scholarly journals Motile curved bacteria are Pareto-optimal

2019 ◽  
Vol 116 (29) ◽  
pp. 14440-14447 ◽  
Author(s):  
Rudi Schuech ◽  
Tatjana Hoehfurtner ◽  
David J. Smith ◽  
Stuart Humphries
Keyword(s):  
Morphological Diversity ◽  
Fundamental Question ◽  
Pareto Optimal ◽  
Selective Pressures ◽  
Microbial Ecosystems ◽  
Trade Offs ◽  
Optimal Region ◽  
Curved Rods ◽  
Curved Rod ◽  
Cell Construction

Curved rods are a ubiquitous bacterial phenotype, but the fundamental question of why they are shaped this way remains unanswered. Through in silico experiments, we assessed freely swimming straight- and curved-rod bacteria of a wide diversity of equal-volume shapes parameterized by elongation and curvature, and predicted their performances in tasks likely to strongly influence overall fitness. Performance trade-offs between these tasks lead to a variety of shapes that are Pareto-optimal, including coccoids, all straight rods, and a range of curvatures. Comparison with an extensive morphological survey of motile curved-rod bacteria indicates that the vast majority of species fall within the Pareto-optimal region of morphospace. This result is consistent with evolutionary trade-offs between just three tasks: efficient swimming, chemotaxis, and low cell construction cost. We thus reveal the underlying selective pressures driving morphological diversity in a widespread component of microbial ecosystems.

scholarly journals Motile curved bacteria are Pareto-optimal

2018 ◽  
Author(s):  
Rudi Schuech ◽  
Tatjana Hoehfurtner ◽  
David Smith ◽  
Stuart Humphries
Keyword(s):  
Morphological Diversity ◽  
Selective Advantage ◽  
Pareto Optimal ◽  
Chemical Gradients ◽  
Microbial Ecosystems ◽  
Optimal Region ◽  
Simple Variation ◽  
Curved Rods ◽  
Curved Rod ◽  
Cell Construction

AbstractCurved-rods are a ubiquitous bacterial phenotype, but the fundamental question of why they are shaped this way remains unanswered. Throughin silicoexperiments, we assessed freely swimming straight- and curved-rod bacteria of a wide diversity of equal-volume shapes parameterized by elongation and curvature, and predicted their performances in tasks likely to strongly influence overall fitness. Performance tradeoffs between these tasks lead to a variety of shapes that are Pareto-optimal, including coccoids, all straight rods, and a range of curvatures. Comparison with an extensive morphological survey of motile curved-rod bacteria indicates that the vast majority of species fall within the Pareto-optimal region of morphospace. This result is consistent with evolutionary tradeoffs between just three tasks: efficient swimming, chemotaxis, and low cell construction cost. We thus reveal the underlying selective pressures driving morphological diversity in a wide-spread component of microbial ecosystems.Significance StatementBacteria exhibit a bewildering diversity of morphologies but despite their impact on nearly all aspects of life, they are frequently classified into a few general categories, usually just ‘spheres’ and ‘rods’. Curved-rod bacteria are one simple variation and are widespread, particularly in the ocean. However, why so many species have evolved this shape is unknown. We show that curvature can increase swimming efficiency, revealing a widely-applicable selective advantage. Furthermore, we show that the distribution of cell lengths and curvatures observed across bacteria in nature are predicted by evolutionary tradeoffs between three tasks influenced by shape: efficient swimming, the ability to detect chemical gradients, and reduced cost of cell construction. We therefore reveal shape as an important component of microbial fitness.

scholarly journals Vertebrate cardiac regeneration: evolutionary and developmental perspectives

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Stephen Cutie ◽  
Guo N. Huang
Keyword(s):  
Cardiac Injury ◽  
Adaptive Immune System ◽  
Cardiac Regeneration ◽  
Heart Regeneration ◽  
Adaptive Immune ◽  
Selective Pressures ◽  
Trade Offs ◽  
Lower Vertebrates ◽  
Complex Adaptive ◽  
And Function

AbstractCardiac regeneration is an ancestral trait in vertebrates that is lost both as more recent vertebrate lineages evolved to adapt to new environments and selective pressures, and as members of certain species developmentally progress towards their adult forms. While higher vertebrates like humans and rodents resolve cardiac injury with permanent fibrosis and loss of cardiac output as adults, neonates of these same species can fully regenerate heart structure and function after injury – as can adult lower vertebrates like many teleost fish and urodele amphibians. Recent research has elucidated several broad factors hypothesized to contribute to this loss of cardiac regenerative potential both evolutionarily and developmentally: an oxygen-rich environment, vertebrate thermogenesis, a complex adaptive immune system, and cancer risk trade-offs. In this review, we discuss the evidence for these hypotheses as well as the cellular participators and molecular regulators by which they act to govern heart regeneration in vertebrates.

scholarly journals Evolutionary trade-offs between unicellularity and multicellularity in budding yeast

2018 ◽  
Author(s):  
Jennie J. Kuzdzal-Fick ◽  
Lin Chen ◽  
Gábor Balázsi
Keyword(s):  
Mitotic Exit ◽  
Fundamental Question ◽  
Bet Hedging ◽  
Evolutionary Transitions ◽  
Wild Yeast ◽  
Yeast Strains ◽  
Trade Offs ◽  
Mitotic Exit Network ◽  
Multicellular Organisms ◽  
Benefits And Costs

ABSTRACTMulticellular organisms appeared on Earth through several independent major evolutionary transitions. Are such transitions reversible? Addressing this fundamental question entails understanding the benefits and costs of multicellularity versus unicellularity. For example, some wild yeast strains form multicellular clumps, which might be beneficial in stressful conditions, but this has been untested. Here we show that unicellular yeast evolves from clump-forming ancestors by propagating samples from suspension after larger clumps have settled. Unicellular yeast strains differed from their clumping ancestors mainly by mutations in the AMN1 (Antagonist of Mitotic exit Network) gene. Ancestral yeast clumps were more resistant to freeze/thaw, hydrogen peroxide, and ethanol stressors than their unicellular counterparts, while unicellularity was advantageous without stress. These findings inform mathematical models, jointly suggesting a trade-off between the benefits and downsides of multicellularity, causing bet-hedging by regulated phenotype switching as a survival strategy in unexpected stress.

scholarly journals Sexual Size Dimorphism and Morphological Evidence Supporting the Recognition of two Subspecies in the Galápagos Dove

The Condor ◽  
2007 ◽  
Vol 109 (1) ◽  
pp. 132-141
Author(s):  
Diego Santiago-Alarcon ◽  
Patricia G. Parker
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Bird Species ◽  
Morphological Data ◽  
Morphological Evidence ◽  
Life History Variation ◽  
Size Dimorphism ◽  
Selective Pressures ◽  
Trade Offs ◽  
Discriminant Analyses

Abstract Abstract Sexual size dimorphism is a conspicuous trait of many wild bird species. Differences in body size between the sexes might reflect selective pressures and trade-offs to optimize performance. Here, we analyze the size dimorphism of the Galápagos Dove (Zenaida galapagoensis) using principal component and discriminant analyses with samples obtained from six islands: Santiago, Santa Fe, Santa Cruz, Española, Genovesa, and Wolf. We also reanalyze published morphological data but also including additional samples from Wolf Island to account for morphological differences among islands. Males were significantly larger than females. Discriminant analyses correctly classified 98% of males and 100% of females, and cross-validation of the model correctly classified 97% of males and 98% of females. We created two sexual size dimorphism indices using wing chord and tarsus as body-size surrogates. Significant differences were found in the sexual size dimorphism index for both measurements among islands. Significant differences in sexual size dimorphism among islands might indicate the role of different selective pressures acting on individual islands (e.g., competition, predation, resources, sexual selection), which might result in life history variation of the species among islands. For the first time, we provide significant morphological evidence supporting the classification of the Galápagos Dove into two subspecies: Z. g. galapagoensis and Z. g. exsul.

scholarly journals Balancing ecosystem services with energy and food security – Assessing trade-offs from reservoir operation and irrigation investments in Kenya's Tana Basin

2014 ◽  
Vol 18 (8) ◽  
pp. 3259-3277 ◽  
Author(s):  
A. P. Hurford ◽  
J. J. Harou
Keyword(s):  
Ecosystem Services ◽  
Optimal Allocation ◽  
Search Algorithm ◽  
Management Strategies ◽  
Decision Makers ◽  
Pareto Optimal ◽  
Management Problem ◽  
Economic Sectors ◽  
Trade Off ◽  
Trade Offs

Abstract. Competition for water between key economic sectors and the environment means agreeing allocations is challenging. Managing releases from the three major dams in Kenya's Tana River basin with its 4.4 million inhabitants, 567 MW of installed hydropower capacity, 33 000 ha of irrigation and ecologically important wetlands and forests is a pertinent example. This research seeks firstly to identify and help decision-makers visualise reservoir management strategies which result in the best possible (Pareto-optimal) allocation of benefits between sectors. Secondly, it seeks to show how trade-offs between achievable benefits shift with the implementation of proposed new rice, cotton and biofuel irrigation projects. To approximate the Pareto-optimal trade-offs we link a water resources management simulation model to a multi-criteria search algorithm. The decisions or "levers" of the management problem are volume-dependent release rules for the three major dams and extent of investment in new irrigation schemes. These decisions are optimised for eight objectives covering the provision of water supply and irrigation, energy generation and maintenance of ecosystem services. Trade-off plots allow decision-makers to assess multi-reservoir rule-sets and irrigation investment options by visualising their impacts on different beneficiaries. Results quantify how economic gains from proposed irrigation schemes trade-off against the disturbance of ecosystems and local livelihoods that depend on them. Full implementation of the proposed schemes is shown to come at a high environmental and social cost. The clarity and comprehensiveness of "best-case" trade-off analysis is a useful vantage point from which to tackle the interdependence and complexity of "water-energy-food nexus" resource security issues.

Cardiovascular System

2019 ◽  
pp. 461-485
Author(s):  
Kevin S. Shah ◽  
Kalyanam Shivkumar ◽  
Mehdi Nojoumi ◽  
Barbara Natterson-Horowitz
Keyword(s):  
Phylogenetic Information ◽  
Healthy Human ◽  
Selective Pressures ◽  
Evolutionary Origins ◽  
Trade Offs ◽  
Species Vulnerability ◽  
System P ◽  
History Of ◽  
Cv Disease ◽  
Comparative Information

Cardiovascular (CV) disease is the leading killer of our species. Various evolutionary lenses can be applied to better understand human vulnerability to CV disorders. The evolutionary origins of a healthy human heart—its myocardial, electrophysiologic, valvular and vascular systems—offers a history of the selective pressures, trade-offs and adaptations leading to the normal mammalian CV systems. Beyond these evolutionary-developmental perspectives, the application of a framework based on Tinbergen’s four questions offers a novel evolutionary lens for understanding our species’ vulnerability to CV pathology. This is done by a consideration of comparative information about non-human animals who spontaneously develop the same CV diseases. This phylogenetic information can then be used to develop trade-off-based adaptive hypotheses to explain the nature and origins of vulnerability to a range of CV pathologies including atherosclerosis, heart failure, valvular heart disease and arrhythmias.

On the Extension of Elastic Two-Ply Filament Yarns

1975 ◽  
Vol 42 (4) ◽  
pp. 821-824 ◽  
Author(s):  
N. C. Huang
Keyword(s):  
Linear Theory ◽  
Cross Section ◽  
Circular Cross Section ◽  
Axial Extension ◽  
Curved Rods ◽  
Curved Rod ◽  
Helical Configuration

This paper deals with the small extension of linearly elastic two-ply filament yarns. Each filament is treated as a long slender curved rod with circular cross section and helical configuration. Analysis is based on the linear theory of slender curved rods. Two problems are investigated, namely, the extension of a yarn with fixed ends and the extension of a yarn with free ends. In comparison with a previous study of a similar problem, it is found that the method adopted in this paper can provide more accurate results and better geometrical and physical insights into the problem. In this study, the yarn elongation and the filament stress are determined for yarns with various helical angles. The effect of the superposition of a twisting moment on the axial extension is also investigated.

scholarly journals Host heterogeneity mitigates virulence evolution

2020 ◽  
Vol 16 (1) ◽  
pp. 20190744 ◽  
Author(s):  
P. Signe White ◽  
Angela Choi ◽  
Rishika Pandey ◽  
Arthur Menezes ◽  
McKenna Penley ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Parasite Prevalence ◽  
Mixed Genotype ◽  
Selective Pressures ◽  
Virulence Evolution ◽  
Specific Host ◽  
Trade Offs ◽  
Evolutionary Trajectories ◽  
Parasite Populations ◽  
Host Heterogeneity

Parasites often infect genetically diverse host populations, and the evolutionary trajectories of parasite populations may be shaped by levels of host heterogeneity. Mixed genotype host populations, compared to homogeneous host populations, can reduce parasite prevalence and potentially reduce rates of parasite adaptation due to trade-offs associated with adapting to specific host genotypes. Here, we used experimental evolution to select for increased virulence in populations of the bacterial parasite Serratia marcescens exposed to either heterogeneous or homogeneous populations of Caenorhabditis elegans . We found that parasites exposed to heterogeneous host populations evolved significantly less virulence than parasites exposed to homogeneous host populations over several hundred bacterial generations. Thus, host heterogeneity impeded parasite adaptation to host populations. While we detected trade-offs in virulence evolution, parasite adaptation to two specific host genotypes also resulted in modestly increased virulence against the reciprocal host genotypes. These results suggest that parasite adaptation to heterogeneous host populations may be impeded by both trade-offs and a reduction in the efficacy of selection as different host genotypes exert different selective pressures on a parasite population.

scholarly journals Functional diversity of small-mammal postcrania is linked to both substrate preference and body size

2020 ◽  
Vol 66 (5) ◽  
pp. 539-553
Author(s):  
Lucas N Weaver ◽  
David M Grossnickle
Keyword(s):  
Body Size ◽  
Phenotypic Diversity ◽  
Small Body ◽  
Ecological Factors ◽  
Morphological Divergence ◽  
Functional Diversification ◽  
Evolutionary Patterns ◽  
Selective Pressures ◽  
Trade Offs ◽  
Body Sizes

Abstract Selective pressures favor morphologies that are adapted to distinct ecologies, resulting in trait partitioning among ecomorphotypes. However, the effects of these selective pressures vary across taxa, especially because morphology is also influenced by factors such as phylogeny, body size, and functional trade-offs. In this study, we examine how these factors impact functional diversification in mammals. It has been proposed that trait partitioning among mammalian ecomorphotypes is less pronounced at small body sizes due to biomechanical, energetic, and environmental factors that favor a “generalist” body plan, whereas larger taxa exhibit more substantial functional adaptations. We title this the Divergence Hypothesis (DH) because it predicts greater morphological divergence among ecomorphotypes at larger body sizes. We test DH by using phylogenetic comparative methods to examine the postcranial skeletons of 129 species of taxonomically diverse, small-to-medium-sized (<15 kg) mammals, which we categorize as either “tree-dwellers” or “ground-dwellers.” In some analyses, the morphologies of ground-dwellers and tree-dwellers suggest greater between-group differentiation at larger sizes, providing some evidence for DH. However, this trend is neither particularly strong nor supported by all analyses. Instead, a more pronounced pattern emerges that is distinct from the predictions of DH: within-group phenotypic disparity increases with body size in both ground-dwellers and tree-dwellers, driven by morphological outliers among “medium”-sized mammals. Thus, evolutionary increases in body size are more closely linked to increases in within-locomotor-group disparity than to increases in between-group disparity. We discuss biomechanical and ecological factors that may drive these evolutionary patterns, and we emphasize the significant evolutionary influences of ecology and body size on phenotypic diversity.

Pareto-optimal formulations for cost versus colorimetric accuracy trade-offs in printer color management

2002 ◽  
Vol 21 (2) ◽  
pp. 132-175 ◽  
Author(s):  
D. J. Littlewood ◽  
P. A. Drakopoulos ◽  
G. Subbarayan
Keyword(s):  
Pareto Optimal ◽  
Color Management ◽  
Trade Offs
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