Muller S Ratchet
Mostrando 1-10 de 10 artigos, teses e dissertações.
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1. Acúmulo de mutações em linhagens assexuadas: uma abordagem via experimentos computacionais / Accumulation of mutations in asexual lineages: a study using computer experiments
Studies about evolution have been developed since Charles Darwins publications about the Origin of species and Natural Selection in 1859. During the XX century major developments were achieved through mathematical and computational modeling, since only few number of species that their evolution can be studied in vivo, once that the time scale involed for dat
Publicado em: 2004
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2. Dinâmica adaptativa, genealogias e testes estatísticos de neutralidade em evolução molecular / Adaptive dynamics, Genealogies and statistical tests of neutrality in molecular evolution
This thesis discusses some topics of molecular evolution, extensively using generating function methods to find analytical results whenever possible. In first place, it gives the exact solution for the dynamics of an infinite population of infinitely long sequences (no back mutations) evolving under the action of deleterious mutations on either multiplicativ
Publicado em: 2004
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3. Dinâmica de modelos de genética de populações com recombinação. / Dynamics of population genetics models with recombination.
Juntamente com o processo de mutação, a recombinação intragênica, vista como a troca recíproca de material genético entre genomas, é um dos principais fatores geradores da diversidade genética. De fato, os diversos mecanismos de recombinação existentes na natureza (sexo, por exemplo) são freqüentemente citados como invenções do processo de evo
Publicado em: 2003
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4. Muller's Ratchet under Epistatic Selection
In a finite asexual population mean fitness may decrease by a process known as Muller's ratchet, which proceeds if all individuals with the minimum number of deleterious alleles are randomly lost. If these alleles have independent effects on fitness, previous analysis suggested that the rate of this decrease either remains constant or, if accumulation of mut
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5. Muller's ratchet decreases fitness of a DNA-based microbe.
Muller proposed that an asexual organism will inevitably accumulate deleterious mutations, resulting in an increase of the mutational load and an inexorable, ratchet-like, loss of the least mutated class [Muller, H.J. (1964) Mutat. Res. 1, 2-9]. The operation of Muller's ratchet on real populations has been experimentally demonstrated only in RNA viruses. Ho
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6. Size of genetic bottlenecks leading to virus fitness loss is determined by mean initial population fitness.
Genetic bottlenecks are important events in the genetic diversification of organisms and colonization of new ecological niches. Repeated bottlenecking of RNA viruses often leads to fitness losses due to the operation of Muller's ratchet. Herein we use vesicular stomatitis virus to determine the transmission population size which leads to fitness decreases of
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7. The solitary wave of asexual evolution
Using a previously undescribed approach, we develop an analytic model that predicts whether an asexual population accumulates advantageous or deleterious mutations over time and the rate at which either process occurs. The model considers a large number of linked identical loci, or nucleotide sites; assumes that the selection coefficient per site is much les
The National Academy of Sciences.
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8. Accelerated evolution and Muller's rachet in endosymbiotic bacteria.
Many bacteria live only within animal cells and infect hosts through cytoplasmic inheritance. These endosymbiotic lineages show distinctive population structure, with small population size and effectively no recombination. As a result, endosymbionts are expected to accumulate mildly deleterious mutations. If these constitute a substantial proportion of new m
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9. Evolution of Fitness in Experimental Populations of Vesicular Stomatitis Virus
The evolution of fitness in experimental clonal populations of vesicular stomatitis virus (VSV) has been compared under different genetic (fitness of initial clone) and demographic (population dynamics) regimes. In spite of the high genetic heterogeneity among replicates within experiments, there is a clear effect of population dynamics on the evolution of f
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10. A century of tobamovirus evolution in an Australian population of Nicotiana glauca.
The evolution over the past century of two tobamoviruses infecting populations of the immigrant plant Nicotiana glauca in New South Wales (NSW), Australia, has been studied. This plant species probably entered Australia in the 1870s. Isolates of the viruses were obtained from N. glauca specimens deposited in the NSW Herbarium between 1899 and 1972, and other