Local thermal extremes shape the nature of herbivore plasticity that controls plant communities

Prevailing views hold that species’ physiological plasticity may confer
resilience to warming, but its importance varies across climatic gradients
(e.g., latitude). Yet, along such gradients local species populations may
experience fine-scale spatially heterogeneous variation in extreme
temperatures and other ecological stressors. We show that at four Cool
(mean diel maximum 29.83°C) and four Warm (mean diel maximum 31.51°C)
sites, interspersed as a spatial mosaic throughout a 26,200 km2 area,
local herbivore populations responded differently to stress from
experimental warming (ambient, warmed) and predation (presence, absence).
 Cool and Warm site herbivore populations utilized different
combinations of behavioral and physiological plasticity to cope with the
dual stressors that were contingent on local temperature extremes. These
unique plastic responses had divergent cascading effects on the plant
community. Our results suggest that paying attention to local population
variation can enhance the ability to predict the fate of natural
communities under environmental change.