In recent studies of primates, the question has been raised whether competitive regimes (egalitarian versus despotic) are species-specific or should rather be considered as sex-specific. To study ...this problem we use an individual-oriented model called DomWorld in which artificial agents are equipped merely to group and compete. In former studies of this model, dominance style appeared to be strongly influenced by the intensity of aggression: by increasing only this intensity of aggression, a great number of the characteristics of an egalitarian society switched to those of a despotic one. Here, we investigate, using DomWorld, a competitive regime of artificial males and females that differ exclusively in their fighting capacity; males having a higher intensity of aggression and a higher initial capacity of winning, such as may be due to a male-biased sexual dimorphism. Unexpectedly it appears that, in the model, even if the intensity of aggression of males is greater than that of females, their hierarchy is still significantly weaker and thus their society less differentiated and more egalitarian than that of females. The explanation is that, due to the higher initial dominance of males (compare larger body size), single events of victory and defeat lead to less differentiation than among females. The greater the sexual difference in initial dominance between the sexes is the more egalitarian the males behave among themselves compared to the behaviour of the females among themselves. These effects are already visible during the initial phases of the hierarchical development. These results resemble findings among primates; in real primates their degree of sexual dimorphism may influence the competitive regime of each sex.
We report the sequence of a matrilineal overthrow in longtailed macaques (Macaca fascicularis) during which the alpha -matriline dropped to the third of four ranks. In the initial phase of the ...overthrow, females from the former second ranking matriline attacked the females of the former alpha -matriline in a sequence which suggests a strategy. They attacked the highest ranking mother first and then directed their attacks toward her daughter, then toward her grand-daughter, and finally toward her great-grand-daughter. This seems to be the most effective way to disrupt the possible interventions of mothers in favor of their daughters.
We report the sequence of a matrilineal overthrow in longtailed macaques (Macaca fascicularis) during which the α-matriline dropped to the third of four ranks. In the initial phase of the overthrow, ...females from the former second ranking matriline attacked the females of the former α-matriline in a sequence which suggests a strategy. They attacked the highest ranking mother first and then directed their attacks toward her daughter, then toward her grand-daughter, and finally toward her great-grand-daughter. This seems to be the most effective way to disrupt the possible interventions of mothers in favor of their daughters.PUBLICATION ABSTRACT
The fate and the methylation of mercury (Hg) in the terrestrial environment are still poorly understood and although the main drivers of release and methylation of mercury in soils are known (low ...redox potential and microbial carbon availability) their interactions are not well understood. This is of concern since many agriculturally used floodplains, where the recurring flooding and agricultural practices (e.g. manure amendments) may have an impact on the fate and the biomethylation of Hg, are at the same time Hg-contaminated. In this study, we modified and validated existing methods to extract and analyze methylmercury (MeHg) by HPLC-ICP-MS in soils and we assessed the Hg and MeHg concentrations in three fields situated in a Hg polluted agricultural floodplain. Further, we incubated the top soil from the three studied fields for 11 days under flooded conditions in presence or absence of 2 mass% of cow manure, a common agricultural amendment in the area. Total Hg and MeHg concentrations ranged from <limit of detection (LOD, 0.012 mg kg-1) to 28.2 mg kg-1 and from 1.2 to 7.8 μg kg-1 respectively. Hg was released to the soil solution after 12 hours with a maximum between day 2 and day 7. MeHg levels in the soil solution were <LOD although it was found in the soil before and after the incubation. The addition of cow manure to saturated soils led to an increase in the MeHg concentrations of the soil solid phase by up to fivefold to a maximum of 26.4 ± 1.1 μg kg-1 (n = 3). Our study demonstrates that the combination of low redox potential because of flooding with common agricultural practices such as the amendment of manures enhances the formation of toxic MeHg.
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