--- _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. Evolution Letters. 2023;7(1). doi:10.1093/evlett/qrac004' apa: 'Mrnjavac, A., Khudiakova, K., Barton, N. H., & Vicoso, B. (2023). Slower-X: Reduced efficiency of selection in the early stages of X chromosome evolution. Evolution Letters. Oxford University Press. https://doi.org/10.1093/evlett/qrac004' 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.” Evolution Letters. Oxford University Press, 2023. https://doi.org/10.1093/evlett/qrac004.' 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,” Evolution Letters, 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.” Evolution Letters, vol. 7, no. 1, qrac004, Oxford University Press, 2023, doi:10.1093/evlett/qrac004.' short: A. Mrnjavac, K. Khudiakova, N.H. Barton, B. Vicoso, Evolution Letters 7 (2023). date_created: 2023-02-06T13:59:12Z date_published: 2023-02-01T00:00:00Z date_updated: 2023-08-16T11:44:32Z 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 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' 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: '9917' abstract: - lang: eng text: Adaptive divergence and speciation may happen despite opposition by gene flow. Identifying the genomic basis underlying divergence with gene flow is a major task in evolutionary genomics. Most approaches (e.g., outlier scans) focus on genomic regions of high differentiation. However, not all genomic architectures potentially underlying divergence are expected to show extreme differentiation. Here, we develop an approach that combines hybrid zone analysis (i.e., focuses on spatial patterns of allele frequency change) with system-specific simulations to identify loci inconsistent with neutral evolution. We apply this to a genome-wide SNP set from an ideally suited study organism, the intertidal snail Littorina saxatilis, which shows primary divergence between ecotypes associated with different shore habitats. We detect many SNPs with clinal patterns, most of which are consistent with neutrality. Among non-neutral SNPs, most are located within three large putative inversions differentiating ecotypes. Many non-neutral SNPs show relatively low levels of differentiation. We discuss potential reasons for this pattern, including loose linkage to selected variants, polygenic adaptation and a component of balancing selection within populations (which may be expected for inversions). Our work is in line with theory predicting a role for inversions in divergence, and emphasizes that genomic regions contributing to divergence may not always be accessible with methods purely based on allele frequency differences. These conclusions call for approaches that take spatial patterns of allele frequency change into account in other systems. acknowledgement: We are very grateful to people who helped with fieldwork, snail processing, and DNA extractions, particularly Laura Brettell, Mårten Duvetorp, Juan Galindo, Anne-Lise Liabot and Irena Senčić. We would also like to thank Magnus Alm Rosenblad and Mats Töpel for their contribution to assembling the Littorina saxatilis genome, Carl André, Pasi Rastas, and Romain Villoutreix for discussion, and two anonymous reviewers for their helpful comments on the manuscript. We are grateful to RapidGenomics for library preparation and sequencing. We thank the Natural Environment Research Council, the European Research Council and the Swedish Research Councils VR and Formas (Linnaeus grant to the Centre for Marine Evolutionary Biology and Tage Erlander Guest Professorship) for funding. P.C. was funded by the University of Sheffield Vice-chancellor's India scholarship. R.F. is funded by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 706376. M. Raf. was supported by the Adlerbert Research Foundation. article_processing_charge: Yes article_type: letter_note author: - first_name: Anja M full_name: Westram, Anja M id: 3C147470-F248-11E8-B48F-1D18A9856A87 last_name: Westram orcid: 0000-0003-1050-4969 - first_name: Marina full_name: Rafajlović, Marina last_name: Rafajlović - first_name: Pragya full_name: Chaube, Pragya last_name: Chaube - first_name: Rui full_name: Faria, Rui last_name: Faria - first_name: Tomas full_name: Larsson, Tomas last_name: Larsson - first_name: Marina full_name: Panova, Marina last_name: Panova - first_name: Mark full_name: Ravinet, Mark last_name: Ravinet - first_name: Anders full_name: Blomberg, Anders last_name: Blomberg - first_name: Bernhard full_name: Mehlig, Bernhard last_name: Mehlig - first_name: Kerstin full_name: Johannesson, Kerstin last_name: Johannesson - first_name: Roger full_name: Butlin, Roger last_name: Butlin citation: ama: 'Westram AM, Rafajlović M, Chaube P, et al. Clines on the seashore: The genomic architecture underlying rapid divergence in the face of gene flow. Evolution Letters. 2018;2(4):297-309. doi:10.1002/evl3.74' apa: 'Westram, A. M., Rafajlović, M., Chaube, P., Faria, R., Larsson, T., Panova, M., … Butlin, R. (2018). Clines on the seashore: The genomic architecture underlying rapid divergence in the face of gene flow. Evolution Letters. Wiley. https://doi.org/10.1002/evl3.74' chicago: 'Westram, Anja M, Marina Rafajlović, Pragya Chaube, Rui Faria, Tomas Larsson, Marina Panova, Mark Ravinet, et al. “Clines on the Seashore: The Genomic Architecture Underlying Rapid Divergence in the Face of Gene Flow.” Evolution Letters. Wiley, 2018. https://doi.org/10.1002/evl3.74.' ieee: 'A. M. Westram et al., “Clines on the seashore: The genomic architecture underlying rapid divergence in the face of gene flow,” Evolution Letters, vol. 2, no. 4. Wiley, pp. 297–309, 2018.' ista: 'Westram AM, Rafajlović M, Chaube P, Faria R, Larsson T, Panova M, Ravinet M, Blomberg A, Mehlig B, Johannesson K, Butlin R. 2018. Clines on the seashore: The genomic architecture underlying rapid divergence in the face of gene flow. Evolution Letters. 2(4), 297–309.' mla: 'Westram, Anja M., et al. “Clines on the Seashore: The Genomic Architecture Underlying Rapid Divergence in the Face of Gene Flow.” Evolution Letters, vol. 2, no. 4, Wiley, 2018, pp. 297–309, doi:10.1002/evl3.74.' short: A.M. Westram, M. Rafajlović, P. Chaube, R. Faria, T. Larsson, M. Panova, M. Ravinet, A. Blomberg, B. Mehlig, K. Johannesson, R. Butlin, Evolution Letters 2 (2018) 297–309. date_created: 2021-08-16T07:45:38Z date_published: 2018-08-20T00:00:00Z date_updated: 2023-09-19T15:08:25Z day: '20' ddc: - '570' department: - _id: BeVi doi: 10.1002/evl3.74 external_id: isi: - '000446774400004' pmid: - '30283683' file: - access_level: open_access checksum: 8524e72507d521416be3f8ccfcd5e3f5 content_type: application/pdf creator: asandaue date_created: 2021-08-16T07:48:03Z date_updated: 2021-08-16T07:48:03Z file_id: '9918' file_name: 2018_EvolutionLetters_Westram.pdf file_size: 764299 relation: main_file success: 1 file_date_updated: 2021-08-16T07:48:03Z has_accepted_license: '1' intvolume: ' 2' isi: 1 issue: '4' language: - iso: eng month: '08' oa: 1 oa_version: Published Version page: 297-309 pmid: 1 publication: Evolution Letters publication_identifier: eissn: - 2056-3744 issn: - 2056-3744 publication_status: published publisher: Wiley quality_controlled: '1' related_material: record: - id: '9930' relation: research_data status: public status: public title: 'Clines on the seashore: The genomic architecture underlying rapid divergence in the face of gene flow' 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: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 2 year: '2018' ...