Network Dynamics

Are species-rich ecosystems more stable?

Dynamic species interactions. Longstanding, beautiful theory suggests not: large, strongly interconnected systems should fall apart. Could stability and diversity coexist when, in reality, species interactions vary through adaptive foraging? Amy Patterson is working on detecting and quantifying dynamic interactions from network time series. Meanwhile, Zachary Jackson is working from the theory angle to understand analytically when adaptive foraging reverses May’s diversity-stability paradox.

More generally, we study the equilibrium and nonequilibrium dynamics of networks where interactions (a) are nonlinear, (b) change over time, or (c) take multiple forms.

Does species turnover happen gradually or suddenly in changing conditions?

A baseline assumption is that communities will experience gradual species turnover with gradual change in temperature or resource levels. Yet many processes including competition, mutualism, environmental engineering, and evolution can create hysteresis and sudden responses to conditions. Should we expect such crash-and-rebuild responses in ecosystems and microbiomes?

Does diversity promote ecological resilience? It is tempting to say ‘yes’, as less-impacted species can help their partners recover from disturbance. Modelling consumer collapse in food webs, we found greater resilience with diversity in ecosystems where species have high functional redundancy. But with low functional redundancy, diversity creates weakest-link dynamics: the collapse of one vulnerable species cascades through an ecosystem.