Mycorrhizal associations are known to be influenced by soil nutrient availability but have been poorly studied in orchids. Mujica et al. studied two terrestrial orchids of the genus Bipinnula from central Chile across a soil nutrient gradient.
They found a significant relationship between soil nutrients and composition, taxonomic richness and phylogenetic diversity of mycorrhizal fungi, which supports the hypothesis that specialization is favored under high soil nutrient availability. Their findings help understand factors that promote the evolution of ecological specialization, a major question for evolutionary biologists since Charles Darwin.