Human impacts on natural systems are driving rapid ecological change and adaptation. Fishing is a strong selective force and is expected to select for earlier and smaller maturation size in heavily exploited species. Interspecific and size-based interactions may also pose substantial selective pressures.
Reductions in maturation size from size-selective fishing have usually been reported from single-species experiments and observations. However, species and size-based interactions may also pose substantial selective pressures. To study the potential role of eco-evolutionary dynamics in marine ecosystems multi-species models that integrate temporal trait dynamics are needed.
We developed a trait-based size spectrum model with stochastic adaptive (selection driven) trait dynamics, where new phenotypes are introduced in the model and their invasion success is tracked through time. We use the model to explore the evolutionary changes in maturation size in the presence and absence of predation and fishing, and their consequences for population and community structure.
Our results show enables greater coexistence of species and prevents the declines in maturation size typically expected from fishing-induced evolution. In the absence of predation, fishing generally has a stronger effect on maturation size, causing decreases in maturation size for the largest species, leading to cascading effects on the size of smaller species.
Models used to support ecosystem-based fisheries management are typically based on trophic interactions and demography without eco-evolutionary processes or changes in species composition through time. Our results demonstrate how species interactions and stochastic introduction of phenotypic variation can alter expected outcomes of trait changes in responses to fishing.
