Yet any optimism vanished within three balls of this contest when Bell and James Taylor were trapped lbw by Mitchell Starc.
Even if a more detailed analysis of agonism across contexts revealed a lack of an effect of food type on agonistic rates, as the current study suggests, it does not necessarily follow that this would indicate a lack of a difference in the strength of within-group contest competition (i.e., rank-related variation in net energy gain) associated with fruit versus leaf eating.
Why the infants of high-ranking females (in contrast to their pregnant mothers) should suffer equally from within-group contest remains unclear.
Furthermore, fruits, being usually seasonal and patchily distributed, increase within-group contest competition, which again increases with the number of competitors.
In contrast, when foods are low quality, highly dispersed, or found in patches that are large relative to group size, within-group contest competition is not expected to occur (Koenig 2002).
Fruits, particularly when occurring clumped in large trees (as is the case in Tangkoko, Kinnaird and O'Brien 2000), are highly defendable food sources that increase within-group contest competition (Mathy and Isbell 2001).
Given that stable and despotic dominance relationships are thought to emerge when within-group contest competition is strong (Isbell 1991; Sterck et al. 1997), it is possible that rank-related variation in food intake can be associated with low rates of agonism due to subordinates avoiding active contest of food against individuals that are almost sure to win the interaction.
According to these models, the occurrence of high-value foods in patches of intermediate size relative to group size and spread is expected to lead to within-group contest competition, that is, rank-related skew in energy gain occurring with or without direct agonistic competition (Janson and van Schaik 1988; Koenig and Borries 2006).
Furthermore, the intensity of within-group contest competition can be expected to increase with group size without any change in resource distribution, as a consequence of a greater number of individuals competing for access to a given patch (Koenig and Borries 2006).
Although suggestive, the absence of a sufficient number of studies documenting variation in energy gain among group members or the occurrence of agonism during feeding versus other behavioral contexts makes it difficult to draw firm conclusions regarding the potential relationship between diet, agonism, and within-group contest competition.
