, 2001b). Other suggested reasons why it might benefit subordinates to defer breeding include reduced foraging skills and associated energetic constraints, negative effects of breeding at the same time as dominants on the fitness of their own offspring, and costs to indirect components of their fitness if dominants are close relatives

(Young, 2009). Evidence of these effects has led to a debate over whether subordinate infertility should be interpreted as a consequence of constraints on subordinate this website breeding imposed by dominants or of voluntary restraint by subordinates caused by the need to avoid attracting aggression from dominants or by high costs of breeding associated with reduced condition or inferior foraging skills (Saltzman, Digby et al., 2009; Young, 2009). However, the distinction between these arguments is not as clear as it may initially appear since subordinates may commonly show restraint because dominants constrain their reproductive

options (Young, 2009). For example, subordinates may respond to the presence of dominants by down-regulating their physiological systems because dominants are likely to evict them if they attempt to breed, so that the likely fitness benefits of competing to breed are low (a reproductive constraint). Evidence that other factors modify the frequency of breeding by subordinates

(such as condition or the absence of unrelated partners) does not necessarily argue for interpretations based on restraint, for effects of this AZD6244 cost kind would be expected under both scenarios. Perhaps the most realistic view is that subordinates commonly show restraint because dominants constrain their reproductive options (Young, 2009). Attempts find more by dominant females to prevent other females from breeding or to reduce their success in rearing offspring are sometimes regarded as examples of spite since they can occur at times when the benefits of reproductive suppression are not obvious or resources are abundant (Stockley & Bro-Jorgensen, 2011). However, although this is theoretically possible (Gardner & West, 2004), the fitness costs of attacks on subordinates and their offspring may often be low while simultaneous breeding by subordinates may often have long-term costs to dominants and their dependents (Clutton-Brock et al., 2010). Consequently, it is probably more realistic to regard attempts by dominants to suppress reproduction by subordinates as an example of selfish behaviour rather than spite. While infanticide by females has attracted less attention than infanticide by males, it is probably more widespread (Rödel et al., 2008) and frequently represents a threat for group-living females (Digby, 2000).