Microbial communities can evade competitive exclusion by diversifying into distinct ecological niches. This spontaneous diversification often occurs amid a backdrop of directional selection on other microbial traits, where competitive exclusion would normally apply. Yet despite their empirical relevance, little is known about how diversification and directional selection combine to determine the ecological and evolutionary dynamics within a community. To address this gap, we introduce a simple, empirically motivated model of eco-evolutionary feedback based on the competition for substitutable resources. Individuals acquire heritable mutations that alter resource uptake rates, either by shifting metabolic effort between resources or by increasing the overall growth rate. While these constitutively beneficial mutations are trivially favored to invade, we show that the accumulated fitness differences can dramatically influence the ecological structure and evolutionary dynamics that emerge within the community. Competition between ecological diversification and ongoing fitness evolution leads to a state of diversification–selection balance, in which the number of extant ecotypes can be pinned below the maximum capacity of the ecosystem, while the ecotype frequencies and genealogies are constantly in flux. Interestingly, we find that fitness differences generate emergent selection pressures to shift metabolic effort toward resources with lower effective competition, even in saturated ecosystems. Wemore »
Narrow and Brittle or Broad and Nimble? Comparing Adaptive Capacity in Simplifying and Diversifying Farming Systems
Humanity faces a triple threat of climate change, biodiversity loss, and global food insecurity. In response, increasing the general adaptive capacity of farming systems is essential. We identify two divergent strategies for building adaptive capacity. Simplifying processes seek to narrowly maximize production by shifting the basis of agricultural production toward centralized control of socially and ecologically homogenized systems. Diversifying processes cultivate social-ecological complexity in order to provide multiple ecosystem services, maintain management flexibility, and promote coordinated adaptation across levels. Through five primarily United States focused cases of distinct agricultural challenges—foodborne pathogens, drought, marginal lands, labor availability, and land access and tenure—we compare simplifying and diversifying responses to assess how these pathways differentially enhance or degrade the adaptive capacity of farming systems in the context of the triple threat. These cases show that diversifying processes can weave a form of broad and nimble adaptive capacity that is fundamentally distinct from the narrow and brittle adaptive capacity produced through simplification. We find that while there are structural limitations and tradeoffs to diversifying processes, adaptive capacity can be facilitated by empowering people and enhancing ecosystem functionality to proactively distribute resources and knowledge where needed and to nimbly respond to changing circumstances. Our cases more »
- Award ID(s):
- 1824871
- Publication Date:
- NSF-PAR ID:
- 10290520
- Journal Name:
- Frontiers in Sustainable Food Systems
- Volume:
- 5
- ISSN:
- 2571-581X
- Sponsoring Org:
- National Science Foundation
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Agricultural landscapes in North America have developed through complex interactions of biophysical, socioeconomic and technological forces. While they can be highly productive, these landscapes are increasingly simplified, causing biodiversity loss. As a result, ecosystem services associated with biodiversity are being dismantled. Agricultural landscape structure arises from collective decisions of farmers over long time periods, which are usually not intentionally coordinated beyond the farm scale. Regaining ecosystem services will require active efforts to intentionally redesign landscapes, in part based on ecological evidence about relationships between landscape structure and ecosystem services. Here we focus on services provided by arthropods and how to foster them at landscape scales. We first provide a brief history of how agricultural landscape structure in temperate North America developed and review the landscape-scale ecological drivers underpinning arthropod-based ecosystem services. We then propose ecological and social principles for designing agricultural landscapes, based on the ecological evidence we reviewed and on previous efforts in agricultural landscape design. Finally, we look ahead to discern prospects for putting agricultural landscape design into practice, including ecological, technological and policy opportunities. To reap benefits from arthropod-based services, future agricultural landscapes will need to increase in structural heterogeneity and diversity across multiple dimensions including crop,more »
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.3389/fsufs.2021.564900
