The Experts below are selected from a list of 41019 Experts worldwide ranked by ideXlab platform
Kevin R. Foster - One of the best experts on this subject based on the ideXlab platform.
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biofilm formation as a response to Ecological Competition
PLOS Biology, 2015Co-Authors: Nuno Oliveira, Esteban Martinezgarcia, William M Durham, Roberto Kolter, Joao B. Xavier, Kevin R. FosterAbstract:Bacteria form dense surface-associated communities known as biofilms that are central to their persistence and how they affect us. Biofilm formation is commonly viewed as a cooperative enterprise, where strains and species work together for a common goal. Here we explore an alternative model: biofilm formation is a response to Ecological Competition. We co-cultured a diverse collection of natural isolates of the opportunistic pathogen Pseudomonas aeruginosa and studied the effect on biofilm formation. We show that strain mixing reliably increases biofilm formation compared to unmixed conditions. Importantly, strain mixing leads to strong Competition: one strain dominates and largely excludes the other from the biofilm. Furthermore, we show that pyocins, narrow-spectrum antibiotics made by other P. aeruginosa strains, can stimulate biofilm formation by increasing the attachment of cells. Side-by-side comparisons using microfluidic assays suggest that the increase in biofilm occurs due to a general response to cellular damage: a comparable biofilm response occurs for pyocins that disrupt membranes as for commercial antibiotics that damage DNA, inhibit protein synthesis or transcription. Our data show that bacteria increase biofilm formation in response to Ecological Competition that is detected by antibiotic stress. This is inconsistent with the idea that sub-lethal concentrations of antibiotics are cooperative signals that coordinate microbial communities, as is often concluded. Instead, our work is consistent with Competition sensing where low-levels of antibiotics are used to detect and respond to the competing genotypes that produce them.
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Competition sensing: the social side of bacterial stress responses
Nature Reviews Microbiology, 2013Co-Authors: Daniel M. Cornforth, Kevin R. FosterAbstract:The field of ecology has long recognized two types of Competition: exploitative Competition, which occurs indirectly through resource consumption, and interference Competition, whereby one individual directly harms another. Here, we argue that these two forms of Competition have played a dominant role in the evolution of bacterial regulatory networks. In particular, we argue that several of the major bacterial stress responses detect Ecological Competition by sensing nutrient limitation (exploitative Competition) or direct cell damage (interference Competition). We call this Competition sensing: a physiological response that detects harm caused by other cells and that evolved, at least in part, for that purpose. A key prediction of our hypothesis is that bacteria will counter-attack when they sense Ecological Competition but not when they sense abiotic stress. In support of this hypothesis, we show that bacteriocins and antibiotics are frequently upregulated by stress responses to nutrient limitation and cell damage but very rarely upregulated by stress responses to heat or osmotic stress, which typically are not Competition related. We argue that stress responses, in combination with the various mechanisms that sense secretions, enable bacteria to infer the presence of Ecological Competition and navigate the 'microbe-kill-microbe' world in which they live.
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Ecological Competition favours cooperation in termite societies
Ecology letters, 2010Co-Authors: Judith Korb, Kevin R. FosterAbstract:Conflict and Competition lie at the heart of the theories of both ecology and sociobiology. Despite this, the interaction between societal conflicts on one hand and Ecological Competition on the other remains poorly understood. Here, we investigate this interaction in two Ecologically similar sympatric termite species, Cryptotermes secundus Hill and Cryptotermes domesticus Haviland. We manipulated the incidence of king and queen loss (within-species conflict) and the incidence of cohabitation of the two species (between-species Competition) in a series of 2 year experiments. Manipulation alone had no detectable effect and most colonies survived the 2-year period. In contrast, promoting both within- and between-species conflict caused the great majority of colonies to die. Moreover, the resulting colony loss was much more rapid in the conflictridden C. domesticus than in C. secundus. Our data suggest that Ecological Competition among species can greatly exacerbate the impact of internal conflicts, thereby promoting the evolution of within-species cooperation.
Bruce E. Lyon - One of the best experts on this subject based on the ideXlab platform.
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The evolution of female ornaments and weaponry: social selection, sexual selection and Ecological Competition
Philosophical transactions of the Royal Society of London. Series B Biological sciences, 2012Co-Authors: Joe Tobias, Robert Montgomerie, Bruce E. LyonAbstract:Ornaments, weapons and aggressive behaviours may evolve in female animals by mate choice and intrasexual Competition for mating opportunities—the standard forms of sexual selection in males. However, a growing body of evidence suggests that selection tends to operate in different ways in males and females, with female traits more often mediating Competition for Ecological resources, rather than mate acquisition. Two main solutions have been proposed to accommodate this disparity. One is to expand the concept of sexual selection to include all mechanisms related to fecundity; another is to adopt an alternative conceptual framework—the theory of social selection—in which sexual selection is one component of a more general form of selection resulting from all social interactions. In this study, we summarize the history of the debate about female ornaments and weapons, and discuss potential resolutions. We review the components of fitness driving ornamentation in a wide range of systems, and show that selection often falls outside the limits of traditional sexual selection theory, particularly in females. We conclude that the evolution of these traits in both sexes is best understood within the unifying framework of social selection.
Rauri C. K. Bowie - One of the best experts on this subject based on the ideXlab platform.
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Social selection parapatry in Afrotropical sunbirds
Evolution; international journal of organic evolution, 2016Co-Authors: Jay P. Mcentee, Joshua V. Peñalba, Chacha Werema, Elia A. Mulungu, Maneno Mbilinyi, David C Moyer, Louis A. Hansen, Jon Fjeldså, Rauri C. K. BowieAbstract:The extent of range overlap of incipient and recent species depends on the type and magnitude of phenotypic divergence that separates them, and the consequences of phenotypic divergence on their interactions. Signal divergence by social selection likely initiates many speciation events, but may yield niche-conserved lineages predisposed to limit each others' ranges via Ecological Competition. Here, we examine this neglected aspect of social selection speciation theory in relation to the discovery of a nonecotonal species border between sunbirds. We find that Nectarinia moreaui and Nectarinia fuelleborni meet in a ∼6 km wide contact zone, as estimated by molecular cline analysis. These species exploit similar bioclimatic niches, but sing highly divergent learned songs, consistent with divergence by social selection. Cline analyses suggest that within-species stabilizing social selection on song-learning predispositions maintains species differences in song despite both hybridization and cultural transmission. We conclude that Ecological Competition between moreaui and fuelleborni contributes to the stabilization of the species border, but that Ecological Competition acts in conjunction with reproductive interference. The evolutionary maintenance of learned song differences in a hybrid zone recommend this study system for future studies on the mechanisms of learned song divergence and its role in speciation.
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Social selection parapatry in an Afrotropical sunbird
2015Co-Authors: Jay P. Mcentee, Joshua V. Peñalba, Chacha Werema, Elia A. Mulungu, Maneno Mbilinyi, David C Moyer, Louis A. Hansen, Jon Fjeldså, Rauri C. K. BowieAbstract:The extent of range overlap of incipient and recent species depends on the type and magnitude of phenotypic divergence that separates them. Trait divergence by social selection likely initiates many speciation events, but may yield niche-conserved lineages predisposed to limit each others ranges via Ecological Competition. Here we examine this neglected aspect of social selection speciation theory in relation to the discovery of a non-ecotonal species border between sunbirds. We find that Nectarinia moreaui and N. fuelleborni meet in a ~6 km wide contact zone, as estimated by molecular cline analysis. These species exploit similar bioclimatic niches, but sing highly divergent learned songs, consistent with divergence by social selection. Cline analyses suggest that within-species stabilizing social selection on song-learning predispositions maintains species differences in song despite both hybridization and cultural transmission in the contact zone. We conclude that Ecological Competition between moreaui and fuelleborni contributes to the stabilization of the species border, but that Ecological Competition acts in conjunction with reproductive interference. The evolutionary maintenance of learned song differences in a hybrid zone recommend this study system for future studies on the mechanisms of learned song divergence and its role in speciation.
Joe Tobias - One of the best experts on this subject based on the ideXlab platform.
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The evolution of female ornaments and weaponry: social selection, sexual selection and Ecological Competition
Philosophical transactions of the Royal Society of London. Series B Biological sciences, 2012Co-Authors: Joe Tobias, Robert Montgomerie, Bruce E. LyonAbstract:Ornaments, weapons and aggressive behaviours may evolve in female animals by mate choice and intrasexual Competition for mating opportunities—the standard forms of sexual selection in males. However, a growing body of evidence suggests that selection tends to operate in different ways in males and females, with female traits more often mediating Competition for Ecological resources, rather than mate acquisition. Two main solutions have been proposed to accommodate this disparity. One is to expand the concept of sexual selection to include all mechanisms related to fecundity; another is to adopt an alternative conceptual framework—the theory of social selection—in which sexual selection is one component of a more general form of selection resulting from all social interactions. In this study, we summarize the history of the debate about female ornaments and weapons, and discuss potential resolutions. We review the components of fitness driving ornamentation in a wide range of systems, and show that selection often falls outside the limits of traditional sexual selection theory, particularly in females. We conclude that the evolution of these traits in both sexes is best understood within the unifying framework of social selection.
Chun-ming Huang - One of the best experts on this subject based on the ideXlab platform.
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Nasal commensal Staphylococcus epidermidis counteracts influenza virus
Scientific Reports, 2016Co-Authors: Hui-wen Chen, Robert T. Schooley, Holger Rohde, Richard L Gallo, Xing Quan Zhang, Chun-ming HuangAbstract:Several microbes, including Staphylococcus epidermidis ( S. epidermidis ), a Gram-positive bacterium, live inside the human nasal cavity as commensals. The role of these nasal commensals in host innate immunity is largely unknown, although bacterial interference in the nasal microbiome may promote Ecological Competition between commensal bacteria and pathogenic species. We demonstrate here that S. epidermidis culture supernatants significantly suppressed the infectivity of various influenza viruses. Using high-performance liquid chromatography together with mass spectrometry, we identified a giant extracellular matrix-binding protein (Embp) as the major component involved in the anti-influenza effect of S. epidermidis . This anti-influenza activity was abrogated when Embp was mutated, confirming that Embp is essential for S. epidermidis activity against viral infection. We also showed that both S. epidermidis bacterial particles and Embp can directly bind to influenza virus. Furthermore, the injection of a recombinant Embp fragment containing a fibronectin-binding domain into embryonated eggs increased the survival rate of virus-infected chicken embryos. For an in vivo challenge study, prior Embp intranasal inoculation in chickens suppressed the viral titres and induced the expression of antiviral cytokines in the nasal tissues. These results suggest that S. epidermidis in the nasal cavity may serve as a defence mechanism against influenza virus infection.
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Fermentation of Propionibacterium acnes, a Commensal Bacterium in the Human Skin Microbiome, as Skin Probiotics against Methicillin-Resistant Staphylococcus aureus
PLoS ONE, 2013Co-Authors: Muya Shu, Sherwin Kuo, Yanhan Wang, Alessandro Coda, Richard L Gallo, Jinghua Yu, Chun-ming HuangAbstract:Bacterial interference creates an Ecological Competition between commensal and pathogenic bacteria. Through fermentation of milk with gut-friendly bacteria, yogurt is an excellent aid to balance the bacteriological ecosystem in the human intestine. Here, we demonstrate that fermentation of glycerol with Propionibacterium acnes (P. acnes), a skin commensal bacterium, can function as a skin probiotic for in vitro and in vivo growth suppression of USA300, the most prevalent community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). We also promote the notion that inappropriate use of antibiotics may eliminate the skin commensals, making it more difficult to fight pathogen infection. This study warrants further investigation to better understand the role of fermentation of skin commensals in infectious disease and the importance of the human skin microbiome in skin health.
