4 research outputs found
Genome evolution and hostâmicrobiome shifts correspond with intraspecific niche divergence within harmful algal bloomâforming Microcystis aeruginosa
Intraspecific niche divergence is an important driver of species range, population abundance and impacts on ecosystem functions. Genetic changes are the primary focus when studying intraspecific divergence; however, the role of ecological interactions, particularly hostâmicrobiome symbioses, is receiving increased attention. The relative importance of these evolutionary and ecological mechanisms has seen only limited evaluation. To address this question, we used Microcystis aeruginosa, the globally distributed cyanobacterium that dominates freshwater harmful algal blooms. These blooms have been increasing in occurrence and intensity worldwide, causing major economic and ecological damages. We evaluated 46 isolates of M. aeruginosa and their microbiomes, collected from 14 lakes in Michigan, USA, that vary over 20âfold in phosphorus levels, the primary limiting nutrient in freshwater systems. Genomes of M. aeruginosa diverged along this phosphorus gradient in genomic architecture and protein functions. Fitness in lowâphosphorus lakes corresponded with additional shifts within M. aeruginosa including genomeâwide reductions in nitrogen use, an expansion of phosphorus assimilation genes and an alternative life history strategy of nonclonal colony formation. In addition to host shifts, despite culturing in commonâgarden conditions, hostâmicrobiomes diverged along the gradient in taxonomy, but converged in function with evidence of metabolic interdependence between the host and its microbiome. Divergence corresponded with a physiological tradeâoff between fitness in lowâphosphorus environments and growth rate in phosphorusârich conditions. Coâoccurrence of genotypes adapted to different nutrient environments in phosphorusârich lakes may have critical implications for understanding how M. aeruginosa blooms persist after initial nutrient depletion. Ultimately, we demonstrate that the intertwined effects of genome evolution, host life history strategy and ecological interactions between a host and its microbiome correspond with an intraspecific niche shift with important implications for whole ecosystem function.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151861/1/mec15198_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151861/2/mec15198.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151861/3/mec15198-sup-0001-Supinfo.pd
COUNTER-DIRECTED ENERGY WEAPONS: DEFENSE OF AIR ASSETS
The global proliferation of directed energy weapon technology presents a new threat for the United States as competitors try to capitalize on the technology's relative high potential of mission success and low operational costs. The use of these weapons necessitates new engineering solutions for naval assets in order to keep pace. It is essential to proactively plan for counter-directed energy weapon methods, tactics, and capabilities. This capstone project characterized the adversarial-directed energy threat environment and developed and evaluated concepts for countering, evading, and neutralizing the potential threat effects against naval assets. In particular, the study focused on high-energy laser weapon systems and their effects on naval unmanned aerial vehicles. Capstone team members developed an evaluation tool that they applied to the concepts. The tool can be adapted to counter and defend a variety of assets. After the team applied systems thinking to this problem, it recommended methods for naval assets to counter these threats.http://archive.org/details/counterdirectede1094564850Civilian, Department of the NavyCivilian, Department of the NavyCivilian, Department of the NavyCivilian, Department of the NavyCivilian, Department of the NavyCivilian, Department of the NavyApproved for public release; distribution is unlimited
Genome evolution and hostâmicrobiome shifts correspond with intraspecific niche divergence within harmful algal bloomâforming Microcystis aeruginosa
Intraspecific niche divergence is an important driver of species range, population abundance and impacts on ecosystem functions. Genetic changes are the primary focus when studying intraspecific divergence; however, the role of ecological interactions, particularly hostâmicrobiome symbioses, is receiving increased attention. The relative importance of these evolutionary and ecological mechanisms has seen only limited evaluation. To address this question, we used Microcystis aeruginosa, the globally distributed cyanobacterium that dominates freshwater harmful algal blooms. These blooms have been increasing in occurrence and intensity worldwide, causing major economic and ecological damages. We evaluated 46 isolates of M. aeruginosa and their microbiomes, collected from 14 lakes in Michigan, USA, that vary over 20âfold in phosphorus levels, the primary limiting nutrient in freshwater systems. Genomes of M. aeruginosa diverged along this phosphorus gradient in genomic architecture and protein functions. Fitness in lowâphosphorus lakes corresponded with additional shifts within M. aeruginosa including genomeâwide reductions in nitrogen use, an expansion of phosphorus assimilation genes and an alternative life history strategy of nonclonal colony formation. In addition to host shifts, despite culturing in commonâgarden conditions, hostâmicrobiomes diverged along the gradient in taxonomy, but converged in function with evidence of metabolic interdependence between the host and its microbiome. Divergence corresponded with a physiological tradeâoff between fitness in lowâphosphorus environments and growth rate in phosphorusârich conditions. Coâoccurrence of genotypes adapted to different nutrient environments in phosphorusârich lakes may have critical implications for understanding how M. aeruginosa blooms persist after initial nutrient depletion. Ultimately, we demonstrate that the intertwined effects of genome evolution, host life history strategy and ecological interactions between a host and its microbiome correspond with an intraspecific niche shift with important implications for whole ecosystem function.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151861/1/mec15198_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151861/2/mec15198.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151861/3/mec15198-sup-0001-Supinfo.pd