Interaction of Dynamics And Structure in Food Webs Jonathan Cannon Gavin Fay Andrew Hein Vanessa Weinberger
Background • The dynamical perspective on food webs asks how populations of consumers and producers vary over short time scales. • Models imitate predation rates, metabolism, predator access to prey, etc. • The structural perspective on food webs asks about static properties of food webs over long time scales. • Models imitate degree distributions, distribution of mass over trophic levels, etc.
Our Questions • In what ways do the structures of food webs constrain the dynamics of food webs? • In particular, what structures promote dynamic stability? • In what ways do the dynamics of food webs determine the growth of network structure? • In particular, how is growth affected by the fact that networks must be somewhat stable in order to persist long enough to grow?
Experiment 1:Construction by Invasion • We started with a hearty source of biomass. • At widely spaced intervals, we introduced a new invading species with a random bodymass and random niche of preferred prey bodymasses. • After each invasion we simulated predation dynamics, allowing species to go extinct at low populations.
What's Next... • More questions... • What motifs are correlated with stability? • What events lead to mass extinctions? • Is this sensitive to our choice of model? • Another experiment... • Search space of food webs by rewiring randomly, keeping more stable webs