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1.
In many species of birds and mammals with a co-operative breeding and rearing system, offspring survival is positively related
to the number of helpers. In the New World callitrichine primates (marmosets and tamarins), adult males are considered as
particularly valuable helpers, and female reproductive success may depend strongly on the males' contribution to infant care.
We analysed the number of offspring (infants, juveniles) in groups of wild pygmy marmosets, Cebuella pygmaea (Callitrichinae, Cebidae, Primates), in relation to the number of adult males and to the number of adult and subadult group
members. In contrast to other callitrichines with a co-operative system of infant care, no relationship was found between
the number of adult males and the number of infants and offspring. However, there was a significant positive relationship
between the number of juveniles and the number of adult and subadult group members. The lack of a relationship between infant
and adult-male number is interpreted as resulting from the reduced importance of adult males as helpers in pygmy marmosets
in comparison to other callitrichines, probably due to the reduced costs of infant care. The relationship between the number
of juveniles and the number of adult and subadult group members is in accordance with increased offspring survival in larger
groups, as observed in other primates.
Received: 1 February 1999 / Received in revised form: 5 June 1999 / Accepted: 29 June 1999 相似文献
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3.
Anne Niedbala Mario Schaffer Tobias Licha Karsten Nödler Hilmar Börnick Hans Ruppert Eckhard Worch 《Chemosphere》2013,90(6):1945-1951
The aim of this study was to systematically investigate the influence of the mono- and divalent inorganic ions Na+ and Ca2+ on the sorption behavior of the monovalent organic cation metoprolol on a natural sandy sediment at pH = 7. Isotherms for the beta-blocker metoprolol were obtained by sediment–water batch tests over a wide concentration range (1–100 000 μg L?1). Concentrations of the competing inorganic ions were varied within freshwater relevant ranges. Data fitted well with the Freundlich sorption model and resulted in very similar Freundlich exponents (n = 0.9), indicating slightly non-linear behavior. Results show that the influence of Ca2+ compared to Na+ is more pronounced. A logarithmic correlation between the Freundlich coefficient KFr and the concentration or activity of the competing inorganic ions was found allowing the prediction of metoprolol sorption on the investigated sediment at different electrolyte concentrations. Additionally, the organic carbon of the sediment was completely removed for investigating the influence of organic matter on the sorption of metoprolol. The comparison between the experiments with and without organic carbon removal revealed no significant contribution of the organic carbon fraction (0.1%) to the sorption of metoprolol on the in this study investigated sediment. Results of this study will contribute to the development of predictive models for the transport of organic cations in the subsurface. 相似文献
4.
Parasites are ubiquitous in populations of free-ranging animals and impact host fitness, but virtually nothing is known about the factors that influence patterns of disease risk across species and the effectiveness of behavioral defenses to reduce this risk. We investigated the correlates of malaria infection (prevalence) in Neotropical primates using data from the literature, focusing on host traits involving group size, body mass, and sleeping behavior. Malaria is spread to these monkeys through anopheline mosquitoes that search for hosts at night using olfactory cues. In comparative tests that used two different phylogenetic trees, we confirmed that malaria prevalence increases with group size in Neotropical primates, as suggested by a previous non-phylogenetic analysis. These results are consistent with the hypothesis that larger groups experience increased risk of attack by mosquitoes, and counter to the hypothesis that primates benefit from the encounter-dilution effect of avoiding actively-seeking insects by living in larger groups. In contrast to non-phylogenetic tests, body mass was significant in fewer phylogeny-based analyses, and primarily when group size was included as a covariate. We also found statistical support for the hypothesis that sleeping in closed microhabitats, such as tree holes or tangles of vegetation, reduces the risk of malaria infection by containing the host cues used by mosquitoes to locate hosts. Due to the small number of evolutionary transitions in sleeping behavior in this group of primates, however, this result is considered preliminary until repeated with a larger sample size. In summary, risk of infection with malaria and other vector-borne diseases are likely to act as a cost of living in groups, rather than a benefit, and sleeping site selection may provide benefits by reducing rates of attack by malaria vectors.Electronic Supplementary Material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
5.
Species that participate in mixed-species groups (MSG) may have complementary roles in antipredator strategies. We studied vigilance in mustached tamarins (Saguinus mystax), small arboreal primates that form stable mixed-species groups with saddleback tamarins (Saguinus fuscicollis), in order to examine how the direction of vigilance changes with different species group compositions and whether the division of labor between the two species can be confirmed. We did so by comparing quantitative and qualitative differences in vigilance behavior between same individuals in and out of association (case A); MSG and single-species groups of the same total group size from two different populations (case B); and MSG of the same group size but with a different ratio of conspecifics to heterospecifics (case C). We predicted that individuals would increase downward scanning when heterospecifics are absent or their percentage is low, but total vigilance would increase only in case A due to the group size effect. However, mustached tamarins increased total vigilance due to horizontal scanning in cases A and C, and the predictions were confirmed only in small-sized groups in case B. Thus, we found indications that associating tamarin species in MSG might complement each other in the direction of vigilance, but the division of labor alone does not satisfactorily explain all the findings. There appear to be other mechanisms at work that define how direction of vigilance changes with group size and species composition. Complementarity of species probably occurs due to species vertical stratification rather than differences in the direction of vigilance. 相似文献
6.
Sorption influenced transport of ionizable pharmaceuticals onto a natural sandy aquifer sediment at different pH 总被引:3,自引:0,他引:3
The pH-dependent transport of eight selected ionizable pharmaceuticals was investigated by using saturated column experiments. Seventy-eight different breakthrough curves on a natural sandy aquifer material were produced and compared for three different pH levels at otherwise constant conditions. The experimentally obtained KOC data were compared with calculated KOC values derived from two different log KOW-log KOC correlation approaches. A significant pH-dependence on sorption was observed for all compounds with pKa in the considered pH range. Strong retardation was measured for several compounds despite their hydrophilic character. Besides an overall underestimation of KOC, the comparison between calculated and measured values only yields meaningful results for the acidic and neutral compounds. Basic compounds retarded much stronger than expected, particularly at low pH when their cationic species dominated. This is caused by additional ionic interactions, such as cation exchange processes, which are insufficiently considered in the applied KOC correlations. 相似文献
7.
Modelling the solute transport under nonequilibrium conditions on the basis of mass transfer equations 总被引:1,自引:0,他引:1
Worch E 《Journal of contaminant hydrology》2004,68(1-2):97-120
A solute transport model that describes nonequilibrium adsorption in soil/groundwater systems by mass transfer equations for film and intraparticle diffusion is presented. The model is useful in cases where breakthrough curve spreading cannot be explained by dispersion only. To evaluate its validity, the model was applied to several data sets from column experiments. The validity was also proved by a comparison with an analytical solution for the limiting case of predominating dispersion. Furthermore, a sensitivity analysis was performed to illustrate the influence of different process and sorption parameters (pore water velocity, intraparticle mass transfer coefficient, isotherm nonlinearity) on the shape of the calculated breakthrough curves. The application of the proposed model is discussed in comparison to the widely used dispersed flow/local equilibrium model, and a relationship between both models, which is based on a lumped parameter approach, is shown. 相似文献
8.
Nonequilibrium sorption of phenols onto geosorbents: the impact of pH on intraparticle mass transfer 总被引:1,自引:0,他引:1
While the pH effect on sorption equilibrium of weak acids on natural sorbents was investigated in a number of studies, less is known about the pH dependence of sorption kinetics. This paper investigates the impact of pH on sorption kinetics during the transport of some selected phenols through a sandy aquifer material. Breakthrough curves measured in column experiments were analyzed using a mass transfer based nonequilibrium model designated as dispersed flow, film and particle diffusion model (DF-FPDM). In this model, the rate limiting intraparticle diffusion is characterized by the mass transfer coefficient, kSaV, which can be determined from breakthrough curves by curve fitting. The experimental results indicate that the kSaV is pH-dependent and inversely correlated with the pH-dependent distribution coefficient, K(d,app). Regression equations are presented that may be used to estimate approximate values of intraparticle mass transfer coefficients on the basis of experimentally determined or LFER predicted distribution coefficients. 相似文献
9.
Daniel Meyer-Kohlstock Gunnar Hädrich Werner Bidlingmaier Eckhard Kraft 《Waste management (New York, N.Y.)》2013,33(3):536-539
Based on a recent survey of German composting plants an evaluation of costs and benefits of composting was attempted. In this regard, several economical, ecological and legal aspects and some interrelations are discussed in this paper. A special emphasis is placed on the fees and compost prices of composting plants. It is also shown how the legal framework provides the economic basis for composting in Germany, how economical and ecological costs and benefits could be assessed, and why it is so difficult to determine the value of composting. 相似文献
10.
Alfatih A. A. Osman Gerhard Geipel Gert Bernhard Eckhard Worch 《Environmental science and pollution research international》2013,20(12):8629-8635
Cryogenic time-resolved laser-induced fluorescence spectroscopy was successfully used to identify uranium binding forms in selected German mineral waters of extremely low uranium concentrations (<2.0 μg/L). The measurements were performed at a low temperature of 153 K. The spectroscopic data showed a prevalence of aquatic species Ca2UO2(CO3)3 in all investigated waters, while other uranyl–carbonate complexes, viz, UO2CO3(aq) and UO2(CO3)2 2?, only existed as minor species. The pH value, alkalinity (CO3 2?), and the main water inorganic constituents, specifically the Ca2+ concentration, showed a clear influence on uranium speciation. Speciation modeling was performed using the most recent thermodynamic data for aqueous complexes of uranium. The modeling results for the main uranium binding form in the investigated waters indicated a good agreement with the spectroscopy measurements. 相似文献