Plant-animal below-ground interaction modifies plant phenotype and its above-ground interaction: a review and a new case study

Ecological interactions play a role in promoting and maintaining biodiversity. These interactions form complex networks of interconnected species. Therefore, changes resulting from an interaction in one of the partners can have indirect consequences on subsequent interactions with other species. Since the mutualism-antagonism continuum is a gradient, a shift in the strength and sign of an interaction is possible, highlighting the dynamic nature of interaction networks. In flowering plants, a wide variety of below- and above-ground interactions are established with a single host plant. Changes in the host, derived from such interactions, can modulate the outcome of the remaining connections in both strength and sign, and the overall configuration of the network. Thus, a species can mediate community-wide consequences through its interaction with the host by altering the plant phenotype. We present a case study where a root infection has unexpected consequences on the pollination host, driving phenotypic changes. This study provides new data on the dynamism of species interactions and the importance of obtaining a global view of interaction networks. Disentangling the direct and indirect effects of interactions and their impact on the rest of the interactions in wild communities is essential for a good understanding of the evolutionary and ecological mechanisms that promote and maintain biodiversity.