Evolutionary consequences of plant-soil feedback

Background/Question/Methods

Soils are one of the first selective environments a seed experiences and yet relatively little is known about the evolutionary relationships and consequences of plant-soil linkages, plant-soil feedbacks and co-evolutionary interactions between soil biota that often mediate these relationships. Given that often the large majority of seedlings die before reproduction, plant-soil interactions early in the life cycle represent a severe selective sieve. Soils may be selective agents across many scales that may differ in time, space and context and may occur through both abiotic and biotic mechanisms. Here we synthesize the published data to date on a range of evolutionary interactions that occur among soils, plants and soil biota with the aim of establishing a predictive framework for when positive and negative feedbacks may occur and large-scale patterns in the strength and direction of soils as selective agents for plants.

Results/Conclusions

The data to date suggest that evolutionary interactions can occur at multiple spheres of the plant-soil interface due to both abiotic and biotic mechanisms occurring independently and in concert. Evolutionary processes such as stabilizing and de-stabilizing selection, local adaptation and co-evolution may occur at multiple scales and range from local adaptation to soil chemistry or nutrient limitation to plant-soil feedback mediated by co-evolutionary interactions with the soil biota; all of which may influence plant traits and species (and community) evolutionary trajectories. We describe a conceptual framework at multiple scales which indicates that evolutionary responses in plant-soil feedback may have short-term consequences at the local scale but different long-term consequences at the landscape scale. At local scales, temporal, spatial and context-specific responses (by plants and the soil biota) may lead to feedback responses that act to selectively stabilize or de-stabilize plant populations and traits. At the landscape scale, long-term patterns in nutrient limitation may interact with soil biota to create de-stabilizing feedbacks that leads to the evolution of suites of plant traits that change through soil development. Thus, interacting feedback loops among soils, plants and the soil biota may result in more predictable evolutionary interactions than previously appreciated.