The smallest of all worlds: Pollination networks

Abstract

A pollination network may be either 2-mode, describing trophic and reproductive interactions between communities of flowering plants and pollinator species within a well-defined habitat, or 1-mode, describing interactions between either plants or pollinators. In a 1-mode pollinator network, two pollinator species are linked to each other if they both visit the same plant species, and vice versa for plants. Properties of 2-mode networks and their derived 1-mode networks are highly correlated and so are properties of 1-mode pollinator and 1-mode plant networks. Most network properties are scale-dependent, i.e. they are dependent upon network size. Pollination networks have the strongest small-world properties of any networks yet studied, i.e. all species are close to each other (short average path length) and species are highly clustered. Species in pollination networks are much more densely linked than species in traditional food webs, i.e. they have a higher density of links, a shorter distance between species, and species are more clustered. r

Marine bacterial, archaeal and protistan association networks reveal ecological linkages

“…We calculated the clustering coefficient, the characteristic path length and the node degree distribution (Watts and Strogatz, 1998;Albert and Barabási, 2002;Dunne et al, 2002;Oleson et al, 2006) of the entire network (microbial and environmental nodes) and just the microbial nodes and compared the structure of the association network with a random network of the same size as well as networks from previous studies ( Table 2). As restricting these analyses to just the microbial parameters did not fundamentally change the network metrics we will discuss the more inclusive values.…”

“…Three network topology characteristics for our network and for a random network of identical size were calculated using Network Analyzer in Cytoscape (Assenov et al, 2008): Clustering coefficient (Cl), the average fraction of pairs of species one link away from a species that are also linked to one another (Watts and Strogatz, 1998;Albert and Barabási, 2002); characteristic path length (L), the average shortest path between all pairs of species (Watts and Strogatz, 1998); and degree distribution, the nodes which have k edges and the probability P(k) that a node will have k edges (Watts and Strogatz, 1998;Dunne et al, 2002;Oleson et al, 2006). We treated edges as undirected when calculating path length and clustering, because the relationships are correlative and could imply interactions in either direction.…”

Biodiversity, Species Interactions and Ecological Networks in a Fragmented World

“…Kromann-Gallop, personal communication). Until such an analysis is made, it remains difficult to compare the properties of different kinds of networks directly (but see Olesen et al, 2006), although such comparisons are theoretically possible (Thebault and Fontaine, 2010), and we therefore address both types as separate cases throughout the paper.…”

A hollow bacterial diversity pattern with elevation in Wolong Nature Reserve, Western Sichuan Plateau

“…The first phase is network construction: Pearson correlation coefficient was used in pairwise similarity matrix calculation and a threshold of 0.78 used for defining adjacency matrices by RMT-based approach. The second phase is network analyses: the topological role of each OUT was determined according to the within-module connectivity (Zi) and among-module connectivity (Pi) (Olesen et al 2006). The network graph was visualized with Cytoscape 3.2.1 (Shannon et al 2003).…”