male group received grooming was more variable than performed grooming and showed stronger dependence on age. No effect of maternal kinship was found in the all-male group, and individual preferences were also less marked in this group than in heterosexual groups. These differences tend to be related to dominance style and dispersal patterns. © 1996 Wiley-Liss, Inc.     

The Comparative Biology of Genetic Variation for Conditional Sex Ratio Behavior in a Parasitic Wasp, Nasonia Vitripennis

Using genetic markers, we tracked the sex ratio behavior of individual females of the parasitic wasp, Nasonia vitripennis, in foundress groups of size 1, 2, 4, 8 and 16. Comparison of 12 isofemale strains extracted from a natural population reveals significant between-strain heterogeneity of sex ratios produced in all sizes of foundress group. Under simple assumptions about population structure, this heterogeneity results in heterogeneity of fitnesses. The strains differ in their conditional sex ratio behavior (the sex ratio response of a female to foundress groups of different sizes). Females of some strains produce more males as foundress group size increases (up to size eight). Females of another strain produce more males when not alone but do not respond differentially to group size otherwise. Females of two other strains show no conditional sex ratio behavior. Females of only two strains behave differently in foundress groups of size 8 and 16. Correlation and regression analyses indicate that the strains differ significantly in their fit to the predictions of an evolutionarily stable strategy (ESS) model of conditional sex ratio behavior. Such heterogeneity contradicts the notion that females of this species possess conditional sex ratio behavior that is optimal in the ESS sense. The results imply that this ESS model is useful but not sufficient for understanding the causal basis of the evolution of this behavior in this species. This is the first report on the sex ratio behavior of individual females in multiple foundress groups in any species of parasitic wasp. Data of this type (and not foundress group or ``patch'''' sex ratios) are essential for testing evolutionary models that predict the sex ratio behaviors of individuals. We suggest that a test for an ESS model include the answers to two important questions: 1) is the model quantitatively accurate? and 2) is there reasonable evidence to indicate that natural selection has caused individuals to manifest the ESS behavior?     

Kinship shapes affiliative social networks but not aggression in ring-tailed coatis

Animal groups typically contain individuals with varying degrees of genetic relatedness, and this variation in kinship has a major influence on patterns of aggression and affiliative behaviors. This link between kinship and social behavior underlies socioecological models which have been developed to explain how and why different types of animal societies evolve. We tested if kinship and age-sex class homophily in two groups of ring-tailed coatis (Nasua nasua) predicted the network structure of three different social behaviors: 1) association, 2) grooming, and 3) aggression. Each group was studied during two consecutive years, resulting in four group-years available for analysis (total of 65 individuals). Association patterns were heavily influenced by agonistic interactions which typically occurred during feeding competition. Grooming networks were shaped by mother-offspring bonds, female-female social relationships, and a strong social attraction to adult males. Mother-offspring pairs were more likely to associate and groom each other, but relatedness had no effect on patterns of aggressive behavior. Additionally, kinship had little to no effect on coalitionary support during agonistic interactions. Adult females commonly came to the aid of juveniles during fights with other group members, but females often supported juveniles who were not their offspring (57% of coalitionary interactions). These patterns did not conform to predictions from socioecological models.     

The cost of defeat: Capuchin groups travel further,faster and later after losing conflicts with neighbors

Although competition between social groups is central to hypotheses about the evolution of human social organization, competitive interactions among group‐mates are thought to play a more dominant role in shaping the behavior and ecology of other primate species. However, few studies have directly tested the impact of intergroup conflicts in non‐human primates. What is the cost of defeat? To address this question, the movements of six neighboring white‐faced capuchin (Cebus capucinus) social groups living on Barro Colorado Island, Panama were tracked simultaneously using an Automated Radio Telemetry System (ARTS), for a period of six months. Groups moved 13% (441 m) further on days they lost interactions compared with days they won interactions. To cover these larger distances, they traveled faster, stopped less frequently, and remained active later in the evening. Defeat also caused groups to alter their patterns of space use. Losing groups had straighter travel paths than winning groups, larger net displacements and were more likely to change their sleeping site. These results demonstrate that losing groups pay increased travel costs and suggest that they forage in low‐quality areas. They provide some of the first direct evidence that intergroup conflicts have important energetic consequences for members of competitively unsuccessful primate social groups. A better understanding of how intergroup competition impacts patterns of individual fitness is thus needed to clarify the role that this group‐level process plays in shaping the evolution of human‐ and non‐human primate behavior. Am J Phys Anthropol 152:79–85, 2013. © 2013 Wiley Periodicals, Inc.     

Effects of pair-housing after social defeat experience on elevated plus-maze behavior in rats

Social defeat experience in male rats causes an increase in anxiety-like behavior in the elevated plus-maze. Some researchers have suggested that housing rats socially following social defeat attenuates and/or prevents an increase in anxiety-like behavior. However, many other studies have shown that individual housing per se enhances anxiety-like behavior even in the absence of social defeat. In the present study, we assessed the relative contributions of the experience of social defeat and housing conditions on animals’ performance in the elevated plus-maze. Rats were assigned to one of the following four groups: defeat/individual housing, defeat/pair-housing, non-defeat/individual housing, and non-defeat/pair-housing. The elevated plus-maze test was conducted 2 weeks after the defeat experience. Our results demonstrated that the defeat/individual housing group spent less time than the other groups in the open arms: moreover, there were no differences between the other three groups. These results confirm the claim that the group-housing of rats prevents an increase in anxiety-like behavior caused by defeat.     

Evaluating social influences on food-processing behavior in white-faced capuchins (Cebus capucinus)

Interpopulation variability in patterns of food processing, similar to what is described as "traditional" or "cultural" variation in chimpanzees (Pan troglodytes) and orangutans (Pongo pygmaeus), was identified in white-faced capuchins (Cebus capucinus). However, recent comparisons of food processing in capuchins were conducted only at the population level, with relatively little attention given to variability among groups, age/sex classes, or individuals. This paper examines variability in the processing of specific food types within the context of various social networks (i.e., patterns of association, rank, and kinship) among free-ranging Cebus capucinus at Santa Rosa National Park in Costa Rica. We collected data on two groups of white-faced capuchins in 2001, identifying rates of "food interest" for each individual, as well as forms of processing for specific food types. Juveniles exhibited the most interest in the food-processing behavior of other group members, and food interest was directed most frequently toward adult females. We identified distinctive processing techniques for several food items (Luehea candida pods, Sloanea terniflora fruits, and caterpillars) that facilitated comparisons among individuals within groups. Food-processing techniques for Sloanea fruit and caterpillars appeared to vary independently of the social networks examined in this study. However, we found evidence that variation in Luehea candida processing is to some degree linked to both patterns of association and social rank. The potential influence of these variables on observed food processing patterns warrants further scrutiny.