Despotic partner choice puts helpers under pressure?

The authors of the target paper (Bergmüller et al., 2007) try o bring order into the many forms ‘cooperation’ takes in the atural world by designing a decision tree, most branches of hich have endpoints well known from the cooperation literaure. The advantage of this exercise is that it helps to classify atural phenomena into the correct pigeonhole and relate it to ther natural phenomena of the same class as well as to existng theoretical considerations. The crucial assumption here is hat a relatively small number of pigeonholes suffices to clasify all observed cooperative phenomena. Otherwise, one has o create ever-smaller branches or accept that many phenomena et stuck between branches. For example, where do we clasify the behaviour of a helper, who gains direct benefits through roup augmentation (pseudo-reciprocity) plus indirect benefits hrough increased reputation (indirect reciprocity) and inclusive tness? One reason the tree presented in the target paper remains more r less orderly is that the authors have left out some important echanisms, such as partner choice in general (see p. 14 of the s) and competitive altruism in particular (Barclay and Willer, 007; Roberts, 1998), as well as restricted themselves to cooprative breeding. My impression is that the tree would become ather bushy without those restrictions and that we will run out of erms at some point. Pigeonholing can be very useful in ordering ur thoughts about phenomena. The risk is that we artificially plit up what is conceptually in fact identical or comparable. In y recent review for Animal Behaviour (Noë, 2006) I went the pposite direction and proposed to concentrate on two essenial parameters: cooperative investment and cooperative returns. oth can come in many disguises, such as reproduction, proection, food, reputation, etc. and can be measured in relative tness or in proximate currencies, such as risk of injury or gains nd losses in time and energy. The puzzle then reduces to idenifying the factors that determine the values of investments and