Peccary movements as determinants of the movements of large cats in Brazilian Amazonia

As part of a study on the ecology of a community of middle-sized and larger mammals in a seasonally dry forest in the far north of the Brazilian Amazonia, peccaries (the white-lipped peccary Tayassu pecari and the collared peccary Tayassu tajacu) and large cats (the jaguar Panthera onca and the puma Puma concolor) were regularly surveyed for 1 year. Diurnal and nocturnal surveys were carried out by the line-transect method, in five different forest types along a 10 km transect, and data were collected on their use of the forest types. The peccary herds and the large cats were sighted regularly throughout the study period, but more frequently over the dry season in the high-ground forests in eastern Maracá. Over the dry season, when food was scarce except in the Buritizals, T. pecari, closely followed by a P. onca, monopolized the Buritizal forests, whereas T. tajacu, followed by a P. concolor, exploited the other available high-ground forest types. Fluctuations in food supply regulated the dynamics of the two species of peccaries, which ultimately determined the whereabouts of the large cat predators. This may be a counter-strategy to survive in an extremely seasonal environment where food, more than any other variable, is the key determinant of the survival of both peccaries and large cats. © 2007 The Zoological Society of London

Carotenoid and protein supplementation have differential effects on pheasant ornamentation and . . .

A currently popular hypothesis states that the expression of carotenoid-dependent sexual ornaments and immune function may be correlated because both traits are positively affected by carotenoids. However, such a correlation may arise for another reason: it is well known that immune function is dependent on nutritional condition. A recent study has suggested that the expression of ornaments may too depend on nutritional condition, as males in good nutritional condition are better at assimilating and/or modulating carotenoids. Thus, carotenoid-dependent ornaments and immune function may be correlated because both are dependent on nutritional condition. To elucidate if, and how, ornamentation and immune function are linked, pheasant diets were supplemented with carotenoid and/or protein in a fully factorial experiment. Carotenoid treatment affected wattle coloration and tail growth, but not cellular or humoral immunity. Immunity was unrelated to males' initial ornamentation including wattle colour. Males in better body condition, measured as residual mass, increased their wattle coloration more when carotenoid supplemented. Protein positively affected humoral but not cellular immunity, but had no effect on ornaments. Cellular, but not humoral, immunity increased with male body condition. Thus, there was no evidence that an immune-stimulatory effect of carotenoids resulted in wattle coloration honestly signalling immune function, but wattle coloration may still signal male body condition

Conditional Responding is Impaired in Chronic Alcoholics

Contains fulltext : 56796.pdf (publisher's version ) (Closed access)Bechara (2003) describes a model for disturbances in executive functions related to addiction. This model involves deficits in decision-making and in suppressing pre-potent representations or response patterns. We tested this model in 29 individuals with longterm heavy alcohol dependency and compared their performance with that of 20 control subjects. Only individuals without memory impairment, with normal intelligence and normal visual response times were included. We examined word fluency, object alternation, spatial stimulus-response incompatibility, extra-dimensional shift learning and decision-making using the Gambling task. We subtracted the performance in a control condition from that of the executive condition, in order to focus specifically on the executive component of each task. Only the object alternation and incompatibility tasks revealed significant differences between the group of alcoholics and the control group. Moreover, response times in the object alternation task correlated with duration of alcohol dependency. The results do not argue in favor of a specific deficit in decision-making or in shifting between relevant representations. We conclude that long-term alcohol abuse leads to an impairment in conditional responding, provided the response depends on former reactions or the inhibition of pre-potent response patterns.15 p