Growth–defense trade-offs shape population genetic composition in an iconic forest tree species
Olivia L. Cope, Ken Keefover‐Ring, Eric L. Kruger, Richard L. Lindroth
Abstract
Significance Genetic diversity is critical for ecological resilience and is maintained when different traits are advantageous in different environments. Traits are not entirely independent, however: When trade-offs occur, selection on one trait may indirectly act on another. Here we examine how environmentally mediated selection for growth interacts with a trade-off between growth and herbivore defense in experimental aspen stands. We show that even an environmentally fixed trait trade-off can lead to real-time divergence in population genetic composition between environments. The underlying growth–defense trade-off led to an eco-evolutionary dynamic wherein high-competition environments selected for fast-growing trees and thus ultimately selected against herbivore resistance. This discovery reveals how patterns of genetic covariation, coupled with environmental variation, can link ecological and evolutionary processes.