Sex differences in the behaviour of immature captive lowland gorillas

Studies of the behaviour of 26 (12 males and 14 females) captive infant and juvenile lowland gorillas showed clear sex differences. Females showed greater interest in young infants and were more active in nest building as well as in solitary and social grooming. Males were more active in locomotive, dominance, and aggressive behaviour and in social play. Hand-rearing further increased aggression. Males were more aggressive when they lived with only one partner, and they rose in rank even above older females, a pattern that has not been observed in naturally reared gorillas.     

The social development of free-ranging infantLemur catta at Berenty reserve,Madagascar

The social development of 11 free-ranging infantLemur catta was examined over the first 16 weeks of the infants' lives. By 16 weeks, infants still occasionally suckled and were carried dorsally, but on the whole, they were independent of their mothers. Sex or mother's rank was not found to affect frequency or type of play behavior. Mother's rank had no effect on frequency of maternal rejections, from the nipple or from riding, but female infants were rejected slightly more frequently than males were. Mothers tended to reject infants more severely and more frequently from dorsal riding than from the nipple. Sex and rank differences were not found with respect to behaviors determined as measures of independence; however, lower-ranking infants engaged in significantly more dependent behaviors than higher-ranking young did. It may be necessary for the infant of a low-ranking mother to maintain closer proximity to its mother for a longer period of time during infancy because such infants may be subject to abuse by higher-ranking group members and, furthermore, may not be as readily rescued in a stressful or dangerous situation as a higher-ranking infant. Sex was not found to be a factor in terms of measures of dependence. The lack of sex differences in developmental behaviors in this species may be related to female dominance, as well as to the fact that, as adults, both sexes engage in aggressive territorial behavirs.     

Costs and benefits of maternal aggression in lactating female rhesus macaques

Data from over 400 hr of observation of mother-infant rhesus macaques indicate that during the first 12 weeks of lactation infants are at risk from other group members and that mothers use aggression as well as restraining to protect them. Maternal aggression was negatively correlated with infant restraining. High-ranking mothers reacted aggressively to individuals handling their infants more than did middle- and low-ranking mothers. Conversely, middle- and low-ranking mothers restrained their infants more than did high-ranking mothers. Maternal aggression did not vary with infant age. Maternal aggression was directed toward a higher proportion of higher-ranking adult females and their immature offspring and was more likely to be followed by counter-aggression than nonmaternal aggression, i.e. aggression not related to interactions involving the infant. Middle-and low-ranking mothers suffered higher costs in terms of retaliation than high-ranking mothers. It is argued that the occurrence and distribution of maternal aggression among species and individuals should depend on the risk posed to infants by conspecifics as well as on the characteristics of the social structure (e.g. degree of asymmetry of agonistic contests) and of the mother (e.g. her dominance rank) which may affect the probability of retaliation.     

Rank and sequence in Caspar Bauhin's Pinax

CAIN, A. J., 1994. Rank and sequence in Caspar Bauhin's Pinax. Bauhin's consistent use of genera, species and binominals, applauded by historians as anticipating Linnaeus's theory and practice, does not appear on closer examination to be intended as anything of the sort. His use of the terms genus and species is as in Aristotelian logic, with a shifting reference, at all taxonomic levels. His typographical layout, emphasizing (but far from invariably employing) single-word names for effectively generic entities, often qualified by ‘and its species’, gives the impression of Linnaean practice, and coincides with it not infrequently, but not with Linnaean theory. The main entities for which it can be said that Bauhin uses fairly consistently a biverbal binominal name-phrase, like Linnaeus' trivial names, were in fact in Linnaeus's eyes two levels of supraspecific groupings. The main entities in Bauhin which Linnaeus recognized as species, as is shown by his quotations in the Species plantarum, are subdivisions of his biverbally or nearly biverbally named groupings, but themselves have multiverbal names. These correspond closely to Linnaeus's diagnostic specific names, not at all to his biverbal trivial names. Bauhin probably had no conception of the species and genus as ranks in the modern sense, first adumbrated by Tournefort and utilized by Linnaeus. Bauhin certainly tried to group forms by natural affinity, as did Theophrastus before him and Linnaeus afterwards. Not being alerted to the importance of the details of the flower and fruit, he used what characters he could find, notably, but not by any means exclusively, leaf shape. He composed the Pinax as a nomenclatural concordance to earlier authors, notably Dioscorides, Theophrastus and Pliny. He retained the sequence of major groups of Theophrastus (as the greatest authority on plants) but reversed it to start with the best-known plants, grasses. Where Theophrastus gave no help, in the cryptogams, Bauhin inserted as a pendant his own series from ferns down to fungi, using the Aristotelian principles of the gradation of forms. His overall arrangement, therefore, is not a simple progression but a chain with pendants. Bauhin is far closer to earlier authors than to Linnaeus, but his typography, along with other authors, may well have helped to incite Linnaeus to a more rigorous and consistent use of ranked groups and biverbal names.     

Rank relations among sisters in semi-free-ranging Barbary macaques (Macaca sylvanus)

Although semi-free-ranging Barbary macaque females are able to outrank older females from lower-ranking matrilines (matrilineal rank acquisition), they do not systematically outrank their older sisters, as is known to be the case for semi-free-ranging rhesus monkeys (Macaca mulatta) and Japanese macaques (Macaca fuscata). We test the hypothesis that differences in the support received by younger sisters against their older sisters and against older lower-ranking females might account for this interspecific difference. Thirty-one sister dyads, members of a group of 109 Barbary macaques living at La Montagne des Singes, France, were observed during 16 months. The results indicate that (1) all females were dominant to their younger sisters, and the latter were never observed to challenge their older sisters; (2) younger sisters received as much kin support against their older sisters as against older lower-ranking females; (3) only very young females received support from their kin against their older sisters; (4) younger sisters received much more support from nonkin females against lower-ranking females than against their older sisters; and (5) Barbary macaque females appear to be supported against their older sisters less frequently than rhesus macaque females are. We conclude that the lack of nonkin support is the main factor accounting for the failure of younger sisters to outrank their older sisters in Barbary macaques. Initially this might result from kin support not being sufficient to induce younger sisters to challenge and to solicit support against their older sisters.     

Towards an understanding of the Sarcostemma viminale (Asclepiadaceae) complex

LIEDE, S. & MEVE, U., 1993. Towards an understanding of the Sarcostemma viminale (Asclepiadaceae) complex. All names in Sarcostemma sensu Bullock (Asclepiadaceae, Asclepiadeae, Cynanchinae) are listed and their current status evaluated. Chromosome numbers are given for most taxa. The typification of S. viminale is clarified. A new subspecies of S. viminale is described from the Orange Free State, South Africa, and relationships of the Namaqualand/Namibia populations are discussed.     

Sons of low-ranking female rhesus macaques can attain high dominance rank in their natal groups

Five adult and subadult sons of middle- and low-ranking female rhesus macaques (Macaca mulatta) were observed to hold high dominance rank in their natal groups during a 12-month study at Cayo Santiago, Puerto Rico. Three of these males also experienced high mating success during at least one mating season. These findings contrast with all previously published accounts of rank acquisition by natal male rhesus macaques in provisioned colonies, and they present a challenge to the hypothesis that natal transfer functions to increase male access to fertile females.     

Social organization in a wild population ofCallithrix jacchus: II. Intragroup social behavior

The social behavior of the common marmoset has been well studied in captivity, but little is known about the social dynamics of this species in its natural habitat. Social relationships were studied in three polygynous groups of common marmosets,Callithrix jacchus, in northeastern Brazil. Breeding adults appeared to be the center of social life and were the most frequent grooming partners or nearest neighbors for most adult group members. The observations of unidirectional agonistic interactions suggest that breeding adults were also dominant over all other group members, but that neither sex was dominant over the other. The dynamics of within-group social relationships are likely to be important determinants in the reproductive strategies employed by marmoset females.