Numerical studies of the frequency trajectories in the process of fixation of null genes at duplicated loci

Maruyama, Takeo; Takahata, Naoyuki

doi:10.1038/hdy.1981.5

Cited by 24 publications

(11 citation statements)

References 22 publications

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“…Therefore T r is approximately equal to [log(1/l)]N for a large population, which indicates that T r for unlinked loci is asymptotically linear to N. Maruyama and Takahata (1981) observed that under the DNR model T r for unlinked duplication is much larger than that of linked in a large population. Lynch and Force (2000) examined the predictions of Eq.…”

Section: Introductionmentioning

confidence: 94%

Mean time to resolution of gene duplication

Cheng

2008

Genetica

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The mean time to resolution of gene duplication (T(r)) is studied in this paper under the double null recessive (DNR) and haplo-insufficient (HI) models within the same analytical and simulation framework. We show that when population size is not too small (more precisely Nmu > 0.1), T(r) for unlinked duplication is usually larger than that for linked and T(r) for unlinked duplication under the HI model might be greatly prolonged, which were consistent with previous observations. Furthermore, by analytical approach we here indicate the primary underlying mechanism is that the frequency of the original (or wild-type) chromosomal haplotype of the linked duplication decreases nearly exponential to zero with time while that of the unlinked decreases quickly to an quasi-equilibrium; and this phenomenon is particularly profound under the HI model, because the quasi-equilibrium frequency of the original chromosomal haplotype (x(0)) under the HI model is higher than that under the DNR model. These results suggest that recombination and HI model might jointly contribute to the marked prolongation of T(r) even in a modest population. The prolonged T(r) and higher quasi-equilibrium frequency of the original allele at both duplicated loci might have offered more opportunities for the emergence of novel genes.

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Section: Introductionmentioning

confidence: 94%

Mean time to resolution of gene duplication

Cheng

2008

Genetica

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“…As might be expected from both the prevalence of polyploidy and its perceived significance, the subject of gene duplication has long attracted the interest of population geneticists [28,106,129,142,146,148,216,217,220]. This work, which traces back at least as far as Haldane and Fisher in the 1930s [53,73], models one or more aspects of gene diversification or silencing using as input parameters factors such as mutation rates, fitness differences among alleles at duplicated loci, and effective population sizes.…”

Section: Evolution Of Duplicated Genesmentioning

confidence: 99%

Genome evolution in polyploids

Wendel

2000

Plant Molecular Evolution

744

923

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Polyploidy is a prominent process in plants and has been significant in the evolutionary history of vertebrates and other eukaryotes. In plants, interdisciplinary approaches combining phylogenetic and molecular genetic perspectives have enhanced our awareness of the myriad genetic interactions made possible by polyploidy. Here, processes and mechanisms of gene and genome evolution in polyploids are reviewed. Genes duplicated by polyploidy may retain their original or similar function, undergo diversification in protein function or regulation, or one copy may become silenced through mutational or epigenetic means. Duplicated genes also may interact through inter-locus recombination, gene conversion, or concerted evolution. Recent experiments have illuminated important processes in polyploids that operate above the organizational level of duplicated genes. These include inter-genomic chromosomal exchanges, saltation ai, non-Mendelian genomic evolution in nascent polyploids, inter-genomic invasion, and cytonuclear stabilization. Notwithstanding many recent insights, much remains to be learned about many aspects of polyploid evolution, including: the role of transposable elements in structural and regulatory gene evolution; processes and significance of epigenetic silencing; underlying controls of chromosome pairing; mechanisms and functional significance of rapid genome changes; cytonuclear accommodation; and coordination of regulatory factors contributed by two, sometimes divergent progenitor genomes. Continued application of molecular genetic approaches to questions of polyploid genome evolution holds promise for producing lasting insight into processes by which novel genotypes are generated and ultimately into how polyploidy facilitates evolution and adaptation.

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“…If gene frequencies are not equal at the two loci, as might be expected with drift or unequal mutation rates, then the inbreeding depression will more closely resemble that with single locus inheritance. Fixation of one of the deleterious alleles can occur when there are unequal mutation rates at the two loci (Christiansen & Frydenberg, 1977) or when the population size is small (Haldane, 1933;Nei, 1969;Ohno, 1972;Nei & Roychoudhury, 1973;Maruyama & Takahata, 1981). Gene silencing by the fixation of null alleles at duplicate loci has occurred frequently in the evolution of presumed ancient polyploids like salmonid and catostomid fishes (Allendorf, 1976;Ferris & Whitt, 1977;Li, 1980) and ferns (Werth eta!., 1985;Bryan & Soltis, 1987;Gastony, 1991;Werth & Windham, 1991).…”

Section: Idmentioning

confidence: 99%

Genetic analysis of inbreeding depression caused by chlorophyll-deficient lethals in Mimulus guttatus

Willis

1992

Heredity

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Two Oregon populations of the partially self-fertilizing Mimulus guttatus, located on Iron Mountain and Cone Peak, were surveyed for the frequency of recessive chlorophyll-deficient lethals by selfing plants collected as seed from the wild. Allelism tests were used to determine the number of different loci with lethal alleles present in the carriers isolated in the population surveys. The frequency of carriers was 0.065 for the Iron Mountain population (23/356) and 0.024 for the Cone Peak population (8/327). Allelism tests of the 31 carriers isolated from both populations revealed the existence of 26 different independently acting loci and two different duplicate locus systems with lethal alleles. These results indicate that the component of inbreeding depression caused by chlorophyll-deficient lethals is not due to single locus heterozygote advantage and is probably caused by mutation-selection balance at many loci. Estimates of the genomic and per locus mutation rates for this class of lethals are in close agreement with those obtained in studies of chlorophyll-deficient lethals in several agricultural plant species. Genetic analysis of a California population of M guttatus, reported in the literature to exhibit an unusually high per locus mutation rate and segregation distortion for a chlorophyll-deficient lethal, revealed that chlorophylldeficiency is inherited as a duplicate gene system. This mode of inheritance, not recognized previously, can explain the appearance of unusually high mutation rates and segregation distortion.

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Numerical studies of the frequency trajectories in the process of fixation of null genes at duplicated loci

Cited by 24 publications

References 22 publications

Mean time to resolution of gene duplication

Mean time to resolution of gene duplication

Genome evolution in polyploids

Genetic analysis of inbreeding depression caused by chlorophyll-deficient lethals in Mimulus guttatus

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