Stability in large webs

Allesina & Tang (2012 Nature): An extension of analytic, Wigner semicircle theorem-like, stability criteria to predator-prey, competition and mutualism cases. Finds predator-prey interactions permit stability in networks as large and complex as real ones. Hierarchy is: competition-mutualism mixture, random, predator-prey. Finds that stability is less likely when both predator-prey networks and mutualistic networks are given more realistic structure (i.e. niche-model structure and nestedness respectively). Continue reading Stability in large webs

Large community evolution models

Several reviews exist on the influence of evolution on food-web structure (Yoshida, 2006; Fussman et al., 2007; Loeuille & Loreau, 2009; Loeuille, 2010). In Brannstrom et al. (2008), we reviewed past theoretical modelling efforts to study food web structure, and the current state of large community evolution models to tackle the problem. The past decade has seen burgeoning growth in the development of large community … Continue reading Large community evolution models

Link distribution in static community models like the niche model

I was recently reading a 2006 review of food web structure by Jennifer Dunne, which includes a very thorough discussion of static community models like the niche model (Williams & Martinez 2000, Nature), and I was struck again by how unclear it is – to me, anyway – what exactly it is that these static models represent. There’s no doubt that they do an excellent … Continue reading Link distribution in static community models like the niche model

Pretty food web graphs

When analysing output from the Webworld food web assembly algorithm (Drossel et al. 2001, J. Theor. Biol.), I often need a good way to quickly summarise the key properties of a web. In a recent project, I created a version of Webworld in which species could invade from outside the web (randomly generated species traits, as opposed to traits derived through mutation of a native … Continue reading Pretty food web graphs

Food web assembly algorithms

A food web assembly algorithm is a series of repeating steps by which a model food web can be created. Starting with one or a few species, new species are permitted to invade at each time step, and are lost at each time step, according to some prespecified rules. There is already a large body of food web assembly literature (Tregonning & Roberts 1979, Post … Continue reading Food web assembly algorithms

Invasibility and food web structure in assembly algorithms

The following is a small literature search I did during my post-doc at CSIRO. The goal was to find system-level food web attributes that are correlated with invasibility. System-level food web attributes It is worth doing a quick overview of what is meant by the “system-level food web attributes” mentioned in the objective. Using the early empirical food web literature, a group of authors noted … Continue reading Invasibility and food web structure in assembly algorithms