A species’ ability to establish and spread is often influenced by different types of biotic interactions encountered in the introduced range. These interactions can be beneficial in nature or antagonistic. Using a comparative approach we address the role of mycorrhizal fungi in the spread of two invasive orchids in Miami, Florida, Cyrtopodium flavum and Eulophia graminae, with that of two rarer native congeners, Cyrtopodium punctatum and Eulophia alta. We accomplished this by sampling and isolating fungi from the roots of each orchid species, and by placing seed packets containing seeds collected from wild individuals in the habitat for two years to obtain the fungi necessary for germination. Then using fungal specific DNA primers we identified the fungal taxa associated with each species. The degree of mycorrhizal specificity was defined as both the number of different distinct fungal taxa (OTU) associated within each species, as well as the phylogenetic breadth between distinct fungal taxa.
Our results showed that the invasive orchids associated with a greater diversity of mycorrhizal fungi (OTU richness = 12, Shannon diversity H’ = 1.20) and are exploiting specific genera of basidiomycete fungi that are widely available in the invaded habitats, and they are capable of utilizing more groups of fungi for seed germination as compared to their native congener (OTU richness = 7, H’ = 0.61). These findings will advance the study of ecology specifically invasions, and species response to environmental change by addressing the role of mycorrhizal symbioses in governing plant distributions in introduced ranges and urban/disturbed habitats, and so allow us to better predict a species invasive potential.