Search results for "adaptation"

2005

Background Despite the two-fold cost of sex, most of the higher animals reproduce sexually. The advantage of sex has been suggested to be its ability, through recombination, to generate greater genetic diversity than asexuality, thus enhancing adaptation in a changing environment. We studied the genetic diversity and the population structure of three closely related species of bag worm moths: two strictly sexual (Dahlica charlottae and Siederia rupicolella) and one strictly asexual (D. fennicella). These species compete for the same resources and share the same parasitoids.

Environmental effects on molecular and phenotypic variation in populations of Eruca sativa across a steep climatic gradient

2013

Abstract In Israel Eruca sativa has a geographically narrow distribution across a steep climatic gradient that ranges from mesic Mediterranean to hot desert environments. These conditions offer an opportunity to study the influence of the environment on intraspecific genetic variation. For this, we combined an analysis of neutral genetic markers with a phenotypic evaluation in common-garden experiments, and environmental characterization of populations that included climatic and edaphic parameters, as well as geographic distribution. A Bayesian clustering of individuals from nine representative populations based on amplified fragment length polymorphism (AFLP) divided the populations into a…

Frequency-dependent selection in human immunodeficiency virus type 1.

2001

Genetic variation is the main evolutionary strategy adopted by RNA viruses and retroviruses. Evolution operates through competition between different individuals in the same environment, resulting in the imposition of the fittest variant. The process of competition could be affected by various factors, including the frequency of the different competing individuals. In order to investigate this aspect, individual virus populations derived from a human immunodeficiency virus type 1 isolate were studied at different competing proportions. The dynamics of variant imposition in each competition experiment permitted the detection of frequency-dependent selection (FDS); i.e. the imposition of vari…

Defects in plant immunity modulate the rates and patterns of RNA virus evolution

2020

AbstractIt is assumed that host genetic variability for susceptibility to infection necessarily conditions virus evolution. Differences in host susceptibility can either drive the virus to diversify into strains that track different defense alleles (e.g., antigenic diversity) or to infect only the most susceptible genotypes. To clarify these processes and their effect on virulence, we have studied how variability in host defense responses determine the evolutionary fate of viruses. To accomplish this, we performed evolution experiments with Turnip mosaic potyvirus in Arabidopsis thaliana mutants. Mutant plants had disruptions in infection-response signaling pathways or in genes whose produc…

Conflict between co-occurring parasites as a confounding factor in manipulation studies?

2005

In their review, Thomas et al. (2005) highlight that, in cases where multiple infections occur in the same intermediate host individual, parasitic manipulation may be the result of not just a single parasite, but may be the cumulative effect of infection by two or more manipulating parasites. Such parasites may be in conflict when they share the same intermediate host but have different final hosts: they may manipulate the host in different ways in order to effect their different transmission p T c r s t s

A genetic background with low mutational robustness is associated with increased adaptability to a novel host in an RNA virus.

2009

Although mutational robustness is central to many evolutionary processes, its relationship to evolvability remains poorly understood and has been very rarely tested experimentally. Here, we measure the evolvability of Vesicular stomatitis virus in two genetic backgrounds with different levels of mutational robustness. We passaged the viruses into a novel cell type to model a host-jump episode, quantified changes in infectivity and fitness in the new host, evaluated the cost of adaptation in the original host and analyzed the genetic basis of this adaptation. Lineages evolved from the less robust genetic background demonstrated increased adaptability, paid similar costs of adaptation to the …

Adaptive response to wine selective pressures shapes the genome of a Saccharomyces interspecies hybrid

2021

During industrial processes, yeasts are exposed to harsh conditions, which eventually lead to adaptation of the strains. In the laboratory, it is possible to use experimental evolution to link the evolutionary biology response to these adaptation pressures for the industrial improvement of a specific yeast strain. In this work, we aimed to study the adaptation of a wine industrial yeast in stress conditions of the high ethanol concentrations present in stopped fermentations and secondary fermentations in the processes of champagne production. We used a commercial Saccharomyces cerevisiae × S. uvarum hybrid and assessed its adaptation in a modified synthetic must (M-SM) containing high ethan…

Clonal Interference and the Evolution of RNA Viruses

1999

In asexual populations, beneficial mutations that occur in different lineages compete with one another. This phenomenon, known as clonal interference, ensures that those beneficial mutations that do achieve fixation are of large effect. Clonal interference also increases the time between fixations, thereby slowing the adaptation of asexual populations. The effects of clonal interference were measured in the asexual RNA virus vesicular stomatitis virus; rates and average effects of beneficial mutations were quantified.

The cost of replication fidelity in an RNA virus

2005

It is often argued that high mutation rates are advantageous for RNA viruses, because they confer elevated rates of adaptation. However, there is no direct evidence showing a positive correlation between mutation and adaptation rates among RNA viruses. Moreover, theoretical work does not argue in favor of this prediction. We used a series of vesicular stomatitis virus clones harboring single amino acid substitutions in the RNA polymerase to demonstrate that changes inducing enhanced fidelity paid a fitness cost, but that there was no positive correlation between mutation an adaptation rates. We demonstrate that the observed mutation rate in vesicular stomatitis virus can be explained by a t…

Epistasis and the Adaptability of an RNA Virus

2005

Abstract We have explored the patterns of fitness recovery in the vesicular stomatitis RNA virus. We show that, in our experimental setting, reversions to the wild-type genotype were rare and fitness recovery was at least partially driven by compensatory mutations. We compared compensatory adaptation for genotypes carrying (1) mutations with varying deleterious fitness effects, (2) one or two deleterious mutations, and (3) pairs of mutations showing differences in the strength and sign of epistasis. In all cases, we found that the rate of fitness recovery and the proportion of reversions were positively affected by population size. Additionally, we observed that mutations with large fitness…