No change in subordinate butterflyfish diets following removal of behaviourally dominant species
Direct interference interactions between species are often mediated by aggression and related to resource use. Interference interactions are frequently asymmetric, whereby one species wins the majority of interactions; however, the effect of this asymmetry on the diet of subordinate species has not received the same attention as the impact of interference on habitat use. Here we experimentally evaluated whether release from asymmetric interference led to increased use of a preferred dietary resource by subordinate species, using coral-feeding butterflyfishes as a model system. Following experimental removal of the behaviourally dominant species, we found no change in diet breadth or foraging on the preferred resource by subordinate species. Our results suggest that release from asymmetric interspecific interference does not necessarily result in changes to subordinate species’ diets, at least not over the course of our study. Rather, consistently asymmetric interactions may contribute to behavioural conditioning of subordinate species, meaning that even in the absence of dominants, subordinate individuals maintain established feeding patterns. Additionally, our results suggest that antagonistic interactions between butterflyfishes may have contributed to niche partitioning and conservatism over evolutionary time scales.
KeywordsInterference competition Experimental removal Coral reefs Butterflyfishes
We thank James Cook University and the Australian Research Council for financial support; SAB was also supported by a Queensland Smart State Ph.D. fellowship. We thank E. Graham, S. Montanari and the staff of the Lizard Island Research Station for assistance in the field. All applicable institutional (JCU Ethics Approval A1730) and national (Great Barrier Marine Park Authority Permit G10/33272.1) guidelines for the care and use of animals were followed.
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