Gene conversion disparity in yeast: its extent, multiple origins, and effects on allele frequencies

ABSTRACT Gene conversion causes deviations from the 2:2 segregation of allele pairs in meiosis. Thus, gene conversion is a potential cause for changes of allele frequencies in populations. Equations are derived for the effects of conversion in a large random-mating population. The influence of gene conversion on allele frequencies is compared with that of spontaneous mutation and meiotic drive.

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The extent to which gene conversion can change allele frequencies in populations

Genetics Research ◽

10.1017/s0016672300020887 ◽

1982 ◽

Vol 39 (2) ◽

pp. 199-217 ◽

Cited By ~ 31

Author(s):

B. C. Lamb ◽

S. Helmi

Keyword(s):

Gene Conversion ◽

Allele Frequencies ◽

Numerical Examples ◽

Critical Comparison ◽

Control Factors ◽

Ascobolus Immersus ◽

Genetic Conversion

SummaryThe gene conversion parameters which affect allele frequencies in populations are defined, and their ranges and typical values are given for several genera of fungi, where meiotic octads and tetrads provide the best information on conversion. Both gene conversion and disparity in direction of conversion are common. Data from Ascobolus immersus show that conversion properties are largely stable with time, but can be changed environmentally and by genetic conversion control factors. Equations are given for the interactions of selection, mutation and gene conversion in determining equilibrium frequencies. Numerical examples, using typical values of conversion parameters from the fungal data, show that for alleles which are selectively neutral or have very low selection coefficients, conversion will often have very large effects on their equilibrium frequencies and may lead to fixation. Where selection coefficients are higher, conversion has major effects on the frequencies of deleterious recessive alleles, but lesser effects on deleterious dominant alleles: a critical comparison is that of s with 2y. The available estimates for conversion parameters (at least in fungi) are of a magnitude to make gene conversion an important factor in evolution.

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The effects of gene conversion control factors on conversion-induced changes in allele frequencies in populations and on linkage disequilibrium

Genetica ◽

10.1007/bf00121510 ◽

1989 ◽

Vol 79 (3) ◽

pp. 167-181 ◽

Cited By ~ 3

Author(s):

B. C. Lamb ◽

S. Helmi

Keyword(s):

Linkage Disequilibrium ◽

Gene Conversion ◽

Allele Frequencies ◽

Control Factors ◽

Induced Changes

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Biased Gene Conversion Skews Allele Frequencies in Human Populations, Increasing the Disease Burden of Recessive Alleles

The American Journal of Human Genetics ◽

10.1016/j.ajhg.2014.09.008 ◽

2014 ◽

Vol 95 (4) ◽

pp. 408-420 ◽

Cited By ~ 32

Author(s):

Joseph Lachance ◽

Sarah A. Tishkoff

Keyword(s):

Gene Conversion ◽

Disease Burden ◽

Allele Frequencies ◽

Human Populations ◽

Biased Gene Conversion

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Geographic variation in Megalorchestia californiana allele frequencies may be caused by winter rather than summer temperatures

Marine Ecology Progress Series ◽

10.3354/meps10363 ◽

2013 ◽

Vol 488 ◽

pp. 201-207

Author(s):

JH McDonald

Keyword(s):

Geographic Variation ◽

Allele Frequencies ◽

Summer Temperatures

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Comparative Analysis of Genetic and Morphological Variation within the Platanthera hyperborea Complex (Orchidaceae)

Systematic Botany ◽

10.1600/036364420x16033962925303 ◽

2020 ◽

Vol 45 (4) ◽

pp. 767-778

Author(s):

Eranga Wettewa ◽

Nick Bailey ◽

Lisa E. Wallace

Keyword(s):

North America ◽

Diploid Species ◽

Morphological Characters ◽

Evolutionary Patterns ◽

Founding Population ◽

Multiple Origins ◽

Geographic Structure ◽

Species Complexes ◽

Nuclear Its ◽

Cryptic Taxa

Abstract—Species complexes present considerable problems for a working taxonomy due to the presence of intraspecific variation, hybridization, polyploidy, and phenotypic plasticity. Understanding evolutionary patterns using molecular markers can allow for a more thorough assessment of evolutionary lineages than traditional morphological markers. In this study, we evaluated genetic diversity and phylogenetic patterns among taxa of the Platanthera hyperborea (Orchidaceae) complex, which includes diploid (Platanthera aquilonis) and polyploid (Platanthera hyperborea, P. huronensis, and P. convallariifolia) taxa spanning North America, Greenland, Iceland, and Asia. We found that three floral morphological characters overlap among the polyploid taxa, but the diploid species has smaller flowers. DNA sequence variation in a plastid (rpL16 intron) and a nuclear (ITS) marker indicated that at least three diploid species have contributed to the genomes of the polyploid taxa, suggesting all are of allopolyploid origin. Platanthera convallariifolia is most like P. dilatata and P. stricta, whereas P. huronensis and P. hyperborea appear to have originated from crosses of P. dilatata and P. aquilonis. Platanthera huronensis, which is found across North America, has multiple origins and reciprocal maternal parentage from the diploid species. By contrast, P. hyperborea, restricted to Greenland and Iceland, appears to have originated from a small founding population of hybrids in which P. dilatata was the maternal parent. Geographic structure was found among polyploid forms in North America. The area of Manitoba, Canada appears to be a contact zone among geographically diverse forms from eastern and western North America. Given the geographic and genetic variation found, we recommend continued recognition of four green-flowered species within this complex, but caution that there may be additional cryptic taxa within North America.

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