The Effective Size of Mixed Sexually and Asexually Reproducing Populations

Yonezawa, Katsuei; Ishii, Takuro; Nagamine, Tsukasa

doi:10.1534/genetics.166.3.1529

Cited by 25 publications

(30 citation statements)

References 27 publications

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“…Because previous authors mainly focused on mean and variance of F IS [19], [22], we wanted to assess if summering the distributions using their first moments could be trusted to describe the variations of distributions of F IS obtained under various levels of asexuality, drift and mutation forces, and to compare them to previous theoretical results.…”

Section: Resultsmentioning

confidence: 99%

The Exact Distributions of FIS under Partial Asexuality in Small Finite Populations with Mutation

Stoeckel

Masson

2014

PLoS ONE

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Reproductive systems like partial asexuality participate to shape the evolution of genetic diversity within populations, which is often quantified by the inbreeding coefficient F IS. Understanding how those mating systems impact the possible distributions of F IS values in theoretical populations helps to unravel forces shaping the evolution of real populations. We proposed a population genetics model based on genotypic states in a finite population with mutation. For populations with less than 400 individuals, we assessed the impact of the rates of asexuality on the full exact distributions of F IS, the probabilities of positive and negative F IS, the probabilities of fixation and the probabilities to observe changes in the sign of F IS over one generation. After an infinite number of generations, we distinguished three main patterns of effects of the rates of asexuality on genetic diversity that also varied according to the interactions of mutation and genetic drift. Even rare asexual events in mainly sexual populations impacted the balance between negative and positive F IS and the occurrence of extreme values. It also drastically modified the probability to change the sign of F IS value at one locus over one generation. When mutation prevailed over genetic drift, increasing rates of asexuality continuously increased the variance of F IS that reached its highest value in fully asexual populations. In consequence, even ancient asexual populations showed the entire F IS spectrum, including strong positive F IS. The prevalence of heterozygous loci only occurred in full asexual populations when genetic drift dominated.

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Section: Resultsmentioning

confidence: 99%

The Exact Distributions of FIS under Partial Asexuality in Small Finite Populations with Mutation

Stoeckel

Masson

2014

PLoS ONE

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“…Equation (10) assumes that sexual and asexual contributions are independent. Predictions relaxing this assumption and extensions to more complex models were given by Yonezawa et al (2000Yonezawa et al ( , 2004. Analytical expressions for these models of mixed sexual and asexual species were also given by Orive (1993) and using coalescence theory.…”

Section: Prediction Of the Effective Population Sizementioning

confidence: 99%

Prediction and estimation of effective population size

2016

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Effective population size (N e ) is a key parameter in population genetics. It has important applications in evolutionary biology, conservation genetics and plant and animal breeding, because it measures the rates of genetic drift and inbreeding and affects the efficacy of systematic evolutionary forces, such as mutation, selection and migration. We review the developments in predictive equations and estimation methodologies of effective size. In the prediction part, we focus on the equations for populations with different modes of reproduction, for populations under selection for unlinked or linked loci and for the specific applications to conservation genetics. In the estimation part, we focus on methods developed for estimating the current or recent effective size from molecular marker or sequence data. We discuss some underdeveloped areas in predicting and estimating N e for future research.Heredity ( INTRODUCTIONThe concept of effective population size, introduced by Sewall Wright (1931, 1933), is central to plant and animal breeding (Falconer and Mackay, 1996), conservation genetics (Frankham et al., 2010;Allendorf et al., 2013) and molecular variation and evolution (Charlesworth and Charlesworth, 2010), as it quantifies the magnitude of genetic drift and inbreeding in real-world populations. A substantial number of extensions to the basic theory and predictions were made since the seminal work of Wright, with main early developments by James Crow and Motoo Kimura (Kimura and Crow, 1963a;Crow and Kimura, 1970) and later by a list of contributors. Several review papers (Crow and Denniston, 1988;Caballero, 1994;Wang and Caballero, 1999;Nomura, 2005a) and population genetic books (Fisher, 1965;Wright, 1969;Ewens, 1979;Nagylaki, 1992) have summarised the existing theory in predicting the effective size of a population at different spatial and timescales under various inheritance modes and demographies. Comparatively, methodological developments (reviewed by Schwartz et al., 1999;Beaumont, 2003a;Wang, 2005;Palstra and Ruzzante, 2008;Luikart et al., 2010;Gilbert and Whitlock, 2015) in estimating the effective size of natural populations from genetic data lag behind but are accelerating in the past decade, thanks to the rapid developments of molecular biology.The classical developments of effective population size theory are based on the rate of change in gene frequency variance (genetic drift) or the rate of inbreeding. The effective population size is defined in reference to the Wright-Fisher idealised population, that is, a hypothetical population with very simplifying characteristics where genetic drift is the only factor in operation, and the dynamics of allelic and genotypic frequencies across generations merely depend on the population census (N) size. The effective size of a real population is then defined as the size of an idealised population, which would give rise to the rate of inbreeding and the rate of change in variance of gene frequencies actually observed in the population under consideration,

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“…Because vegetative regeneration is possible even when seedling establishment is impaired or rare, new habitats can be utilized and recovery from disturbances can commence; this has been extensively documented in the American aspen, Populus tremuloides (Mock et al 2008). Although no general trend has been established, it has been suggested that clonality affects population genetics parameters such as effective population size, linkage disequilibrium, and heterozygosity (Balloux et al 2003;Yonezawa et al 2004). At the local scale, uneven spatial distribution of clonal ramets can generate spatial genetic structure (SGS) in established populations (Reusch et al 1999).…”

Section: Communicated By S González-martínezmentioning

confidence: 99%

SSR-based analysis of clonality, spatial genetic structure and introgression from the Lombardy poplar into a natural population of Populus nigra L. along the Loire River

Chenault¹,

Arnaud‐Haond

Juteau³

et al. 2011

Tree Genetics & Genomes

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A scarcity of favourable habitats and introgression from exotic cultivars are two major threats to black poplars (Populus nigra L.) in Europe. Natural vegetative propagation contributes to maintenance of the species in areas where seedling recruitment is limited. Exhaustive sampling of all mature trees in a natural P. nigra stand (413 individuals at recorded positions), genotyping at 11 SSR loci, and a standardized analysis framework resulted in a precise description of clonality in terms of (a) frequency, (b) spatial growth form, and (c) impacts on the overall spatial genetic structure (SGS). The high proportion of replicated genotypes detected resulted in a genotypic richness (R) of 0.47. Up to 18 ramets were found per multilocus lineage (MLL), but 95% of MLLs contained fewer than five ramets (Pareto index β=1.07). No significant difference in vegetative propagation potential was found between genders. Uneven spatial distribution of ramets, with clustering of clonal ramets (aggregation index A c =0.62) and near-zero intermingling between MLLs (clonal dominance index D c = 0.99), resulted in a 'phalanx' clonal growth form, explaining most of the SGS observed over short distances (0-20 m, Sp=0.0324). Although they did not exhibit the typical columnar shape of the Lombardy poplar (P. nigra var. italica), five trees were found to be probable F 1 hybrids of this old and widely distributed cultivar.

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The Effective Size of Mixed Sexually and Asexually Reproducing Populations

Cited by 25 publications

References 27 publications

The Exact Distributions of FIS under Partial Asexuality in Small Finite Populations with Mutation

The Exact Distributions of FIS under Partial Asexuality in Small Finite Populations with Mutation

Prediction and estimation of effective population size

SSR-based analysis of clonality, spatial genetic structure and introgression from the Lombardy poplar into a natural population of Populus nigra L. along the Loire River

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