The Effective Size of Annual Plant Populations: The Interaction of a Seed Bank with Fluctuating Population Size in Maintaining Genetic Variation

2002 ◽  
Vol 160 (2) ◽  
pp. 195-204 ◽  
Author(s):  
Leonard Nunney
Keyword(s):  
Genetic Variation ◽  
Population Size ◽  
Seed Bank ◽  
Effective Size ◽  
Annual Plant ◽  
Plant Populations

scholarly journals How general are positive relationships between plant population size, fitness and genetic variation?

2006 ◽  
Vol 94 (5) ◽  
pp. 942-952 ◽  
Author(s):  
ROOSA LEIMU ◽  
PIA MUTIKAINEN ◽  
JULIA KORICHEVA ◽  
MARKUS FISCHER
Keyword(s):  
Genetic Variation ◽  
Population Size ◽  
Plant Population ◽  
Positive Relationships ◽  
Plant Population Size

A Neutral Model With Fluctuating Population Size and Its Effective Size

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 381-388
Author(s):  
Masaru Iizuka ◽  
Hidenori Tachida ◽  
Hirotsugu Matsuda
Keyword(s):  
Asymptotic Behavior ◽  
Population Size ◽  
Diffusion Model ◽  
Arithmetic Mean ◽  
Harmonic Mean ◽  
Effective Size ◽  
Neutral Model ◽  
Average Heterozygosity ◽  
Special Case ◽  
Concrete Model

Abstract We consider a diffusion model with neutral alleles whose population size is fluctuating randomly. For this model, the effects of fluctuation of population size on the effective size are investigated. The effective size defined by the equilibrium average heterozygosity is larger than the harmonic mean of population size but smaller than the arithmetic mean of population size. To see explicitly the effects of fluctuation of population size on the effective size, we investigate a special case where population size fluctuates between two distinct states. In some cases, the effective size is very different from the harmonic mean. For this concrete model, we also obtain the stationary distribution of the average heterozygosity. Asymptotic behavior of the effective size is obtained when the population size is large and/or autocorrelation of the fluctuation is weak or strong.

scholarly journals The distribution of mutational effects on fitness in Caenorhabditis elegans inferred from standing genetic variation

2020 ◽  
Author(s):  
Kimberly J. Gilbert ◽  
Stefan Zdraljevic ◽  
Daniel E. Cook ◽  
Asher D. Cutter ◽  
Erik C. Andersen ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Caenorhabditis Elegans ◽  
Population Size ◽  
Genomic Structure ◽  
Random Mating ◽  
Population Substructure ◽  
C Elegans ◽  
Fitness Effects ◽  
Self Fertilization ◽  
New Mutations

ABSTRACTThe distribution of fitness effects for new mutations is one of the most theoretically important but difficult to estimate properties in population genetics. A crucial challenge to inferring the distribution of fitness effects (DFE) from natural genetic variation is the sensitivity of the site frequency spectrum to factors like population size change, population substructure, and non-random mating. Although inference methods aim to control for population size changes, the influence of non-random mating remains incompletely understood, despite being a common feature of many species. We report the distribution of fitness effects estimated from 326 genomes of Caenorhabditis elegans, a nematode roundworm with a high rate of self-fertilization. We evaluate the robustness of DFE inferences using simulated data that mimics the genomic structure and reproductive life history of C. elegans. Our observations demonstrate how the combined influence of self-fertilization, genome structure, and natural selection can conspire to compromise estimates of the DFE from extant polymorphisms. These factors together tend to bias inferences towards weakly deleterious mutations, making it challenging to have full confidence in the inferred DFE of new mutations as deduced from standing genetic variation in species like C. elegans. Improved methods for inferring the distribution of fitness effects are needed to appropriately handle strong linked selection and selfing. These results highlight the importance of understanding the combined effects of processes that can bias our interpretations of evolution in natural populations.

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