The role of the queen in circadian rhythms of honeybees (Apis mellifera L.)

Summary Colonies and smaller social groups of honeybees (Apis mellifera carnica L.) show distinct free-running circadian rhythms similar to that of individual organisms. The workers of a colony synchronize their individual rhythms to one overall group rhythm. Caste plays an important role in this synchronization process. Queens were introduced into worker groups which were entrained to a phase-shifted light/dark cycle. The introduction of the queen caused a shift in the free-running phase under constant dark conditions. Single introduced workers had no effect on the free-running rhythms. This indicates that the queen plays an important role in the synchronization of circadian rhythms of honeybee colonies.     

Social dominance,seasonal movements,and spatial segregation in African elephants: a contribution to conservation behavior

The structure of dominance relationships among individuals in a population is known to influence their fitness, access to resources, risk of predation, and even energy budgets. Recent advances in global positioning system radio telemetry provide data to evaluate the influence of social relationships on population spatial structure and ranging tactics. Using current models of socio-ecology as a framework, we explore the spatial behaviors relating to the maintenance of transitive (i.e., linear) dominance hierarchies between elephant social groups despite the infrequent occurrence of contests over resources and lack of territorial behavior. Data collected from seven families of different rank demonstrate that dominant groups disproportionately use preferred habitats, limit their exposure to predation/conflict with humans by avoiding unprotected areas, and expend less energy than subordinate groups during the dry season. Hence, our data provide strong evidence of rank derived spatial partitioning in this migratory species. These behaviors, however, were not found during the wet season, indicating that spatial segregation of elephants is related to resource availability. Our results indicate the importance of protecting preexisting social mechanisms for mitigating the ecological impacts of high density in this species. This analysis provides an exemplar of how behavioral research in a socio-ecological framework can serve to identify factors salient to the persistence and management of at risk species or populations. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Impact assessment of the European biofuel directive on land use and biodiversity

This paper presents an assessment of the potential impact of the EUs biofuel directive on European land use and biodiversity. In a spatially explicit analysis, it is determined which ecologically valuable land use types are likely to be directly replaced by biofuel crops. In addition, it is determined which land use types may be indirectly replaced by biofuel crops through competition over land between biofuel and food crops. Four scenarios of land use change are analyzed for the period 2000–2030 while for each scenario two policy variants are analyzed respectively with and without implementation of the biofuel directive. The results indicate that the area of semi natural vegetation, forest and High Nature Value farmland directly replaced by biofuel crops is small in all scenarios and differs little between policy variants. The direct effects of the directive on European land use and biodiversity therefore are relatively minor. The indirect effects of the directive on European land use and biodiversity are much larger than its direct effects. The area semi natural vegetation is found to be 3–8% smaller in policy variants with the directive as compared to policy variants without the directive. In contrast, little difference is found between the policy variants with respect to the forest area. The results of this study show that the expected indirect effects of the directive on biodiversity are much greater than its direct effects. This suggests that indirect effects need to be taken explicitly into account in assessing the environmental effects of biofuel crop cultivation and designing sustainable pathways for implementing biofuel policies.     

A Validation Study of a Rapid Field-Based Rating System for Discriminating Among Flow Permanence Classes of Headwater Streams in South Carolina

Rapid field-based protocols for classifying flow permanence of headwater streams are needed to inform timely regulatory decisions. Such an existing method was developed for and has been used in North Carolina since 1998. The method uses ordinal scoring of 26 geomorphology, hydrology, and biology attributes of streams. The attribute scores are summed and compared to threshold scores to assign a flow permanence class. Our study objective was to evaluate the method’s ability to classify the flow permanence of forested stream reaches from Piedmont and Southeastern Plains ecoregions in South Carolina. Ephemeral reaches scored significantly lower than intermittent and perennial reaches, but scores from intermittent and perennial reaches did not differ. Scores collected in the dry and wet seasons were strongly correlated, indicating that the method was seasonally stable. Scores had positive nonlinear relationships with the maximum recorded wet duration and the proportion of the record that reaches were wet, but were not related to drying frequency. Scores of the presence of baseflow in the dry season were more important in flow permanence classification than those from the wet season. Other important attributes and parameters in discriminating flow classes were macrobenthos, rooted upland plants, bankfull width, drainage area, and ecoregion. Although the North Carolina method did not consistently differentiate intermittent from perennial reaches, the indicator-based approach is a strong foundation from which to build a protocol for South Carolina. Adding measures like bankfull width and drainage area, weighting by ecoregion, or shifting thresholds may be warranted modifications for South Carolina.