@article{21486,
  abstract     = {Sex-chromosome systems are highly variable across animals, but how they transition from one to another is not well understood. Diptera have undergone multiple sex-chromosome turnovers and expansions while maintaining their general chromosomal content, which makes them an ideal clade to study such transitions. We analyzed more than 100 dipteran whole-genome assemblies and identified 4 new lineages that underwent sex-chromosome turnover (in addition to the 5 previously reported). We find that the majority of turnovers happened in the group Schizophora, which tend to have fewer genes on Muller element F (the chromosome homologous to the ancestral insect X chromosome) than lower dipterans, a factor previously hypothesized to facilitate turnover. Most derived X chromosomes have higher GC content than autosomes, consistent with a high prevalence of male achiasmy in Diptera. In addition, an excess of gene movement out of the X is detected for most of these new X chromosomes, and many of these moved genes have high testis expression in Drosophila, suggesting that out-of-X gene movement contributes to the long-term demasculinization of X chromosomes.},
  author       = {Layana Franco, Lorena Alexandra and Toups, Melissa A and Vicoso, Beatriz},
  issn         = {2056-3744},
  journal      = {Evolution Letters},
  number       = {3},
  publisher    = {Oxford University Press},
  title        = {{Causes and consequences of sex-chromosome turnovers in Diptera}},
  doi          = {10.1093/evlett/qrag003},
  volume       = {10},
  year         = {2026},
}

@article{20009,
  abstract     = {The suppression of recombination between young X and Y chromosomes is a crucial step in their evolution, but why it occurs is not known. The detailed characterization of the polymorphic sex chromosomes of the fourspine stickleback by Liu et al. promises to shed new light on this longstanding question.},
  author       = {Vicoso, Beatriz},
  issn         = {0169-5347},
  journal      = {Trends in Ecology and Evolution},
  number       = {8},
  pages        = {728--730},
  publisher    = {Elsevier},
  title        = {{Sex chromosome evolution in action in fourspine sticklebacks}},
  doi          = {10.1016/j.tree.2025.06.010},
  volume       = {40},
  year         = {2025},
}

@article{20182,
  abstract     = {Sex chromosomes have evolved many times throughout the tree of life, and understanding what has shaped their unusual morphological, sequence, and regulatory features has been a long-standing goal. Most early insights into insect sex chromosome biology came from a few model species, such as the fruit fly Drosophila melanogaster, which limited broad-scale evolutionary inferences. More recently, extensive comparative genomics studies have uncovered several unexpected patterns, which we highlight in this review. First, we describe the conservation of the ancestral X chromosome over 450 million years but also its recurrent turnover (i.e. its reversal to an autosome when a new X chromosome arose) in at least one order. We then summarize classical and more recent findings on how insects modulate the expression of X-linked genes following the degradation of the Y chromosome and how the diverse mechanisms of dosage compensation identified may elucidate important principles of sex chromosome regulatory evolution.},
  author       = {Toups, Melissa A and Vicoso, Beatriz},
  issn         = {2214-5753},
  journal      = {Current Opinion in Insect Science},
  publisher    = {Elsevier},
  title        = {{Insect sex chromosome evolution: Conservation, turnover, and mechanisms of dosage compensation}},
  doi          = {10.1016/j.cois.2025.101411},
  volume       = {72},
  year         = {2025},
}

@phdthesis{20449,
  abstract     = {Males and females of many  species differ in morphology, physiology, and behavior. In taxa
with genetic sex determination, sexual differentiation arises largely from sex-biased gene
expression, which varies across tissues, developmental stages, and lineages. Increasing
evidence highlights chromatin configuration, which can exist in open or closed states, and can
be shaped by sex-determination path ways, as a key regulatory layer of this dimorphism.
Degeneration of the Y or W chromosome further contributes to sex -specific differences by
altering gene copy numbers relative to autosomes in heterogametic sex. To mitigate these
imbalances, many eukaryotes have independently evolved dosage compensation mechanisms,
often mediated through chromatin -level regulation. In this thesis, we investigate the
evolutionary dynamics of sex chromosome differentiation in two species, Artemia franciscana
and Cameraria  ohridella , with a particular focus on the extent of dosage compensation
following gene loss in the heterogametic sex and the potential chromatin-based mechanisms
underlying this process. We further characterize sex -biased gene expression and its regulation
through histone modifications. Our analyses also reveal that the A. franciscana genome is
highly repetitive, with many genes containing intronic transposable elements. We find that
enrichment of histonemo difications associated with constitutive heterochromatin, positively
correlates with variation in gene expression levels. Collectively, these findings underscore role
of chromatin regulation in shaping the evolution of sex chromosomes and sexual
differentiation. },
  author       = {Bett, Vincent K},
  issn         = {2663-337X},
  pages        = {114},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{Evolution and regulation of the Z chromosome}},
  doi          = {10.15479/AT-ISTA-20449},
  year         = {2025},
}

@article{19735,
  abstract     = {The males and females of the brine shrimp Artemia franciscana are highly dimorphic, and this dimorphism is associated with substantial sex-biased gene expression in heads and gonads. How these sex-specific patterns of expression are regulated at the molecular level is unknown. A. franciscana also has differentiated ZW sex chromosomes, with complete dosage compensation, but the molecular mechanism through which compensation is achieved is unknown. Here, we conducted CUT&TAG assays targeting 7 post-translational histone modifications (H3K27me3, H3K9me2, H3K9me3, H3K36me3, H3K27ac, H3K4me3, and H4K16ac) in heads and gonads of A. franciscana, allowing us to divide the genome into 12 chromatin states. We further defined functional chromatin signatures for all genes, which were correlated with transcript level abundances. Differences in the occupancy of the profiled epigenetic marks between sexes were associated with differential gene expression between males and females. Finally, we found a significant enrichment of the permissive H4K16ac histone mark in the Z-specific region in both tissues of females but not males, supporting the role of this histone mark in mediating dosage compensation of the Z chromosome.},
  author       = {Bett, Vincent K and Trejo Arellano, Minerva S and Vicoso, Beatriz},
  issn         = {1537-1719},
  journal      = {Molecular Biology and Evolution},
  number       = {5},
  publisher    = {Oxford University Press},
  title        = {{Chromatin landscape is associated with sex-biased expression and Drosophila-like dosage compensation of the Z chromosome in Artemia franciscana}},
  doi          = {10.1093/molbev/msaf085},
  volume       = {42},
  year         = {2025},
}