scholarly journals Competition and Synergy BetweenProchlorococcusandSynechococcusUnder Ocean Acidification Conditions

2018 ◽  
Author(s):  
Margaret A. Knight ◽  
J. Jeffrey Morris
Keyword(s):  
Frequency Dependence ◽  
Growth Rates ◽  
Culture Media ◽  
Poor Response ◽  
Relative Fitness ◽  
Fitness Advantage ◽  
Heterotrophic Microbes ◽  
Mutualistic Relationship ◽  
Unialgal Culture ◽  
Dramatic Shift

ABSTRACTAnthropogenic CO2emissions are projected to lower the pH of the open ocean by 0.2 to 0.3 units over the next century. Laboratory experiments show that different phytoplankton taxa exhibit a wide variety of responses, with some strains having higher fitness under projected future conditions, and others being negatively impacted. Previous studies have suggested thatProchlorococcusandSynechococcus, the numerically dominant picophytoplankton in the oceans, have very different responses to elevated CO2that may result in a dramatic shift in their relative abundances in future oceans. Here we show that these two genera experience faster exponential growth rates under future CO2conditions, similar to most other cyanobacteria that have been studied. However,Prochlorococcusstrains have significantly lower realized growth rates due to more extreme lag periods after exposure to fresh culture media. Surprisingly, however,Synechococcuswas unable to outcompeteProchlorococcusin co-culture at elevated CO2. Under these conditions,Prochlorococcus’ poor response to elevated CO2disappeared, and it showed negative frequency dependence in its relative fitness compared toSynechococcus, with a significant fitness advantage when it was initially rare. Moreover, bothSynechococcusandProchlorococcushad faster growth rates in co-culture with each other than either had in unialgal culture. We speculate that this negative frequency dependence is an outgrowth of reductive Black Queen evolution operating on both taxa that has resulted in a passively mutualistic relationship analogous to that connectingProchlorococcuswith the “helper” heterotrophic microbes in its environment.

A Bird's-Eye View of Pollination: Biotic Interactions as Drivers of Adaptation and Community Change

2019 ◽  
Vol 50 (1) ◽  
pp. 477-502 ◽  
Author(s):  
Anton Pauw
Keyword(s):  
Community Composition ◽  
Bird Species ◽  
Biotic Interactions ◽  
Population Level ◽  
Community Change ◽  
Plant Evolution ◽  
Relative Fitness ◽  
Fitness Advantage ◽  
Bird Evolution ◽  
Composition I

Nectarivorous birds and bird-pollinated plants are linked by a network of interactions. Here I ask how these interactions influence evolution and community composition. I find near complete evidence for the effect of birds on plant evolution. Experiments show the process in action—birds select among floral phenotypes in a population—and comparative studies find the resulting pattern—bird-pollinated species have long-tubed, red flowers with large nectar volumes. Speciation is accomplished in one “magical” step when adaptation for bird pollination brings about divergent morphology and reproductive isolation. In contrast, evidence that plants drive bird evolution is fragmentary. Studies of selection on population-level variation are lacking, but the resulting pattern is clear—nectarivorous birds have evolved a remarkable number of times and often have long bills and brush-tipped or tubular tongues. At the level of the ecological guild, birds select among plant species via an effect on seed set and thus determine plant community composition. Plants simultaneously influence the relative fitness of bird species and thus determine the composition of the bird guild. Interaction partners may give one guild member a constant fitness advantage, resulting in competitive exclusion and community change, or may act as limiting resources that depress the fitness of frequent species, thus stabilizing community composition and allowing the coexistence of diversity within bird and plant guilds.

scholarly journals The Growth Advantage in Stationary-Phase PhenotypeConferred by rpoS Mutations Is Dependent on the pH andNutrientEnvironment

2003 ◽  
Vol 185 (24) ◽  
pp. 7044-7052 ◽  
Author(s):  
Michael J. Farrell ◽  
Steven E. Finkel
Keyword(s):  
Stationary Phase ◽  
Batch Culture ◽  
Environmental Conditions ◽  
Sole Source ◽  
Culture Conditions ◽  
Luria Bertani ◽  
Relative Fitness ◽  
Wild Type ◽  
Fitness Advantage ◽  
Casamino Acids

ABSTRACT Escherichia coli cells that are aged in batch culture display an increased fitness referred to as the growth advantage in stationary phase, or GASP, phenotype. A common early adaptation to this culture environment is a mutant rpoS allele, such as rpoS819, that results in attenuated RpoS activity. However, it is important to note that during long-term batch culture, environmental conditions are in flux. To date, most studies of the GASP phenotype have focused on identifying alleles that render an advantage in a specific environment, Luria-Bertani broth (LB) batch culture. To determine what role environmental conditions play in rendering relative fitness advantages to E. coli cells carrying either the wild-type or rpoS819 alleles, we performed competitions under a variety of culture conditions in which either the available nutrients, the pH, or both were manipulated. In LB medium, we found that while the rpoS819 allele confers a strong competitive fitness advantage at basic pH, it confers a reduced advantage under neutral conditions, and it is disadvantageous under acidic conditions. Similar results were found using other media. rpoS819 conferred its greatest advantage in basic minimal medium in which either glucose or Casamino Acids were the sole source of carbon and energy. In acidic medium supplemented with either Casamino Acids or glucose, the wild-type allele conferred a slight advantage. In addition, populations were dynamic under all pH conditions tested, with neither the wild-type nor mutant rpoS alleles sweeping a culture. We also found that the strength of the fitness advantage gained during a 10-day incubation is pH dependent.

scholarly journals Dynamics of mitochondrial inheritance in the evolution of binary mating types and two sexes

2013 ◽  
Vol 280 (1769) ◽  
pp. 20131920 ◽  
Author(s):  
Zena Hadjivasiliou ◽  
Nick Lane ◽  
Robert M. Seymour ◽  
Andrew Pomiankowski
Keyword(s):  
Relative Fitness ◽  
Uniparental Inheritance ◽  
Dependent Manner ◽  
Mating Types ◽  
Mitochondrial Mutation ◽  
Unicellular Eukaryotes ◽  
Fitness Advantage ◽  
Mitochondrial Population ◽  
Fitness Benefits

The uniparental inheritance (UPI) of mitochondria is thought to explain the evolution of two mating types or even true sexes with anisogametes. However, the exact role of UPI is not clearly understood. Here, we develop a new model, which considers the spread of UPI mutants within a biparental inheritance (BPI) population. Our model explicitly considers mitochondrial mutation and selection in parallel with the spread of UPI mutants and self-incompatible mating types. In line with earlier work, we find that UPI improves fitness under mitochondrial mutation accumulation, selfish conflict and mitonuclear coadaptation. However, we find that as UPI increases in the population its relative fitness advantage diminishes in a frequency-dependent manner. The fitness benefits of UPI ‘leak’ into the biparentally reproducing part of the population through successive matings, limiting the spread of UPI. Critically, while this process favours some degree of UPI, it neither leads to the establishment of linked mating types nor the collapse of multiple mating types to two. Only when two mating types exist beforehand can associated UPI mutants spread to fixation under the pressure of high mitochondrial mutation rate, large mitochondrial population size and selfish mutants. Variation in these parameters could account for the range of UPI actually observed in nature, from strict UPI in some Chlamydomonas species to BPI in yeast. We conclude that UPI of mitochondria alone is unlikely to have driven the evolution of two mating types in unicellular eukaryotes.

scholarly journals Unique Regulation of the DosR Regulon in the Beijing Lineage of Mycobacterium tuberculosis

2016 ◽  
Vol 199 (2) ◽  
Author(s):  
Pilar Domenech ◽  
Jason Zou ◽  
Alexandra Averback ◽  
Nishath Syed ◽  
Daniele Curtis ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Multidrug Resistant ◽  
Treatment Programs ◽  
Nucleotide Polymorphisms ◽  
Content Type ◽  
Fitness Advantage ◽  
Mechanistic Basis ◽  
Dramatic Shift ◽  
Dosr Regulon ◽  
The Impact

ABSTRACT The DosR regulon, a set of 48 genes normally expressed in Mycobacterium tuberculosis under conditions that inhibit aerobic respiration, is controlled via the DosR-DosS/DosT two-component system. While the regulon requires induction in most M. tuberculosis isolates, for members of the Beijing lineage, its expression is uncoupled from the need for signaling. In our attempts to understand the mechanistic basis for this uncoupling in the Beijing background, we previously reported the identification of two synonymous single-nucleotide polymorphisms (SNPs) within the adjacent Rv3134c gene. In the present study, we have interrogated the impact of these SNPs on dosR expression in wild-type strains, as well as a range of dosR-dosS-dosT mutants, for both Beijing and non-Beijing M. tuberculosis backgrounds. In this manner, we have unequivocally determined that the C601T dosR promoter SNP is the sole requirement for the dramatic shift in the pattern of DosR regulon expression seen in this globally important lineage. Interestingly, we also show that DosT is completely nonfunctional within these strains. Thus, a complex series of evolutionary steps has led to the present-day Beijing DosR phenotype that, in turn, potentially confers a fitness advantage in the face of some form of host-associated selective pressure. IMPORTANCE Mycobacterium tuberculosis strains of the Beijing lineage have been described as being of enhanced virulence compared to other lineages, and in certain regions, they are associated with the dramatic spread of multidrug-resistant tuberculosis (TB). In terms of trying to understand the functional basis for these broad epidemiological phenomena, it is interesting that, in contrast to the other major lineages, the Beijing strains all constitutively overexpress members of the DosR regulon. Here, we identify the mutational events that led to the evolution of this unique phenotype. In addition, our work highlights the fact that important phenotypic differences exist between distinct M. tuberculosis lineages, with the potential to impact the efficacy of diagnosis, vaccination, and treatment programs.

Comparison of growth rates of Tritrichomonas foetus isolates from various geographic regions using three different culture media

2000 ◽  
Vol 89 (3) ◽  
pp. 199-208 ◽  
Author(s):  
Zhao-Rong Lun ◽  
Sarah Parker ◽  
Alvin A. Gajadhar
Keyword(s):  
Growth Rates ◽  
Culture Media ◽  
Tritrichomonas Foetus ◽  
Geographic Regions

scholarly journals Effects of Different Culture Media on Growth and Proliferation of Dendrobium ‘Earsakul’ Protocorm-like Bodies

2015 ◽  
Vol 25 (5) ◽  
pp. 681-686 ◽  
Author(s):  
Piyada A. Tantasawat ◽  
Apinya Khairum ◽  
Kitiya Arsakit ◽  
Oythip Poolsawat ◽  
Paniti Pornbungkerd ◽  
...  
Keyword(s):  
Solanum Lycopersicum ◽  
Growth Rates ◽  
Culture Media ◽  
Musa Acuminata ◽  
Weight Increase ◽  
Second Step ◽  
Multiplication Rate ◽  
Control Medium ◽  
Fresh Weight ◽  
Commercial Micropropagation

The effects of culture media on growth and proliferation of ‘Earsakul’ dendrobium (Dendrobium) protocorm-like bodies (PLBs) were evaluated in a two-step culture. After culturing on each of the four first step media for 4 months and on each of the four second step media for 4 months, the greatest total PLB fresh weight, increase in number of PLBs and growth rates were obtained when using Vacin and Went medium 1 (VW1) in both culture steps compared with those in 15 other medium combinations. Starting from 0.5 g of PLBs, culturing on VW1 for 8 months achieved a total of 415.25 g of PLBs, a multiplication rate of 830-fold. The supplementation of tomato (Solanum lycopersicum) and substitution of ‘Hom Thong’ banana [Musa acuminata (AAA group)] with ‘Khai’ banana [M. acuminata (AA group)] in this new medium promoted growth and proliferation of dendrobium PLBs 2.4-fold over the control medium, suggesting its usefulness in commercial micropropagation.

scholarly journals The impacts of cytoplasmic incompatibility factor (cifA and cifB) genetic variation on phenotypes

Genetics ◽  
2021 ◽  
Vol 217 (1) ◽  
Author(s):  
J Dylan Shropshire ◽  
Rachel Rosenberg ◽  
Seth R Bordenstein
Keyword(s):  
Genetic Basis ◽  
Cytoplasmic Incompatibility ◽  
Relative Fitness ◽  
Evolutionary Divergence ◽  
Fitness Advantage ◽  
Variation Patterns ◽  
Different Strains ◽  
Embryonic Death

Abstract Wolbachia are maternally transmitted, intracellular bacteria that can often selfishly spread through arthropod populations via cytoplasmic incompatibility (CI). CI manifests as embryonic death when males expressing prophage WO genes cifA and cifB mate with uninfected females or females harboring an incompatible Wolbachia strain. Females with a compatible cifA-expressing strain rescue CI. Thus, cif-mediated CI confers a relative fitness advantage to females transmitting Wolbachia. However, whether cif sequence variation underpins incompatibilities between Wolbachia strains and variation in CI penetrance remains unknown. Here, we engineer Drosophila melanogaster to transgenically express cognate and non-cognate cif homologs and assess their CI and rescue capability. Cognate expression revealed that cifA;B native to D. melanogaster causes strong CI, and cognate cifA;B homologs from two other Drosophila-associated Wolbachia cause weak transgenic CI, including the first demonstration of phylogenetic type 2 cifA;B CI. Intriguingly, non-cognate expression of cifA and cifB alleles from different strains revealed that cifA homologs generally contribute to strong transgenic CI and interchangeable rescue despite their evolutionary divergence, and cifB genetic divergence contributes to weak or no transgenic CI. Finally, we find that a type 1 cifA can rescue CI caused by a genetically divergent type 2 cifA;B in a manner consistent with unidirectional incompatibility. By genetically dissecting individual CI functions for type 1 and 2 cifA and cifB, this work illuminates new relationships between cif genotype and CI phenotype. We discuss the relevance of these findings to CI’s genetic basis, phenotypic variation patterns, and mechanism.

scholarly journals Diversity of sequence types and impact of fitness cost among carbapenem-resistant Acinetobacter baumannii isolates from Tripoli, Libya

2021 ◽  
Author(s):  
Antoine G. Abou Fayad ◽  
Louis-Patrick Haraoui ◽  
Ahmad Sleiman ◽  
Mohamad Jaafar ◽  
Abdulaziz Zorgani ◽  
...  
Keyword(s):  
Molecular Epidemiology ◽  
Acinetobacter Baumannii ◽  
Doubling Time ◽  
Core Genome ◽  
Carbapenem Resistance ◽  
Relative Fitness ◽  
Fitness Advantage ◽  
Carbapenem Resistant ◽  
Sequence Types ◽  
Hospital Transmission

We investigated the molecular epidemiology of 21 carbapenem-resistant A. baumannii from Libya, and assessed their relative fitness. Core-genome MLST revealed five inter-hospital transmission clusters. Three clusters were associated with the international clones (IC) IC1, IC2, and IC7. Carbapenem-resistance was associated with bla OXA-23, bla GES-11 , or bla NDM-1 . Compared to A. baumannii DSM 30008, the doubling time was similar over 10 hours, but after 16 hours, half the isolates grew to higher densities, suggesting a fitness advantage.

scholarly journals The Whi2p-Psr1p/Psr2p complex regulates interference competition and expansion of cells with competitive advantage in yeast colonies

2020 ◽  
Vol 117 (26) ◽  
pp. 15123-15131
Author(s):  
Jana Maršíková ◽  
Martina Pavlíčková ◽  
Derek Wilkinson ◽  
Libuše Váchová ◽  
Otakar Hlaváček ◽  
...  
Keyword(s):  
Interference Competition ◽  
Relative Fitness ◽  
Cell Subpopulation ◽  
Cell Competition ◽  
Phenotypic Differentiation ◽  
Form Complex ◽  
Competition And Cooperation ◽  
Fitness Advantage ◽  
Cell Subpopulations ◽  
Synchronization Pattern

Yeast form complex highly organized colonies in which cells undergo spatiotemporal phenotypic differentiation in response to local gradients of nutrients, metabolites, and specific signaling molecules. Colony fitness depends on cell interactions, cooperation, and the division of labor between differentiated cell subpopulations. Here, we describe the regulation and dynamics of the expansion of papillae that arise during colony aging, which consist of cells that overcome colony regulatory rules and disrupt the synchronized colony structure. We show that papillae specifically expand within the U cell subpopulation in differentiated colonies. Papillae emerge more frequently in some strains than in others. Genomic analyses further revealed that the Whi2p-Psr1p/Psr2p complex (WPPC) plays a key role in papillae expansion. We show that cells lacking a functional WPPC have a sizable interaction-specific fitness advantage attributable to production of and resistance to a diffusible compound that inhibits growth of other cells. Competitive superiority and high relative fitness ofwhi2andpsr1psr2strains are particularly pronounced in dense spatially structured colonies and are independent of TORC1 and Msn2p/Msn4p regulators previously associated with the WPPC function. The WPPC function, described here, might be a regulatory mechanism that balances cell competition and cooperation in dense yeast populations and, thus, contributes to cell synchronization, pattern formation, and the expansion of cells with a competitive fitness advantage.

scholarly journals Adaptive value of PGM polymorphism in laboratory populations of Drosophila melanogaster

1980 ◽  
Vol 36 (3) ◽  
pp. 265-276 ◽  
Author(s):  
M. Carfagna ◽  
L. Fucci ◽  
L. Gaudio ◽  
G. Pontecorvo ◽  
R. Rubino
Keyword(s):  
Drosophila Melanogaster ◽  
Culture Media ◽  
Allele Frequencies ◽  
Relative Fitness ◽  
Frequency Dependent Selection ◽  
Density Dependent ◽  
Adaptive Value ◽  
Laboratory Populations ◽  
Nutritional Environment ◽  
Density Dependent Selection

SUMMARYExperiments have been performed to show that PGM polymorphism for the two common electrophoretic allozymes, PGMA and PGMB, in Drosophila melanogaster has adaptive value. Firstly, the allele frequencies converge to the same equilibrium value in six experimental populations. Secondly, density-dependent selection operates. Thirdly, the relative fitness of the three genotypes varies in modified culture media. PGM polymorphism is maintained by frequency-dependent selection and heterotic selection: the first mechanism operates to reach equilibrium frequency, the second cooperates to maintain it. The experiments performed with modified culture media favour the view that the two allozymes have different affinities for two components which are present in the nutritional environment. These components may be either substrates or other factors involved in the reaction catalyzed by PGM.

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