Does Climate Change Pose a Threat to the Guild Mimicry System of Australian Orchids?

Global warming is one of the biggest threats to global biodiversity causing not only changes in the patterns of precipitation and temperature but also disturbing ecological interactions. The aim of our study was to forecast the effect of climate change on the distribution of food-deceptive orchid species whose pollination strategy relies on a strict association with pollinators and co-occurring rewarding Faboideae plants. We used the ecological niche modeling approach to evaluate future overlap of the suitable niches of studied orchid species with the predicted distribution of their ecological partners. Models were made based on two different global circulation models (FIO, CNRM). CNRM projections predict expansion of orchids' geographical range. In contrast, FIO prediction is less optimistic, forecasting species range contraction. The studied Faboideae species showed different responses to predicted global warming with no consistent patterns in how their suitable niches might change. Most climate change projections and scenarios of the future modifications of temperature and precipitation patterns do not predict significant loss of suitable niches of Trichocolletes bees (Colletidae) pollinating Diuris species. However, global warming has the potential to disrupt interactions between the studied orchids and their co-occurring pea plants by altering the overlap of their geographical ranges which can further disturb pollination success. CNRM projections predict an overall loss of Faboideae within the potential geographical range of Diuris brumalis. Conversely, FIO projections suggest a less extensive predicted divergence. Our simulations offer suggestions for conservation strategies of orchids and potentially for other species that have a similar pollination strategy. The areas indicated here as suitable in the future for the occurrence of all ecological partners can be important climate refugia to consider in local conservation plans. The approach used in our study can serve as a model for understanding the potential effects of climate change on the strength of the pollination system via food deception.