Achiasmy and sex chromosome evolution

Satomura, Kazuhiro; Osada, Naoki; Endo, Toshinori

doi:10.1016/j.egg.2019.100046

Cited by 14 publications

(14 citation statements)

References 153 publications

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“…Third, quantitative differences in recombination rate between sexes are common (heteroehiasmy; Lenormand and Dutheil, 2005); and even in some cases, recombination is totally absent in the heterogametic sex (26 cases of achiasmy reported; Satomura et al, 2019). As the sex chromosomes spend less time in the heterogametic sex ( of its time in XY males or in ZW females) than autosomes do ( of their time), achiasmy enhances the opportunity for neutral alleles to escape from the sex-linked incompatible loci to the extent that the sex chromosomes become a weaker interspecies barrier than autosomes (; confirming the trend of Muirhead and Presgraves, 2016).…”

Section: Discussionmentioning

confidence: 99%

The rates of introgression and barriers to genetic exchange between hybridizing species: sex chromosomes vs. autosomes

Fraïssé

Sachdeva

2020

Preprint

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Interspecific crossing experiments have shown that sex chromosomes play a major role in the reproductive isolation of many species. However, their ability to act as reproductive barriers, which hamper interspecific genetic exchange, has hardly been evaluated quantitatively in relation to autosomes. Yet, this genome-wide limitation of gene flow is essential for understanding the complete separation of species, and thus speciation. Here, we develop a mainland-island model of secondary contact between hybridizing species of a XY (or ZW) sexual system. We obtain theoretical predictions for the frequency of introgressed alleles, and the strength of the barrier to neutral gene flow of the two types of chromosomes carrying multiple interspecific barrier loci. Theoretical predictions are obtained for scenarios where introgressed alleles are rare. We show that the same analytical expressions apply for sex chromosomes and autosomes, but with different effective parameters. The specific features of sex chromosomes (hemizygosity and absence of recombination in the heterogametic sex) lead to reduced levels of introgression of the X (or Z) compared to autosomes. This effect is enhanced by certain types of dosage compensation or sex-biased forces; but it remains overall small (except when incompatibilities are recessive). We discuss these predictions in light of empirical data comprising model-based tests of introgression and dine surveys in various biological systems.

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Section: Discussionmentioning

confidence: 99%

The rates of introgression and barriers to genetic exchange between hybridizing species: sex chromosomes vs. autosomes

Fraïssé

Sachdeva

2020

Preprint

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“…Large families, and correspondingly many recombination events, are necessary to achieve the power required to characterize nonrecombining regions on sex chromosomes. This approach also cannot be used in species with sex‐limited recombination (e.g., several Diptera and Lepidoptera; see Satomura, Osada, & Endo, for a complete review).…”

Section: Guide For Identifying Sex Chromosomesmentioning

confidence: 99%

How to identify sex chromosomes and their turnover

et al. 2019

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Although sex is a fundamental component of eukaryotic reproduction, the genetic systems that control sex determination are highly variable. In many organisms the presence of sex chromosomes is associated with female or male development. Although certain groups possess stable and conserved sex chromosomes, others exhibit rapid sex chromosome evolution, including transitions between male and female heterogamety, and turnover in the chromosome pair recruited to determine sex. These turnover events have important consequences for multiple facets of evolution, as sex chromosomes are predicted to play a central role in adaptation, sexual dimorphism, and speciation. However, our understanding of the processes driving the formation and turnover of sex chromosome systems is limited, in part because we lack a complete understanding of interspecific variation in the mechanisms by which sex is determined. New bioinformatic methods are making it possible to identify and characterize sex chromosomes in a diverse array of non‐model species, rapidly filling in the numerous gaps in our knowledge of sex chromosome systems across the tree of life. In turn, this growing data set is facilitating and fueling efforts to address many of the unanswered questions in sex chromosome evolution. Here, we synthesize the available bioinformatic approaches to produce a guide for characterizing sex chromosome system and identity simultaneously across clades of organisms. Furthermore, we survey our current understanding of the processes driving sex chromosome turnover, and highlight important avenues for future research.

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“…Our current knowledge of neo-sex chromosome evolution and differentiation is primarily due to extensive work on Drosophila (e.g. [95][96][97][98]). In this model, males do not recombine (male achiasmy), therefore recombination is immediately arrested after fusion to a Y chromosome.…”

Section: Plos Geneticsmentioning

confidence: 99%

Meiosis reveals the early steps in the evolution of a neo-XY sex chromosome pair in the African pygmy mouse Mus minutoides

et al. 2020

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Sex chromosomes of eutherian mammals are highly different in size and gene content, and share only a small region of homology (pseudoautosomal region, PAR). They are thought to have evolved through an addition-attrition cycle involving the addition of autosomal segments to sex chromosomes and their subsequent differentiation. The events that drive this process are difficult to investigate because sex chromosomes in almost all mammals are at a very advanced stage of differentiation. Here, we have taken advantage of a recent translocation of an autosome to both sex chromosomes in the African pygmy mouse Mus minutoides, which has restored a large segment of homology (neo-PAR). By studying meiotic sex chromosome behavior and identifying fully sex-linked genetic markers in the neo-PAR, we demonstrate that this region shows unequivocal signs of early sex-differentiation. First, synapsis and resolution of DNA damage intermediates are delayed in the neo-PAR during meiosis. Second, recombination is suppressed or largely reduced in a large portion of the neo-PAR. However, the inactivation process that characterizes sex chromosomes during meiosis does not extend to this region. Finally, the sex chromosomes show a dual mechanism of association at metaphase-I that involves the formation of a chiasma in the neo-PAR and the preservation of an ancestral achiasmate mode of association in the non-homologous segments. We show that the study of meiosis is crucial to apprehend the onset of sex chromosome differentiation, as it introduces structural and functional constrains to sex chromosome evolution. Synapsis and DNA repair dynamics are the first processes affected in the incipient differentiation of X and Y chromosomes, and they may be involved in accelerating their evolution. This provides one of the very first reports of early steps in neo-sex chromosome differentiation in mammals, and for the first time a cellular framework for the addition-attrition model of sex chromosome evolution.

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Achiasmy and sex chromosome evolution

Cited by 14 publications

References 153 publications

The rates of introgression and barriers to genetic exchange between hybridizing species: sex chromosomes vs. autosomes

The rates of introgression and barriers to genetic exchange between hybridizing species: sex chromosomes vs. autosomes

How to identify sex chromosomes and their turnover

Meiosis reveals the early steps in the evolution of a neo-XY sex chromosome pair in the African pygmy mouse Mus minutoides

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