Persistence Increases with Diversity and Connectance in Trophic Metacommunities

We are interested in understanding if metacommunity dynamics contribute to the persistence of complex spatial food webs subject to colonization-extinction dynamics. We study persistence as a measure of stability of communities within discrete patches, and ask how do species diversity, connectance, and topology influence it in spatially structured food webs.We answer this question first by identifying two general mechanisms linking topology of simple food web modules and persistence at the regional scale. We then assess the robustness of these mechanisms to more complex food webs with simulations based on randomly created and empirical webs found in the literature. We find that linkage proximity to primary producers and food web diversity generate a positive relationship between complexity and persistence in spatial food webs. The comparison between empirical and randomly created food webs reveal that the most important element for food web persistence under spatial colonization-extinction dynamics is the degree distribution: the number of prey species per consumer is more important than their identity.With a simple set of rules governing patch colonization and extinction, we have predicted that diversity and connectance promote persistence at the regional scale. The strength of our approach is that it reconciles the effect of complexity on stability at the local and the regional scale. Even if complex food webs are locally prone to extinction, we have shown their complexity could also promote their persistence through regional dynamics. The framework we presented here offers a novel and simple approach to understand the complexity of spatial food webs

What Does Ethics Have to do with Leadership?

© 2013, Springer Science+Business Media Dordrecht. Accounts of leadership in relation to ethics can and do go wrong in several ways that may lead us too quickly into thinking there is a tighter relationship between ethics and leadership than we have reason to believe. Firstly, these accounts can be misled by the centrality of values talk in recent discussions of leadership into thinking that values of a particular kind are sufficient for leadership. Secondly, the focus on character in recent leadership accounts can lead to a similar error. The assumption here is that because good character is often a locus of descriptions of leaders, such character is necessary and sufficient for leadership. Thirdly, we can fall victim to an observer bias that colors our accounts of the leaders we admire and thus wish to either have or be, which in turn leads to the fourth way in which accounts of leadership can go wrong in their description of the role of ethics in leadership. Through inattention or through wishful thinking accounts of leadership can become merely prescriptive and stipulate that ethics is requisite and at least partly constitutive of leadership. Keeping in mind these ways in which accounts of leadership commonly go astray, we can say that any adequate account of leadership must, at least in the first instance, be able to differentiate not only between leadership and good ethical character, but also between leadership and power, authority, influence, managerial ability, and charisma. Taking a closer look at some of the ways that the relation between leadership and ethics is misconstrued is necessary to better understanding both leadership and its connection to ethics. It is, however, just a first step. Asking whether we have reason to think of leadership as an Aristotelian virtue should, we think, enable us to give a more accurate and useful account of the complexity of the relation. It also captures underlying reasons for wanting to see the two as intrinsically connected