Interaction of Dynamics And Structure in Food Webs Jonathan Cannon Gavin Fay Andrew Hein

1. Interaction of Dynamics And Structure in Food Webs Jonathan Cannon Gavin Fay Andrew Hein Vanessa Weinberger

2. 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.

3. 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?

4. 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.

7. Species Count

8. 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