---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
PlanS_conform: '1'
_id: '20223'
abstract:
- lang: eng
  text: The first influential hypothesis for sex chromosome evolution was proposed
    in 1914 by H. J. Muller, who argued that once recombination was suppressed between
    the X and Y chromosomes, Y-linked genes become “sheltered” from selection, leading
    to accumulation of recessive loss-of-function (LOF) mutations and decay of Y-linked
    genes. The hypothesis fell out of favor in the 1970s because early mathematical
    models failed to support it and data on the dominance of lethal mutations were
    viewed as incompatible with the hypothesis. We reevaluate the main arguments against
    Muller's hypothesis and find that they do not conclusively exclude a role for
    sheltering in sex chromosome evolution. By relaxing restrictive assumptions of
    earlier models, we show that sheltering promotes fixation of LOF mutations with
    sexually dimorphic fitness effects, resulting in decay of X-linked genes that
    are exclusively expressed by males and Y-linked genes that are primarily, though
    not necessarily exclusively, expressed by females. We further show that drift
    and other processes contributing to Y degeneration (i.e. selective interference
    and regulatory evolution) expand conditions of Y-linked gene loss by sheltering.
    The actual contribution of sheltering to sex chromosome evolution hinges upon
    the distribution of dominance and sex-specific fitness effects of LOF mutations,
    which we discuss.
acknowledged_ssus:
- _id: ScienComp
acknowledgement: We thank Filip Ruzicka, Colin Olito, Akane Uesugi, Melissa Toups,
  Daniel Jeffries, the Associate Editor, and anonymous reviewers, for comments and
  suggestions on earlier versions of the paper. We are particularly grateful to Deborah
  Charlesworth and Brian Charlesworth for extensive comments on two different drafts
  of the manuscript. We also thank Aneil Agrawal and Thomas Lenormand for email correspondence
  about the data on dominance and ways to interpret it. Technical support was provided
  by ISTA Scientific Computing Unit.
article_number: msaf177
article_processing_charge: Yes
article_type: original
author:
- first_name: Andrea
  full_name: Mrnjavac, Andrea
  id: 353FAC84-AE61-11E9-8BFC-00D3E5697425
  last_name: Mrnjavac
- first_name: Beatriz
  full_name: Vicoso, Beatriz
  id: 49E1C5C6-F248-11E8-B48F-1D18A9856A87
  last_name: Vicoso
  orcid: 0000-0002-4579-8306
- first_name: Tim
  full_name: Connallon, Tim
  last_name: Connallon
citation:
  ama: Mrnjavac A, Vicoso B, Connallon T. An extension of Muller’s sheltering hypothesis
    for the evolution of sex chromosome gene content. <i>Molecular Biology and Evolution</i>.
    2025;42(8). doi:<a href="https://doi.org/10.1093/molbev/msaf177">10.1093/molbev/msaf177</a>
  apa: Mrnjavac, A., Vicoso, B., &#38; Connallon, T. (2025). An extension of Muller’s
    sheltering hypothesis for the evolution of sex chromosome gene content. <i>Molecular
    Biology and Evolution</i>. Oxford University Press. <a href="https://doi.org/10.1093/molbev/msaf177">https://doi.org/10.1093/molbev/msaf177</a>
  chicago: Mrnjavac, Andrea, Beatriz Vicoso, and Tim Connallon. “An Extension of Muller’s
    Sheltering Hypothesis for the Evolution of Sex Chromosome Gene Content.” <i>Molecular
    Biology and Evolution</i>. Oxford University Press, 2025. <a href="https://doi.org/10.1093/molbev/msaf177">https://doi.org/10.1093/molbev/msaf177</a>.
  ieee: A. Mrnjavac, B. Vicoso, and T. Connallon, “An extension of Muller’s sheltering
    hypothesis for the evolution of sex chromosome gene content,” <i>Molecular Biology
    and Evolution</i>, vol. 42, no. 8. Oxford University Press, 2025.
  ista: Mrnjavac A, Vicoso B, Connallon T. 2025. An extension of Muller’s sheltering
    hypothesis for the evolution of sex chromosome gene content. Molecular Biology
    and Evolution. 42(8), msaf177.
  mla: Mrnjavac, Andrea, et al. “An Extension of Muller’s Sheltering Hypothesis for
    the Evolution of Sex Chromosome Gene Content.” <i>Molecular Biology and Evolution</i>,
    vol. 42, no. 8, msaf177, Oxford University Press, 2025, doi:<a href="https://doi.org/10.1093/molbev/msaf177">10.1093/molbev/msaf177</a>.
  short: A. Mrnjavac, B. Vicoso, T. Connallon, Molecular Biology and Evolution 42
    (2025).
date_created: 2025-08-24T22:01:31Z
date_published: 2025-08-01T00:00:00Z
date_updated: 2025-09-30T14:25:57Z
day: '01'
ddc:
- '570'
department:
- _id: BeVi
doi: 10.1093/molbev/msaf177
external_id:
  isi:
  - '001547617100001'
  pmid:
  - '40713898'
file:
- access_level: open_access
  checksum: f40abffa56cb1e9ff65800f2a7d7b39a
  content_type: application/pdf
  creator: dernst
  date_created: 2025-09-02T07:47:32Z
  date_updated: 2025-09-02T07:47:32Z
  file_id: '20274'
  file_name: 2025_MolecularBioEvolution_Mrnjavac.pdf
  file_size: 1239841
  relation: main_file
  success: 1
file_date_updated: 2025-09-02T07:47:32Z
fulldoi: https://doi.org/10.1093/molbev/msaf177
has_accepted_license: '1'
intvolume: '        42'
isi: 1
issue: '8'
language:
- iso: eng
month: '08'
oa: 1
oa_version: Published Version
pmid: 1
publication: Molecular Biology and Evolution
publication_identifier:
  eissn:
  - 1537-1719
  issn:
  - 0737-4038
publication_status: published
publisher: Oxford University Press
quality_controlled: '1'
related_material:
  link:
  - relation: software
    url: https://git.ista.ac.at/bvicoso/xydegenerate
scopus_import: '1'
status: public
title: An extension of Muller's sheltering hypothesis for the evolution of sex chromosome
  gene content
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 42
year: '2025'
...
---
OA_place: publisher
OA_type: gold
_id: '19370'
abstract:
- lang: eng
  text: Sex-linked and autosomal loci experience different selective pressures and
    evolutionary dynamics. X (or Z) chromosomes are often hemizygous in males (or
    females), as Y (or W) chromosomes often degenerate. Such hemizygous regions can
    be under greater efficacy of selection, as recessive mutations are immediately
    exposed to selection in the heterogametic sex leading to faster adaptation and
    faster divergence on the X chromosome (the so-called Faster-X or Faster-Z effect).
    However, in young nonrecombining regions, Y/W chromosomes often have many functional
    genes, and many X/Z-linked loci are therefore diploid. The sheltering of recessive
    mutations on the X/Z by the Y/W homolog is expected to drive slower adaptation
    for diploid X/Z loci, i.e. a reduction in the efficacy of selection. While the
    Faster-X effect has been studied extensively, much less is known empirically about
    the evolutionary dynamics of diploid X or Z chromosomes. Here, we took advantage
    of published population genomic data in the female-heterogametic human parasite
    Schistosoma japonicum to characterize the gene content and diversity levels of
    the diploid and hemizygous regions of the Z chromosome. We used different metrics
    of selective pressures acting on genes to test for differences in the efficacy
    of selection in hemizygous and diploid Z regions, relative to autosomes. We found
    consistent patterns suggesting reduced Ne, and reduced efficacy of purifying selection,
    on both hemizygous and diploid Z regions. Moreover, relaxed selection was particularly
    pronounced for female-biased genes on the diploid Z, as predicted by recent theoretical
    work.
acknowledgement: The authors would like to thank three anonymous reviewers for comments
  and suggestions. We are also grateful to Christelle Fraïsse, Marwan Elkrewi, and
  Filip Ruzicka for the help in this project.
article_number: evaf021
article_processing_charge: Yes
article_type: original
author:
- first_name: Andrea
  full_name: Mrnjavac, Andrea
  id: 353FAC84-AE61-11E9-8BFC-00D3E5697425
  last_name: Mrnjavac
- first_name: Beatriz
  full_name: Vicoso, Beatriz
  id: 49E1C5C6-F248-11E8-B48F-1D18A9856A87
  last_name: Vicoso
  orcid: 0000-0002-4579-8306
citation:
  ama: Mrnjavac A, Vicoso B. Reduced efficacy of selection on a young Z chromosome
    region of schistosoma japonicum. <i>Genome Biology and Evolution</i>. 2025;17(2).
    doi:<a href="https://doi.org/10.1093/gbe/evaf021">10.1093/gbe/evaf021</a>
  apa: Mrnjavac, A., &#38; Vicoso, B. (2025). Reduced efficacy of selection on a young
    Z chromosome region of schistosoma japonicum. <i>Genome Biology and Evolution</i>.
    Oxford University Press. <a href="https://doi.org/10.1093/gbe/evaf021">https://doi.org/10.1093/gbe/evaf021</a>
  chicago: Mrnjavac, Andrea, and Beatriz Vicoso. “Reduced Efficacy of Selection on
    a Young Z Chromosome Region of Schistosoma Japonicum.” <i>Genome Biology and Evolution</i>.
    Oxford University Press, 2025. <a href="https://doi.org/10.1093/gbe/evaf021">https://doi.org/10.1093/gbe/evaf021</a>.
  ieee: A. Mrnjavac and B. Vicoso, “Reduced efficacy of selection on a young Z chromosome
    region of schistosoma japonicum,” <i>Genome Biology and Evolution</i>, vol. 17,
    no. 2. Oxford University Press, 2025.
  ista: Mrnjavac A, Vicoso B. 2025. Reduced efficacy of selection on a young Z chromosome
    region of schistosoma japonicum. Genome Biology and Evolution. 17(2), evaf021.
  mla: Mrnjavac, Andrea, and Beatriz Vicoso. “Reduced Efficacy of Selection on a Young
    Z Chromosome Region of Schistosoma Japonicum.” <i>Genome Biology and Evolution</i>,
    vol. 17, no. 2, evaf021, Oxford University Press, 2025, doi:<a href="https://doi.org/10.1093/gbe/evaf021">10.1093/gbe/evaf021</a>.
  short: A. Mrnjavac, B. Vicoso, Genome Biology and Evolution 17 (2025).
corr_author: '1'
date_created: 2025-03-09T23:01:27Z
date_published: 2025-02-01T00:00:00Z
date_updated: 2026-07-29T08:36:27Z
day: '01'
ddc:
- '570'
department:
- _id: BeVi
doi: 10.1093/gbe/evaf021
external_id:
  isi:
  - '001423671400001'
  pmid:
  - '39913672'
file:
- access_level: open_access
  checksum: e3aa993e3d6dad10cb806c243fa57408
  content_type: application/pdf
  creator: dernst
  date_created: 2025-03-10T08:25:59Z
  date_updated: 2025-03-10T08:25:59Z
  file_id: '19378'
  file_name: 2025_GBE_Mrnjavac.pdf
  file_size: 768371
  relation: main_file
  success: 1
file_date_updated: 2025-03-10T08:25:59Z
fulldoi: https://doi.org/10.1093/gbe/evaf021
has_accepted_license: '1'
intvolume: '        17'
isi: 1
issue: '2'
language:
- iso: eng
month: '02'
oa: 1
oa_version: Published Version
pmid: 1
publication: Genome Biology and Evolution
publication_identifier:
  eissn:
  - 1759-6653
publication_status: published
publisher: Oxford University Press
quality_controlled: '1'
related_material:
  link:
  - relation: software
    url: https://git.ista.ac.at/amrnjava/schistosomes_slower_z
  record:
  - id: '18549'
    relation: earlier_version
    status: public
scopus_import: '1'
status: public
title: Reduced efficacy of selection on a young Z chromosome region of schistosoma
  japonicum
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 17
year: '2025'
...
---
OA_embargo: '6'
OA_place: publisher
_id: '18531'
abstract:
- lang: eng
  text: "Sex chromosomes and autosomes exhibit very different evolutionary dynamics.\r\nThe
    Y chromosome usually degenerates, leaving many X-linked loci hemizygous in\r\nmales.
    Since recessive X-linked mutations are always exposed to selection in males,\r\nselection
    is more efficient on the X chromosome than on autosomes on recessive\r\nmutations,
    leading to faster adaptation on the X chromosome than other genomic\r\nregions,
    if beneficial mutations are on average recessive (known as the Faster-X\r\neffect).
    In the presence of the functional, but non-recombining gametolog on the Y (as\r\nis
    often the case in young non-recombining regions), recessive mutations are\r\nsheltered
    from selection on the X chromosome. We model this scenario and show that\r\nthe
    efficiency of selection is reduced on diploid X loci due to sheltering by the
    Y\r\nchromosome. Reduced efficiency of selection leads to slower adaptation and\r\nincreased
    accumulation of deleterious mutations (Slower-X effect). We extended this\r\nmodel
    to explore the effect of sex-specific selection on degeneration of sex\r\nchromosomes,
    showing theoretically that male-limited genes degenerate on the X\r\nchromosome
    and female-biased genes degenerate on the Y chromosome. This\r\nprediction depends
    on the effective population size and the mutation rate, explaining\r\nthe variety
    of sex chromosome degeneration patterns observed in nature.\r\nTo test for direct
    evidence of a Slower-X (or Slower-Z) effect, we analyzed the\r\nZW sex chromosomes
    of the flatworm Schistosoma japonicum, which have a very\r\nyoung non-recombining
    region with non-degenerated W. Diploid Z-linked genes have\r\nhigher ratios of
    non-synonymous to synonymous polymorphisms than autosomal\r\ngenes, supporting
    reduced efficiency of selection on the diploid Z region. These results\r\nprovide
    evidence of sheltering by the W chromosome, a mechanism that could\r\ncontribute
    to Z (X) chromosome degeneration, and illustrate contrasting evolutionary\r\npatterns
    in old and young sex chromosome regions. In addition, genes with sexspecific patterns
    of expression show opposite patterns of selection in the young\r\n(diploid) and
    old (hemizygous) Z, showing the complex manner in which sex-specific selection
    shapes the evolutionary patterns of sex chromosomes. "
acknowledged_ssus:
- _id: ScienComp
- _id: CampIT
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Andrea
  full_name: Mrnjavac, Andrea
  id: 353FAC84-AE61-11E9-8BFC-00D3E5697425
  last_name: Mrnjavac
citation:
  ama: Mrnjavac A. Early stages of sex chromosome evolution. 2024. doi:<a href="https://doi.org/10.15479/at:ista:18531">10.15479/at:ista:18531</a>
  apa: Mrnjavac, A. (2024). <i>Early stages of sex chromosome evolution</i>. Institute
    of Science and Technology Austria. <a href="https://doi.org/10.15479/at:ista:18531">https://doi.org/10.15479/at:ista:18531</a>
  chicago: Mrnjavac, Andrea. “Early Stages of Sex Chromosome Evolution.” Institute
    of Science and Technology Austria, 2024. <a href="https://doi.org/10.15479/at:ista:18531">https://doi.org/10.15479/at:ista:18531</a>.
  ieee: A. Mrnjavac, “Early stages of sex chromosome evolution,” Institute of Science
    and Technology Austria, 2024.
  ista: Mrnjavac A. 2024. Early stages of sex chromosome evolution. Institute of Science
    and Technology Austria.
  mla: Mrnjavac, Andrea. <i>Early Stages of Sex Chromosome Evolution</i>. Institute
    of Science and Technology Austria, 2024, doi:<a href="https://doi.org/10.15479/at:ista:18531">10.15479/at:ista:18531</a>.
  short: A. Mrnjavac, Early Stages of Sex Chromosome Evolution, Institute of Science
    and Technology Austria, 2024.
corr_author: '1'
date_created: 2024-11-11T08:40:45Z
date_published: 2024-11-11T00:00:00Z
date_updated: 2026-07-29T08:36:28Z
day: '11'
ddc:
- '576'
degree_awarded: PhD
department:
- _id: GradSch
- _id: BeVi
doi: 10.15479/at:ista:18531
file:
- access_level: closed
  checksum: 3e48b163c22114ef5d5371f758668289
  content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
  creator: amrnjava
  date_created: 2024-11-13T12:15:28Z
  date_updated: 2025-05-11T22:30:04Z
  embargo_to: open_access
  file_id: '18551'
  file_name: AMrnjavac_thesis_library.docx
  file_size: 26870629
  relation: source_file
  title: Early stages of sex chromosome evolution
- access_level: open_access
  checksum: 3ead60c1b678e7dcf018043aef3b5db2
  content_type: application/pdf
  creator: amrnjava
  date_created: 2024-11-13T12:15:54Z
  date_updated: 2025-05-11T22:30:04Z
  embargo: 2025-05-11
  file_id: '18552'
  file_name: AMrnjavac_thesis_library.pdf
  file_size: 4228766
  relation: main_file
  title: Early stages of sex chromosome evolution
file_date_updated: 2025-05-11T22:30:04Z
fulldoi: https://doi.org/10.15479/at:ista:18531
has_accepted_license: '1'
keyword:
- Sex chromosomes
- evolution
- selection
- sheltering
language:
- iso: eng
month: '11'
oa: 1
oa_version: Published Version
page: '181'
publication_identifier:
  issn:
  - 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
  record:
  - id: '12521'
    relation: part_of_dissertation
    status: public
  - id: '18549'
    relation: part_of_dissertation
    status: public
status: public
supervisor:
- first_name: Beatriz
  full_name: Vicoso, Beatriz
  id: 49E1C5C6-F248-11E8-B48F-1D18A9856A87
  last_name: Vicoso
  orcid: 0000-0002-4579-8306
title: Early stages of sex chromosome evolution
tmp:
  image: /images/cc_by_nc_nd.png
  legal_code_url: https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode
  name: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
    (CC BY-NC-ND 4.0)
  short: CC BY-NC-ND (4.0)
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2024'
...
---
OA_place: repository
_id: '18549'
abstract:
- lang: eng
  text: "Sex-linked and autosomal loci experience different selective pressures and\r\nevolutionary
    dynamics. X (or Z) chromosomes are often hemizygous, as Y (or W)\r\nchromosomes
    often degenerate. Such hemizygous regions can be under greater\r\nefficacy of
    selection, as recessive mutations are immediately exposed to selection in\r\nthe
    heterogametic sex (the so-called Faster-X or Faster-Z effect). However, in young\r\nnon-recombining
    regions, Y/W chromosomes often have many functional genes, and\r\nmany X/Z-linked
    loci are therefore diploid. The sheltering of recessive mutations on\r\nthe X/Z
    by the Y/W homolog is expected to drive a Slower-X (Slower-Z) effect for\r\ndiploid
    X/Z loci, i.e. a reduction in the efficacy of selection. While the Faster-X effect\r\nhas
    been studied extensively, much less is known empirically about the evolutionary\r\ndynamics
    of diploid X or Z chromosomes. Here, we took advantage of published\r\npopulation
    genomic data in the female-heterogametic human parasite Schistosoma\r\njaponicum
    to characterize the gene content and diversity levels of the diploid and\r\nhemizygous
    regions of the Z chromosome. We used different metrics of selective\r\npressures
    acting on genes to test for differences in the efficacy of selection in\r\nhemizygous
    and diploid Z regions, relative to autosomes. We found consistent\r\npatterns
    suggesting reduced Ne, and reduced efficacy of purifying selection, on both\r\nhemizygous
    and diploid Z regions. Moreover, relaxed selection was particularly\r\npronounced
    for female-biased genes on the diploid Z, as predicted by Slower-Z\r\ntheory.\r\n"
article_processing_charge: No
author:
- first_name: Andrea
  full_name: Mrnjavac, Andrea
  id: 353FAC84-AE61-11E9-8BFC-00D3E5697425
  last_name: Mrnjavac
- first_name: Beatriz
  full_name: Vicoso, Beatriz
  id: 49E1C5C6-F248-11E8-B48F-1D18A9856A87
  last_name: Vicoso
  orcid: 0000-0002-4579-8306
biorxivid: 1
citation:
  ama: Mrnjavac A, Vicoso B. Evidence of a Slower-Z effect in Schistosoma japonicum.
    <i>bioRxiv</i>. doi:<a href="https://doi.org/10.1101/2024.07.02.601697">10.1101/2024.07.02.601697</a>
  apa: Mrnjavac, A., &#38; Vicoso, B. (n.d.). Evidence of a Slower-Z effect in Schistosoma
    japonicum. <i>bioRxiv</i>. <a href="https://doi.org/10.1101/2024.07.02.601697">https://doi.org/10.1101/2024.07.02.601697</a>
  chicago: Mrnjavac, Andrea, and Beatriz Vicoso. “Evidence of a Slower-Z Effect in
    Schistosoma Japonicum.” <i>BioRxiv</i>, n.d. <a href="https://doi.org/10.1101/2024.07.02.601697">https://doi.org/10.1101/2024.07.02.601697</a>.
  ieee: A. Mrnjavac and B. Vicoso, “Evidence of a Slower-Z effect in Schistosoma japonicum,”
    <i>bioRxiv</i>. .
  ista: Mrnjavac A, Vicoso B. Evidence of a Slower-Z effect in Schistosoma japonicum.
    bioRxiv, <a href="https://doi.org/10.1101/2024.07.02.601697">10.1101/2024.07.02.601697</a>.
  mla: Mrnjavac, Andrea, and Beatriz Vicoso. “Evidence of a Slower-Z Effect in Schistosoma
    Japonicum.” <i>BioRxiv</i>, doi:<a href="https://doi.org/10.1101/2024.07.02.601697">10.1101/2024.07.02.601697</a>.
  short: A. Mrnjavac, B. Vicoso, BioRxiv (n.d.).
corr_author: '1'
date_created: 2024-11-13T09:12:08Z
date_published: 2024-07-04T00:00:00Z
date_updated: 2026-09-12T22:31:10Z
day: '04'
department:
- _id: BeVi
doi: 10.1101/2024.07.02.601697
external_id:
  biorxivid:
  - 10.1101/2024.07.02.601697
fulldoi: https://doi.org/10.1101/2024.07.02.601697
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.1101/2024.07.02.601697
month: '07'
oa: 1
oa_version: Preprint
publication: bioRxiv
publication_status: draft
related_material:
  record:
  - id: '19370'
    relation: later_version
    status: public
  - id: '18531'
    relation: dissertation_contains
    status: public
status: public
title: Evidence of a Slower-Z effect in Schistosoma japonicum
tmp:
  image: /images/cc_by_nc_nd.png
  legal_code_url: https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode
  name: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
    (CC BY-NC-ND 4.0)
  short: CC BY-NC-ND (4.0)
type: preprint
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2024'
...
---
_id: '12521'
abstract:
- lang: eng
  text: Differentiated X chromosomes are expected to have higher rates of adaptive
    divergence than autosomes, if new beneficial mutations are recessive (the “faster-X
    effect”), largely because these mutations are immediately exposed to selection
    in males. The evolution of X chromosomes after they stop recombining in males,
    but before they become hemizygous, has not been well explored theoretically. We
    use the diffusion approximation to infer substitution rates of beneficial and
    deleterious mutations under such a scenario. Our results show that selection is
    less efficient on diploid X loci than on autosomal and hemizygous X loci under
    a wide range of parameters. This “slower-X” effect is stronger for genes affecting
    primarily (or only) male fitness, and for sexually antagonistic genes. These unusual
    dynamics suggest that some of the peculiar features of X chromosomes, such as
    the differential accumulation of genes with sex-specific functions, may start
    arising earlier than previously appreciated.
acknowledgement: We thank the Vicoso and Barton groups and ISTA Scientific Computing
  Unit. We also thank two anonymous reviewers for their valuable comments. This work
  was supported by the European Research Council under the European Union’s Horizon
  2020 research and innovation program (grant agreements no. 715257 and no. 716117).
article_number: qrac004
article_processing_charge: Yes (via OA deal)
article_type: original
author:
- first_name: Andrea
  full_name: Mrnjavac, Andrea
  id: 353FAC84-AE61-11E9-8BFC-00D3E5697425
  last_name: Mrnjavac
- first_name: Kseniia
  full_name: Khudiakova, Kseniia
  id: 4E6DC800-AE37-11E9-AC72-31CAE5697425
  last_name: Khudiakova
  orcid: 0000-0002-6246-1465
- first_name: Nicholas H
  full_name: Barton, Nicholas H
  id: 4880FE40-F248-11E8-B48F-1D18A9856A87
  last_name: Barton
  orcid: 0000-0002-8548-5240
- first_name: Beatriz
  full_name: Vicoso, Beatriz
  id: 49E1C5C6-F248-11E8-B48F-1D18A9856A87
  last_name: Vicoso
  orcid: 0000-0002-4579-8306
citation:
  ama: 'Mrnjavac A, Khudiakova K, Barton NH, Vicoso B. Slower-X: Reduced efficiency
    of selection in the early stages of X chromosome evolution. <i>Evolution Letters</i>.
    2023;7(1). doi:<a href="https://doi.org/10.1093/evlett/qrac004">10.1093/evlett/qrac004</a>'
  apa: 'Mrnjavac, A., Khudiakova, K., Barton, N. H., &#38; Vicoso, B. (2023). Slower-X:
    Reduced efficiency of selection in the early stages of X chromosome evolution.
    <i>Evolution Letters</i>. Oxford University Press. <a href="https://doi.org/10.1093/evlett/qrac004">https://doi.org/10.1093/evlett/qrac004</a>'
  chicago: 'Mrnjavac, Andrea, Kseniia Khudiakova, Nicholas H Barton, and Beatriz Vicoso.
    “Slower-X: Reduced Efficiency of Selection in the Early Stages of X Chromosome
    Evolution.” <i>Evolution Letters</i>. Oxford University Press, 2023. <a href="https://doi.org/10.1093/evlett/qrac004">https://doi.org/10.1093/evlett/qrac004</a>.'
  ieee: 'A. Mrnjavac, K. Khudiakova, N. H. Barton, and B. Vicoso, “Slower-X: Reduced
    efficiency of selection in the early stages of X chromosome evolution,” <i>Evolution
    Letters</i>, vol. 7, no. 1. Oxford University Press, 2023.'
  ista: 'Mrnjavac A, Khudiakova K, Barton NH, Vicoso B. 2023. Slower-X: Reduced efficiency
    of selection in the early stages of X chromosome evolution. Evolution Letters.
    7(1), qrac004.'
  mla: 'Mrnjavac, Andrea, et al. “Slower-X: Reduced Efficiency of Selection in the
    Early Stages of X Chromosome Evolution.” <i>Evolution Letters</i>, vol. 7, no.
    1, qrac004, Oxford University Press, 2023, doi:<a href="https://doi.org/10.1093/evlett/qrac004">10.1093/evlett/qrac004</a>.'
  short: A. Mrnjavac, K. Khudiakova, N.H. Barton, B. Vicoso, Evolution Letters 7 (2023).
corr_author: '1'
date_created: 2023-02-06T13:59:12Z
date_published: 2023-02-01T00:00:00Z
date_updated: 2026-09-12T22:31:10Z
day: '01'
ddc:
- '570'
department:
- _id: GradSch
- _id: BeVi
doi: 10.1093/evlett/qrac004
ec_funded: 1
external_id:
  isi:
  - '001021692200001'
  pmid:
  - '37065438'
file:
- access_level: open_access
  checksum: a240a041cb9b9b7c8ba93a4706674a3f
  content_type: application/pdf
  creator: dernst
  date_created: 2023-08-16T11:43:33Z
  date_updated: 2023-08-16T11:43:33Z
  file_id: '14068'
  file_name: 2023_EvLetters_Mrnjavac.pdf
  file_size: 2592189
  relation: main_file
  success: 1
file_date_updated: 2023-08-16T11:43:33Z
fulldoi: https://doi.org/10.1093/evlett/qrac004
has_accepted_license: '1'
intvolume: '         7'
isi: 1
issue: '1'
keyword:
- Genetics
- Ecology
- Evolution
- Behavior and Systematics
language:
- iso: eng
month: '02'
oa: 1
oa_version: Published Version
pmid: 1
project:
- _id: 256E75B8-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '716117'
  name: Optimal Transport and Stochastic Dynamics
- _id: 250BDE62-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '715257'
  name: Prevalence and Influence of Sexual Antagonism on Genome Evolution
publication: Evolution Letters
publication_identifier:
  issn:
  - 2056-3744
publication_status: published
publisher: Oxford University Press
quality_controlled: '1'
related_material:
  record:
  - id: '18531'
    relation: dissertation_contains
    status: public
scopus_import: '1'
status: public
title: 'Slower-X: Reduced efficiency of selection in the early stages of X chromosome
  evolution'
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 7
year: '2023'
...
---
_id: '12248'
abstract:
- lang: eng
  text: Eurasian brine shrimp (genus Artemia) have closely related sexual and asexual
    lineages of parthenogenetic females, which produce rare males at low frequencies.
    Although they are known to have ZW chromosomes, these are not well characterized,
    and it is unclear whether they are shared across the clade. Furthermore, the underlying
    genetic architecture of the transmission of asexuality, which can occur when rare
    males mate with closely related sexual females, is not well understood. We produced
    a chromosome-level assembly for the sexual Eurasian species Artemia sinica and
    characterized in detail the pair of sex chromosomes of this species. We combined
    this new assembly with short-read genomic data for the sexual species Artemia
    sp. Kazakhstan and several asexual lineages of Artemia parthenogenetica, allowing
    us to perform an in-depth characterization of sex-chromosome evolution across
    the genus. We identified a small differentiated region of the ZW pair that is
    shared by all sexual and asexual lineages, supporting the shared ancestry of the
    sex chromosomes. We also inferred that recombination suppression has spread to
    larger sections of the chromosome independently in the American and Eurasian lineages.
    Finally, we took advantage of a rare male, which we backcrossed to sexual females,
    to explore the genetic basis of asexuality. Our results suggest that parthenogenesis
    is likely partly controlled by a locus on the Z chromosome, highlighting the interplay
    between sex determination and asexuality.
acknowledged_ssus:
- _id: ScienComp
acknowledgement: "This work was supported by the European Research Council under the
  European Union’s Horizon 2020 research and innovation program (grant agreement no.
  715257) and by the Austrian Science Foundation (FWF SFB F88-10).\r\nWe thank the
  Vicoso group for comments on the manuscript and the ISTA Scientific computing team
  and the Vienna Biocenter Sequencing facility for technical support."
article_number: iyac123
article_processing_charge: No
article_type: original
author:
- first_name: Marwan N
  full_name: Elkrewi, Marwan N
  id: 0B46FACA-A8E1-11E9-9BD3-79D1E5697425
  last_name: Elkrewi
  orcid: 0000-0002-5328-7231
- first_name: Uladzislava
  full_name: Khauratovich, Uladzislava
  id: 5eba06f4-97d8-11ed-9f8f-d826ebdd9434
  last_name: Khauratovich
- first_name: Melissa A
  full_name: Toups, Melissa A
  id: 4E099E4E-F248-11E8-B48F-1D18A9856A87
  last_name: Toups
  orcid: 0000-0002-9752-7380
- first_name: Vincent K
  full_name: Bett, Vincent K
  id: 57854184-AAE0-11E9-8D04-98D6E5697425
  last_name: Bett
- first_name: Andrea
  full_name: Mrnjavac, Andrea
  id: 353FAC84-AE61-11E9-8BFC-00D3E5697425
  last_name: Mrnjavac
- first_name: Ariana
  full_name: Macon, Ariana
  id: 2A0848E2-F248-11E8-B48F-1D18A9856A87
  last_name: Macon
- first_name: Christelle
  full_name: Fraisse, Christelle
  id: 32DF5794-F248-11E8-B48F-1D18A9856A87
  last_name: Fraisse
  orcid: 0000-0001-8441-5075
- first_name: Luca
  full_name: Sax, Luca
  id: 701c5602-97d8-11ed-96b5-b52773c70189
  last_name: Sax
- first_name: Ann K
  full_name: Huylmans, Ann K
  id: 4C0A3874-F248-11E8-B48F-1D18A9856A87
  last_name: Huylmans
  orcid: 0000-0001-8871-4961
- first_name: Francisco
  full_name: Hontoria, Francisco
  last_name: Hontoria
- first_name: Beatriz
  full_name: Vicoso, Beatriz
  id: 49E1C5C6-F248-11E8-B48F-1D18A9856A87
  last_name: Vicoso
  orcid: 0000-0002-4579-8306
citation:
  ama: Elkrewi MN, Khauratovich U, Toups MA, et al. ZW sex-chromosome evolution and
    contagious parthenogenesis in Artemia brine shrimp. <i>Genetics</i>. 2022;222(2).
    doi:<a href="https://doi.org/10.1093/genetics/iyac123">10.1093/genetics/iyac123</a>
  apa: Elkrewi, M. N., Khauratovich, U., Toups, M. A., Bett, V. K., Mrnjavac, A.,
    Macon, A., … Vicoso, B. (2022). ZW sex-chromosome evolution and contagious parthenogenesis
    in Artemia brine shrimp. <i>Genetics</i>. Oxford University Press. <a href="https://doi.org/10.1093/genetics/iyac123">https://doi.org/10.1093/genetics/iyac123</a>
  chicago: Elkrewi, Marwan N, Uladzislava Khauratovich, Melissa A Toups, Vincent K
    Bett, Andrea Mrnjavac, Ariana Macon, Christelle Fraisse, et al. “ZW Sex-Chromosome
    Evolution and Contagious Parthenogenesis in Artemia Brine Shrimp.” <i>Genetics</i>.
    Oxford University Press, 2022. <a href="https://doi.org/10.1093/genetics/iyac123">https://doi.org/10.1093/genetics/iyac123</a>.
  ieee: M. N. Elkrewi <i>et al.</i>, “ZW sex-chromosome evolution and contagious parthenogenesis
    in Artemia brine shrimp,” <i>Genetics</i>, vol. 222, no. 2. Oxford University
    Press, 2022.
  ista: Elkrewi MN, Khauratovich U, Toups MA, Bett VK, Mrnjavac A, Macon A, Fraisse
    C, Sax L, Huylmans AK, Hontoria F, Vicoso B. 2022. ZW sex-chromosome evolution
    and contagious parthenogenesis in Artemia brine shrimp. Genetics. 222(2), iyac123.
  mla: Elkrewi, Marwan N., et al. “ZW Sex-Chromosome Evolution and Contagious Parthenogenesis
    in Artemia Brine Shrimp.” <i>Genetics</i>, vol. 222, no. 2, iyac123, Oxford University
    Press, 2022, doi:<a href="https://doi.org/10.1093/genetics/iyac123">10.1093/genetics/iyac123</a>.
  short: M.N. Elkrewi, U. Khauratovich, M.A. Toups, V.K. Bett, A. Mrnjavac, A. Macon,
    C. Fraisse, L. Sax, A.K. Huylmans, F. Hontoria, B. Vicoso, Genetics 222 (2022).
corr_author: '1'
date_created: 2023-01-16T09:56:10Z
date_published: 2022-10-01T00:00:00Z
date_updated: 2026-09-12T22:30:31Z
day: '01'
ddc:
- '570'
department:
- _id: BeVi
doi: 10.1093/genetics/iyac123
ec_funded: 1
external_id:
  isi:
  - '000850270300001'
  pmid:
  - '35977389'
file:
- access_level: open_access
  checksum: f79ff5383e882ea3f95f3da47a78029d
  content_type: application/pdf
  creator: dernst
  date_created: 2023-01-30T08:59:58Z
  date_updated: 2023-01-30T08:59:58Z
  file_id: '12440'
  file_name: 2022_Genetics_Elkrewi.pdf
  file_size: 1347136
  relation: main_file
  success: 1
file_date_updated: 2023-01-30T08:59:58Z
fulldoi: https://doi.org/10.1093/genetics/iyac123
has_accepted_license: '1'
intvolume: '       222'
isi: 1
issue: '2'
keyword:
- Genetics
language:
- iso: eng
month: '10'
oa: 1
oa_version: Published Version
pmid: 1
project:
- _id: 250BDE62-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '715257'
  name: Prevalence and Influence of Sexual Antagonism on Genome Evolution
- _id: 34ae1506-11ca-11ed-8bc3-c14f4c474396
  grant_number: F8810
  name: The highjacking of meiosis for asexual reproduction
publication: Genetics
publication_identifier:
  issn:
  - 1943-2631
publication_status: published
publisher: Oxford University Press
quality_controlled: '1'
related_material:
  record:
  - id: '11653'
    relation: research_data
    status: public
  - id: '19386'
    relation: dissertation_contains
    status: public
scopus_import: '1'
status: public
title: ZW sex-chromosome evolution and contagious parthenogenesis in Artemia brine
  shrimp
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 222
year: '2022'
...
