Complementary resource preferences spontaneously emerge in diauxic microbial communities

Many microbes grow diauxically, utilizing the available resources one at a time rather than simultaneously. The properties of communities of microbes growing diauxically remain poorly understood, largely due to a lack of theory and models of such communities. Here, we develop and study a minimal model of diauxic microbial communities assembling in a serially diluted culture. We find that unlike co-utilizing communities, diauxic community assembly repeatably and spontaneously leads to communities with complementary resource preferences, namely communities where species prefer different resources as their top choice. Simulations and theory explain that the emergence of complementarity is driven by the disproportionate contribution of the top choice resource to the growth of a diauxic species. Additionally, we develop a geometric approach for analyzing serially diluted communities, with or without diauxie, which intuitively explains several additional emergent community properties, such as the apparent lack of species which grow fastest on a resource other than their most preferred resource. Overall, our work provides testable predictions for the assembly of natural as well as synthetic communities of diauxically shifting microbes.

Complementary resource preferences spontaneously emerge in diauxic microbial communities

Most microbes grow diauxically, utilizing the available resources one at a time rather than simultaneously. The properties of communities of microbes growing diauxically remain poorly understood, largely due to a lack of theory and models of such communities. Here, we develop and study a minimal model of diauxic microbial communities assembling in a serially diluted culture. We find that community assembly repeatably and spontaneously leads to communities with complementary resource preferences i.e., communities where species prefer different resources as their top choice. Simulations and theory explain that the emergence of complementarity is driven by the disproportionate contribution of the top choice resource to the growth of a species. Additionally, we develop a geometric approach for analyzing serially diluted communities, with or without diauxie, which intuitively explains several additional emergent community properties, such as the apparent lack of species which grow fastest on a resource other than their most preferred resource. Overall, our work provides testable predictions for the assembly of natural as well as synthetic communities of diauxically shifting microbes.

Disturbance Triggers Non-Linear Microbe-Environment Feedbacks

Conceptual frameworks linking microbial community membership, properties, and processes with the environment and emergent function have been proposed but remain untested. Here we refine and test a recent conceptual framework using hyporheic zone sediments exposed to wetting/drying transitions. Throughout the system we found threshold-like responses to the duration of desiccation. Membership of the putatively active community – but not the whole community – responded due to enhanced deterministic selection (an emergent community property). Concurrently, the thermodynamic properties of organic matter became less favorable for oxidation (an environmental component) and respiration decreased (a microbial process). While these responses were step functions of desiccation, we observed continuous monotonic relationships among community assembly, respiration, and organic matter thermodynamics. Placing the results in context of our conceptual framework points to previously unrecognized internal feedbacks that are initiated by disturbance, mediated by thermodynamics, and that cause the impacts of disturbance to be dependent on the history of disturbance.

Bounding and Binding: Trajectories of Community-Organization Emergence Following a Major Disruption

An important and underexamined topic in the growing literature on community-embedded organizing concerns situations in which dramatic shifts in the environment require the time-sensitive re-establishment of both communities and organizations to address urgent needs. We conduct a qualitative study of emergent community-organization trajectories in the aftermath of the 2010 Haiti earthquake and explore differences in the processes and interactions between emerging organizations and communities. Despite all organizations in our data facing the same external shock, they differed in how they interpreted the nature of crisis-induced voids, established boundaries to build and organize communities, and created connections to bind themselves to their communities. We compare and contrast these differences to reveal three trajectories of community-organization emergence, explain why these trajectories initially formed in the ways they did, and identify unique mechanisms that led to these trajectories’ divergence. Our findings contribute to the literature on community-embedded organizing by demonstrating how organizations re-establish communities while simultaneously emerging within those communities.

Taming of ‘Openness' in Software Innovation Systems

In large-scale open source software (OSS) innovation ecosystems that incorporate firms, a variety of measures are taken to tame the potentially chaotic activities and align the contributions of various participants with the strategic priorities of major stakeholders. Such taming rests on the dual desires of this emergent community of firms to unleash the innovation potential of OSS and to drive it to a certain direction, and it emerges in the form of various organizational activities. By drawing on a sample of large-scale OSS ecosystems, the authors discuss that methods employed for taming are isomorphic, and overview the emerging strategic pattern for establishing systems of innovation. This pattern involves a related set of practices to balance virtues of OSS community while introducing corporate discipline. In contrast to approaches such as open innovation, which favor isolated reasoning, they present a systemic and historical perspective to explain the continuum in emergence and establishment of strategic patterns.

Reducing Recurrent Care Proceedings: Building a Local Evidence Base in England

Recent studies of public law care proceedings within the family justice system in England and Wales suggest that up to a quarter of all mothers who appear in such proceedings will reappear within a subsequent—or recurrent—set of such proceedings within seven years. In the last decade, new interdisciplinary research spanning social work, clinical psychology and sociology has defined and investigated the previously hidden challenge and social costs of ‘recurrent care proceedings’ (RCP). This article adds to this new field by analysing the core values, practice and impact of three different local services in the northwest of England working with birth parents to reduce the risk of recurrent proceedings. The article combines data gathered from the three distinct services using a common evaluation framework co-produced by the authors working with service leads, practitioners and users. It explores how all three services are seeking to reduce the risk of recurrent care proceedings in their local areas without requiring women to use long acting reversible contraception (LARC) or other forms of contraception as a condition of accessing the service. It concludes that insights gained from these and cognate services can inform an emergent community of practice in the recurrent care field.

Disturbance Triggers Non-Linear Microbe-Environment Feedbacks

Conceptual frameworks linking microbial community membership, properties, and processes with the environment and emergent function have been proposed but remain untested. Here we refine and test a recent conceptual framework using hyporheic zone sediments exposed to wetting/drying transitions. Throughout the system we found threshold-like responses to the duration of desiccation. Membership of the putatively active community--but not the whole community--responded due to enhanced deterministic selection (an emergent community property). Concurrently, the thermodynamic properties of organic matter became less favorable for oxidation (an environmental component) and respiration decreased (a microbial process). While these responses were step functions of desiccation, we observed continuous monotonic relationships among community assembly, respiration, and organic matter thermodynamics. Placing the results in context of our conceptual framework points to previously unrecognized internal feedbacks that are initiated by disturbance, mediated by thermodynamics, and that cause the impacts of disturbance to be dependent on the history of disturbance.