scholarly journals Support for faster and more adaptive Z chromosome evolution in two divergent lepidopteran lineages

Evolution ◽  
2021 ◽  
Author(s):  
Andrew J. Mongue ◽  
Megan E. Hansen ◽  
James R. Walters
Keyword(s):  
Chromosome Evolution ◽  
Z Chromosome

scholarly journals Chromosomal Analysis in Crotophaga ani (Aves, Cuculiformes) Reveals Extensive Genomic Reorganization and an Unusual Z-Autosome Robertsonian Translocation

Cells ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 4
Author(s):  
Rafael Kretschmer ◽  
Ricardo José Gunski ◽  
Analía del Valle Garnero ◽  
Thales Renato Ochotorena de Freitas ◽  
Gustavo Akira Toma ◽  
...  
Keyword(s):  
Robertsonian Translocation ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Rare Event ◽  
Chromosome Morphology ◽  
Z Chromosome ◽  
Molecular Cytogenetic ◽  
Intrachromosomal Rearrangements ◽  
Genomic Reorganization

Although cytogenetics studies in cuckoos (Aves, Cuculiformes) have demonstrated an interesting karyotype variation, such as variations in the chromosome morphology and diploid number, their chromosome organization and evolution, and relation with other birds are poorly understood. Hence, we combined conventional and molecular cytogenetic approaches to investigate chromosome homologies between chicken and the smooth-billed ani (Crotophaga ani). Our results demonstrate extensive chromosome reorganization in C. ani, with interchromosomal rearrangements involving macro and microchromosomes. Intrachromosomal rearrangements were observed in some macrochromosomes, including the Z chromosome. The most evolutionary notable finding was a Robertsonian translocation between the microchromosome 17 and the Z chromosome, a rare event in birds. Additionally, the simple short repeats (SSRs) tested here were preferentially accumulated in the microchromosomes and in the Z and W chromosomes, showing no relationship with the constitutive heterochromatin regions, except in the W chromosome. Taken together, our results suggest that the avian sex chromosome is more complex than previously postulated and revealed the role of microchromosomes in the avian sex chromosome evolution, especially cuckoos.

scholarly journals Evolutionary Dynamics of Sex Chromosomes of Paleognathous Birds

2019 ◽  
Vol 11 (8) ◽  
pp. 2376-2390 ◽  
Author(s):  
Luohao Xu ◽  
Simon Yung Wa Sin ◽  
Phil Grayson ◽  
Scott V Edwards ◽  
Timothy B Sackton
Keyword(s):  
Sex Chromosomes ◽  
Evolutionary Dynamics ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Z Chromosome ◽  
Recombination Suppression ◽  
Evolutionary Forces ◽  
Genomic Level ◽  
Standard Models ◽  
Pseudoautosomal Regions

Abstract Standard models of sex chromosome evolution propose that recombination suppression leads to the degeneration of the heterogametic chromosome, as is seen for the Y chromosome in mammals and the W chromosome in most birds. Unlike other birds, paleognaths (ratites and tinamous) possess large nondegenerate regions on their sex chromosomes (PARs or pseudoautosomal regions). It remains unclear why these large PARs are retained over >100 Myr, and how this retention impacts the evolution of sex chromosomes within this system. To address this puzzle, we analyzed Z chromosome evolution and gene expression across 12 paleognaths, several of whose genomes have recently been sequenced. We confirm at the genomic level that most paleognaths retain large PARs. As in other birds, we find that all paleognaths have incomplete dosage compensation on the regions of the Z chromosome homologous to degenerated portions of the W (differentiated regions), but we find no evidence for enrichments of male-biased genes in PARs. We find limited evidence for increased evolutionary rates (faster-Z) either across the chromosome or in differentiated regions for most paleognaths with large PARs, but do recover signals of faster-Z evolution in tinamou species with mostly degenerated W chromosomes, similar to the pattern seen in neognaths. Unexpectedly, in some species, PAR-linked genes evolve faster on average than genes on autosomes, suggested by diverse genomic features to be due to reduced efficacy of selection in paleognath PARs. Our analysis shows that paleognath Z chromosomes are atypical at the genomic level, but the evolutionary forces maintaining largely homomorphic sex chromosomes in these species remain elusive.

scholarly journals Evolutionary dynamics of sex chromosomes of paleognathous birds

2018 ◽  
Author(s):  
Luohao Xu ◽  
Simon Yung Wa Sin ◽  
Phil Grayson ◽  
Scott V. Edwards ◽  
Timothy B. Sackton
Keyword(s):  
Sex Chromosomes ◽  
Evolutionary Dynamics ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Z Chromosome ◽  
Recombination Suppression ◽  
Evolutionary Forces ◽  
Genomic Level ◽  
Standard Models ◽  
Pseudoautosomal Regions

AbstractStandard models of sex chromosome evolution propose that recombination suppression leads to the degeneration of the heterogametic chromosome, as is seen for the Y chromosome in mammals and the W chromosome in most birds. Unlike other birds, paleognaths (ratites and tinamous) possess large non-degenerate regions on their sex chromosomes (PARs or pseudoautosomal regions). It remains unclear why these large PARs are retained over more than 100 MY, and how this retention impacts the evolution of sex chromosomes within this system. To address this puzzle, we analysed Z chromosome evolution and gene expression across 12 paleognaths, several of whose genomes have recently been sequenced. We confirm at the genomic level that most paleognaths retain large PARs. As in other birds, we find that all paleognaths have incomplete dosage compensation on the regions of the Z chromosome homologous to degenerated portions of the W (differentiated regions or DRs), but we find no evidence for enrichments of male-biased genes in PARs. We find limited evidence for increased evolutionary rates (faster-Z) either across the chromosome or in DRs for most paleognaths with large PARs, but do recover signals of faster-Z evolution in tinamou species with mostly degenerated W chromosomes, similar to the pattern seen in neognaths. Unexpectedly, in some species PAR-linked genes evolve faster on average than genes on autosomes, suggested by diverse genomic features to be due to reduced efficacy of selection in paleognath PARs. Our analysis shows that paleognath Z chromosomes are atypical at the genomic level, but the evolutionary forces maintaining largely homomorphic sex chromosomes in these species remain elusive.

scholarly journals Interaction between sex-determining genes from two species: clues from Xenopus hybrids

2021 ◽  
Vol 376 (1833) ◽  
pp. 20200104 ◽  
Author(s):  
Álvaro S. Roco ◽  
Adrián Ruiz-García ◽  
Mónica Bullejos
Keyword(s):  
Sex Chromosomes ◽  
Ovarian Development ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Parental Species ◽  
Z Chromosome ◽  
Gonadal Differentiation ◽  
Theme Issue ◽  
Testicular Differentiation

Hybrids provide an interesting model to study the evolution of sex-determining genes and sex chromosome systems as they offer the opportunity to see how independently evolving sex-determining pathways interact in vivo . In this context, the genus Xenopus represents a stimulating model, since species with non-homologous sex chromosomes and different sex-determining genes have been identified. In addition, the possibility of interspecies breeding is favoured in this group, which arose by alloploidization events, with species ploidy ranging from 2 n = 2 x = 20 in X. tropicalis (the only diploid representative of the genus) to 2 n = 12 x = 108 in X. ruwenzoriensis . To study how two sex-determining genes interact in vivo , X. laevis × X. tropicali s hybrids were produced. Gonadal differentiation in these hybrids revealed that the dm-w gene is dominant over X. tropicalis male-determining sex chromosomes (Y or Z), even though the Y chromosome is dominant in X. tropicalis (Y > W>Z). In the absence of the dm-w gene (the Z chromosome from X. laevis is present), the W chromosome from X. tropicalis is able to trigger ovarian development. Testicular differentiation will take place in the absence of W chromosomes from any of the parental species. The dominance/recessivity relationships between these sex-determining loci in the context of either parental genome remains unknown. This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)’.

scholarly journals Frequency of Cancer Genes on the Chicken Z Chromosome and Its Human Homologues: Implications for Sex Chromosome Evolution

2007 ◽  
Vol 2007 ◽  
pp. 1-8 ◽  
Author(s):  
Rami Stiglec ◽  
Matthias Kohn ◽  
James Fong ◽  
Tariq Ezaz ◽  
Horst Hameister ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Tumor Development ◽  
Single Copy ◽  
Z Chromosome ◽  
Cancer Genes ◽  
Database Analysis ◽  
Evolutionary Forces ◽  
Selection For

It has been suggested that there are special evolutionary forces that act on sex chromosomes. Hemizygosity of the X chromosome in male mammals has led to selection for male-advantage genes, and against genes posing extreme risks of tumor development. A similar bias against cancer genes should also apply to the Z chromosome that is present as a single copy in female birds. Using comparative database analysis, we found that there was no significant underrepresentation of cancer genes on the chicken Z, nor on the Z-orthologous regions of human chromosomes 5 and 9. This result does not support the hypothesis that genes involved in cancer are selected against on the sex chromosomes.

scholarly journals A Genetic Map of Ostrich Z Chromosome and the Role of Inversions in Avian Sex Chromosome Evolution

2018 ◽  
Vol 10 (8) ◽  
pp. 2049-2060 ◽  
Author(s):  
Homa Papoli Yazdi ◽  
Hans Ellegren
Keyword(s):  
Genetic Map ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Z Chromosome ◽  
Sex Chromosome Evolution

scholarly journals Sex chromosome degeneration, turnover, and sex-biased expression of sex-linked transcripts in African clawed frogs ( Xenopus )

2021 ◽  
Vol 376 (1832) ◽  
pp. 20200095 ◽  
Author(s):  
Xue-Ying Song ◽  
Benjamin L. S. Furman ◽  
Tharindu Premachandra ◽  
Martin Knytl ◽  
Caroline M. S. Cauret ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Z Chromosome ◽  
Sex Chromosome Evolution ◽  
Theme Issue ◽  
Recombination Suppression ◽  
Closely Related Species ◽  
African Clawed Frog ◽  
Clawed Frog

The tempo of sex chromosome evolution—how quickly, in what order, why and how their particular characteristics emerge during evolution—remains poorly understood. To understand this further, we studied three closely related species of African clawed frog (genus Xenopus ), that each has independently evolved sex chromosomes. We identified population polymorphism in the extent of sex chromosome differentiation in wild-caught Xenopus borealis that corresponds to a large, previously identified region of recombination suppression. This large sex-linked region of X. borealis has an extreme concentration of genes that encode transcripts with sex-biased expression, and we recovered similar findings in the smaller sex-linked regions of Xenopus laevis and Xenopus tropicalis . In two of these species, strong skews in expression (mostly female-biased in X. borealis , mostly male-biased in X. tropicalis ) are consistent with expectations associated with recombination suppression, and in X. borealis , we hypothesize that a degenerate ancestral Y-chromosome transitioned into its contemporary Z-chromosome. These findings indicate that Xenopus species are tolerant of differences between the sexes in dosage of the products of multiple genes, and offer insights into how evolutionary transformations of ancestral sex chromosomes carry forward to affect the function of new sex chromosomes. This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part I)’.

scholarly journals Evolutionary Strata on the Chicken Z Chromosome: Implications for Sex Chromosome Evolution

Genetics ◽  
2004 ◽  
Vol 167 (1) ◽  
pp. 367-376 ◽  
Author(s):  
Lori-Jayne Lawson Handley ◽  
Helene Ceplitis ◽  
Hans Ellegren
Keyword(s):  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Z Chromosome ◽  
Sex Chromosome Evolution

scholarly journals The genome sequence of the lesser marbled fritillary, Brenthis ino, and evidence for a segregating neo-Z chromosome

2021 ◽  
Author(s):  
Alexander Mackintosh ◽  
Dominik Laetsch ◽  
Tobias Baril ◽  
Robert Foster ◽  
Vlad Dincă ◽  
...  
Keyword(s):  
Chromosome Number ◽  
Genome Assembly ◽  
Chromosome Evolution ◽  
Population Genomics ◽  
The Other ◽  
Z Chromosome ◽  
Valuable Resource ◽  
Male Individual ◽  
Show Evidence ◽  
Chromosome Level

The lesser marbled fritillary, Brenthis ino (Rottemburg, 1775), is a species of Palearctic butterfly. Male B. ino individuals have been reported to have between 12 and 14 pairs of chromosomes, a much reduced chromosome number than is typical in butterflies. Here we present a chromosome-level genome assembly for B. ino, as well as gene and transposable element annotations. The assembly is 411.8 Mb in span with contig and scaffold N50s of 9.6 and 29.5 Mb respectively. We also show evidence that the male individual from which we generated HiC data was heterozygous for a neo-Z chromosome, consistent with inheriting 14 chromosomes from one parent and 13 from the other. This genome assembly will be a valuable resource for studying chromosome evolution in Lepidoptera, as well as for comparative and population genomics more generally.

scholarly journals ZZ Top: faster and more adaptive Z chromosome evolution in two Lepidoptera

2020 ◽  
Author(s):  
Andrew J. Mongue ◽  
Megan E. Hansen ◽  
James R. Walters
Keyword(s):  
Adaptive Evolution ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Monarch Butterfly ◽  
Z Chromosome ◽  
X Chromosomes ◽  
Mixed Support ◽  
Repeated Evolution ◽  
Opposing Effects ◽  
Haploid Selection

AbstractThe rate of divergence for Z or X chromosomes is theoretically predicted to be greater than autosomes, but the possible explanations for this pattern vary, as do empirical results from diverse taxa. Even among moths and butterflies (Lepidoptera), which generally share a single-origin Z chromosome, the handful of available studies give mixed support for faster or more adaptive evolution of the Z chromosome, depending on the species assayed. Here, we examine the molecular evolution of Z chromosomes in two additional lepidopteran species: the Carolina sphinx moth and the monarch butterfly, the latter of which possesses a recent chromosomal fusion yielding a segment of newly Z-linked DNA. We find evidence for both faster and more adaptive Z chromosome evolution in both species, though this effect is strongest in the neo-Z portion of the monarch sex chromosome. The neo-Z is less male-biased than expected of a Z chromosome, and unbiased and female-biased genes drive the signal for adaptive evolution here. Together these results suggest that male-biased gene accumulation and haploid selection have opposing effects on long-term rates of adaptation and may help explain the discrepancies in previous findings as well as the repeated evolution of neo-sex chromosomes in Lepidoptera.

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