Network Motifs: Simple Building Blocks of Complex Networks

Abstract

Complex networks are studied across many fields of science. To uncover their structural design principles, we defined "network motifs," patterns of interconnections occurring in complex networks at numbers that are significantly higher than those in randomized networks. We found such motifs in networks from biochemistry, neurobiology, ecology, and engineering. The motifs shared by ecological food webs were distinct from the motifs shared by the genetic networks of Escherichia coli and Saccharomyces cerevisiae or from those found in the World Wide Web. Similar motifs were found in networks that perform information processing, even though they describe elements as different as biomolecules within a cell and synaptic connections between neurons in Caenorhabditis elegans. Motifs may thus define universal classes of networks. This approach may uncover the basic building blocks of most networks.

Concomitant predation on parasites is highly variable but constrains the ways in which parasites contribute to food web structure

“…A food web motif represents a unique interaction pattern such as three‐species food chains, apparent competition, or trophic loops (Milo et al . 2002; Kashtan et al . 2004; Stouffer et al .…”

A pooling-deconvolution strategy for biological network elucidation

“…Finally, many topological motifs have been described for complex networks (including electronic circuits, the World Wide Web, cells, the brain, ecological systems, and social networks) 31 . However, not all motifs occur in biological networks (the same is true for nonbiological networks).…”

A unifying view of 21st century systems biology

“…In many instances new metaphors need to be invented to reflect new fundamental findings or novel hypotheses, as in ''genetic code", ''transcription" and ''translation" for molecular biology. Accordingly, biologists along with mathematicians, physicists and engineers are in the process of introducing their own vocabulary with old and newer notions such as positive and negative ''feedback circuits", ''feedforward loops" [14], ''interactome" networks [15], ''scale-free" [16] and ''small-world" [17] networks, ''hubs" [18], ''date and party hubs" [19]. Although it remains unclear at this stage which of these concepts and terms will sustain the test of time, they illustrate nicely the creative forces of our burgeoning field.…”