Male intergroup mobility in a wild population of the Barbary macaque (Macaca sylvanus), Ghomaran rif mountains,Morocco

In this two-year study of a Barbary macaque population (n = 162) in the Ghomaran region of Morocco, 13 cases of males separated from their assumed natal groups were observed (nine visits of nonresident males to groups, two males isolated from groups as much as one day and one night, and two sets of snow tracks indicating males travel +7 km as isolates). Males left their assumed natal groups primarily in the mating season (12 cases), focused their interactions on estrous females of other groups, and were observed to copulate with these females in two cases. All males leaving their assumed natal groups were estimated to be between 5 and 8 years of age, with one exception (+ 15 years). It could not be determined whether males younger than 5 years moved between groups, or whether any males made permanent intergroup transfers. Regardless, the data from this study indicate that male intergroup mobility (and intergroup gene flow) was higher than has been previously assumed for this species. A prior theory that Barbary macaque groups are highly inbred, and that this is causally related to the evolution of male-infant care in this species, is not supported by the data of this study.     

Group fission in a semifree-ranging population of Barbary macaques (Macaca sylvanus)

During a 16-month study of semifree-ranging Barbary macaques (Macaca sylvanus) the group under observation divided into two groups. Observations were carried out in 1987–1988, at «La Montagne des Singes,” Kintzheim, France. A subgroup of monkeys, which was already cohesive at the beginning of the study, became progressively autonomous in relation to the rest of the main group, during the mating season. Overt aggression between the males of the two groups during this period brought about the fission. Only low-ranking genealogies left their group of origin. Dominance relations between females remained identical in both groups except for one lineage. The alpha male and the alpha female of the subgroup had a close relationship before the fission occurred. The sequence of agonistic intergroup relations is described and analyzed in relation to male sexual competition and female alliance power. The results suggest that: (1) the males of the subgroup instigated the fission because it was the best strategy for them to counter sexual competition; and (2) the females followed the males in order to maintain their alliance network, necessary to insure their dominance status over subordinate females.     

Male Migration in Barbary Macaques (Macaca sylvanus) at Affenberg Salem

We analyzed male migration during a 20-year period in the free-ranging Barbary macaque population of Affenberg Salem. Most natal migrations occurred around puberty, but only one third of all males left the natal group. Secondary group transfers were rare. All males immediately transferred to other bisexual groups. Migration rates were highest during periods with high adult female/male ratios within social groups. Immigrants highly preferred groups with fewer males of their own age than in the natal group, and many males immigrated into groups that had no male their own age. These groups originated from a skewed distribution of resident males during group fissions. A comparison of emigrants with their natal peers supports the inbreeding avoidance hypothesis as cause of emigration rather than the male competition avoidance hypothesis. Emigrants had no lower individual rank position and did not come from lower-ranking matrilines. Emigrants had more female maternal relatives, especially sisters. Males without female relatives almost never emigrated. Conversely, there is virtually no indication that emigrants were evicted from the natal group. Emigrants had no increased mortality. Paternity data revealed that the reproductive success of emigrants and natal males is similar, indicating that emigration had no reproductive cost. Many similarities between emigrants and natal males that separated from female maternal kin during group fissions suggest that inner migration during fissions is an alternative way to avoid maternal inbreeding. The mating system resulted in a genetic structure within social groups that largely diminished the chances for paternal inbreeding even without recognizing paternal kin.     

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.     

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.     

Female sexual behavior and sexual swelling size as potential cues for males to discern the female fertile phase in free-ranging Barbary macaques (Macaca sylvanus) of Gibraltar

Although female catarrhine primates show cyclic changes in sexual behavior and sexual swellings, the value of these sexual signals in providing information to males about timing of the fertile phase is largely unclear. Recently, we have shown that in Barbary macaques, males receive information from females which enables them to discern the fertile phase and to focus their reproductive effort accordingly. Here, we investigate the nature of the cues being used by examining female sexual behavior and the size of sexual swelling as potential indicators of the fertile phase. We collected behavioral data and quantified swelling size using digital images of 11 females of the Gibraltar Barbary macaque population and related the data to the time of ovulation and the fertile phase as determined from fecal hormone analysis. We found that rates of female sexual behaviors were not correlated with female estrogen levels and did not significantly differ between the fertile and non-fertile phases of the cycle. In contrast, swelling size was significantly correlated with female estrogen levels and increased predictably towards ovulation with size being maximal during the fertile phase. Moreover, frequencies of male ejaculatory copulations showed a strong positive correlation with swelling size and highest rates were found during maximum swelling. Our data provide strong evidence that female Barbary macaques honestly signal the probability of fertility through sexual swelling and that males apparently use this information to time their mating activities. Honest advertising of the fertile phase might be part of a female strategy to manipulate male mating behavior for their own advantage, such as ensure fertilization with high quality sperm or influence paternity outcome.     

Male swarms at landmarks and scramble competition polygyny inPolistes gallicus (Hymenoptera: Vespidae)

At the end of summer, males of Polistes gallicusfly in swarms around vertical landmarks and land in clusters on their favorite perches, where they drag their legs and abdomen. Here males occasionally crowd around a perched female; they make no effort to defend an exclusive mating territory but instead attempt to copulate by displacing rivals from the female. In this work we describe this spatial-nuptial system, which entails site fidelity without territoriality, unisexual swarms, common patrol routes, collective sexual approaches, and scramble competition polygyny. Mating success is evaluated in relation to the familiarity with flight paths (routine patrollers versus newcomers), to the type of sexual approach (single males versus in- group males), and, in the laboratory, to the individual activity level.     

三种外来入侵斑潜蝇种间竞争研究进展

美洲斑潜蝇、南美斑潜蝇、三叶斑潜蝇是危害蔬菜、花卉的世界性大害虫。不同种间相互更替或取代的现象时有发生。根据国内外相关研究报道,综述了对近年来3种斑潜蝇种间竞争的研究。对斑潜蝇种间更替和取代现象的分析显示,生殖干扰、新生物型的出现、天敌、生态位、寄主植物以及抗药性等因素可能是影响它们种间竞争的关键。以期为斑潜蝇种群演替研究及防治策略制定提供参考。