Microbial eco-evolutionary responses amplify global soil carbon loss with climate warming

Abstract

Soil microbes respond to warming climates through variation in traits linked to the decomposition of soil organic matter, which impacts global soil carbon emissions. Microbial trait variation is shaped by eco-evolutionary processes; yet soil carbon models largely ignore such processes and their implications for global responses to warming. Here, we apply eco-evolutionary theory to a microbe-enzyme model to optimize a key microbial trait controlling decomposition and re-calculate soil carbon projections. Eco-evolutionary optimization leads microbes subject to warming to allocate more resources to enzyme production, which leads to faster decomposition and larger soil carbon loss, especially in cold regions. As a consequence, microbial optimization significantly amplifies global soil carbon loss by 2100 relative to current models, most strongly at high latitudes. This analysis demonstrates the potential importance of microbial eco-evolutionary dynamics in carbon-cycle feedbacks to climate change.

Microbial evolution—An under‐appreciated driver of soil carbon cycling

“…By incorporating competition for resources (e.g., carbon and nutrients; space) between evolved and ancestral strains, this method captures some of the complex dynamics of ecological and evolutionary processes occurring within microbial communities. For instance, Abs et al (2022) applied adaptive dynamics to predict the eco-evolutionary dynamics of microbial communities in response to global warming, specifically focusing on allocation to enzyme production as a trait (Figure 4). Their findings revealed that warming reduces the likelihood of cheating for soluble resources, leading to a higher investment in enzyme production.…”

“…For instance, Abs et al. (2022) applied adaptive dynamics to predict the eco‐evolutionary dynamics of microbial communities in response to global warming, specifically focusing on allocation to enzyme production as a trait (Figure 4). Their findings revealed that warming reduces the likelihood of cheating for soluble resources, leading to a higher investment in enzyme production.…”

“…Effect of microbial adaptation modeled with adaptive dynamics on soil C stocks (Abs et al., 2022). (a) The effect of adaptation to global warming by 2100 is heterogeneous in space, with the strongest effect in cold regions.…”

How do soil microbes shape ecosystem biogeochemistry in the context of global change?

“…More mechanistic modelling approaches are starting to emerge. Abs et al proposed a mathematical method based on game theory to predict the microbial community eco-evolutionary response to warming (Abs et al, 2022). This method accounts for progressive community trait change modifying the ecological environment (resources, competition), which initiates an eco-evolutionary feedback to modify selection of community traits.…”

“…Given that environmental selection varies between locations and over time, microbial parameters should reflect spatiotemporal variation. An early attempt to integrate spatio‐temporal variation in microbial composition demonstrated that projections of C loss by 2100 nearly doubled (Abs et al, 2022), highlighting the need to better understand what environmental factors determine microbial properties, especially within a community context.…”