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61.
Mats Olsson 《Behavioral ecology and sociobiology》1994,34(3):169-173
A honey bee (Apis mellifera) queen mates with about ten haploid drones, thus producing colonies composed of about ten subfamilies of super-sisters. An increasing but controversial body of literature supports the views that: (1) Members of each subfamily within a colony can recognise each other, and distinguish supersisters from half-sisters. (2) Members of each subfamily use this recognition information and increase the reproductive fitness of their own subfamily at the expense of half-sisters through behaviour termed nepotism. A mathematical model is developed that shows that task specialisation by subfamilies, and bees that repeatedly undertake the behaviour within subfamilies, can influence the numbers of interactions among super-sisters, relative to the numbers of interactions between half-sisters. The model is then evaluated using a data set pertaining to trophallaxis behaviour in a two-subfamily colony. It is concluded that with this data set, task specialisation and subfamily recognition were indeed confounded, suggesting that the apparent subfamily recognition could easily have been an artefact of task specialisation.
Correspondence to: B.P. Oldroyd 相似文献
62.
Mats Olsson 《Behavioral ecology and sociobiology》1993,32(5):337-341
Summary Male sand lizards (Lacerta agilis) are polygynous and guard individual females for several hours to days after copulation. Even though the copulation itself only lasts 2–4 min, the total time that a male invests per female is considerably more and may constitute a substantial investment during a mating season. In such situations, when male copulation frequency is constrained, or when variation in female fecundity is high, mate choice by males may be adaptive. Large body size in female sand lizards is correlated with higher fecundity. In choice experiments performed in the laboratory, male sand lizards preferred to court large females rather than small females. In addition, when there was little difference in size between the females in the experiment, the males visited the two females more often before they started to court the preferred female. The results from a field study during 1984 and 1987–1990 showed that females are non-aggressive, have small neighboring home ranges (c. 100 m2) and may share burrows and sites for thermoregulation. This means that females can be found close together and thus gives males the opportunity to choose a mate. Assortative mating with respect to size was observed in a natural population, as well as a limited number of direct choices of females by males. These results support the results of the choice experiment. 相似文献
63.
Löfgren S Aastrup M Bringmark L Hultberg H Lewin-Pihlblad L Lundin L Karlsson GP Thunholm B 《Ambio》2011,40(8):836-856
Recovery from anthropogenic acidification in streams and lakes is well documented across the northern hemisphere. In this
study, we use 1996–2009 data from the four Swedish Integrated Monitoring catchments to evaluate how the declining sulfur deposition
has affected sulfate, pH, acid neutralizing capacity, ionic strength, aluminum, and dissolved organic carbon in soil water,
groundwater and runoff. Differences in recovery rates between catchments, between recharge and discharge areas and between
soil water and groundwater are assessed. At the IM sites, atmospheric deposition is the main human impact. The chemical trends
were weakly correlated to the sulfur deposition decline. Other factors, such as marine influence and catchment features, seem
to be as important. Except for pH and DOC, soil water and groundwater showed similar trends. Discharge areas acted as buffers,
dampening the trends in streamwater. Further monitoring and modeling of these hydraulically active sites should be encouraged. 相似文献
64.
Environmental change challenges local and global survival of populations and species. In a species-poor environment like the
Baltic Sea this is particularly critical as major ecosystem functions may be upheld by single species. A complex interplay
between demographic and genetic characteristics of species and populations determines risks of local extinction, chances of
re-establishment of lost populations, and tolerance to environmental changes by evolution of new adaptations. Recent studies
show that Baltic populations of dominant marine species are locally adapted, have lost genetic variation and are relatively
isolated. In addition, some have evolved unusually high degrees of clonality and others are representatives of endemic (unique)
evolutionary lineages. We here suggest that a consequence of local adaptation, isolation and genetic endemism is an increased
risk of failure in restoring extinct Baltic populations. Additionally, restricted availability of genetic variation owing
to lost variation and isolation may negatively impact the potential for evolutionary rescue following environmental change. 相似文献
65.
66.
Charlotta Pers Lars Rahm Anders Jonsson Ann-Kristin Bergström Mats Jansson 《Environmental Modeling and Assessment》2001,6(3):159-172
The organic carbon balance of a lake with high input of allochthonous organic carbon is modelled integrating physical, chemical and biological processes. The physical model captures the behaviour of real thermal stratification in the lake for different flow situations during the period 1993–1997. The dissolved organic carbon model is based on simulated trajectories of water parcels. By tracking parcels, account is kept of environmental factors such as temperature and radiation as well as DOC quality for each parcel. The DOC concentration shows seasonal variations primarily dependent on inflow. The organic matter degradation (bacterial- and photodegradation) in the lake amounts to 1.5–2.5 mg C l–1 yr–1, where photooxidation is responsible for approximately 10%. The estimated DIC production in the lake is large compared to sediment mineralisation and primary production. The main conclusion is that the model with the selected parameterisations of the degradation processes reasonably well describes the DOC dynamics in a forest lake. 相似文献
67.
The efficiency of conversion of light to electrical energy with the help of conjugated polymers and molecules is rapidly improving. The optical absorption properties of these materials can be designed, and implemented via molecular engineering. Full coverage of the solar spectrum is thus feasible. Narrow absorption spectra allow construction of tandem solar cells. The poor transport properties of these materials require thin devices, which limits optical absorption. Alternative device geometries for these flexible materials compensate for the optical absorption by light trapping, and allow tandem cells. 相似文献
68.
69.
Annika Åberg Mats Tysklind Tohr Nilsson Matthew MacLeod Annika Hanberg Rolf Andersson Sture Bergek Richard Lindberg Karin Wiberg 《Environmental science and pollution research international》2010,17(1):26-39
Background, aim, and scope
The main pathway for human exposure to the highly toxic polychlorinated-p-dioxins and polychlorinated furans [polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)] is via dietary intake. Other exposure pathways may, however, be important in close proximity to point sources, such as wood preservation sites, where PCDD/F contaminated chlorophenols (CP) were previously used. In this study, a heavily PCDD/F contaminated CP saw mill site in Sweden was investigated. Human exposure through a broad spectrum of exposure pathways was assessed. Such studies are in demand since the question whether contaminated sites represent a current or future risk can only be answered by detailed site-specific risk assessments. 相似文献70.
Building future scenarios and uncovering persisting challenges of participatory forest management in Chilimo Forest, Central Ethiopia 总被引:1,自引:0,他引:1
Kassa H Campbell B Sandewall M Kebede M Tesfaye Y Dessie G Seifu A Tadesse M Garedew E Sandewall K 《Journal of environmental management》2009,90(2):1004-1013
We examined the changes in forest status and people's livelihoods through building future scenarios for Chilimo Forest in Central Ethiopia where participatory forest management (PFM) is being implemented. Participatory methods were employed to collect data, and a dynamic modeling technique was applied to explore trends over time. By integrating the more quantitative model outputs with qualitative insights, information on forests and livelihoods was summarized and returned to users, both to inform them and get feedback. A scenario of open access without PFM provides higher income benefits in the short term but not over the longer term, as compared to a scenario with PFM. Follow up meetings were organized with national decision makers to explore the possibility of new provisions in the national forest proclamation related to joint community-state ownership of forests. Project implementers must constantly work towards improving short term incentives from PFM, as these may be insufficient to garner support for PFM. Other necessary elements for PFM to succeed include: ensuring active participation of the communities in the process; and, clarifying and harmonizing the rules and regulations at different levels. 相似文献