scholarly journals Environmental fluctuations reshape an unexpected diversity-disturbance relationship in a microbial community

2020 ◽  
Author(s):  
Christopher P. Mancuso ◽  
Hyunseok Lee ◽  
Clare I. Abreu ◽  
Jeff Gore ◽  
Ahmad S. Khalil
Keyword(s):  
Environmental Control ◽  
Community Diversity ◽  
Environmental Disturbances ◽  
Intermediate Disturbance ◽  
Disturbance Intensity ◽  
Fundamental Limitations ◽  
Continuous Culture System ◽  
Distinct Features ◽  
Organizational Principles ◽  
Consumer Resource

SummaryEnvironmental disturbances have long been theorized to play a significant role in shaping the diversity and composition of ecosystems1,2. However, fundamental limitations in our ability to specify the characteristics of a disturbance in the field and laboratory have produced an inconsistent picture of diversity-disturbance relationships (DDRs) that shape the structure of ecosystems3. Here, using a recently developed continuous culture system with tunable environmental control4, we decomposed a dilution disturbance into intensity and fluctuation components5,6, and tested their effects on the diversity of a soil-derived bacterial community across hundreds of replicate cultures. We observed an unexpected U-shaped relationship between community diversity and disturbance intensity in the absence of fluctuations, an observation counter to classical intuition. Adding fluctuations erased the U-shape and increased community diversity across all disturbance intensities. All of these results are well-captured by a Monod consumer resource model, which further reveals how U-shaped DDRs emerge based on a novel “niche flip” mechanism in which competitive outcomes flip and coexistence regimes subsequently collapse at intermediate disturbance levels. Broadly, our results demonstrate how distinct features of an environmental disturbance can interact in complex ways to govern ecosystem assembly and produce all the major classes of DDRs, without invoking other organizational principles. With these findings, we construct a unifying framework that reconciles the disparate DDRs observed in nature, and propose strategies for predictively reshaping the compositional complexity of microbiomes and other ecosystems.

scholarly journals Environmental fluctuations reshape an unexpected diversity-disturbance relationship in a microbial community

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Christopher P Mancuso ◽  
Hyunseok Lee ◽  
Clare I Abreu ◽  
Jeff Gore ◽  
Ahmad S Khalil
Keyword(s):  
Microbial Community ◽  
Culture System ◽  
Community Diversity ◽  
Environmental Disturbance ◽  
Resource Model ◽  
Modeling Framework ◽  
Environmental Disturbances ◽  
Disturbance Intensity ◽  
Distinct Features ◽  
Consumer Resource

Environmental disturbances have long been theorized to play a significant role in shaping the diversity and composition of ecosystems. However, an inability to specify the characteristics of a disturbance experimentally has produced an inconsistent picture of diversity-disturbance relationships (DDRs). Here, using a high-throughput programmable culture system, we subjected a soil-derived bacterial community to dilution disturbance profiles with different intensities (mean dilution rates), applied either constantly or with fluctuations of different frequencies. We observed an unexpected U-shaped relationship between community diversity and disturbance intensity in the absence of fluctuations. Adding fluctuations increased community diversity and erased the U-shape. All our results are well-captured by a Monod consumer resource model, which also explains how U-shaped DDRs emerge via a novel 'niche flip' mechanism. Broadly, our combined experimental and modeling framework demonstrates how distinct features of an environmental disturbance can interact in complex ways to govern ecosystem assembly and offers strategies for reshaping the composition of microbiomes.

scholarly journals Microbial species interactions determine community diversity in fluctuating environments

2020 ◽  
Author(s):  
Shota Shibasaki ◽  
Mauro Mobilia ◽  
Sara Mitri
Keyword(s):  
Species Interactions ◽  
Intermediate Disturbance Hypothesis ◽  
Community Diversity ◽  
Intermediate Disturbance ◽  
Microbial Species ◽  
As Species ◽  
Species Pairs ◽  
Local Extinctions ◽  
Harsh Conditions ◽  
Strength Of Competition

AbstractMicroorganisms often live in environments that fluctuate between mild and harsh conditions. Although such fluctuations are bound to cause local extinctions and affect species diversity, it is unknown how diversity changes at different fluctuation rates and how this relates to changes in species interactions. Here, we use a mathematical model describing the dynamics of resources, toxins, and microbial species in a chemostat where resource supplies switch. Over most of the explored parameter space, species competed, but the strength of competition peaked at either low, high, or intermediate switching rates depending on the species’ sensitivity to toxins. Importantly, however, the strength of competition in species pairs was a good predictor for how community diversity changed over the switching rate. In sum, predicting the effect of environmental switching on competition and community diversity is difficult, as species’ properties matter. This may explain contradicting results of earlier studies on the intermediate disturbance hypothesis.

scholarly journals Richness and Diversity of Bacterioplankton Species along an Estuarine Gradient in Moreton Bay, Australia

2004 ◽  
Vol 70 (6) ◽  
pp. 3425-3433 ◽  
Author(s):  
Ian Hewson ◽  
Jed A. Fuhrman
Keyword(s):  
Intergenic Spacer ◽  
Operational Taxonomic Unit ◽  
Community Diversity ◽  
Strong Correlations ◽  
Intermediate Disturbance ◽  
Moreton Bay ◽  
Coral Sea ◽  
Internally Transcribed Spacer ◽  
Richness And Diversity Patterns ◽  
Bacterioplankton Communities

ABSTRACT Bacterioplankton community diversity was investigated in the subtropical Brisbane River-Moreton Bay estuary, Australia (27�25′S, 153�5′E). Bacterial communities were studied using automated rRNA intergenic spacer analysis (ARISA), which amplifies 16S-23S ribosomal DNA internally transcribed spacer regions from mixed-community DNA and detects the separated products on a fragment analyzer. Samples were collected from eight sites throughout the estuary and east to the East Australian Current (Coral Sea). Bacterioplankton communities had the highest operational taxonomic unit (OTU) richness, as measured by ARISA at eastern bay stations (S [total richness] = 84 to 85 OTU) and the lowest richness in the Coral Sea (S = 39 to 59 OTU). Richness correlated positively with bacterial abundance; however, there were no strong correlations between diversity and salinity, NO3 − and PO4 3− concentrations, or chlorophyll a concentration. Bacterioplankton communities at the riverine stations were different from communities in the bay or Coral Sea. The main differences in OTU richness between stations were in taxa that each represented 0.1% (the detection limit) to 0.5% of the total amplified DNA, i.e., the “tail” of the distribution. We found that some bacterioplankton taxa are specific to distinct environments while others have a ubiquitous distribution from river to sea. Bacterioplankton richness and diversity patterns in the estuary are potentially a consequence of greater niche availability, mixing of local and adjacent environment communities, or intermediate disturbance. Furthermore, these results contrast with previous reports of spatially homogeneous bacterioplankton communities in other coastal waters.

Thermal Considerations in Lens Regulator Systems

1970 ◽  
Vol 28 ◽  
pp. 358-359
Author(s):  
K.C. Newton
Keyword(s):  
Electron Microscope ◽  
Thermal Effects ◽  
Environmental Control ◽  
Reference Networks ◽  
Better Than

Thermal effects in lens regulator systems have become a major problem with the extension of electron microscope resolution capabilities below 5 Angstrom units. Larger columns with immersion lenses and increased accelerating potentials have made solutions more difficult by increasing the power being handled. Environmental control, component choice, and wiring design provide answers, however. Figure 1 indicates with broken lines where thermal problems develop in regulator systemsExtensive environmental control is required in the sampling and reference networks. In each case, stability better than I ppm/min. is required. Components with thermal coefficients satisfactory for these applications without environmental control are either not available or priced prohibitively.

Consumer Resource Needs Scale

1998 ◽  
Author(s):  
Dennis N. Bristow ◽  
John C. Mowen
Keyword(s):  
Resource Needs ◽  
Consumer Resource

Disentangling the role of shared ancestry and the environment on leaf stable isotopes

2019 ◽  
Author(s):  
Marko J. Spasojevic ◽  
Sören Weber1
Keyword(s):  
Stable Isotopes ◽  
Environmental Conditions ◽  
Evolutionary History ◽  
Environmental Control ◽  
Phylogenetic Signal ◽  
Individual Species ◽  
Habitat Types ◽  
Δ13c And Δ15n ◽  
Environmental Controls ◽  
Shared Ancestry

Stable carbon (C) and nitrogen (N) isotopes in plants are important indicators of plant water use efficiency and N acquisition strategies. While often regarded as being under environmental control, there is growing evidence that evolutionary history may also shape variation in stable isotope ratios (δ13C and δ15N) among plant species. Here we examined patterns of foliar δ13C and δ15N in alpine tundra for 59 species in 20 plant families. To assess the importance of environmental controls and evolutionary history, we examined if average δ13C and δ15N predictably differed among habitat types, if individual species exhibited intraspecific trait variation (ITV) in δ13C and δ15N, and if there were a significant phylogenetic signal in δ13C and δ15N. We found that variation among habitat types in both δ13C and δ15N mirrored well-known patterns of water and nitrogen limitation. Conversely, we also found that 40% of species exhibited no ITV in δ13C and 35% of species exhibited no ITV in δ15N, suggesting that some species are under stronger evolutionary control. However, we only found a modest signal of phylogenetic conservatism in δ13C and no phylogenetic signal in δ15N suggesting that shared ancestry is a weaker driver of tundra wide variation in stable isotopes. Together, our results suggest that both evolutionary history and local environmental conditions play a role in determining variation in δ13C and δ15N and that considering both factors can help with interpreting isotope patterns in nature and with predicting which species may be able to respond to rapidly changing environmental conditions.

Nature, poetry and medicine in late 18th century England: a unified perspective of Erasmus Darwin

1976 ◽  
Vol 7 (4) ◽  
pp. 537-537
Author(s):  
M. McNEIL
Keyword(s):  
18Th Century ◽  
Human Society ◽  
Nature Poetry ◽  
Medicine And Philosophy ◽  
Late 18Th Century ◽  
Medical Theory ◽  
Lunar Society Of Birmingham ◽  
Organizational Principles ◽  
Century Science ◽  
Erasmus Darwin

Erasmus Darwin was the focus and embodiment of provincial England in his day. Renowned as a physician, he spent much of his life at Lichfield. He instigated the founding of the Lichfield Botanic Society, which provided the first English translation of the works of Linnaeus, and established a botanic garden; the Lunar Society of Birmingham; the Derby Philosophical Society; and two provincial libraries. A list of Darwin's correspondents and associates reads like a "who's who" of eighteenth century science, industry, medicine and philosophy. His poetry was also well received by his contemporaries and he expounded the evolutionary principles of life. Darwin can be seen as an English equivalent of Lamarck, being a philosopher of nature and human society. His ideas have been linked to a multitude of movements, including the nosological movement in Western medicine, nineteenth century utilitarianism, Romanticism in both Britain and Germany, and associationist psychology. The relationships between various aspects of Darwin's interests and the organizational principles of his writings were examined. His poetical form and medical theory were not peripheral to his study of nature but intrinsically linked in providing his contemporaries with a panorama of nature. A richer, more integrated comprehension of Erasmus Darwin as one of the most significant and representative personalities of his era was presented.

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