Evolution and regulation of animal sex chromosomes

Nature Reviews Genetics, Journal Year: 2024, Volume and Issue: unknown

Published: July 18, 2024

Language: Английский

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Selection can favor a recombination landscape that limits polygenic adaptation

Molecular Biology and Evolution, Journal Year: 2025, Volume and Issue: 42(1)

Published: Jan. 1, 2025

Abstract Modifiers of recombination rates have been described but the selective pressures acting on them and their effect adaptation to novel environments remain unclear. We performed experimental evolution in nematode Caenorhabditis elegans using alternative rec-1 alleles modifying position meiotic crossovers along chromosomes without detectable direct fitness effects. show that a environment is impaired by allele decreases genomic regions containing variation. However, impairs indirectly favored selection, because it increases reduces associations among beneficial deleterious variation located its chromosomal vicinity. These results validate theoretical expectations about suggest genome-wide polygenic little consequence indirect selection rate modifiers.

Language: Английский

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Diversification and recurrent adaptation of the synaptonemal complex in Drosophila

PLoS Genetics, Journal Year: 2025, Volume and Issue: 21(1), P. e1011549 - e1011549

Published: Jan. 13, 2025

The synaptonemal complex (SC) is a protein-rich structure essential for meiotic recombination and faithful chromosome segregation. Acting like zipper to paired homologous chromosomes during early prophase I, the symmetrical where central elements are connected on two sides by transverse filaments chromatin-anchoring lateral elements. Despite being found in most major eukaryotic taxa implying deeply conserved evolutionary origin, several components of exhibit unusually high rates sequence turnover. This puzzlingly exemplified SC Drosophila , display no identifiable homologs outside genus. Here, we exhaustively examine history taking comparative phylogenomic approach with species density circumvent obscured homology due rapid evolution. Contrasting starkly against other genes involved pairing, show significantly elevated coding evolution combination relaxed constraint recurrent, widespread positive selection. In particular, element cona filament c(3) G have diversified through tandem retro-duplications, repeatedly generating paralogs novel germline activity. striking case molecular convergence, that independently arose distant lineages evolved under selection convergent truncations protein termini testes expression. Surprisingly, expression prone change suggesting recurrent regulatory which, many species, resulted even though males achiasmic. Overall, our study recapitulates poor conservation components, further uncovers lack extends modalities including copy number, genomic locale, regulation. Considering common ancestor, suggest activity male germline, while still poorly understood, may be prime target constant pressures driving repeated adaptations innovations.

Language: Английский

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Widespread Recombination Suppression Facilitates Plant Sex Chromosome Evolution

Molecular Biology and Evolution, Journal Year: 2020, Volume and Issue: 38(3), P. 1018 - 1030

Published: Oct. 22, 2020

Classical models suggest that recombination rates on sex chromosomes evolve in a stepwise manner to localize sexually antagonistic variants the which they are beneficial, thereby lowering of between X and Y chromosomes. However, it is also possible chromosome formation occurs regions with preexisting suppression. To evaluate these possibilities, we constructed linkage maps chromosome-scale genome assembly for dioecious plant Rumex hastatulus. This species has polymorphic karyotype young neo-sex chromosome, resulting from Robertsonian fusion an autosome, part its geographic range. We identified shared using comparative genetic two cytotypes. found sex-linked both ancestral embedded large low recombination. Furthermore, our comparison landscape autosomal homolog indicates mainly preceded linkage. These patterns not unique chromosomes; all were characterized by massive suppressed spanning most each chromosome. represents extreme case periphery-biased seen other systems Across chromosomes, gene repetitive sequence density correlated rate, variation differing element type. Our findings ancestrally may facilitate subsequent evolution heteromorphic

Language: Английский

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The Diversity and Evolution of Sex Chromosomes in Frogs

Genes, Journal Year: 2021, Volume and Issue: 12(4), P. 483 - 483

Published: March 26, 2021

Frogs are ideal organisms for studying sex chromosome evolution because of their diversity in differentiation and sex-determination systems. We review 222 anuran frogs, spanning ~220 Myr divergence, with characterized chromosomes, discuss evolution, phylogenetic distribution transitions between homomorphic heteromorphic states, as well Most (~75%) anurans have XY systems being three times more common than ZW remaining (~25%) almost equally represented. There Y-autosome fusions 11 species, no W-/Z-/X-autosome known. The phylogeny represents at least 19 16 cases independent chromosomes from homomorphy, the likely ancestral state. Five lineages mostly which might evolved due to demographic sexual selection attributes those lineages. Males do not recombine over most genome, regardless is heterogametic sex. Nevertheless, telomere-restricted recombination has once. More comparative genomic studies needed understand evolutionary trajectories among frog lineages, especially

Language: Английский

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When and how do sex‐linked regions become sex chromosomes?

Evolution, Journal Year: 2021, Volume and Issue: 75(3), P. 569 - 581

Published: Feb. 16, 2021

The attention given to heteromorphism and genetic degeneration of "classical sex chromosomes" (Y chromosomes in XY systems, the W ZW systems that were studied first are best described) has perhaps created impression absence recombination between is inevitable. I here argue continued often be expected, surprising demands further study, involvement selection reduced not yet well understood. Despite a long history investigations chromosome pairs, there need for more quantitative approaches studying sex-linked regions. describe scheme help understand relationships different properties Specifically, focus on their sizes (differentiating small regions extensive fully ones), times when they evolved, differentiation, review studies using DNA sequencing nonmodel organisms providing information about processes causing these properties.

Language: Английский

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Poorly differentiated XX/XY sex chromosomes are widely shared across skink radiation

Proceedings of the Royal Society B Biological Sciences, Journal Year: 2021, Volume and Issue: 288(1943), P. 20202139 - 20202139

Published: Jan. 20, 2021

Differentiated sex chromosomes are believed to be evolutionarily stable, while poorly differentiated considered prone turnovers. With around 1700 currently known species forming

Language: Английский

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Sex chromosome evolution: hallmarks and question marks

Molecular Biology and Evolution, Journal Year: 2024, Volume and Issue: 41(11)

Published: Oct. 16, 2024

Abstract Sex chromosomes are widespread in species with separate sexes. They have evolved many times independently and display a truly remarkable diversity. New sequencing technologies methodological developments allowed the field of molecular evolution to explore this diversity large number model nonmodel organisms, broadening our vision on mechanisms involved their evolution. Diverse studies us better capture common evolutionary routes that shape sex chromosomes; however, we still mostly fail explain why so diverse. We review over half century theoretical empirical work chromosome highlight pending questions origins, turnovers, rearrangements, degeneration, dosage compensation, gene content, rates also report recent progress understanding ultimate reasons for chromosomes’ existence.

Language: Английский

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A pedigree-based map of crossovers and non-crossovers in aye-ayes (Daubentonia madagascariensis)

Published: Nov. 11, 2024

Gaining a better understanding of rates and patterns meiotic recombination is crucial for improving evolutionary genomic modelling, with applications ranging from demographic to selective inference. Although previous research has provided important insights into the landscape crossovers in humans other haplorrhines, our both considerably more common outcome (i.e., non-crossovers) as well landscapes distantly-related primates strepsirrhines) remains limited owing difficulties associated identification non-crossover tracts species sampling. Thus, order elucidate this under-studied branch primate clade, we here characterize crossover aye-ayes utilizing whole-genome sequencing data six three-generation pedigrees three two-generation multi-sibling families, so doing provide novel process shaping diversity one world's most critically endangered species.

Language: Английский

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Pseudoreplication in genomics-scale datasets

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2020, Volume and Issue: unknown

Published: Nov. 13, 2020

Abstract In genomics-scale datasets, loci are closely packed within chromosomes and hence provide correlated information. Averaging across as if they were independent creates pseudoreplication, which reduces the effective degrees of freedom ( df’ ) compared to nominal freedom, df . This issue has been known for some time, but consequences have not systematically quantified entire genome. Here we measured pseudoreplication (quantified by ratio / a common metric genetic differentiation F ST measure linkage disequilibrium between pairs r 2 ). Based on data simulated using models SLiM msprime that allow efficient forward-in-time coalescent simulations while precisely controlling population pedigrees, estimated measuring rate decline in variance mean more used. For both indices, increases with N e genome size, expected. However, even large genomes, plateaus after few thousand loci, components analysis indicates limiting factor is uncertainty associated sampling individuals rather than genes. Pseudoreplication less extreme , ≤0.01 can occur datasets tens thousands loci. Commonly-used block-jackknife methods consistently overestimated var( ), producing very conservative confidence intervals. Predicting based our modeling results function L S size provides robust way quantify precision datasets.

Language: Английский

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