Ontogenetic changes and the stability of rhesus monkey dominance relationships

Dominance relationships were studied in a rhesus monkey group during five consecutive years. The group consisted of eight stable matriarchies and an adult male class which was replaced at the start, and again at the midpoint, of the study. Immature males were selectively harvested to maintain a sex ratio typical of natural troops. Maximum group size during the study was 77 animals.Dominance relationships were remarkably stable, with only 4.4% of dyads failing to show unidirectional relationships. Despite this stability, a linear ranking of all group members was not possible. Male dominance relationships with other males were among the most stable, following the fighting which ensued on male introductions. Male introductions did not disrupt female dominance relationships.Adult female dominance relationships were also quite stable, but immature females slowly achieved dominance over older sisters and females subordinate to their mothers. Such reversals were the result of processes lasting over many months. Many dominance assertions occurred prior to puberty but a significant number occurred following sexual maturity. Maturing females did not reverse dominance relationships according to any particular hierarchial order and, as a consequence, many were subordinate to animals that were dominated by others that they dominated.Although there was an alpha male that was dominant to all animals in the group, adult females dominated most adult males. Adult males, however, often reciprocated aggression directed at them. They almost invariably threatened or countercharged aggressive immature animals regardless of matriarchial membership. Adult males dominated some adult and most young females, even in families containing matriarchs and adult females to which the adult males always submitted.The dominance relationships of young males were similar to those of their sisters, until puberty. Young males did not necessarily bypass adult males that their mothers outranked, and often failed to win against adult females that their mothers dominated. Adolescent female aggression against females is seldom interfered with by adult males, and females may actively aid one another against males. In contrast, the aggression of young males often elicits interference by adult males, and young males often become the targets of redirected aggression in the group. As a consequence, whereas young females rise in rank to positions adjacent to their mothers, adolescent males often suffer losses to animals that they had dominated as juveniles.     

Social relationships between adult male and immature rhesus macaques

Social relationships of adult male rhesus macaques (Macaca mulatta) were studied over a period of 14 months. Sixteen focal males were chosen from a single group in the Cayo Santiago colony, Puerto Rico. Immatures were defined as infants, yearlings and 2-year-olds. There was a tendency for males to spend more time in proximity to immatures in the birth seasons than in the mating season. Time spent in proximity to immatures was correlated with male dominance rank. Several male-immature dyads had persistent relationships and nine were apparent throughout the study period. Most of the latter involved the top-ranking males. There were no consistent effects of sex or rank of the immature on the distribution of persistent relationships. In almost all male-immature dyads the immature was primarily responsible for maintaining proximity. Two ways were found in which immatures could benefit from these relationships. Protection and agonistic aiding of immatures by adult males were rare, but occurred exclusively in dyads with persistent relationships. In addition, immatures apparently gained greater access to food resources as a result of their relationships with adult males. There was no clear evidence of adult males benefiting from these relationships.     

Agonistic aiding: Kinship,rank, age,and sex influences

An analysis of 3,774 episodes of agonistic aiding collected during a two-year study of a rhesus monkey group (Macaca, mulatta) indicated the differential influence of kinship and rank relationships on the participation of different age-sex classes in both aid to victims and aid to aggressors. Most aiding favored victims rather than aggressors and was much more likely to occur when matrilineal kin were involved. Females were more likely to aid than were males, and the frequency of their participation increased with age. Females were much more influenced by kinship than were males and defended or aggressively supported kin against any third party regardless of dominance relationships. Adult males seldom aided against animals that were dominant to themselves; the rare exceptions occurred when adult males defended kin. Aiding was far more likely to occur if the victim was squealing, and noisy agonistic episodes often involved multiple aiders on both sides. Aiding patterns had some potential to insure dominance rank inheritance within families, in accordance with the Kawamura hypothesis. In aiding animals outside of their own matrilines, however, group members aided randomly with respect to this model. There was little evidence that aiding functioned to support individuals when they targeted animals to which they should be dominant as adults based on matrilineal dominance relationships. Most defensive aiding seemed to function primarily to defend victims (primarily kin) of aggression. Aggressive support of the attacker, on the other hand, seemed to function primarily to reinforce coalitions with the attacker. The identity of the victim was unimportant as long as it was neither kin to nor dominant to the aider. Aggressive support of attackers did not overturn existing dominance relationships.     

Effects of castration on androstenedione, testosterone and dihydrotestosterone plasma levels in adult male rats

In the present study we investigated the effects of castration on androstenedione (A), testosterone (T) and dihydrotestosterone (DHT) plasma levels in adult male rats 5 and 47 days after castration. In another group of 60-day-old castrated rats, the three steroids have been evaluated during testosterone propionate administration. Our data show that 5 days after orchiectomy all three steroids were significantly decreased (p less than 0.001) with respect to control values. 47 days after orchiectomy, T and DHT were also significantly decreased with respect to the control group. In both groups of orchiectomized rats the A/T ratio increased significantly with respect to controls. On the contrary, the T/DHT ratio sharply decreased. This suggests that DHT, in orchiectomized rats, could derive from precursors other than T. A negative correlation between A and the T/DHT ratio was observed 47 days after castration in adult animals and emphasized upon testosterone propionate administration. In the latter group, T was significantly lower while A is significantly augmented with respect to control values. Finally, the above-mentioned negative correlation indicates a possible prevalent role of A in contributing to the circulating levels of DHT in adult orchiectomized rats.     

Affiliative relationships and reciprocity among adult male bonnet macaques (Macaca radiata) at Arunachala Hill, India

In captivity, male bonnet macaques (Macaca radiata) frequently express "friendship" toward one another, including affiliative behavior such as huddling, grooming, coalitionary support, and sitting in close proximity. The purpose of this study was to determine whether wild adult male bonnet macaques also express "friendship" by investigating whether or not (1) adult male bonnet macaques have affiliative social relationships with other males, (2) the strength of social relationships varies among dyads, (3) there is time-matched reciprocity in allogrooming among dyads, and if so, whether the level of reciprocity occurs within a bout of grooming, a day, or over 2 months (the limit of this study), and (4) a correlation exists between the strength of social relationships and dominance ranks among adult males. Focal samples totaling 150 hr on all seven adult males in one study group were conducted to record both agonistic and affiliative interactions. Agonistic interactions were used to construct a dominance hierarchy, whereas affiliative interactions (sitting in proximity to within 1 m with and without grooming) were used to quantify the existence and strength of social bonds within dyads. Results show that adult male bonnet macaques had differentiated affiliative relationships with other males in their group. There was little reciprocity of grooming within a bout of grooming or within a day, but greater reciprocity over the study period of 2 months. There was no correlation between dominance ranking distance and the strength of affiliative relationship within dyads; however, within dyads lower-ranking males groomed higher-ranking males more than vice versa. This study suggests that friendships in male bonnet macaques are characterized not by immediate tit-for-tat reciprocal altruism, but by reciprocity over a longer time span, and that affiliative social relationships may be less constrained by agonistic relationships than is the case in more despotic species of macaques.     

Group formation of previously single-caged adult rhesus macaques for the purpose of environmental enrichment.

An attempt was made to form two groups of 6 previously single-caged adult female and 6 previously single-caged adult male rhesus macaques. The study was based on the premise that simultaneous introduction of familiar animals reduces the risks involved during group formation. Future group members were therefore given ample opportunity to physically interact with each other on a one-to-one basis and were considered ready for group formation only when they had demonstrated compatibility and clear-cut dominance-subordination relationships. Both group formation attempts were failures. Aggressive incompatibility was heralded by certain subjects challenging other partners to whom they had originally been subordinate. Aggressive harassment was intensive and persistent. Victims showed no resistance except for fear-grinning and crouching in submission. They did so to no avail. Both groups were split again within the first hour of introduction to avoid fatal consequences. It was concluded, that unlike pair-housing, group-housing of previously single caged adult rhesus macaques is associated with considerable risks which cannot be overcome by systematically familiarizing all group members before the animals are introduced as a group. There is no guarantee that well established dyadic relationships do not break down within the more complex social structure of the group, thereby triggering aggressive conflicts that put the animals' safety into undue jeopardy.     

Social relationships and individual contribution to cooperative behaviour in captive common marmosets (Callithrix jacchus)

The social relationships between the members of a family consisting of eight captive common marmosets (Callithrix jacchus) are here examined, as well as the participation of individual family members in infant carrying and defensive behaviour against non-related intruders (adolescent males). Within the social relationships, a clear division of the family into three subgroups (parents, adult offspring, non-adult offspring) could be determined, whereby the adult offspring, especially with respect to the parents, occupy a peripheral position. In the types of cooperative behaviour examined here, substantial participation in infant carrying could be observed in only four family members (parents, adult son, one subadult daughter), and in defence against intruders in only two family members (adult son, one subadult daughter). Participation in infant carrying remained stable throughout the study period. Conversely, individual changes in participation in defence against intruders could be determined, dependent upon the presence of infants carried. The advantages and disadvantages of social substructuring observed are discussed here, in particular the peripheral position of adult offspring, possible connections in individually varied participation in cooperative behaviour, and possible regulative mechanisms. In view of past studies on cooperative behaviour among marmosets, it is here presumed that pronounced individual differences result from a division of labour within the family with respect to various aspects of cooperative behaviour.     

Variation in tree growth,mortality and recruitment among topographic positions in a warm temperate forest

Questions: Do the population dynamics of trees differ among topographic positions and, if so, how does topographic position affect the population dynamics of species that are distributed in a topography‐specific manner? Which is the most important life stage in determining vegetation patterns? Location: Primary and secondary warm temperate evergreen broad‐leaved forest (40 ‐ 280 m a.s.l.) on the western part of Yakushima Island, Japan. Methods: Mortality, recruitment, DBH growth and distribution of stems (= 5 cm DBH) in a 2.62‐ha plot were surveyed in 1992 and 2002 to determine the relationships between population parameters and (1) topography and (2) distribution patterns of 17 common tree species. Results: Common species (n = 17) were classified into three distribution pattern groups: group A, distributed mainly on convex slopes; group B, on concave slopes, and group C, not aggregated with respect to topographic position. Stem mortality, recruitment and DBH growth were greater in group A than in group B within each topographic class. The hierarchy of stem mortality among topographic classes for groups A and B was convex > planar > concave. Stem recruitment density was relatively high on the convex and concave slopes, respectively, for groups A and B. Conclusions The topographical positions of adult trees were not always most suited for adult survival and growth. For group A, the distribution pattern of adults was determined in the juvenile stage, while this was not the case for group B. Studies of juvenile stages are important for understanding the demographic basis of vegetation distribution patterns.     

Age- and gender-related changes in body size, adiposity, and endocrine and metabolic parameters in free-ranging rhesus macaques.

Normative age- and gender-related changes in body composition, serum lipids, testosterone, and insulin-like growth factor (IGF-1) were examined in the Cayo Santiago free-ranging rhesus macaques. In both adult males and females, body weights, crown-rump lengths, and circumference of the limbs were lowest in the oldest group (20+ years of age) as compared with other adult age classes. Body fat, as reflected in subcutaneous fatfold thickness and waist/thigh ratios, were higher in adult females than adult males. This gender dimorphism was first detectable among the 6-9 year old age group. Greatest body fat among females was observed in the 10-14 age group, whereas in males the highest values were observed in the 15-19 age group. Differences in body composition were also observed with respect to reproductive status. Although there were no gender differences in overall cholesterol levels, there were age-related differences between males and females, and only in males were cholesterol values positively related to adiposity. There were no age- or gender-related differences in triglyceride values, but levels were significantly higher in pregnant females in comparison with other reproductive states. Levels of testosterone were not significantly related to any morphometric parameter and values did not decrease significantly with age. Levels of IGF-1 exhibited a significant age-related decrease among adult males, and females had higher levels independent of age. The similarities between the present findings and human studies suggest that further studies in the free-ranging rhesus macaques would provide a bridge between studies of laboratory-housed primates and studies of human beings with respect to the etiology of obesity and life-history changes in body composition and endocrine and metabolic parameters.     

Male-male relationships among wild bonobos (Pan paniscus) at Wamba,Republic of Zaire

Male-male relationships among wild bonobos (Pan paniscus) in two adjacent unitgroups (E1 and E2 groups), which were formed by division of the E group, were studied at Wamba, in the Central Zaire Basin, by analyzing the proximity and social interactions among males. Dominant-subordinate relationships between a male-male dyad were easily recognized from the directions of individual agonistic interactions. Male bonobos rarely joined forces in aggression. Clear differences in social status existed between adult and adolescent male bonobos in both groups, as reported in the case of chimpanzees (Pan troglodytes). The presence of mothers in the unit-group greatly influenced the dominant-subordinate relationships among males through strong mother-son bonds in both groups. However, the extent of the mother-son bonds differed between the groups. Males in the E2 group participated more frequently in agonistic or affinitive interactions than did males in the E1 group. Males in the E1 group were divided spatially into several clusters, while there were cohesive relationships among the adult males in the E2 group. The difference in intensities of mother-son bonds between the groups may be explained by the distribution of males at the time of the division of the E group. Differences in male-male relationships between bonobos and chimpanzees seem to be related to differences in intra- and inter-unit-group competition among males between the two species. Male chimpanzees may achieve coexistence by manipulating ambivalent relationships that are caused by intra- and inter-unit-group competition among them, while male bonobos may achieve coexistence by decreasing intra- and inter-unit-group competition among them.     

Social Relationships among Males in Multimale Siamang Groups

I quantified social and spatial interactions among adults in 4 multimale siamang (Symphalangus syndactylus) groups to evaluate the importance of aggression and avoidance in mediating male-male relationships. Actual genetic relationships among adults are unknown, but available mitochondrial data suggest that in 3 of 4 groups, neither male was the offspring or maternal sibling of the female, whereas in the fourth group, a matrilineal relationship between the female and 1 adult male was not excluded. Rates of aggression involving male-male dyads were very low. One male-female dyad maintained closer spatial cohesion than those of other adult dyads in 3 of 4 groups. Nonetheless, all adult males spent substantial percentages of their time ≤20 m from other adults in their groups. The percentages of time that male-male dyads spent in social grooming interactions did not differ from those of male-female dyads. In 3 groups, both males copulated with the group female. While previous studies have reported high rates of aggression between adult males and subadult male group members in siamangs, my results suggest that male-male relationships in multimale groups at Way Canguk were relatively harmonious. Acceptance of multimale grouping (and in some cases sexual polyandry) suggests that the benefits outweigh the costs under some circumstances. If there was a genetic relationship between males, then tolerance of delayed dispersal and copulation with the adult female may function as a form of parental investment. Males may also benefit from multimale grouping via enhanced territorial defense or reduced costs of mate defense.     

Phylogenetic relationships among Heliconiinae genera based on morphology (Lepidoptera: Nymphalidae)

Abstract.  Phylogenetic relationships among Heliconiinae genera are proposed based on early-stage and adult morphology. Parsimony analyses of forty-nine species in twenty-nine genera indicate that Heliconiinae can be divided into four main groups: (1) Pardopsis , Acraea and Actinote ; (2) Cethosia plus Neotropical genera; (3) Oriental genera and (4) fritillaries. Analyses of adult characters suggested that Oriental genera form a monophyletic group, whereas those of adult plus early-stage characters artificially split this group into three separate lineages. Our character set does not contain enough phylogenetic information to resolve relationships among fritillary genera with confidence, and further studies of this group are needed. The classification of the Heliconiinae is revised based on our results.     

The phylogeny of the superfamily Coccoidea (Hemiptera: Sternorrhyncha) based on the morphology of extant and extinct macropterous males

Currently, 49 families of scale insects are recognised, 33 of which are extant. Despite more than a decade of DNA sequence‐based phylogenetic studies of scales insects, little is known with confidence about relationships among scale insects families. Multiple lines of evidence support the monophyly of a group of 18 scale insect families informally referred to as the neococcoids. Among neococcoid families, published DNA sequence‐based estimates have supported Eriococcidae paraphyly with respect to Beesoniidae, Dactylopiidae, and Stictococcidae. No other neococcoid interfamily relationship has been strongly supported in a published study that includes exemplars of more than ten families. Likewise, no well‐supported relationships among the 15 extant scale insect families that are not neococcoids (usually referred to as ‘archaeococcoids’) have been published. We use a Bayesian approach to estimate the scale insect phylogeny from 162 adult male morphological characters, scored from 269 extant and 29 fossil species representing 43/49 families. The result is the most taxonomically comprehensive, most resolved and best supported estimate of phylogenetic relationships among scale insect families to date. Notable results include strong support for (i) Ortheziidae sister to Matsucoccidae, (ii) a clade comprising all scale insects except for Margarodidae s.s., Ortheziidae and Matsucoccidae, (iii) Coelostomidiidae paraphyletic with respect to Monophlebidae, (iv) Eriococcidae paraphyletic with respect to Stictococcidae and Beesoniidae, and (v) Aclerdidae sister to Coccidae. We recover strong support for a clade comprising Phenacoleachiidae, Pityococcidae, Putoidae, Steingeliidae and the neococcoids, along with a sister relationship between this clade and Coelostomidiidae + Monophlebidae. In addition, we recover strong support for Pityococcidae + Steingeliidae as sister to the neococcoids. Data from fossils were incomplete, and the inclusion of extinct taxa in the data matrix reduced support and phylogenetic structure. Nonetheless, these fossil data will be invaluable in DNA sequence‐based and total evidence estimates of phylogenetic divergence times.     

Determinants of Affiliative Interactions between Adult Males and Lactating Females in Pigtail Macaques (Macaca nemestrina nemestrina)

In some species of Cercopithecine primates, unrelated adult males and females maintain affiliative relationships ('friendships') that are apparently unrelated to mating or parental care. This study investigated the occurrence of friendships in a captive group of pigtail macaques, and some of their possible determinants. Study subjects were six adult males and 15 adult females with their newborn infants. Females were focally observed for 2 h every week during the first 12 wk of lactation. With the exception of the fourth-ranking male, adult males showed little interest in initiating affiliative interactions with lactating females and their infants. Most episodes of contact and grooming were initiated by high-ranking females and directed to the alpha male. Because female grooming was not generally reciprocated by the alpha male, it is likely that females benefited from associating with him in terms of agonistic support or protection. Genetic data on paternity determination indicated that the fourth-ranking male, who displayed high levels of affiliation towards mother-infant dyads, sired most of the infants born in the group in the year prior to this study. Thus, whereas females may be interested in associating with males to obtain their support, some males may affiliate with females as a consequence of their previous mating relationships with them or to increase the chances of future mating success. Taken together, however, the findings of this study provide little evidence that adult males and lactating females maintain strong reciprocal bonds that may qualify as friendships.     

Body weight as an indication of density-dependent population regulation in badgers (Meles meles) at Woodchester Park, Gloucestershire

The body weights of badgers were examined to look for density-dependent effects of the increase in group size at Woodchester Park, Gloucestershire. The weight of badgers in 21 groups were studied from 1978–1993. A significant negative relationship was found between weight and group size in breeding adult females in autumn and winter, and adult males in summer, such that increase in group size caused a decrease in weight. However, these relationships were affected by year-to-year changes and random variation, and overall there was no downward trend in body weight. The existence of density-dependent effects on badger populations at high density was consistent with previous findings     

Sociophysiology of squirrel monkeys

Primate sociophysiology is an emerging discipline concerned with understanding the proximate mechanisms that contribute to the generation and maintenance of species-typical social systems. Studies of squirrel monkeys illustrate that sociophysiological processes are more varied than is commonly assumed with respect to both the effective social dimensions that influence physiological function and the nature of concomitant physiological effects. For adult squirrel monkeys, a major consequence of social stimulation is altered regulation of pituitary-adrenal, pituitary-gonadal, and autonomic function. In females, socially-induced physiological changes appear to be independent of specific interindividual relationships with other adults, whereas in males, many sociophysiological effects can be understood only when specific relational attributes are considered. In all instances, adult relationships are associated with distinctly different sociophysiological profiles than have been found for the mother-infant relationship and do not conform to the stress/buffering model within which they are often interpreted.     

The influence of habitat on behaviour in a group of St. Kitts green monkeys

The relationships between specific ecological variables and the expression of behaviours were investigated in a group of green monkeys ( Cercopithecus aethiops ) inhabiting an ecologically diverse home range on the dry savanna-like peninsula of St. Kitts, West Indies. The group's behaviour was shown to vary between areas that differed with respect to four factors produced from a factor analysis of 20 ecological variables.
A number of relationships between behaviour and ecology were found that have not been previously described. Social behaviours were negatively related to cover, while attention behaviours were positively related to cover. Agonistic behaviours and affiliative behaviours were positively related to food abundance. Open areas with edge proved to be important to the group, and a number of behaviours were expressed for longer durations and/or more frequently in these areas. Comparisons of this study with others illustrates a need to examine carefully behavioural ecological relationships using quantitative methodology.     

Biometry of stomata in Blechnum species (Blechnaceae) with some taxonomic and ecological implications for the ferns

Morphological stomatal traits, such as size, form and frequency, have been subject of much literature, including their relationships with environmental factors. However, little effort have focused on ferns, and very few in the genus Blechnum. Stomatal length, width and frequency (as stomatal index) of a number of specimens of fourteen Neotropical species of Blechnum were measured in adult pinnae. The aim of the work was to find biometrical relationships between stomatal traits and between stomatal traits and habit, habitat and ecosystem of the plants. Statistical analyses of data were conducted using Exploratory Data Analysis and Multivariate Statistical Methods. Stomatal length and width showed a very high correlation, suggesting an endogenous, genetic control, thus giving these traits a considerable diagnostic utility. With respect to the relationships between stomatal traits and environment, we found significant statistical relationships between altitude and stomatal index. We also addressed the interpretation of the ecological-selective significance of various assemblages of stomatal traits in a diverse conjunction of habits, habitats and ecosystems.     

Group Fission in Barbary Macaques (Macaca sylvanus) at Affenberg Salem

We analyzed eight group fissions occurring during a 20-year period in three groups of a free-ranging provisioned Barbary macaque population. The founder group fissioned four times within 3.5 years after transfer to the enclosure, indicating that external factors—new environment, more space, absence of other groups—facilitated group fissions. Two groups resulting from these fissions, split twice within 2.5 and 1 years, respectively, many years later. The process of fissioning lasted from a few months to almost 2 years. Fissions were preceded by peripheralization/subgrouping of mainly young adult males (8-10 years old), suggesting that male competition was the primary force for the fissions. The males were joined by middle- to low-ranking but not the lowest-ranking females. The resulting new groups were usually smaller than the groups in which the former -matriline—old groups—stayed, and they were also more variable in size and sex ratio, suggesting that variable numbers of surplus individuals were expelled during fission. Mean adult sex ratios were similar in both groups after fission, indicating that the competitively superior males in the old groups (groups + -matriline) could not increase their breeding opportunities. Female kin, even of large matrilinies, almost always stayed together during fission. Natal males strongly preferred to join the old groups, and this preference was most pronounced in juveniles and subadults. Hence, most natal males stayed with maternally related females, i.e., remained true natal males, if the females stayed in old groups. They were separated from female kin, i.e., became seminatal, if the females joined the new groups. These seminatal males did not differ from natal males with respect to matrilineal rank, but they had more female relatives, above all more close relatives (sisters), indicating that avoidance of mating with maternal kin was important for group choice. Despite joining the same group as female kin during fissioning, breeding opportunities of natal males (ratio of unrelated females/male) were not less than that of their seminatal peers, because natal males had fewer female relatives. Only a minority of both groups of males would have done better by joining the alternative group. Paternal relatives were distributed during fission by chance, and loss of patrilinies was therefore much less pronounced. We conclude that the rules governing social relationships among Barbary macaque males are less apt to cope with the high number of males resulting from provisioning, whereas the rules regulating social relationships of females living in a nepotistic, female-bonded society are very robust in this respect.     

The phylogeny of some Papilio species based on interspecific hybridization data

Abstract. Adults of different species of the genus Papilio can easily be mated by hand-pairing. The data on egg hatchability, adult formation and F₁ fertility in these interspecific hybrids show notable variations according to the crosses. Using these data, values of a differentiation index for each cross were calculated. These estimates of genetic distance were then used to study the phylo-genetic relationships of the species involved. The data are consistent with the existence of the following groups, each consisting of closely related species: the black Papilio supergroup, the Papilio memnon group, the P.demoleus group, the P.xuthus group, the P.machaon group, the P.bianor group, the P.glaucus group and the P.troilus group. The phylogenetic relationships revealed by these data generally coincide with the relationships established by classical taxonomy. In cases where there are differences of opinion among taxonomists, the writer's data usually support one or other of them.