Meeting Abstract

59.4  Tuesday, Jan. 6  Historical constraints on host use in herbivorous marine amphipods POORE, A G B*; SOTKA, E E; University of New South Wales; College of Charleston a.poore@unsw.edu.au

It is commonly assumed that marine herbivores are relatively unspecialised consumers, lacking the strong historical associations between herbivore and plant taxa that are evident among terrestrial insect herbivores. Detailed information on the associations between herbivore taxa and their hosts is largely lacking for marine herbivores and is required for predicting herbivore distributions, the impacts of herbivores on plant assemblages and the evolution of specialisation. We analysed host use data for an abundant family of herbivorous amphipods (Ampithoidae) to test the hypotheses that host breadth and composition varied among herbivore lineages, and the role of non-polar secondary metabolites in determining these patterns. The number and composition of hosts used per amphipod species varied among amphipod genera, indicating strong historical patterns to host use in this family. These patterns were not confounded by the uneven distribution of host taxa among geographic regions. The presence of biologically active secondary metabolites in hosts did not predict the composition of herbivorous amphipods, however the more specialised amphipods were those that were never found on chemically-rich hosts a result in contrast to the usual predictions of increasing specialisation being associated with tolerance to plant metabolites.