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101.
Summary Hierarchies in worker dominance are well developed in reproductive workers of the Cape honeybee (Apis mellifera capensis Esch.). Elements that influence worker dominance (trophallactic behaviour, fecundity, queen substance content) are mainly genetically determined. The estimated values for the heritabilities in the broader sense range from 0.27 to 0.89. This genetically based hierarchy leads to new insight into the theory of natural selection in honeybees. Besides selection at the colony level, or selection at the level of reproductives, natural selection also operates at the level of the individual worker bee within a colony. 相似文献
102.
103.
R. Hesse 《Die Naturwissenschaften》1929,17(29):571-575
104.
Taxodium distichum (L.) Rich.]. The study site, a swamp in St. Martin Parish, Louisiana, has received municipal wastewater for the last 40 years.
Growth chronologies from 1920 to 1992 were developed from cross-dated tree core samples taken from treated and control sites
with similar size and age classes. Mean diameter increment (DINC) and mean basal area increment (BAI) chronologies were constructed
separately for each stand. These chronologies were then summarized by tree and stand into seven nine-year intervals resulting
in three pretreatment intervals from 1926 to 1952 and four treatment intervals from 1953 to 1988. Significant differences
in growth response between sites showed a consistent pattern of growth enhancement in the treated site coincident with the
onset of effluent discharge. The ratio of treated to control baldcypress growth rates (computed from DINC) averaged 0.74 during
the pretreatment period and 1.53 during the treatment period. Over the period of study, control DINC decreased from 77 mm
to 29 mm/nine-year interval, while treatment DINC increased slightly from 40 mm to 47 mm/nine-year interval. Control BAI did
not increase significantly and averaged 192 cm2/nine-year interval. There was a significant increase in treatment BAI from 129 to 333 cm2/nine-year interval over the period of record. These results clearly demonstrate sustained long-term baldcypress growth enhancement
throughout 40 years of municipal effluent discharge. 相似文献
105.
Elke I. Zimmer Thomas G. Preuss Steve Norman Barbara Minten Virginie Ducrot 《Environmental Sciences Europe》2018,30(1):36
Background
Available literature and regulatory studies show that the severity of effects of beta-cyfluthrin (a synthetic pyrethroid) on fish is influenced by the magnitude and duration of exposure. To investigate how the exposure pattern to beta-cyfluthrin (constant vs peak) may influence the response of the fish, we used a mechanistic effect model to predict the survival and growth of the rainbow trout over its early life stages (i.e. egg, alevin and swim-up fry). We parameterized a toxicokinetic–toxicodynamic (TKTD) module in combination with a dynamic energy budget model enabling us to describe uptake and elimination, as well as to predict the threshold concentration for survival and sublethal effects (feeding behaviour and growth). This effect model was calibrated using data from an early life stage experiment where trout was exposed to a constant concentration of cyfluthrin. The model was validated by comparing model predictions to independent data from a pulsed-exposure study with early life stages of rainbow trout.Results
The co-occurrence of effects on behaviour and growth raised the possibility that these were interrelated, i.e. impairment of feeding behaviour may have led to reduced food intake and slower growth. We, therefore, included ‘effect on feeding’ as mode of action in the TKTD module. At higher concentrations, the constant exposure led to death. The model was able to adequately capture this effect pattern in the calibration. The model was able to adequately predict the response of fish eggs, alevins and swim-up fry, from both the qualitative (response pattern) and quantitative points of view.Conclusions
Since the model was successfully validated, it can be used to predict survival and growth of early life stages under various realistic time-variable exposure profiles (e.g. profiles from FOCUS surface water modelling) of beta-cyfluthrin.106.
1 and C2 hydrocarbons (trichloroethane, trichloroethene, tetrachloroethene, dichloromethane). Measures aiming at the reduction of
toxic emissions and ozone depletion potential (ODP) may possibly lead to a shift of environmental impacts towards higher energy
consumption, emission of waste water, and volatile organic compounds (VOC) with photochemical oxidant creation potential (POCP).
The present article concerns itself with a life cycle assessment of the three main degreasing processes in order to compare
their integral environmental impacts with one another. This is supplemented by presenting the methodology of the life cycle
inventory life cycle inventory analysis (LCI). Generally, the applicability of the established LCI method can be shown quite
clearly. However, some difficulties arise, especially at the stage of the goal definition, as the use of the process and the
functional unit cannot be pinned down as easily and neatly as for most other products. The definition of the use of the process
and the functional unit is not as straightforward as for most products. Among the potential functional units identified are
the mass of removed impurities, cleaning time, cleaning work, percentage of purity, throughput of parts, loads, mass or surface
and virtual coefficients. The mass of removed impurities turned out to be the most suitable parameter for measuring the technical
performance of degreasing processes. The article discusses background, purpose, scope, system boundaries, target group, process
tree and representativeness of the present study. 相似文献
107.
Antonia Köhler Philipp Hildenbrand Elke Schleucher Rüdiger Riesch Lenin Arias-Rodriguez Bruno Streit Martin Plath 《Behavioral ecology and sociobiology》2011,65(8):1513-1523
Sexual harassment by males has the potential to affect almost any aspect of female behavior and life history. Using Atlantic
mollies (Poecilia mexicana) as a model—a species in which males do not court but almost constantly try to forcefully mate with females—we asked whether
and how male harassment influences (a) females’ time budgets and (b) feeding rates (e.g., through frequent flight from male
approaches), and (c) whether metabolic rates are increased as a response to stress. Field observations in a natural P. mexicana population revealed that males (average feeding rate 15%) spent far less time feeding than females (60%), and clearly traded
off frequent pursuit of females with foraging. Most importantly, females’ feeding times were dramatically reduced when being
pursued by a harassing male. Also in standardized lab experiments, females spent significantly less time feeding when accompanied
by a male as compared to being in the presence of another female. This effect was also observed when partner fish (male or
female) were presented only visually, but could not interact physically with the focal female. It seems, therefore, that females
increase vigilance when a harassing male is around, which keeps them from feeding even before males actually approach them.
Based on the latter result, we asked whether a stress-induced increase in metabolic rates would be discernible. We measured
oxygen consumption and gill ventilation frequencies (opercular rates) of females in different social contexts (alone, with
another female, or a male). The predicted, strong body mass dependency of both physiological parameters was uncovered, but
no evidence for an effect of social context was detected. We argue that male harassment represents such a constant (but non-lethal)
stressor for poeciliid females that their metabolic stress responses have adapted to this through habituation. 相似文献
108.
Living in groups is a widespread phenomenon in many animal taxa. The reduction of predation risk is thought to be an important cause for the formation of groups. Consequently, grouping behavior is particularly pronounced during vulnerable life stages, i.e., as juveniles. However, group living does not only provide benefits but also imposes costs on group members, e.g., increased competition for food. Thus, benefits of grouping behavior might not be evident when predation risk is absent. The adaptive significance of living and also developing in a group independent from predation risk has received relatively little attention although this might have important implications on the evolution and maintenance of group living. The first aim of the present study was to examine whether the social environment affects juvenile performance in the cichlid fish Pelvicachromis taeniatus and, secondly, whether kinship affects social behavior. Kin selection theory predicts benefits from grouping with kin. Here, we demonstrate that juveniles reared in a group grow on average faster compared to juveniles reared in isolation under standardized laboratory conditions without predation risk. Furthermore, we found significant differences in social behavior between juveniles reared in a group and reared in isolation. Fish reared in isolation were significantly more aggressive and less willing to shoal than group-reared fish. As expected, genetic relatedness influenced social behavior in group-reared fish as well: dyads of juveniles consisting of kin showed increased group cohesiveness compared to non-kin dyads. We discuss the potential benefits of group living in general and living with kin in particular. 相似文献
109.
Spatial and temporal variability in the relationship between cyanobacterial biomass and microcystins
Som Cit Sinang Elke S. Reichwaldt Anas Ghadouani 《Environmental monitoring and assessment》2013,185(8):6379-6395
The increasing incidence of toxic cyanobacterial blooms, together with the difficulties to reliably predict cyanobacterial toxin (e.g. microcystins) concentration, has created the need to assess the predictive ability and variability of the cyanobacterial biomass–microcystin relationship, which is currently used to assess the risk to human and ecosystems health. To achieve this aim, we assessed the relationship between cyanobacterial biomass and microcystin concentration on a spatiotemporal scale by quantifying the concentration of cyanobacterial biomass and microcystin in eight lakes over 9 months. On both a temporal and spatial scale, the variability of microcystin concentration exceeded that of cyanobacterial biomass by up to four times. The relationship between cyanobacterial biomass and microcystin was weak and site specific. The variability of cyanobacterial biomass only explained 25 % of the variability in total microcystin concentration and 7 % of the variability of cellular microcystin concentration. Although a significant correlation does not always imply real cause, the results of multiple linear regression analysis suggest that the variability of cyanobacterial biomass and cellular microcystin concentration is influenced by salinity and total phosphorus, respectively. The weak cyanobacterial biomass–microcystin relationship, coupled with the fact that microcystin was present in concentrations exceeding the WHO drinking water guidelines (1 μg?L?1) in most of the collected samples, emphasizes the high risk of error connected to the traditional indirect microcystin risk assessment method. 相似文献