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991.
Dugatkin LA 《Die Naturwissenschaften》2002,89(12):533-541
The evolution of cooperation has long been a topic near and dear to the hearts of behavioral and evolutionary ecologists. Cooperative behaviors run the gamut from fairly simple to very complicated and there are a myriad of ways to study cooperation. Here I shall focus on three paths that have been delineated in the study of intraspecific cooperation among unrelated individuals: reciprocity, byproduct mutualism, and group selection. In each case, I attempt to delineate the theory underlying each of these paths and then provide examples from the empirical literature. In addition, I shall briefly touch upon some recent work that has attempted to examine (or re-examine) the role of cognition and phylogeny in the study of cooperative behavior. While empirical and theoretical work has made significant strides in the name of better understanding the evolution and maintenance of cooperative behavior in animals, much work remains for the future. From the point of view of the moralist, the animal world is on about the same level as the gladiator's show. The creatures are fairly well treated, and set to fight; whereby the strongest, the swiftest and the cunningest live to fight another day. The spectator has no need to turn his thumb down, as no quarter is given
the weakest and the stupidest went to the wall, while the toughest and the shrewdest, those who were best fitted to cope with their circumstances, but not the best in any other way, survived. Life was a continuous free fight, and
a war of each against all was the normal state of existence. (Huxley 1888) 相似文献
992.
993.
R. Williamson M. E. D. Allison T. J. Bentley S. M. C. Lim E. Watson J. Chapple S. Adam M. Boulton 《黑龙江环境通报》1989,9(10):727-734
Inexpensive and accurate carrier testing for cystic fibrosis (CF) will be possible in the near future. There are no existing studies on the attitudes of English persons in the community to carrier testing for CF or any other recessive disorder. We have conducted a trial study of 166 persons at two schools, two doctors' surgeries, and a family planning clinic. Only a minority had clear pre-existing knowledge of cystic fibrosis and its genetic nature. However, over 80 per cent of those questioned expressed interest in knowing their carrier status. Although it is well known that uptake can only be assessed when a service is in place, and while further studies are required to confirm that testing will be of interest to couples of reproductive age with no previous knowledge of CF, the data strongly suggest that there will be interest in communitywide testing for CF carrier status when such a test becomes available in the United Kingdom. 相似文献
994.
A. M. Watson 《Die Naturwissenschaften》1964,51(21):506-506
995.
Ultrasonic examination in a thirty-eight year old woman about to undergo midtrimester amniocentesis suggested an intra-abdominal fetal mass confirmed by amniography. The mass was a grossly distended urinary bladder. The patient aborted spontaneously before chromosome analysis demonstrated a 47,XY, + 18 karyotype. 相似文献
996.
997.
Mortality-risk Valuation and Age: Stated Preference Evidence 总被引:3,自引:0,他引:3
998.
We study a continuous-time removal model for estimating the population size for a population in which a sub-population size
ratio is known. The maximum likelihood estimate and the optimal martingale estimate of the population size are obtained; these
are shown to be equivalent. A comparison between the proposed estimator and the maximum likelihood estimate which ignores
the information on the known size ratio is made, using a simulation study. The asymptotic variances of these two estimators
are also obtained, and a comparison between them is made. The sensitivity of mis-specification of the known size ratio is
examined. We also apply the corresponding discrete-time model to the proposed continuous-time setting, and study the efficiency
of the corresponding discrete-time type estimator relative to the proposed estimator. 相似文献
999.
Sound ecosystem management meshes socioeconomic attitudes and values with sustainable natural resource practices. Adaptive management is a model for guiding natural resource managers in this process. Ecosystems and the societies that use them are continually evolving. Therefore, managers must be flexible and adaptable in the face of uncertainty and lack of knowledge. To couple good science to management, it is important to develop goals, models, and hypotheses that allow us to systematically learn as we manage. Goals and models guide the development and implementation of management practices. The need to evaluate models and test hypotheses mandates monitoring, which feeds into a continuous cycle of goal and model reformulation. This paper reviews the process of adaptive management and describes how it is being applied to oak/pine savanna restoration at Necedah National Wildlife Refuge as an illustration. Our aim is to help managers design their own adaptive management models for successful ecosystem management. 相似文献
1000.
Alan Neale 《Journal of Environmental Planning and Management》1994,37(3):335-347
Stabilisation of atmospheric concentrations of greenhouse gases, as proposed by the 1992 Earth Summit, implies massive behavioural changes by firms and consumers. Case studies of three key sectors—domestic space heating, domestic appliances, and personal transport—suggest that neither economic instruments nor regulatory controls would, in themselves, be sufficient to bring about the necessary investment in energy efficient products and processes. Attention is focused on specific features of the UK economy which inhibit energy conservation, such as the price sensitive nature of UK markets for consumer durables and the pervasive influence of short‐termism on business calculations. 相似文献