Reproductive mutualisms of Australian Acacia species

For most alien plant species, successful establishment and spread involves producing viable seeds and dispersing those seeds to sites suitable for germination and survival. Seed set and dispersal can beneft from reciprocally benefcial interactions (mutualisms) with pollinators and seed dispersers. However, plant species vary in their dependence on mutualists for seed set and dispersal, and their ability to access mutualists in new locations: those that form specialized interactions are less likely to encounter compatible mutualists than those that are generalist. We outline a framework describing how dependence and specialization on reproductive mutualists could infuence the role of mutualisms in successful colonization and invasion, present the results of a systematic literature review on reproductive mutualisms in Australian Acacia species ('wattles'), and synthesize results of current studies within the context of our framework. Pollination and seed dispersal mutualisms in wattles appear to be facultative and generalist. While some species depend more heavily on forming pollination mutualisms for successful reproduction than others, this dependence may be offset by the large number of fowers produced. The proportion of wattle species for which dependence or specialization on reproductive mutualisms has been characterized is low, and results are mixed. Few species have been studied in non-native locations, with research limited to only 13 of the 172 countries to which wattles have been introduced. Linking reproductive mutualisms with invasion outcomes requires characterizing species along axes of both dependence and specialization. The lack of data across species and locations hinders our ability to do so for wattles, such that the role of reproductive mutualisms in invasions remains unclear. As wattles are considered a model system for examining the role of biotic interactions in invasion, understanding the role of reproductive mutualisms in their invasion has implications for understanding the drivers of invasion more generally.