Early bird dynamics reduce selection imposed by species interactions in boom-and-bust regimes

In boom-and-bust growth regimes, interspecific interactions reduce their impact on selection via an early bird effect, concentrating selection when populations are small and resources abundant.

• Why it matters: The evolutionary strength of species interactions varies across ecosystems, but the mechanism behind this variability is not well understood.
• What they did: Using consumer-resource simulations and analytical approximations, the study compares steady chemostat-like growth with boom-and-bust cycles to track how interaction-driven selection changes across growth phases.
• The result: Boom-and-bust dynamics diminish how growth-rate-reducing interactions alter selection, while mortality-based interactions (e.g., lethal toxins) operate across phases and can be amplified.