排序方式: 共有4条查询结果,搜索用时 0 毫秒
1
1.
Aggression and resource sharing among foundresses in the social wasp Polistes dominulus: testing transactional theories of conflict 总被引:3,自引:0,他引:3
Tug-of-war models of within-group conflict predict that the frequency of conflict will be positively related to the degree
of reproductive sharing within the group; in contrast, a negative relationship supports transactional models, in which reproductive
payments among group members limit the degree of within-group selfishness. We tested predictions of the tug-of-war and transactional
models by examining cofoundress interactions during the founding (preworker) phase of colony development in 30 naturally nesting
colonies of the paper wasp Polistes dominulus. We found that the mean rate of foundress aggression and the mean probability of food sharing were significantly negatively
associated, which supports the prediction of the transactional, not the tug-of-war model. Further, cofoundress aggression
significantly increased over the founding phase (independently of temperature), while the fraction of aggression initiated
by the dominant (alpha) foundress significantly decreased over this period. We show that both of these results are predicted
by the transactional model of within-group conflict. Interestingly, the alpha’s rate of aggression was significantly positively
temperature dependent, while the beta’s was not. This indicates that the alpha’s aggression level may often be near her physiological
maximum, while the beta’s aggression is limi- ted by other factors, contradicting the prediction of the tug-of-war model.
Moreover, the alpha’s aggression was significantly positively temperature dependent only in the second half of the founding
period, as predicted by the transactional model since this is when there is least reproductive sharing. Finally, our results
indicate that the alpha’s level of aggression depends on the resources controlled by the beta.
Received: 18 January 2000 / Revised: 19 June 2000 / Accepted: 24 June 2000 相似文献
2.
The flagship of the Environmental Protection Agency's regulatory reinvention initiative, Project XL has been touted as a regulatory
blueprint for a site-specific, performance-based pollution-control system, but widespread complaints about the costs of the
program beg the question of whether the costs of tailoring regulations to individual facilities are manageable. To address
this question, this paper presents original survey data on a sample of 11 XL projects. We find that the fixed costs of putting
in place XL agreements are substantial, averaging over $450,000 per firm. While stakeholder negotiations are widely cited
as the principal source for these costs, we find that they actually arise mainly from interaction between participating facilities
and the EPA. Moreover, EPA management problems are perceived by our survey respondents as having inflated project development
costs. Finally, we find that the key factors that explains differences in costs across XL projects are the scope and complexity
of the project proposal. These findings suggest that Project XL favors large firms that can afford to pay significant project
development costs, that EPA management problems must be resolved to reduce costs, and that there may be a significant economic
bias against complex and innovative proposals—precisely the type of proposals that Project XL was designed to foster in order
to improve the efficiency of the regulatory system. 相似文献
3.
Structure of pathways in ecological networks: relationships between length and number 总被引:1,自引:0,他引:1
In ecosystems network, structure determines adjacent (direct) and non-adjacent (indirect) pathways over which energy, matter, and information can flow. The more pathways, the more possible ways the conservative substance can move in zero-sum transactions between network nodes that the pathways interconnect, and the more possible non-conservative, nonzero-sum relations can be secondarily derived from these. Structural analysis is a tool we employ, from a family of input–output methods for exploring zero- and nonzero-sum attributes of environmental networks, to count pathways of varying length between network nodes. In this paper, we examine the relationship between pathway length (k) and number (Pk) as determined by system size (n, number of nodes) and extent and pattern of connectance (C). We develop a measure (ma) of pathway growth in numbers with increasing length, and then normalize this to the maximum rate possible (ma/mc) for a given system size. These measures apply to two pathway types—paths, ma(0) and ma(0)/mc(0), which forbid adjacent node repetitions, and walks, ma(1) and ma(1)/mc(1), which allow them. We find that network size has a curvilinear effect on the pathway number versus length relationship, and extent and pattern of connectance are convolved. Values computed for the paths and walks of three ecosystem models (oyster reef, freshwater marsh, and reservoir cove) are used to compare their pathway structure. 相似文献
4.
Two experimental tests of the relationship between group stability and aggressive conflict in Polistes wasps 总被引:1,自引:0,他引:1
Two field experiments were used to examine how the relative benefits of cooperation influence within-group conflict in foundress associations of the paper wasp Polistes dominulus. P. dominulus foundresses can either nest alone or cooperate with other foundresses. We experimentally manipulated the relative benefits of co-foundress associations vs independent reproduction and tested the effect on aggressive within-group conflict. First, we examined aggression between alpha and beta co-foundresses before and after lower-ranking foundresses were removed. Removal of subordinates increases the relative contributions of the remaining subordinates to group reproductive output as there are fewer adults to care for the brood. Transactional models predict that group conflict over reproductive shares will increase as the relative benefits of grouping increase. As predicted, aggression between the co-foundresses significantly increased following subordinate removal. Second, we experimentally reduced ecological constraints on independent nesting by placing a previously orphaned, adoptable nest comb near the occupied nests. Providing an independent breeding opportunity is predicted to increase the benefits of independent reproduction relative to those of cooperating, thereby reducing group stability and aggression. As predicted, aggression between dominant and subordinate foundresses significantly decreased after the orphaned comb was presented. Therefore, group members sense variation in ecological constraints and relative productivity contributions and quickly modulate their behavior in response. Overall, these two experiments suggest that paper wasps behave as if within-group competition is limited by the threat of group dissolution such that stable groups where cooperation is strongly favored can withstand higher levels of conflict than unstable groups. 相似文献
1