PARENT SESSION
Contributed Oral Session 85: Mutualism: Pollination
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 520 C, Level 5, Palais des congrès de Montréal
Simple assemblage rules explain the nested topology of plant-pollinator networks.
Santamaría, Luis*,1, Rodríguez-Gironés, Miguel2, 1 Instituto Mediterráneo de Estudios Avanzados, Esporles, Balearic Islands, Spain2 Estación Experimental de Zonas Aridas, Almería, Spain
ABSTRACT- Recent work on plant-pollinator mutualistic interactions has focused on the topological properties of entire networks. Plant-pollinator networks are highly nested and while their connectivity (C) decreases with network size, their nestedness (N) increases with connectivity and size. Despite the interest awaken by the description of these general characteristics of plant-pollinator networks, no one has examined to date the biological processes responsible for the observed patterns. Using a simple model, we show that assemblage rules derived from trophic niche partition among pollinators can explain the topological properties of plant-pollination networks. A model based on classical co-evolutionary processes that assume an increased narrowing of the ecological niche shared by each plant-pollinator pair as a result of the evolutionary process (symmetric specialization model) resulted in network scaling properties opposite to those describing real-world data in practically all cases (vg. for N and C). In contrast, a model based on simple evolutionary mechanisms that decouple evolutionary and ecological specialization in an asymmetric way (i.e. differently for plants and pollinators; asymmetric specialization model) was consistent with the topological properties of real-world networks (vg. logarithmic increase in N and potential decrease in C with network species richness). The evolution of asymmetric specialization is best explained by process of niche partitioning that involve the participation of other members of the community in the co-evolutionary process. Hence, such evolutionary mechanism provides an explicit link between pair-wise and diffuse coevolution that is in good agreement with the topological properties of plant- pollination networks.
Key words: mutualistic network, nestedness, asymmetric specialization, parasite avoidance