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排序方式: 共有900条查询结果,搜索用时 31 毫秒
841.
842.
Nest Predators and Fragmentation: a Review and Meta-Analysis 总被引:14,自引:0,他引:14
Anna D. Chalfoun ‡ Frank R. Thompson III † Mary J. Ratnaswamy§ 《Conservation biology》2002,16(2):306-318
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P.W. Frank 《Marine Biology》1975,31(2):181-192
At higher latitudes along the west coast of the USA the herbivorous intertidal snail Tegula funebralis (Adams, 1854) lives longer, grows more slowly, but attains a larger size than further south. To the north, age distributions are less predictable and often far from stationary. The differences, which have some generality, can be explained either by a primary temperature effect joined with increased hazards to planktonic larvae in the north, or else may result from a combination of interactions between intensity of predation, population density and food supply. Growth rates of transplanted individuals suggest a genetic basis for the latitudinal differences. 相似文献
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Frédérique?DuboisEmail author éric?Wajnberg Frank?Cézilly 《Behavioral ecology and sociobiology》2004,56(3):228-236
Although the extensive variation in divorce rates among monogamous bird species has stimulated several theoretical accounts, the mechanisms underlying divorce strategies remain poorly understood. Here, we use an individual-based simulation model to investigate the adaptiveness of mechanisms of mate choice in the context of remating. Our model compares the fitness of females that choose a mate during each breeding season using one of two different decision rules; best-of-n females sample n potential partners and then select the male with the highest quality, whereas better option females choose a mate whose quality is maximal among the non-mated individuals they sampled the season before. It is assumed in the model that best-of-n females have no a priori information about the quality of potential partners and systematically decide to divorce at the beginning of each breeding season before searching for a new mate. Conversely, better option females use the information they gained the season before, and may retain their previous partner if they have no opportunity to mate with an individual of better quality. Results from simulations indicate that the best-of-n decision rule should be favoured when there is a large variation in male quality and low costs of mate sampling. On the other hand, the probability that the better option rule may invade the population is predicted to increase with male survival rate. However, changes in male mortality had no marked influence on the expected proportion of divorcing pairs, contrary to previous theoretical expectations.Communicated by H. Kokko 相似文献
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Frank J. Convery 《Integrated Assessment》2000,1(2):165-176
In this paper, the following key issues are addressed: the so-called “South” – the Group of 77 and China – and how to engage
their interest and commitment; the purported savings if the flexible mechanisms are availed of, and the macro-economic impacts
of meeting the Kyoto objectives; the associated issues of narrowing the extent and scope for such trading by setting a limit
on how much can be traded, and “hot air” – the surplus quota above their own projected needs which Russia and most of the
old Soviet Union have to offer; operational issues, including units to be traded, monitoring and enforcement, allocation of
permits, competitiveness and risk management; in the case of emissions trading, the initial allocation of permits.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献