scholarly journals Standing Genetic Variation Drives Repeatable Experimental Evolution in Outcrossing Populations of Saccharomyces cerevisiae

2014 ◽  
Vol 31 (12) ◽  
pp. 3228-3239 ◽  
Author(s):  
Molly K. Burke ◽  
Gianni Liti ◽  
Anthony D. Long
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Variation ◽  
Experimental Evolution

scholarly journals Crossing design shapes patterns of genetic variation in synthetic recombinant populations of Saccharomyces cerevisiae

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mark A. Phillips ◽  
Ian C. Kutch ◽  
Kaitlin M. McHugh ◽  
Savannah K. Taggard ◽  
Molly K. Burke
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Variation ◽  
Experimental Evolution ◽  
Complex Traits ◽  
Inbred Lines ◽  
Equal Proportion ◽  
Adaptive Potential ◽  
Synthetic Populations ◽  
The Impact ◽  
Isogenic Strains

Abstract“Synthetic recombinant” populations have emerged as a useful tool for dissecting the genetics of complex traits. They can be used to derive inbred lines for fine QTL mapping, or the populations themselves can be sampled for experimental evolution. In the latter application, investigators generally value maximizing genetic variation in constructed populations. This is because in evolution experiments initiated from such populations, adaptation is primarily fueled by standing genetic variation. Despite this reality, little has been done to systematically evaluate how different methods of constructing synthetic populations shape initial patterns of variation. Here we seek to address this issue by comparing outcomes in synthetic recombinant Saccharomyces cerevisiae populations created using one of two strategies: pairwise crossing of isogenic strains or simple mixing of strains in equal proportion. We also explore the impact of the varying the number of parental strains. We find that more genetic variation is initially present and maintained when population construction includes a round of pairwise crossing. As perhaps expected, we also observe that increasing the number of parental strains typically increases genetic diversity. In summary, we suggest that when constructing populations for use in evolution experiments, simply mixing founder strains in equal proportion may limit the adaptive potential.

scholarly journals Crossing design shapes patterns of genetic variation in synthetic recombinant populations of Saccharomyces cerevisiae

2021 ◽  
Author(s):  
Mark A Phillips ◽  
Ian C Kutch ◽  
Molly Burke
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Variation ◽  
Experimental Evolution ◽  
Complex Traits ◽  
De Novo ◽  
Equal Proportion ◽  
Combination Strategies ◽  
The Impact ◽  
Isogenic Strains ◽  
Recombinant Population

Multiparent or synthetic recombinant populations those created by combining distinct isogenic founders to establish a single recombinant background have emerged as a useful tool for dissecting the genetics of complex traits. Synthetic recombinant populations can be used to derive inbred lines in which quantitative traits can be mapped, or the recombinant populations themselves can be sampled for experimental evolution. Especially for the latter application, investigators generally value maximizing genetic variation in a recombinant population; in other words, a population harboring relatively equal contributions of the genetic backgrounds of each isogenic founder strain is a desirable resource. It is well-documented that in evolution experiments initiated from recombinant or outbred ancestral populations, the subsequent adaptation that occurs in evolved populations is driven by standing genetic variation, rather than de novo mutations. Despite the demonstrated importance of initial genetic variation to the adaptive process, little has been done to systematically evaluate methods of constructing a synthetic recombinant population, for creating resources for evolution experiments. Here we seek to address this issue by comparing patterns of genetic variation in different synthetic recombinant populations of Saccharomyces cerevisiae created using one of two combination strategies: pairwise crossing of isogenic strains or simple mixing of strains in equal proportion. We also explore the impact of the varying the number of parental strains used in each strategy. We find that more genetic variation is initially present and subsequently maintained over generations when population construction includes a round of pairwise crossing. We also observe that when using a given crossing strategy, increasing the number of parental strains typically increases genetic diversity. In summary, we suggest that when creating recombinant populations for use in experimental evolution studies, simply mixing founder strains in equal proportion may limit the adaptive potential of that population.

scholarly journals Long-Term Experimental Evolution in Escherichia coli. VI. Environmental Constraints on Adaptation and Divergence

Genetics ◽  
1997 ◽  
Vol 146 (2) ◽  
pp. 471-479 ◽  
Author(s):  
Michael Travisano
Keyword(s):  
Escherichia Coli ◽  
Genetic Variation ◽  
Experimental Evolution ◽  
Population Genetic ◽  
Environmental Constraints ◽  
Asymmetric Pattern ◽  
Nutrient Environment ◽  
Mean Fitness ◽  
Population Genetic Variation

The effect of environment on adaptation and divergence was examined in two sets of populations of Escherichia coli selected for 1000 generations in either maltose- or glucose-limited media. Twelve replicate populations selected in maltose-limited medium improved in fitness in the selected environment, by an average of 22.5%. Statistically significant among-population genetic variation for fitness was observed during the course of the propagation, but this variation was small relative to the fitness improvement. Mean fitness in a novel nutrient environment, glucose-limited medium, improved to the same extent as in the selected environment, with no statistically significant among-population genetic variation. In contrast, 12 replicate populations previously selected for 1000 generations in glucose-limited medium showed no improvement, as a group, in fitness in maltose-limited medium and substantial genetic variation. This asymmetric pattern of correlated responses suggests that small changes in the environment can have profound effects on adaptation and divergence.

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 simple multicellularity increases environmental complexity

2016 ◽  
Author(s):  
María Rebolleda-Gómez ◽  
William C. Ratcliff ◽  
Jonathon Fankhauser ◽  
Michael Travisano
Keyword(s):  
Fluid Dynamics ◽  
Saccharomyces Cerevisiae ◽  
Experimental Evolution ◽  
Single Cells ◽  
Environmental Complexity ◽  
Major Transitions ◽  
Rapid Diversification ◽  
Ecological Mechanisms ◽  
Major Transitions In Evolution ◽  
Maintenance Of Diversity

AbstractMulticellularity—the integration of previously autonomous cells into a new, more complex organism—is one of the major transitions in evolution. Multicellularity changed evolutionary possibilities and facilitated the evolution of increased complexity. Transitions to multicellularity are associated with rapid diversification and increased ecological opportunity but the potential mechanisms are not well understood. In this paper we explore the ecological mechanisms of multicellular diversification during experimental evolution of the brewer’s yeast, Saccharomyces cerevisiae. The evolution from single cells into multicellular clusters modifies the structure of the environment, changing the fluid dynamics and creating novel ecological opportunities. This study demonstrates that even in simple conditions, incipient multicellularity readily changes the environment, facilitating the origin and maintenance of diversity.

Experimental evolution reveals natural selection on standing genetic variation

2009 ◽  
Vol 41 (2) ◽  
pp. 251-257 ◽  
Author(s):  
Henrique Teotónio ◽  
Ivo M Chelo ◽  
Martina Bradić ◽  
Michael R Rose ◽  
Anthony D Long
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Experimental Evolution

scholarly journals Environments with a high probability of incompatible crosses do not select for mate avoidance in spider mites

2018 ◽  
Author(s):  
Leonor R Rodrigues ◽  
Flore Zélé ◽  
Inês Santos ◽  
Sara Magalhães
Keyword(s):  
Genetic Variation ◽  
Mate Choice ◽  
Mixed Infection ◽  
Host Species ◽  
Experimental Evolution ◽  
High Probability ◽  
Spider Mite ◽  
Cytoplasmic Incompatibility ◽  
Spider Mites ◽  
Infection Frequency

AbstractArthropods are often infected withWolbachiainducing cytoplasmic incompatibility (CI), whereby crosses between uninfected females and infected males yield unviable fertilized offspring. Although uninfected females benefit from avoiding mating withWolbachia-infected males, this behaviour is not present in all host species. Here we measured the prevalence of this behaviour across populations of the spider miteTetranychus urticae. Females from five populations originally fully infected withWolbachiashowed no preference, possibly because they did not face the choice between compatible and incompatible mates in their environment. Hence, to determine whether this behaviour could be selected in populations with intermediateWolbachiainfection frequency, we performed 15 generations of experimental evolution of spider-mite populations under i) fullWolbachiainfection, ii) no infection, or iii) mixed infection. In the latter selection regime, where uninfected females were exposed to infected and uninfected males at every generation, mating duration increased relative to the uninfected regime, suggesting the presence of genetic variation for mating traits. However, mate choice did not evolve. Together, these results show that CI-inducingWolbachiaalone does not necessarily lead to the evolution of pre-copulatory strategies in uninfected hosts, even at intermediate infection frequency.

Sign in / Sign up

Export Citation Format

Share Document