A Test of Two Skew Models to Explain Cooperative Breeding

Synopsis Two competing models, reproductive skew and skew selection, have been constructed to explain the evolution of cooperation among unrelated breeders. Reproductive skew is a trade-off model that assumes breeding occurs under scarce resource conditions. One breeder gains units of fecundity at the expense of other breeders during aggressive, altruistic or tug-of-war transactions. After joining, the distribution of fecundity among breeders shifts from symmetrical to asymmetrical. In contrast, skew selection is a surplus model that assumes breeding occurs during a springtime glut. Skew selection assumes that fecundity among breeders is initially asymmetrical and that joining reduces the asymmetry of fecundity. This paper reports findings from a breeding experiment on the fire ant, Solenopsis invicta, which supported skew selection rather than reproductive skew. Joining was a win-win strategy for alpha and beta breeders; beta breeders gained within-group survival benefits; alpha breeders gained between-group survival benefits. In summary, skew selection extends Darwin’s theory of natural selection by revealing the self-interested core of cooperative breeding.      

Negating the inverse elasticity rule

The views and opinions expressed here are not necessarily those of the Colorado Public Utilities Commission.     

Can the Nation Afford Pensions?

Demography-the worsening ratio of the economically active to inactive-will make pensions in their present form unsustainable. Welfarism in the form of universal state pension provision for all can only wither-any individual wishing to do better than his neighbour will have to rely on his own savings.     

麦肯锡调查：当今的企业如何对一线进行管理

大多数企业并未对一线管理人员提供足够的培训,或者对其职责进行恰当的定位,以创造最大价值。令该问题雪上加霜的是,高层领导常常意识不到妨碍一线绩效提高的问题。而拥有得力的一线管理人员的企业则采取与之不同的做法。     

Interaction between central planners and firms: The uncertainty of target adjustment

Conclusions The interaction between planners and firms in a centrally planned economy has already been treated by a number of authors. They have generally focused upon the firm's performance in the face of various reward structures and have, with the exception of Gindin (1970) and Snowberger (1977), not dealt explicitly with the feed-back effect this performance has on the planners' adjustment of the reward structure for the future. This paper has extended the previous analysis of the feedback mechanism into the case where a firm knows that the planners have the power to make such adjustments but does not know precisely what form they will take. We have developed models which reflect several different ways in which a firm might respond to this uncertainty. Furthermore, we have introduced an adjustment scheme which considers the performance of all firms in the industry when setting a target for any one of them, in addition to treating the ordinary assumption that a firm's future target depends only upon its own present underor overfulfillment.8060 Niwot Road, # 19, Longmont, Colorado 80501, USA.