Abstract

Adaptation to abiotic stresses generally relies on traits that are not independent from those affecting species interactions. Still, the impact of such evolutionary processes on coexistence remains elusive. Here, we studied two spider mite species evolving separately on tomato plants that either hyper-accumulated cadmium, a stressful environment for the mites, or on control plants without cadmium. Through combining experimental evolution and structural stability theory, we found that adaptation to cadmium of both species shifted predictions from exclusion to coexistence. This shift occured due to a simultaneous increase in intra and a decrease in interspecific competition, but only in cadmium environments. These predictions were further confirmed with complementary experiments of population dynamics, underscoring that evolution of single species in a new environment, even in absence of interspecific competitors, shapes species coexistence. Hence, population shifts to novel environments may have unforeseen evolutionary consequences for community composition and the maintenance of species diversity.