Biological indicators of ecosystem health: insights from Taiwan figs and fig-wasp communities – BIO Figs

What explains variation in species richness'from the taxonomic, phylogenetic, or ecological points of view'among geographical regions' Is variation associated with local (adaptive or neutral) processes, or are regional processes determinant, especially through long-distance immigration or through secondary contacts between complete sets of species evolved in separation' To understand how current biogeographic patterns of species and community diversity were produced, we will analyse how a group of interacting organisms that has become a model system in community ecology'Figs, their specific pollinators and associated wasp communities'established and diversified in a totally new habitat, Taiwan. Taiwan constitutes a contact zone between the Philippine and the continental floras and faunas. Such contact zones between different biogeographic provinces may provide a unique key to determine to what extent patterns of species occurrence and abundance are due to niche separation and how much they are due to species redundancy. Indeed, what preserves the identities of biotas in contact zones between long-separate floras and faunas' Do competition and pre-emption of space limit the spread of ecologically redundant species into the other biota? Taiwan presents a fascinating opportunity to analyse ecological and evolutionary processes in sites of active biotic exchange: it is a recent contact zone (less than 2.5 million years old between two different biotas. Ficus and associated insects are uniquely appropriate models for this study. Each Ficus species is host to a specific community of associated wasps, among them one or two mutualistic pollinating wasps, and a variable number of parasites presenting diversified biologies (gallers, inquilines, parasitoids). We will use this reasonably sized model system (the 28 species of genus Ficus occurring on Taiwan and their 120 plus associated wasp species) to investigate its current diversity, ecology and ongoing diversification processes. We will analyze in detail the biology of particular focal Ficus species and their associated faunas, to understand processes at fine scales of space and time. We will also undertake a global taxonomic, phylogeographic and genetic evaluation of the geographic origin of all the Ficus and insect species involved, and study ongoing diversification processes. This systematic treatment of the origins and ecological functioning of a whole set of plant and insect communities at the scale of a transition ground between biogeographical provinces will be unparalleled in its scope, and could serve as a model system for understanding the origin of biodiversity and its role in the functioning of ecosystems. The results will provide insights into what determines current biodiversity. Because current biodiversity is probably largely determined by relatively long term regional conditions, the results will enable to integrate longer time effects on biodiversity of current habitat modifications. Comparisons with the diversity data we will collect from more heavily impacted habitats in the Philippines will provide answers as to the short term effects of major habitat loss. The project is based on a consortium including world experts on fig and fig wasp taxonomy, phylogeny and biology but also strong local expertise on Taiwan figs, and in particular on location and phenology of all species. Feasibility of the project was assessed during the ?International Symposium on Fig and Fig wasps' organised by the National Taiwan University in Taipei in September 2008 (Orchid program, NSC-MAE). Ficus are also effectively used in reforestation projects as they are keystone resources for many fruit dispersing animals, which in turn play an important role in forest regeneration. Because of the understanding of the complex interaction between figs and their associated wasps, team members are consulted or are involved as advisors in such restoration programs.