scholarly journals Genetic architecture constrains exploitation of siderophore cooperation inBurkholderia cenocepacia

2019 ◽  
Author(s):  
Santosh Sathe ◽  
Anugraha Mathew ◽  
Kirsty Agnoli ◽  
Leo Eberl ◽  
Rolf Kümmerli
Keyword(s):  
Evolutionary Biology ◽  
Genetic Architecture ◽  
Evolutionary Dynamics ◽  
Receptor Gene ◽  
Burkholderia Cenocepacia ◽  
Model Organisms ◽  
The Media ◽  
Microbial Systems ◽  
Competition Assays ◽  
Microbial Study

Explaining how cooperation can persist in the presence of cheaters, exploiting the cooperative acts, is a challenge for evolutionary biology. While microbial systems have proved extremely useful to test evolutionary theory and identify mechanisms maintaining cooperation, our knowledge is often limited to insights gained from a few model organisms. Here, we introduce siderophore secretion by the bacteriumBurkholderia cenocepaciaas a novel study system. Using a combination of phenotypic and competition assays we found that ornibactin, the main siderophore used for iron scavenging in this species, is secreted into the media, can be shared as public good between cells, but cannot be exploited by ornibactin-defective mutants. Molecular analysis revealed that cheating is compromised because the ornibactin receptor gene and genes involved in ornibactin synthesis are co-expressed from the same operon, such that disruptive mutations in the upstream synthesis genes compromise receptor availability. To prove that it is the genetic architecture of the siderophore locus that prevents cheating, we broke the linked traits by expressing the ornibactin receptor from a plasmid, a measure that turned the ornibactin mutant into a functional cheater. A literature survey acrossBurkholderiaspecies suggests that the genetic linkage independently broke over evolutionary time scales in several lineages, indicating that cheating and countermeasures might be under selection. Altogether, our results highlight that expanding our repertoire of microbial study systems leads to new discoveries and reinforce the view that social interactions shape evolutionary dynamics in microbial communities.

scholarly journals Evolutionary ecology of microorganisms: from the tamed to the wild

2015 ◽  
Author(s):  
Jay T Lennon ◽  
Vincent J Denef
Keyword(s):  
Evolutionary Biology ◽  
Evolutionary Dynamics ◽  
Evolutionary Ecology ◽  
Community Context ◽  
Ecological Processes ◽  
Rates Of Evolution ◽  
Ecological Principles ◽  
Managed Ecosystems ◽  
Microbial Systems ◽  
Empirical Approaches

An overarching goal of biology is to understand how evolutionary and ecological processes generate and maintain biodiversity. While evolutionary biologists interested in biodiversity tend to focus on the mechanisms controlling rates of evolution and how this influences the phylogenetic relationship among species, ecologists attempt to explain the distribution and abundance of taxa based upon interactions among species and their environment. Recently, a more concerted effort has been made to integrate some of the theoretical and empirical approaches from the fields of ecology and evolutionary biology. This integration has been motivated in part by the growing evidence that evolution can happen on “rapid” or contemporary time scales, suggesting that eco-evolutionary feedbacks can alter system dynamics in ways that cannot be predicted based on ecological principles alone. As such, it may be inappropriate to ignore evolutionary processes when attempting to understand ecological phenomena in natural and managed ecosystems. In this chapter, we highlight why it is particularly important to consider eco-evolutionary feedbacks for microbial populations. We emphasize some of the major processes that are thought to influence the strength of eco-evolutionary dynamics, provide an overview of methods used to quantify the relative importance of ecology and evolution, and showcase the importance of considering evolution in a community context and how this may influence the dynamics and stability of microbial systems under novel environmental conditions.

scholarly journals Evolutionary ecology of microorganisms: from the tamed to the wild

2015 ◽  
Author(s):  
Jay T Lennon ◽  
Vincent J Denef
Keyword(s):  
Evolutionary Biology ◽  
Evolutionary Dynamics ◽  
Evolutionary Ecology ◽  
Community Context ◽  
Ecological Processes ◽  
Rates Of Evolution ◽  
Ecological Principles ◽  
Managed Ecosystems ◽  
Microbial Systems ◽  
Empirical Approaches

An overarching goal of biology is to understand how evolutionary and ecological processes generate and maintain biodiversity. While evolutionary biologists interested in biodiversity tend to focus on the mechanisms controlling rates of evolution and how this influences the phylogenetic relationship among species, ecologists attempt to explain the distribution and abundance of taxa based upon interactions among species and their environment. Recently, a more concerted effort has been made to integrate some of the theoretical and empirical approaches from the fields of ecology and evolutionary biology. This integration has been motivated in part by the growing evidence that evolution can happen on “rapid” or contemporary time scales, suggesting that eco-evolutionary feedbacks can alter system dynamics in ways that cannot be predicted based on ecological principles alone. As such, it may be inappropriate to ignore evolutionary processes when attempting to understand ecological phenomena in natural and managed ecosystems. In this chapter, we highlight why it is particularly important to consider eco-evolutionary feedbacks for microbial populations. We emphasize some of the major processes that are thought to influence the strength of eco-evolutionary dynamics, provide an overview of methods used to quantify the relative importance of ecology and evolution, and showcase the importance of considering evolution in a community context and how this may influence the dynamics and stability of microbial systems under novel environmental conditions.

"Evolution Canyon": A Microcosm of Life's Evolution Focusing on Adaptation and Speciation

2006 ◽  
Vol 52 (3-4) ◽  
pp. 501-506 ◽  
Author(s):  
Eviatar Nevo
Keyword(s):  
Species Richness ◽  
Evolutionary Biology ◽  
Evolutionary Dynamics ◽  
Sympatric Speciation ◽  
Model Organisms ◽  
Adaptive Divergence ◽  
Transplant Experiment ◽  
Nucleotide Polymorphisms ◽  
Evolution Canyon ◽  
As Stress

Local microcosmic natural laboratories, dubbed "Evolution Canyon" (EC) models, reinforce studies of regional and global macrocosmic ecological theaters across life and unravelevolution in action.The EC model laboratories permit genomic, proteomic, and phenomic studies highlighting speciation and adaptation at a microscale. Critical transplant experiment tests can evaluate interslope differential fitness. Novel techniques of genetic mapping, sequence nucleotide polymorphisms (SNPs), and wide genome coding and noncoding expressions can unravel evolutionary dynamics. Finally, fundamental problems such as stress effects on nonrandom mutations, lateral transfers, splicing variations, sex, and social evolutions, and adaptive strategies of prokaryotes and eukaryotes are testable. We are studying four "Evolution Canyons" (EC I-IV) in the Carmel, Galilee, Negev, and Golan mountains. We've identified 2,500 species in EC I (Carmel) from bacteria to mammals in an area of 7,000 m. Higher terrestrial species richness was found on the more stressful tropical "African" slope (AS). Aquatic species richness was higher on the milder, temperate "European" slope (ES). In soil fungi we found interslope local and regional adaptive divergence in sex, melanism, and conidia. In nine out of 14 (64%) model organisms across life we identified largely higher genetic polymorphisms on the more stressful "African" slope. In some model species we found higher mutation rates, gene conversion, recombination, DNA repair, and larger genome size as well as interslope divergent micro-satellites, molecular polymorphisms, retrotransposons, and wide-genome gene expression on the more stressful AS. Remarkably, interslope incipient sympatric speciation was found across life. The "Evolution Canyon" model represents the Israeli ecological equivalent of the Galapagos Islands. Micro-climatic selection overrides drift and drives both interslope adaptive radiation and incipient sympatric speciation. The EC model could potentially highlight many mysteries of evolutionary biology.

scholarly journals Evolutionary ecology of microorganisms: from the tamed to the wild

2015 ◽  
Author(s):  
Jay T Lennon ◽  
Vincent J Denef
Keyword(s):  
Evolutionary Biology ◽  
Evolutionary Dynamics ◽  
Evolutionary Ecology ◽  
Community Context ◽  
Ecological Processes ◽  
Rates Of Evolution ◽  
Ecological Principles ◽  
Managed Ecosystems ◽  
Microbial Systems ◽  
Empirical Approaches

An overarching goal of biology is to understand how evolutionary and ecological processes generate and maintain biodiversity. While evolutionary biologists interested in biodiversity tend to focus on the mechanisms controlling rates of evolution and how this influences the phylogenetic relationship among species, ecologists attempt to explain the distribution and abundance of taxa based upon interactions among species and their environment. Recently, a more concerted effort has been made to integrate some of the theoretical and empirical approaches from the fields of ecology and evolutionary biology. This integration has been motivated in part by the growing evidence that evolution can happen on “rapid” or contemporary time scales, suggesting that eco-evolutionary feedbacks can alter system dynamics in ways that cannot be predicted based on ecological principles alone. As such, it may be inappropriate to ignore evolutionary processes when attempting to understand ecological phenomena in natural and managed ecosystems. In this chapter, we highlight why it is particularly important to consider eco-evolutionary feedbacks for microbial populations. We emphasize some of the major processes that are thought to influence the strength of eco-evolutionary dynamics, provide an overview of methods used to quantify the relative importance of ecology and evolution, and showcase the importance of considering evolution in a community context and how this may influence the dynamics and stability of microbial systems under novel environmental conditions.

Hybrid Zones and the Genetic Architecture of a Barrier to Gene Flow Between Two Sunflower Species

Genetics ◽  
1999 ◽  
Vol 152 (2) ◽  
pp. 713-727 ◽  
Author(s):  
Loren H Rieseberg ◽  
Jeannette Whitton ◽  
Keith Gardner
Keyword(s):  
Genetic Study ◽  
Genetic Architecture ◽  
Chromosomal Rearrangements ◽  
Pollen Sterility ◽  
Model Organisms ◽  
Hybrid Zones ◽  
Reproductive Barriers ◽  
Natural Hybrid ◽  
Generation Times ◽  
Helianthus Petiolaris

Abstract Genetic analyses of reproductive barriers represent one of the few methods by which theories of speciation can be tested. However, genetic study is often restricted to model organisms that have short generation times and are easily propagated in the laboratory. Replicate hybrid zones with a diversity of recombinant genotypes of varying age offer increased resolution for genetic mapping experiments and expand the pool of organisms amenable to genetic study. Using 88 markers distributed across 17 chromosomes, we analyze the introgression of chromosomal segments of Helianthus petiolaris into H. annuus in three natural hybrid zones. Introgression was significantly reduced relative to neutral expectations for 26 chromosomal segments, suggesting that each segment contains one or more factors that contribute to isolation. Pollen sterility is significantly associated with 16 of these 26 segments, providing a straightforward explanation of why this subset of blocks is disadvantageous in hybrids. In addition, comparison of rates of introgression across colinear vs. rearranged chromosomes indicates that close to 50% of the barrier to introgression is due to chromosomal rearrangements. These results demonstrate the utility of hybrid zones for identifying factors contributing to isolation and verify the prediction of increased resolution relative to controlled crosses.

scholarly journals Sex, amitosis, and evolvability in the ciliate Tetrahymena thermophila

2021 ◽  
Author(s):  
Jason A Tarkington ◽  
Hao Zhang ◽  
Ricardo Azevedo ◽  
Rebecca Zufall
Keyword(s):  
Genetic Variation ◽  
Experimental Evolution ◽  
Evolutionary Biology ◽  
Genetic Architecture ◽  
Nuclear Division ◽  
Tetrahymena Thermophila ◽  
Laboratory Populations ◽  
Evolutionary Success ◽  
Sexual Progeny ◽  
Open Question

Understanding the mechanisms that generate genetic variation, and thus contribute to the process of adaptation, is a major goal of evolutionary biology. Mutation and genetic exchange have been well studied as mechanisms to generate genetic variation. However, there are additional processes that may also generate substantial genetic variation in some populations and the extent to which these variation generating mechanisms are themselves shaped by natural selection is still an open question. Tetrahymena thermophila is a ciliate with an unusual mechanism of nuclear division, called amitosis, which can generate genetic variation among the asexual descendants of a newly produced sexual progeny. We hypothesize that amitosis thus increases the evolvability of newly produced sexual progeny relative to species that undergo mitosis. To test this hypothesis, we used experimental evolution and simulations to compare the rate of adaptation in T. thermophila populations founded by a single sexual progeny to parental populations that had not had sex in many generations. The populations founded by a sexual progeny adapted more quickly than parental populations in both laboratory populations and simulated populations. This suggests that the additional genetic variation generated by amitosis of a heterozygote can increase the rate of adaptation following sex and may help explain the evolutionary success of the unusual genetic architecture of Tetrahymena and ciliates more generally.

scholarly journals Evolution of correlated complexity in the radically different courtship signals of birds-of-paradise

2018 ◽  
Author(s):  
Russell A. Ligon ◽  
Christopher D. Diaz ◽  
Janelle L. Morano ◽  
Jolyon Troscianko ◽  
Martin Stevens ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Evolutionary Biology ◽  
Evolutionary Dynamics ◽  
Functional Integration ◽  
Empirical Support ◽  
Evolutionary Patterns ◽  
Evolutionary Innovation ◽  
Birds Of Paradise ◽  
Analytical Approaches

Ornaments used in courtship often vary wildly among species, reflecting the evolutionary interplay between mate preference functions and the constraints imposed by natural selection. Consequently, understanding the evolutionary dynamics responsible for ornament diversification has been a longstanding challenge in evolutionary biology. However, comparing radically different ornaments across species, as well as different classes of ornaments within species, is a profound challenge to understanding diversification of sexual signals. Using novel methods and a unique natural history dataset, we explore evolutionary patterns of ornament evolution in a group - the birds-of-paradise - exhibiting dramatic phenotypic diversification widely assumed to be driven by sexual selection. Rather than the tradeoff between ornament types originally envisioned by Darwin and Wallace, we found positive correlations among cross-modal (visual/acoustic) signals indicating functional integration of ornamental traits into a composite unit - the courtship phenotype. Furthermore, given the broad theoretical and empirical support for the idea that systemic robustness - functional overlap and interdependency - promotes evolutionary innovation, we posit that birds-of-paradise have radiated extensively through ornamental phenotype space as a consequence of the robustness in the courtship phenotype that we document at a phylogenetic scale. We suggest that the degree of robustness in courtship phenotypes among taxa can provide new insights into the relative influence of sexual and natural selection on phenotypic radiations.Author SummaryAnimals frequently vary widely in ornamentation, even among closely related species. Understanding the patterns that underlie this variation is a significant challenge, requiring comparisons among drastically different traits - like comparing apples to oranges. Here, we use novel analytical approaches to quantify variation in ornamental diversity and richness across the wildly divergent birds-of-paradise, a textbook example of how sexual selection can profoundly shape organismal phenotypes. We find that color and acoustic complexity, along with behavior and acoustic complexity, are positively correlated across evolutionary time-scales. Positive covariation among ornament classes suggests that selection is acting on correlated suites of traits - a composite courtship phenotype - and that this integration may be partially responsible for the extreme variation we see in birds-of-paradise.

scholarly journals Negative frequency-dependent selection maintains coexisting genotypes during fluctuating selection

2019 ◽  
Author(s):  
Caroline B. Turner ◽  
Sean W. Buskirk ◽  
Katrina B. Harris ◽  
Vaughn S. Cooper
Keyword(s):  
Evolutionary Dynamics ◽  
Burkholderia Cenocepacia ◽  
Natural Environments ◽  
Fluctuating Selection ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Fluctuating Environment ◽  
Fluctuating Environments ◽  
Negative Frequency Dependent Selection ◽  
Selection For

AbstractNatural environments are rarely static; rather selection can fluctuate on time scales ranging from hours to centuries. However, it is unclear how adaptation to fluctuating environments differs from adaptation to constant environments at the genetic level. For bacteria, one key axis of environmental variation is selection for planktonic or biofilm modes of growth. We conducted an evolution experiment with Burkholderia cenocepacia, comparing the evolutionary dynamics of populations evolving under constant selection for either biofilm formation or planktonic growth with populations in which selection fluctuated between the two environments on a weekly basis. Populations evolved in the fluctuating environment shared many of the same genetic targets of selection as those evolved in constant biofilm selection, but were genetically distinct from the constant planktonic populations. In the fluctuating environment, mutations in the biofilm-regulating genes wspA and rpfR rose to high frequency in all replicate populations. A mutation in wspA first rose rapidly and nearly fixed during the initial biofilm phase but was subsequently displaced by a collection of rpfR mutants upon the shift to the planktonic phase. The wspA and rpfR genotypes coexisted via negative frequency-dependent selection around an equilibrium frequency that shifted between the environments. The maintenance of coexisting genotypes in the fluctuating environment was unexpected. Under temporally fluctuating environments coexistence of two genotypes is only predicted under a narrow range of conditions, but the frequency-dependent interactions we observed provide a mechanism that can increase the likelihood of coexistence in fluctuating environments.

scholarly journals Phenotype bias determines how RNA structures occupy the morphospace of all possible shapes

2020 ◽  
Author(s):  
Kamaludin Dingle ◽  
Fatme Ghaddar ◽  
Petr Šulc ◽  
Ard A. Louis
Keyword(s):  
Natural Selection ◽  
Rna Secondary Structure ◽  
Evolutionary Biology ◽  
Evolutionary Dynamics ◽  
Coarse Grained ◽  
Rna Structures ◽  
Non Coding Rna ◽  
Ultimate Cause ◽  
Uniform Random Sampling ◽  
Bias Versus

The relative prominence of developmental bias versus natural selection is a long standing controversy in evolutionary biology. Here we demonstrate quantitatively that developmental bias is the primary explanation for the occupation of the morphospace of RNA secondary structure (SS) shapes. By using the RNAshapes method to define coarse-grained SS classes, we can directly measure the frequencies that non-coding RNA SS shapes appear in nature. Our main findings are, firstly, that only the most frequent structures appear in nature: The vast majority of possible structures in the morphospace have not yet been explored. Secondly, and perhaps more surprisingly, these frequencies are accurately predicted by the likelihood that structures appear upon uniform random sampling of sequences. The ultimate cause of these patterns is not natural selection, but rather strong phenotype bias in the RNA genotype-phenotype (GP) map, a type of developmental bias that tightly constrains evolutionary dynamics to only act within a reduced subset of structures which are easy to “find”.

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