Male dispersal patterns in white-faced capuchins, Cebus capucinus: Part 1: patterns and causes of natal emigration

This is the first of two papers examining male dispersal patterns in white-faced capuchins. Our study was based on behavioural and demographic data collected on multiple groups of white-faced capuchins in Santa Rosa National Park, Costa Rica since 1985. Here we examine the patterns and proximate causation of male natal dispersal. Natal dispersal in white-faced capuchins occurred at a median age of 4.5 years, with no males remaining in the natal group past 8 years. Initial departure from the natal group appeared to be in response to an attraction to extragroup males and dispersing groupmates. Rates of parallel dispersal (dispersal with co-resident males and/or into groups containing familiar males) were very high for natal males (71-82%), and this pattern of dispersal may have evolved to increase inclusive fitness benefits in male-dispersed species. Additionally, this pattern of dispersal probably increases survivorship among dispersing males who are not yet physically mature, as is common in white-faced capuchins.     

The function of food-associated calls in white-faced capuchin monkeys, Cebus capucinus, from the perspective of the signaller

In many species, call recipients respond to food-associated calls by approaching the signaller. For this reason, most studies of food-associated calls focus on the benefits to a signaller of attracting a particular audience to a food source. Although call recipients respond as if they have been informed about the location of a food source, it is not necessarily the case that the primary function of food-associated calls is to inform others. I combined naturalistic observations and food placement experiments to investigate the environmental and social influences on call production in white-faced capuchin monkeys to assess other possible functions of food-associated calls. Individuals did not call under the circumstances predicted by an information-sharing hypothesis. The quantity of food and the age-sex composition of the audience did not influence call production, but food type did. Individuals produced more food-associated calls when they discovered fruit compared with insects or eggs. Results of observations of social interactions after food discovery indicated another possible function of food-associated calls. Individuals who called when they discovered food were less likely to be approached by others who were in visual contact than individuals who remained silent. Individuals who did not call when they discovered food were more likely to call subsequently if a higher-ranking, as opposed to a lower-ranking, animal approached them. Furthermore, individuals who called when approached by higher-ranking animals were less likely to receive aggression than individuals who did not call. Therefore, food-associated calls may function to announce food ownership, thereby decreasing aggression from other individuals.     

Vitis pollen dispersal in and from organic vineyards: I. Pollen trap and soil pollen data

The recent discovery of Roman vineyards in Britain [Antiquity 75 (2001) 745] based on both archaeological and palynological data has raised questions concerning the palynological record of viticulture in NW Europe. This paper presents data collected from 30 pollen traps and 29 soil pollen samples from within, and around, three organic vineyards in England. The soil trap data were collected over one flowering season. Within-vineyard pollen accumulation is compared with off-site accumulation and the soil pollen data. Although there is extremely high intravineyard variation in Vitis accumulation, the data confirm the role of stemflow transport and the exponential decrease in Vitis pollen accumulation with distance away from the vineyard. Pollen trap values of over 2% total pollen (TP) Vitis and soils with over 0.2% TP (based on 1000+ pollen sum) are likely to indicate the on-site presence of a vineyard. This is in accordance with the values recorded from known Roman vineyards in the Nene Valley. A compilation of occasional finds of Vitis pollen in England reveals typical values of 0.2% or less; although higher values are recorded, they are generally an artefact of a low total pollen count. However, the clustering of these occasional finds into the Roman and high Medieval periods suggests that long-distance Vitis influx increased during periods of widespread viticulture in NW Europe including England. The monitoring of Vitis pollen dispersal suggests that where encountered as part of routine pollen counting, the total pollen sum should be increased to ca. 1000 TP in order to establish a better estimate of the frequency of occurrence. This will allow palynology to play a less ambiguous part in the mapping of ancient viticulture.     

Cardioprotection: A radical view: Free radicals in pre and postconditioning

A series of brief (a few minutes) ischemia/reperfusion cycles (ischemic preconditioning, IP) limits myocardial injury produced by a subsequent prolonged period of coronary artery occlusion and reperfusion. Postconditioning (PostC), which is a series of brief (a few seconds) reperfusion/ischemia cycles at reperfusion onset, attenuates also ischemia/reperfusion injury. In recent years the main idea has been that reactive oxygen species (ROS) play an essential, though double-edged, role in cardioprotection: they may participate in reperfusion injury or may play a role as signaling elements of protection in the pre-ischemic phase. It has been demonstrated that preconditioning triggering is redox-sensitive, using either ROS scavengers or ROS generators. We have shown that nitroxyl triggers preconditioning via pro-oxidative, and/or nitrosative stress-related mechanism(s). Several metabolites, including acetylcholine, bradykinin, opioids and phenylephrine, trigger preconditioning-like protection via a mitochondrial K_ATP-ROS-dependent mechanism. Intriguingly, and contradictory to the above mentioned theory of ROS as an obligatory part of reperfusion-induced damage, some studies suggest the possibility that some ROS at low concentrations could protect ischemic hearts against reperfusion injury. Yet, we demonstrated that ischemic PostC is also a cardioprotective phenomenon that requires the intervention of redox signaling to be protective. Emerging evidence suggests that in a preconditioning scenario a redox signal is required during the first few minutes of myocardial reperfusion following the index ischemic period. Intriguingly, the ROS signaling in the early reperfusion appear crucial to both preconditioning- and postconditioning-induced protection. Therefore, our and others' results suggest that the role of ROS in reperfusion may be reconsidered as they are not only deleterious.     

Comparative observations on some middle and upper miocenehyaenids,Genera: PercrocutaKretzoi, AllohyaenaKretzoi, AdcrocutaKretzoi (Mammalia,Carnivora, Hyaenidae)

This study deals with the «percrocutoid hyaenids,present in Eurasia and in Africa in faunas of late Middle Miocene (Astaracian) to terminal Miocene (Vallesian, Turolian) age. These hyaenid species are characterized by certain dental apomorphies (loss of M^2/2, specialization of the carnassials P⁴/M₁, tendency for the hypertrophy of the anterior premolars) which differentiate them from other hyaenids with which they are found associated. In recent literature, these hyaenids have been attributed to the genera PercrocutaKretzoi and AdcrocutaKretzoi, the latter of which is monospecific. In fact some should be removed from the genus Percrocuta and assigned to the genus AllohyaenaKretzoi, itself subdivided into the two subgenera, AllohyaenaKretzoi and DinocrocutaSchmidt-Kittler. The genus Adcrocuta is retained and the characters which distinguish this genus from HyaenictisGaudry are discussed.This study is based on revision of all, or nearly allsuch specimens, described and figured or in collections, of which certain among them have been hardly or poorly known. Particular attention has been given to their geologic age and their distribution in Neogene mammalian faunas (Mein's zones). Their apomorphies, considered in relation to their temporal distributions, permit an interpretation of the phylogenetic relationships of their several lineages which is consistant with the proposed systematic revision of the group.The radiation of «percrocutoid hyaenids would appear to have occurred in three phases. At the beginning of the Astaracian, after the dispersal of Anchitherium, the genus Percrocuta appeared with several species of relatively small size; in Eurasia this genus does not seem to have persisted after the middle Astaracian, although it did so in the sub-Himalayan Siwaliks. At the end of the Astaracian it was apparently succeeded by the genus Allohyaena, and resulting in gigantic forms (subgenus Dinocrocuta) coincident in Eurasia and in Africa with the extension of Hipparion. The third phase of the radiation is represented by the genus Adcrocuta, which unlike the others, was monospecific. This single species, A. eximia, occurs initially, and very rarely in the upper Vallesian; however, in the middle Turolian it is common and widespread throughout Eurasia where it, perhaps, limited the expansion of Dinocrocuta.     

Hydration pressure and phase transitions of phospholipids: I. Piezotropic approach

Dehydration reduces the main phase transition pressure of phospholipids. An analysis based on the Gibbs-Duhem equation shows how the shift of the transition pressure is correlated to the hydration pressure.By using Fourier transform infrared (FT-IR) spectroscopy we determined the hydration-dependent phase transition pressure. The application of our new approach gives hydration pressure values which agree with the values obtained with the osmotic stress method.