Disturbance regimes - cycles of fire, flood, drought, and other phenomena - can reduce animal and plant populations through direct mortality and destruction of habitat. Evolutionary theory suggests that organisms can evolve strategies for surviving disturbances, but only if disturbances occur with sufficient predictability (i.e., regularly in time or in tandem with an environmental cue). The Southwestern aquatic insect Abedus herberti is ideal for testing this hypothesis, because at least 36 disjunct populations inhabit streams with flood regimes ranging from highly predictable (severe flash floods occur in tandem with rainfall events) to highly unpredictable (floods occur without antecedent rainfall). Previous research has shown that in streams with predictable flood regimes, Abedus has evolved the ability detect rainfall and reliably escape flash floods. This project will use behavioral experiments, mathematical theory, and molecular techniques to answer the following: How does flash flood predictability affect the rate and degree of trait evolution? Does gene flow between populations adapted to different flood regimes interfere with evolution? How rapidly can populations evolve in response to altered flood regimes?
The project has conservation implications for organisms in flow-regulated rivers, fire-managed forests, and other ecosystems where disturbance regimes are being altered by humans. The project will take place in Oregon, Arizona, and Sonora, and will foster collaborations between US and Mexican biologists and students.
