Chasing Ecological Interactions

Abstract

Basic research on biodiversity has concentrated on individual species-naming new species, studying distribution patterns, and analyzing their evolutionary relationships. Yet biodiversity is more than a collection of individual species; it is the combination of biological entities and processes that support life on Earth. To understand biodiversity we must catalog it, but we must also assess the ways species interact with other species to provide functional support for the Tree of Life. Ecological interactions may be lost well before the species involved in those interactions go extinct; their ecological functions disappear even though they remain. Here, I address the challenges in studying the functional aspects of species interactions and how basic research is helping us address the fast-paced extinction of species due to human activities.

Fig 1. The structure of ecological interactions.

Top: examples of ecological interactions between plants and animals. (A) Ariel toucan (Ramphastos ariel) (Ramphastidae) feeding on palmito juçara fruits (Euterpe edulis) (Arecaceae) in the Brazilian Atlantic rainforest. (B) Ectatomma tuberculatum over extra-floral nectaries at the base of a leaf of Qualea multiflora (Vochysiaceae) in the cerrado vegetation (Brazil). (C) A carpenter bee (Xylocopa violacea) (Apidae) visiting an Allium ampeloprasum (Liliaceae) (wild garlic) inflorescence in Southeast Spain. Bottom: different visualizations of the complexity of interaction networks among species (colored spheres) illustrated by their actual links (light green lines). (D) Food webs typically describe all the interactions occurring in a given ecosystem with multiple trophic levels. (E) Most plant–animal interactions can be displayed as bipartite graphs describing the pairwise pattern of mutual interdependencies among two distinct sets of animals (orange nodes) and plants (yellow nodes). (F) Interactions among species with a higher degree of intimacy, such as ant–plants, show a distinct pattern of structure, often with multiple distinct groups (modules) of closely intimate associations. Image credits: (A) José Augusto Balieiro, with permission; (B) Denise Lange and Kleber del-Claro, with permission; (C) Pedro Jordano. Panels D, E, and F were produced with FoodWeb3D, written by R.J. Williams, and provided by the Pacific Ecoinformatics and Computational Ecology Lab (www.foodwebs.org).