The long-term survival and climatic distribution of mixotrophic and mycoheterotrophic orchids

Orchid germination depends on their fungal partner; however, there are no broadscale analyses evaluating the actual overlap between orchids and their mycorrhizal symbionts. The aim of this research was to evaluate the importance of mycorrhizal fungi for the occurrence of two species of orchids using ecological niche modeling (ENM). Two sets of future orchid distribution models were created – the first one was based on bioclimatic data only, and the second one included information about the distribution of fungal symbionts. The jackknife test indicated that for both mixotrophic and mycoheterotrophic orchids, the presence of symbiotic fungi is crucial for their occurrence, and ENM analyses revealed that both orchids face habitat loss as a result of predicted changes in climate. In the case of the mixotrophic orchid, the presence of symbiotic fungi can compensate for unfavorable climatic conditions. Problems and limitations in modeling the distributions of species are discussed in terms of the symbiotic relationship.