In cooperative breeders, parents that receive help with offspring care may either maintain their own effort or reduce it in compensation so that offspring gain little. Here, I build on an approach developed by McNamara et al. (McNamara, Gasson, and Houston 1999. Incorporating rules for...

Models of biparental care predict that parents should compensate incompletely for any change in their partner's investment. Experimental tests have, however, yielded results that range from full compensation, through a lack of any reaction, to a matching response. Here we suggest a new, adaptive...

Intrasexual polymorphisms have evolved in a wide range of organisms. Most of them have been interpreted as the product of conditional strategies in which the tactic an individual adopts is determined by some aspect of state (e.g., age, size, condition). However, there are a few examples that...

Studies of mate choice commonly ignore variation in preferences and assume that all individuals should favor the highest-quality mate available. However, individuals may differ in their mate preferences according to their own age, experience, size, or genotype. In the present study, we highlight...

Current discussions of offspring begging typically assume either that it is a signal directed at parents or that it represents a form of scramble competition to gain access to them. However, offspring might also display to inform nest mates that they will contest the next food item to be...

We used a reproductive skew framework to consider the evolution of parental and alloparental effort in cooperatively breeding groups. The model provides the first theoretical treatment of rent payment (the "pay-to-stay" hypothesis) for the evolution of helping behavior of subordinates. According...