Plants encounter natural antagonist threats of varying intensity and respond by activating multiple defense traits. Due to the fitness costs associated with producing defense traits, plants are expected to activate less costly traits first, reserving more costly defenses for potentially more severe damage (“cheaper first hypothesis”), but evidence to date is scarce. Here, we tested this hypothesis by measuring six putative defense traits in the annual plant Ambrosia artemisiifolia. We found that all traits were effective against insect herbivores, but production of three of them more strongly reduced plant growth, suggesting higher growth costs. When plants were attacked by insect herbivores, less costly traits were induced first, even at the lowest levels of damage, while more costly traits were activated only after higher damage thresholds. This cost-dependent sequential pattern was consistently observed in plants when challenged by 12 different herbivore species from three insect orders. These findings demonstrate that plants can employ the “cheaper first” sequential induction defense strategy, potentially allowing them to reduce defense costs and maximize fitness. Our study provides new insights into how plants fine-tune their defense responses under variable antagonistic pressures.

This "RangeShiftData" dataset supports the study "Eco-evolutionary Responses of Species Distributions to Climate Change." It contains comprehensive data on species range shift rates, alongside detailed taxonomic information, geographic coordinates, climate niche metrics, and global distribution patterns, providing valuable insights for ecological and evolutionary research.

This "RangeShiftData" dataset supports the study "Eco-evolutionary Responses of Species Distributions to Climate Change." It contains comprehensive data on species range shift rates, alongside detailed taxonomic information, geographic coordinates, climate niche metrics, and global distribution patterns, providing valuable insights for ecological and evolutionary research.

Plant-soil feedback (PSF) is an important driver of plant community dynamics. Our study revealed that when soil was conditioned by more than four species, community-level PSFs were dominated by specific species rather than being an aggregation of single-species PSFs.

Plant-soil feedback (PSF) is an important driver of plant community dynamics. Our study revealed that when soil was conditioned by more than four species, community-level PSFs were dominated by specific species rather than being an aggregation of single-species PSFs.

Plant-soil feedback (PSF) is an important driver of plant community dynamics. Our study revealed that when soil was conditioned by more than four species, community-level PSFs were dominated by specific species rather than being an aggregation of single-species PSFs.

Plant-soil feedback (PSF) is an important driver of plant community dynamics. Our study revealed that when soil was conditioned by more than four species, community-level PSFs were dominated by specific species rather than being an aggregation of single-species PSFs.

Plant-soil feedback (PSF) is an important driver of plant community dynamics. Our study revealed that when soil was conditioned by more than four species, community-level PSFs were dominated by specific species rather than being an aggregation of single-species PSFs.

Invasive plant species can alter soil abiotic and biotic properties, with some changes persisting long after the primary invader's eradication. However, how soil legacies will influence secondary invasions following control of primary invaders remains unclear, hindering development of targeted control and post-removal management strategies. We used Solidago canadensis as the primary invader and established five field soil conditioning treatments: control (bare plots), invasion treatment (unmanaged invaded plots), three management treatments (invaded plots managed by cutting, herbicide application or burning). Subsequently, we assessed responses of nine pairs of secondary invaders and native congeners in these conditioned soils within a greenhouse setting. We found that Solidago invasion decreased soil nutrients including available nitrogen, phosphorus and potassium and increased soil pathogen diversity. While these soil legacies reduced the growth of both secondary invaders and native congeners, they disproportionately enhanced the biomass advantage of secondary invaders, resulting in a predisposition to secondary invasions. Compared to unmanaged invaded plots, cutting did not further modify soil properties, and both herbicide application and burning had no effect on soil pathogen diversity but strongly increased soil available nutrients. Consequently, cutting had no impact on secondary invasions, while increased available nutrients in herbicide application and burning treatments weakened the intensity of secondary invasions. Notably, secondary invaders distantly related to Solidago benefited more from soil legacies, irrespective of management method. These results underscore the role of soil legacy effects in facilitating secondary invasions and highlight phylogenetic distance from the primary invader as a crucial factor in determining secondary invader success.

Invasive plant species can alter soil abiotic and biotic properties, with some changes persisting long after the primary invader's eradication. However, how soil legacies will influence secondary invasions following control of primary invaders remains unclear, hindering development of targeted control and post-removal management strategies. We used Solidago canadensis as the primary invader and established five field soil conditioning treatments: control (bare plots), invasion treatment (unmanaged invaded plots), three management treatments (invaded plots managed by cutting, herbicide application or burning). Subsequently, we assessed responses of nine pairs of secondary invaders and native congeners in these conditioned soils within a greenhouse setting. We found that Solidago invasion decreased soil nutrients including available nitrogen, phosphorus and potassium and increased soil pathogen diversity. While these soil legacies reduced the growth of both secondary invaders and native congeners, they disproportionately enhanced the biomass advantage of secondary invaders, resulting in a predisposition to secondary invasions. Compared to unmanaged invaded plots, cutting did not further modify soil properties, and both herbicide application and burning had no effect on soil pathogen diversity but strongly increased soil available nutrients. Consequently, cutting had no impact on secondary invasions, while increased available nutrients in herbicide application and burning treatments weakened the intensity of secondary invasions. Notably, secondary invaders distantly related to Solidago benefited more from soil legacies, irrespective of management method. These results underscore the role of soil legacy effects in facilitating secondary invasions and highlight phylogenetic distance from the primary invader as a crucial factor in determining secondary invader success.