Migration feedback induces emergent ecotypes and abrupt transitions in evolving populations

We explore the connection between migration patterns and emergent behaviorsof evolving populations in spatially heterogeneous environments. Despiteextensive studies in ecologically and medically important systems, a unifyingframework that clarifies this connection and makes concrete predictions remainsmuch needed. Using a simple evolutionary model on a network of interconnectedhabitats with distinct fitness landscapes, we demonstrate a fundamentalconnection between migration feedback, emergent ecotypes, and an unusual formof discontinuous critical transition. We show how migration feedback generatesspatially non-local niches in which emergent ecotypes can specialize. Ruggedfitness landscapes lead to a complex, yet understandable, phase diagram inwhich different ecotypes coexist under different migration patterns. Thediscontinuous transitions are distinct from the standard first-order phasetransitions in statistical physics. They arise due to simultaneoustranscritical bifurcations and exhibit a "fine structure" due to symmetrybreaking between intra- and inter-ecotype interactions. We suggest feasibleexperiments to test our predictions.