Low recombination rates in sexual species and sex–asex transitions

Haag, Christoph R.; Theodosiou, Loukas; Zahab, Roula; Lenormand, Thomas

doi:10.1098/rstb.2016.0461

Cited by 19 publications

(32 citation statements)

References 127 publications

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“…There are several exceptions: some chromosomes do not recombine in one sex (e.g. achiasmate species; see §2c) and often more than one CO per chromosome is observed on larger chromosomes (see [ 62 ]). Under the obligate CO requirement, a higher recombination rate could be achieved by increasing the number of chromosomes or by having smaller chromosomes; bird genomes, containing many microchromosomes, provide support for this hypothesis [ 37 , 63 ].…”

Section: Patterns Of Variation In Recombinationmentioning

confidence: 99%

Variation in recombination frequency and distribution across eukaryotes: patterns and processes

Stapley

Feulner

Johnston

et al. 2017

Phil. Trans. R. Soc. B

359

408

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Recombination, the exchange of DNA between maternal and paternal chromosomes during meiosis, is an essential feature of sexual reproduction in nearly all multicellular organisms. While the role of recombination in the evolution of sex has received theoretical and empirical attention, less is known about how recombination rate itself evolves and what influence this has on evolutionary processes within sexually reproducing organisms. Here, we explore the patterns of, and processes governing recombination in eukaryotes. We summarize patterns of variation, integrating current knowledge with an analysis of linkage map data in 353 organisms. We then discuss proximate and ultimate processes governing recombination rate variation and consider how these influence evolutionary processes. Genome-wide recombination rates (cM/Mb) can vary more than tenfold across eukaryotes, and there is large variation in the distribution of recombination events across closely related taxa, populations and individuals. We discuss how variation in rate and distribution relates to genome architecture, genetic and epigenetic mechanisms, sex, environmental perturbations and variable selective pressures. There has been great progress in determining the molecular mechanisms governing recombination, and with the continued development of new modelling and empirical approaches, there is now also great opportunity to further our understanding of how and why recombination rate varies.This article is part of the themed issue ‘Evolutionary causes and consequences of recombination rate variation in sexual organisms’.

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Section: Patterns Of Variation In Recombinationmentioning

confidence: 99%

Variation in recombination frequency and distribution across eukaryotes: patterns and processes

Stapley

Feulner

Johnston

et al. 2017

Phil. Trans. R. Soc. B

359

408

View full text Add to dashboard Cite

show abstract

“…Colombo [80] also gives an explicit characterization of what we callr, phrased as a generalization of the RI. Finally, Haag et al [81], after noting that terminal crossovers cause little shuffling and that map length is therefore an imperfect measure of genome-wide shuffling, suggest a better measure to be 'the average likelihood that a [crossover] occurs between two randomly chosen genes'. However, no mathematical expression that incorporates crossover position in the measurement of genome-wide shuffling has been developed and implemented.…”

Section: Introductionmentioning

confidence: 99%

A rigorous measure of genome-wide genetic shuffling that takes into account crossover positions and Mendel’s second law

Veller

Kleckner

Nowak

2017

Preprint

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Comparisons of genetic recombination, whether across species, the sexes, individuals, or different chromosomes, require a measure of total recombination. Traditional measures, such as map length, crossover frequency, and the recombination index, are not influenced by the positions of crossovers along chromosomes. Intuitively, though, a crossover in the middle of a chromosome causes more recombination than a crossover at the tip. Similarly, two crossovers very close to each other cause less recombination than if they were evenly spaced. Here, we study a measure of total recombination that does account for crossover position: average r, the probability that a random pair of loci recombines in the production of a gamete. Consistent with intuition, average r is larger when crossovers are more evenly spaced. We show that average r can be decomposed into distinct components deriving from intra-chromosomal recombination (crossing over) and inter-chromosomal recombination (independent assortment of chromosomes), allowing separate analysis of these components. Average r can be calculated given knowledge of crossover positions either at meiosis I or in gametes/offspring. Technological advances in cytology and sequencing over the past two decades make calculation of average r possible, and we demonstrate its calculation for male and female humans using both kinds of data.

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“…Colombo (81) also gives an explicit characterization of what we callr phrased as a generalization of the RI. Finally, Haag et al (82), after noting that terminal COs cause little shuffling and that map length is, therefore, an imperfect measure of genome-wide shuffling, suggest a better measure to be "the average likelihood that a CO occurs between two randomly chosen genes." However, no mathematical expression that A B Fig.…”

mentioning

confidence: 99%

A rigorous measure of genome-wide genetic shuffling that takes into account crossover positions and Mendel’s second law

Veller

Kleckner

Nowak

2019

Proc. Natl. Acad. Sci. U.S.A.

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Comparative studies in evolutionary genetics rely critically on evaluation of the total amount of genetic shuffling that occurs during gamete production. Such studies have been hampered by the absence of a direct measure of this quantity. Existing measures consider crossing-over by simply counting the average number of crossovers per meiosis. This is qualitatively inadequate, because the positions of crossovers along a chromosome are also critical: a crossover toward the middle of a chromosome causes more shuffling than a crossover toward the tip. Moreover, traditional measures fail to consider shuffling from independent assortment of homologous chromosomes (Mendel’s second law). Here, we present a rigorous measure of genome-wide shuffling that does not suffer from these limitations. We define the parameter r¯ as the probability that the alleles at two randomly chosen loci are shuffled during gamete production. This measure can be decomposed into separate contributions from crossover number and position and from independent assortment. Intrinsic implications of this metric include the fact that r¯ is larger when crossovers are more evenly spaced, which suggests a selective advantage of crossover interference. Utilization of r¯ is enabled by powerful emergent methods for determining crossover positions either cytologically or by DNA sequencing. Application of our analysis to such data from human male and female reveals that (i) r¯ in humans is close to its maximum possible value of 1/2 and that (ii) this high level of shuffling is due almost entirely to independent assortment, the contribution of which is ∼30 times greater than that of crossovers.

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Low recombination rates in sexual species and sex–asex transitions

Cited by 19 publications

References 127 publications

Variation in recombination frequency and distribution across eukaryotes: patterns and processes

Variation in recombination frequency and distribution across eukaryotes: patterns and processes

A rigorous measure of genome-wide genetic shuffling that takes into account crossover positions and Mendel’s second law

A rigorous measure of genome-wide genetic shuffling that takes into account crossover positions and Mendel’s second law

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