Plant-Animal Mutualistic Networks: The Architecture of Biodiversity

Abstract

Abstract. The mutualistic interactions between plants and the animals that pollinate them or disperse their fruits have molded the organization of Earths's biodiversity. These interactions create networks of interdependence often times involving dozens or hundreds of species. Recent research has used concepts from graph theory to characterize the architecture of these networks. Mutualistic networks are heterogeneous, nested and build upon weak and asymmetric links among species. This network architecture highly affects its robustness to perturbations such as the extinction of a species.Redes mutualistas planta-animal: la arquitectura de la biodiversidad Resumen. Las interacciones de beneficio mutuo entre las plantas y los animales que las polinizan o dispersan sus semillas han jugado un papel muy relevante en la generación de biodiversidad en la Tierra. Estas interacciones crean redes de interdependencia que suelen involucrar decenas o centenares de especies. Investigación reciente ha utilizado conceptos de la teoría de grafos para caracterizar la arquitectura de estas redes. Las redes mutualistas son heterogéneas, anidadas y construidas sobre interacciones débiles y asimétricas entre especies. La arquitectura de estas redes afecta en gran medida su robustez ante perturbaciones como la extinción de una especie.The mutualistic interactions between plants and the animals that pollinate them or disperse their seeds have molded the organization of Earths's biodiversity. Plants have created new niches for insect diversification, which in turn may have increased plant diversification. The importance of these mutually beneficial interactions can be grasped by considering that more than 90% of tree species in the tropical forests need animals to complete their life cycle. Animal extinction would result in the consequent extinction of plants.Historically, the first studies on mutualistic interactions focused on highly specialized, pairwise interactions. These examples of an almost perfect matching between the morphology of a flower and that of an insect have illustrated textbook covers since Darwin's time, but they are probably the exception rather than the norm. Mutualistic interactions may involve dozens or even hundreds of species interacting in complex ways. Progress in coevolutionary studies during the last two decades has been made by studying how small groups of species interact in a community context and how these interactions change through time and space ([9]). More recently, the physics of complex networks has provided tools and concepts to tackle entire plant-animal coevolutionary networks. These results have unambiguously concluded that mutualistic networks are highly heterogeneous (the bulk of species have a few interactions, but a few species have many more interactions than expected by chance, [6]); nested (specialists interact with proper subsets of * This paper is based on a lecture delivered by the author, at the International Symposium Mathematics for the XXIth Century, 221J. Bascompte the species ge...

Four Central Points About Coevolution

“…In one wellstudied community in Costa Rica 65 hawkmoth species interact with 31 plant species from various plant families that have converged on floral traits adapted to pollination by hawkmoths (Haber and Frankie 1989). The scientific problem of how coevolution shapes larger webs of interacting species is one of the most active areas of current coevolutionary research, and there is still a great deal to learn (Bascompte et al 2006;Thompson 2006;Bascompte and Jordano 2007;Guimarães et al 2007;Jordano 2010).…”

Reconstructing past ecological networks: the reconfiguration of seed-dispersal interactions after megafaunal extinction

“…the species in a community form a network of interactions whose structure has implications for the ecological and evolutionary dynamics of the populations (may 1972;Pimm 2002;Dunne 2006;bascompte and Jordano 2007). although snapshots in time are required to assess the structure of the community, ecological communities are constantly losing and gaining species through extinctions and invasions, thus network structure is continuously changing (Petanidou et al 2008).…”

Implications of newly-formed seed-dispersal mutualisms between birds and introduced plants in northern California, USA

“…Non-natives can be limited by competition with or herbivory by resident species (Cogni 2010;Corbin and D'Antonio 2004;Naeem et al 2000). On the other hand, positive interactions such as mutualisms with dispersers, pollinators, or soil biota may permit invasion of new environments (Bascompte and Jordano 2007;Reinhart and Callaway 2006). Furthermore, such mutualisms are generally diffuse, with many mutualist species interacting with each plant species (Aslan and Rejmánek 2010;Bascompte and Jordano 2007;Jordano 1987b).…”

“…On the other hand, positive interactions such as mutualisms with dispersers, pollinators, or soil biota may permit invasion of new environments (Bascompte and Jordano 2007;Reinhart and Callaway 2006). Furthermore, such mutualisms are generally diffuse, with many mutualist species interacting with each plant species (Aslan and Rejmánek 2010;Bascompte and Jordano 2007;Jordano 1987b). For this reason, many introduced plants with fleshy fruits are able to develop effective dispersal interactions with resident fauna (e.g., Bartuszevige and Gorchov 2006;Drummond 2005;Gosper et al 2005;Panetta and McKee 1997;Renne et al 2002).…”