Not Only Single Mating in Stingless Bees

Queens of the large, pantropical and fully eusocial taxon Meliponinae (stingless bees) are generally considered to be singly mated. We indirectly estimated queen mating frequency in two meliponids, Melipona beecheii and Scaptotrigona postica, by examining genotypes of workers at microsatellite DNA loci. Microsatellites were highly variable, providing suitable markers with which to assign patrilinial origin of workers within colonies headed by single queens. Queen mating frequency varied between 1 and 3 (M. beecheii) and 1 and 6 (S. postica), representing the first clear documentation of polyandry in the Meliponinae. Effective paternity frequency, m _e , was lower, although above 2 for S. postica. Stingless bees may provide suitable subjects for the testing of recent inclusive fitness arguments describing intracolony kin conflict in social Hymenoptera. Received: 26 August 1998 / Accepted in revised form: 18 November 1998     

On the origin of fiber calcite crystals in moonmilk deposits

In this study, we show that moonmilk subaerial speleothems in Altamira Cave (Spain) consist of a network of fiber calcite crystals and active microbial structures. In Altamira moonmilks, the study of the typology and distribution of fiber crystals, extracellular polymeric substances, and microorganisms allowed us to define the initial stages of fiber crystal formation in recent samples as well as the variations in the microstructural arrangement in more evolved stages. Thus, we have been able to show the existence of a relationship among the different types of fiber crystals and their origins. This allowed us to outline a model that illustrates the different stages of formation of the moonmilk, developed on different substrata, concluding that microbes influence physicochemical precipitation, resulting in a variety of fiber crystal morphologies and sizes.     

Identification of chemical hazards for terrestrial plants in the regulatory context: Comparison of OECD and ISO guidelines

Standardized test protocols are used in the regulatory context for identifying the hazardous properties of chemicals, wastes, and contaminated materials. This paper compares the relevance of two guidelines measuring effects on terrestrial plants, the OECD TG 208 and the ISO TG 22030 and presents the scientific basis for a recent decision of the European Chemicals Agency (ECHA) under the European chemicals regulation REACH. If there are no specific phytotoxicity alerts, both guidelines are considered suitable for assessing long-term hazards, providing that a sufficient number of species is included in the OECD protocol, the recommended minimum number is six, which offer a reasonably broad selection of species to account for interspecies sensitivity. The proposed methodology, based on a combination of probabilistic assessments using Monte Carlo analysis, can be adapted for supporting similar decisions under specific regulatory processes; for example, for assessing contaminated soils or pesticides’ applications.     

Population Viability Analysis of Captive and Released Bearded Vulture Populations

With the computer program VORTEX I ran a series of simulations of the Bearded Vulture ( Gypaetus barbatus ) population held in captivity in European zoos and of the population released in the Alps. The simulations showed that the risk of extinction of the captive population with the extraction rates currently in use is low. It seems possible to maintain the current release rate of two fledglings per year at each of the four release sites in the Alps, but it does not seem possible to increase the release rate by expanding the project to other European mountains without dangerously depleting the captive population. The models showed that the most effective way to increase the release rate without increasing the captive population size is by improving hatching success in captivity. The information on the demographic parameters of the Bearded Vulture population released in the Alps was not good enough to predict the ultimate fate of the present population or to allow for recommendations on how long the population should continue to be supplemented. Although it will be necessary to wait some years to see if Bearded Vultures are able to breed in the wild in the Alps and to estimate fecundity rates, it should be possible to improve the monitoring of the individuals released to obtain more-precise survival estimates. The models of the captive and released population also showed that it should at least be possible to have an artificially supplemented Bearded Vulture population in the Alps, but because this is not the goal of the present reintroduction project, the organizations involved should decide whether this is a politically or economically desirable goal.     

Hybridization and the Extinction of Rare Plant Species

Much has been written about the role of interspecific competition, disease, herbivory, and the loss of key mutualisms in the extinction of rare plant species. Interspecific hybridization rarely is considered among the biotic interactions that promote extinction. We show how hybridization may contribute to the demise of rare plant species through demographic swamping and genetic assimilation by an abundant congener. We contend that the growth of the hybrid subpopulation is the key to rare species assimilation, and we show how the production of hybrid seed, the fitness of hybrids, and pest pressure affect hybrid proliferation. We also discuss how habitat disturbance, unspecialized pollinators, and weak crossing barriers promote hybridization, and how the negative consequences of hybridization are unlikely to be compensated for by immigration from conspecific populations. We also illustrate stages in the demise of species in island floras. We suggest that hybridization is an increasing threat to rare species because ecological barriers are being disrupted by human activities.     

Up to 95 % reduction of chemical oxygen demand of slaughterhouse effluents using Fenton and photo-Fenton oxidation

Meat industries produce effluents containing high concentrations of organic and inorganic compounds, which must be removed before being discharged or reused. Advanced oxidation processes using Fenton reaction coupled with UV, solar radiation, and electrochemical oxidation are promising methods. Here, we treated the effluent from an anaerobic digester using: (a) the photoelectro-Fenton process, using a system with a Ti-RuO₂ anode and a carbon felt cathode, (b) the solar photo-Fenton process, using a batch reactor and a compound parabolic collector, and (c) a combination of Fenton and solar photo-Fenton processes. The effluent had an initial chemical oxygen demand (COD) of 1159 mgL^?1, and we obtained high removal efficiencies of COD, up to 95 %, using the combination of Fenton and solar photo-Fenton processes.     

Spike dives of juvenile southern bluefin tuna (<Emphasis Type="Italic">Thunnus maccoyii</Emphasis>): a navigational role?

Tunas make sharp descents and ascents around dawn and dusk called spike dives. We examine spike dives of 21 southern bluefin tuna (Thunnus maccoyii) implanted with archival tags in the Great Australian Bight. Using a new way to categorize this behavior, we show that spike dives are similar among all the fish in the study. The dive profiles are mirror images at dawn and dusk and are precisely timed with respect to sunrise and sunset. We analyze the possible reasons for spike dives, considering the timing of spike dives, the characteristic dive profile, and the tuna's magnetic habitat. In addition, we present anatomical evidence for elaboration of the pineal organ, which is light mediated and has been implicated in navigation in other vertebrates. The new evidence presented here leads us to suspect that spike dives represent a survey related to navigation.     

Influence of task demands on occupational stress: Gender differences

IntroductionOccupational stress is a common phenomenon in our society, and generates problems for both workers' health and the functioning of organizations. Over past decades numerous studies have examined occupational stress from the perspective of gender, offering somewhat contradictory results. Some of them found no differences and others indicated that either men or women suffer from greater amounts of occupational stress.MethodThe purpose of this study was to analyze gender differences in stress in situations that involve certain occupational demands. The data used were taken from a random sample population of 11,054 (5,917 men and 5,137 women) from the VI National Survey on Working Conditions (NSWC) which was conducted in Spain in 2007. To carry out this study, a probabilistic model was constructed using Bayesian networks, with the following variables related to task demands: working with tight deadlines, quick work, intellectually demanding work, complicated tasks, repetitive tasks, excessive work, and work demanding high attention levels.ResultsThe results of this study reveal that: the indicators studied significantly increased stress levels; women initially had higher stress levels than men; and when exposed to determined task demands, stress differences between genders tended to increase.Impact on IndustryCompanies need to consider the gender of their workers when assigning tasks in high demand/stress jobs.