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1.
The primary dilemma in evolutionarily stable mutualisms is that natural selection for cheating could overwhelm selection for cooperation. Cheating need not entail parasitism; selection favours cheating as a quantitative trait whenever less‐cooperative partners are more fit than more‐cooperative partners. Mutualisms might be stabilised by mechanisms that direct benefits to more‐cooperative individuals, which counter selection for cheating; however, empirical evidence that natural selection favours cheating in mutualisms is sparse. We measured selection on cheating in single‐partner pairings of wild legume and rhizobium lineages, which prevented legume choice. Across contrasting environments, selection consistently favoured cheating by rhizobia, but did not favour legumes that provided less benefit to rhizobium partners. This is the first simultaneous measurement of selection on cheating across both host and symbiont lineages from a natural population. We empirically confirm selection for cheating as a source of antagonistic coevolutionary pressure in mutualism and a biological dilemma for models of cooperation. 相似文献
2.
Alan Holland 《Bioethics》2016,30(7):490-499
Julian Savulescu's principle of procreative beneficence (PB) states that, other things being equal, and of the possible children they could have, a couple contemplating procreation are morally obliged to (attempt to) procreate the child with the best chance of the best life. The critique of PB is in three parts. The first part argues that PB rests on a particular conception of the good life, and that alternative conceptions of the good life afford no obvious way in which PB can be rendered operational. The second part identifies six flaws in the attempt to justify PB in terms of a particular conception of the good life according to which the best life is understood as the life with the most well‐being. The third part explores some of the uncertainties that surround the potential implications and ramifications of adopting the principle. The overall purpose is not to demonstrate that the principle is untenable, but only to demonstrate that no compelling reason has yet been given for adhering to it. 相似文献