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711.
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
712.
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
713.
Mortality-risk Valuation and Age: Stated Preference Evidence 总被引:3,自引:0,他引:3
714.
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
715.
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
716.
Alan J. Domaracki Gopal Sistla Sury N. Putta 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1068-1072
Air parcel trajectories originating from three locations in New York State are calculated for a three year period using the ARL-ATAD long-range transport model. Model output consisting of a trajectory segment's end point longitude and latitude position are analyzed to describe the long-range transport climatology by computing the frequency of occurrence of segment end points terminating over 33 receptor areas comprising east-central North America and a portion of the Atlantic Ocean. Results of the frequency of occurrence data show how often air pollutants emitted at or near the origin may be expected to drift over a specific downwind region. For the New York City airshed, it was found that 26.2% of the trajectories remain over New York State for transport times of 3 h and the frequency decreases to 5.2% after 24 h of transport. Approximately 40% of all trajectories are found to be over the Atlantic Ocean after 3 h of transport. When allowances are made for losses of data over the Atlantic Ocean, up to 64% of all trajectories are over the Atlantic Ocean after 24 h of transport. This frequency of trajectories over the Atlantic Ocean was found to be in agreement with wet and dry deposition modeling results conducted for power plants in New York City. 相似文献
717.
Edward E. DeMartini Todd W. Anderson Alan M. Friedlander James P. Beets 《Marine Biology》2011,158(11):2437-2447
Group incidence and size are described for recruit parrotfishes, wrasses, and damselfishes on Hawaiian reefs over 3 years
(2006–2008) at sites spanning the archipelago (20–28°N, 155–177°W). Coral-poor and coral-rich areas were surveyed at sites
with both low (Hawaii Island) and high (Midway Atoll) predator densities, facilitating examination of relations among predator
and recruit densities, habitat, and group metrics. Predator and recruit densities varied spatially and temporally, with a
sixfold range in total recruit densities among years. Group (≥2 recruits) metrics varied with time and tracked predator and
recruit densities and the proportion of schooling species. Groups often included heterospecifics whose proportion increased
with group size. A non-saturating relationship between group size and recruit density suggests that the anti-predator benefits
of aggregation exceeded competitive costs. Grouping behavior may have overarching importance for recruit survival–even at
high recruit densities–and merits further study on Hawaiian reefs and elsewhere. 相似文献
718.
Shoufan Fang George Z. Gertner Alan B. Anderson Heidi R. Howard Patricia Sullivan Chris Otto 《Journal of environmental management》2010,91(3):772-780
Vehicle use during military training activities results in soil disturbance and vegetation loss. The capacity of lands to sustain training is a function of the sensitivity of lands to vehicle use and the pattern of land use. The sensitivity of land to vehicle use has been extensively studied. Less well understood are the spatial patterns of vehicle disturbance. Since disturbance from off-road vehicular traffic moving through complex landscapes varies spatially, a spatially explicit nonlinear regression model (disturbance model) was used to predict the pattern of vehicle disturbance across a training facility. An uncertainty analysis of the model predictions assessed the spatial distribution of prediction uncertainty and the contribution of different error sources to that uncertainty.For the most part, this analysis showed that mapping and modeling process errors contributed more than 95% of the total uncertainty of predicted disturbance, while satellite imagery error contributed less than 5% of the uncertainty. When the total uncertainty was larger than a threshold, modeling error contributed 60% to 90% of the prediction uncertainty. Otherwise, mapping error contributed about 10% to 50% of the total uncertainty. These uncertainty sources were further partitioned spatially based on other sources of uncertainties associated with vehicle moment, landscape characterization, satellite imagery, etc. 相似文献
719.
An understanding of the trophic organization patterns of tropical littoral fish assemblages can contribute to the knowledge
of key ecosystem processes while simultaneously assisting to validate large-scale biogeographic patterns (i.e. latitudinal
patterns in fish herbivory). In the present study, the diets of eight fish species inhabiting the tide pools of a rocky shore
on the western coast of Colombia (tropical eastern Pacific) are documented. A total of 17 prey items were identified, with
a major representation (average percent by weight) of crabs and macroalgae items in the guts of all species. Small crustacean
prey items (crabs, shrimps, copepods and amphipods) dominated the diets of most species, but consumption of macroalgae and
diatoms by a significant number of species was also observed. We identified four significant trophic guilds within the assemblage
using multivariate techniques (cluster analysis and nMDS): an omnivorous guild, consisting of Malacoctenus zonifer and the smallest size class of Bathygobius ramosus; a small-prey carnivorous guild, consisting of the intermediate size classes of B. ramosus and the smallest size class of Gobiesox adustus; a large-prey carnivorous guild, consisting of both largest size classes of B. ramosus and G. adustus; and an herbivorous guild consisting of Abudefduf concolor, A. troschelii and Chaenomugil proboscideus. The diet of two species slightly overlapped those of the rest of the assemblage and did not conform to any guild (Echidna nocturna and Halichoeres aestuaricola). It is hypothesised that guild formation may be a consequence of aggregation of species at abundant resources in the intertidal
zone rather than a direct consequence of inter-specific competition. Ontogenetic changes in diets were observed in two resident
species of the assemblage (B. ramosus and G. adustus). The latitudinal trend for herbivory inside this tropical assemblage is discussed in comparison with similar temperate studies
in the eastern Pacific. 相似文献