--- _id: '563' abstract: - lang: eng text: "In continuous populations with local migration, nearby pairs of individuals have on average more similar genotypes\r\nthan geographically well separated pairs. A barrier to gene flow distorts this classical pattern of isolation by distance. Genetic similarity is decreased for sample pairs on different sides of the barrier and increased for pairs on the same side near the barrier. Here, we introduce an inference scheme that utilizes this signal to detect and estimate the strength of a linear barrier to gene flow in two-dimensions. We use a diffusion approximation to model the effects of a barrier on the geographical spread of ancestry backwards in time. This approach allows us to calculate the chance of recent coalescence and probability of identity by descent. We introduce an inference scheme that fits these theoretical results to the geographical covariance structure of bialleleic genetic markers. It can estimate the strength of the barrier as well as several demographic parameters. We investigate the power of our inference scheme to detect barriers by applying it to a wide range of simulated data. We also showcase an example application to a Antirrhinum majus (snapdragon) flower color hybrid zone, where we do not detect any signal of a strong genome wide barrier to gene flow." article_processing_charge: No author: - first_name: Harald full_name: Ringbauer, Harald id: 417FCFF4-F248-11E8-B48F-1D18A9856A87 last_name: Ringbauer orcid: 0000-0002-4884-9682 - first_name: Alexander full_name: Kolesnikov, Alexander id: 2D157DB6-F248-11E8-B48F-1D18A9856A87 last_name: Kolesnikov - first_name: David full_name: Field, David last_name: Field - first_name: Nicholas H full_name: Barton, Nicholas H id: 4880FE40-F248-11E8-B48F-1D18A9856A87 last_name: Barton orcid: 0000-0002-8548-5240 citation: ama: Ringbauer H, Kolesnikov A, Field D, Barton NH. Estimating barriers to gene flow from distorted isolation-by-distance patterns. Genetics. 2018;208(3):1231-1245. doi:10.1534/genetics.117.300638 apa: Ringbauer, H., Kolesnikov, A., Field, D., & Barton, N. H. (2018). Estimating barriers to gene flow from distorted isolation-by-distance patterns. Genetics. Genetics Society of America. https://doi.org/10.1534/genetics.117.300638 chicago: Ringbauer, Harald, Alexander Kolesnikov, David Field, and Nicholas H Barton. “Estimating Barriers to Gene Flow from Distorted Isolation-by-Distance Patterns.” Genetics. Genetics Society of America, 2018. https://doi.org/10.1534/genetics.117.300638. ieee: H. Ringbauer, A. Kolesnikov, D. Field, and N. H. Barton, “Estimating barriers to gene flow from distorted isolation-by-distance patterns,” Genetics, vol. 208, no. 3. Genetics Society of America, pp. 1231–1245, 2018. ista: Ringbauer H, Kolesnikov A, Field D, Barton NH. 2018. Estimating barriers to gene flow from distorted isolation-by-distance patterns. Genetics. 208(3), 1231–1245. mla: Ringbauer, Harald, et al. “Estimating Barriers to Gene Flow from Distorted Isolation-by-Distance Patterns.” Genetics, vol. 208, no. 3, Genetics Society of America, 2018, pp. 1231–45, doi:10.1534/genetics.117.300638. short: H. Ringbauer, A. Kolesnikov, D. Field, N.H. Barton, Genetics 208 (2018) 1231–1245. date_created: 2018-12-11T11:47:12Z date_published: 2018-03-01T00:00:00Z date_updated: 2023-09-11T13:42:38Z day: '01' department: - _id: NiBa - _id: ChLa doi: 10.1534/genetics.117.300638 external_id: isi: - '000426219600025' intvolume: ' 208' isi: 1 issue: '3' language: - iso: eng main_file_link: - open_access: '1' url: https://www.biorxiv.org/content/10.1101/205484v1 month: '03' oa: 1 oa_version: Preprint page: 1231-1245 publication: Genetics publication_status: published publisher: Genetics Society of America publist_id: '7251' quality_controlled: '1' related_material: record: - id: '200' relation: dissertation_contains status: public scopus_import: '1' status: public title: Estimating barriers to gene flow from distorted isolation-by-distance patterns type: journal_article user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 208 year: '2018' ... --- _id: '200' abstract: - lang: eng text: This thesis is concerned with the inference of current population structure based on geo-referenced genetic data. The underlying idea is that population structure affects its spatial genetic structure. Therefore, genotype information can be utilized to estimate important demographic parameters such as migration rates. These indirect estimates of population structure have become very attractive, as genotype data is now widely available. However, there also has been much concern about these approaches. Importantly, genetic structure can be influenced by many complex patterns, which often cannot be disentangled. Moreover, many methods merely fit heuristic patterns of genetic structure, and do not build upon population genetics theory. Here, I describe two novel inference methods that address these shortcomings. In Chapter 2, I introduce an inference scheme based on a new type of signal, identity by descent (IBD) blocks. Recently, it has become feasible to detect such long blocks of genome shared between pairs of samples. These blocks are direct traces of recent coalescence events. As such, they contain ample signal for inferring recent demography. I examine sharing of IBD blocks in two-dimensional populations with local migration. Using a diffusion approximation, I derive formulas for an isolation by distance pattern of long IBD blocks and show that sharing of long IBD blocks approaches rapid exponential decay for growing sample distance. I describe an inference scheme based on these results. It can robustly estimate the dispersal rate and population density, which is demonstrated on simulated data. I also show an application to estimate mean migration and the rate of recent population growth within Eastern Europe. Chapter 3 is about a novel method to estimate barriers to gene flow in a two dimensional population. This inference scheme utilizes geographically localized allele frequency fluctuations - a classical isolation by distance signal. The strength of these local fluctuations increases on average next to a barrier, and there is less correlation across it. I again use a framework of diffusion of ancestral lineages to model this effect, and provide an efficient numerical implementation to fit the results to geo-referenced biallelic SNP data. This inference scheme is able to robustly estimate strong barriers to gene flow, as tests on simulated data confirm. alternative_title: - ISTA Thesis article_processing_charge: No author: - first_name: Harald full_name: Ringbauer, Harald id: 417FCFF4-F248-11E8-B48F-1D18A9856A87 last_name: Ringbauer orcid: 0000-0002-4884-9682 citation: ama: Ringbauer H. Inferring recent demography from spatial genetic structure. 2018. doi:10.15479/AT:ISTA:th_963 apa: Ringbauer, H. (2018). Inferring recent demography from spatial genetic structure. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:th_963 chicago: Ringbauer, Harald. “Inferring Recent Demography from Spatial Genetic Structure.” Institute of Science and Technology Austria, 2018. https://doi.org/10.15479/AT:ISTA:th_963. ieee: H. Ringbauer, “Inferring recent demography from spatial genetic structure,” Institute of Science and Technology Austria, 2018. ista: Ringbauer H. 2018. Inferring recent demography from spatial genetic structure. Institute of Science and Technology Austria. mla: Ringbauer, Harald. Inferring Recent Demography from Spatial Genetic Structure. Institute of Science and Technology Austria, 2018, doi:10.15479/AT:ISTA:th_963. short: H. Ringbauer, Inferring Recent Demography from Spatial Genetic Structure, Institute of Science and Technology Austria, 2018. date_created: 2018-12-11T11:45:10Z date_published: 2018-02-21T00:00:00Z date_updated: 2023-09-20T12:00:56Z day: '21' ddc: - '576' degree_awarded: PhD department: - _id: NiBa doi: 10.15479/AT:ISTA:th_963 file: - access_level: open_access checksum: 8cc534d2b528ae017acf80874cce48c9 content_type: application/pdf creator: system date_created: 2018-12-12T10:14:55Z date_updated: 2020-07-14T12:45:23Z file_id: '5111' file_name: IST-2018-963-v1+1_thesis.pdf file_size: 5792935 relation: main_file - access_level: closed checksum: 6af18d7e5a7e2728ceda2f41ee24f628 content_type: application/zip creator: dernst date_created: 2019-04-05T09:30:12Z date_updated: 2020-07-14T12:45:23Z file_id: '6224' file_name: 2018_thesis_ringbauer_source.zip file_size: 113365 relation: source_file file_date_updated: 2020-07-14T12:45:23Z has_accepted_license: '1' language: - iso: eng license: https://creativecommons.org/licenses/by-nc/4.0/ month: '02' oa: 1 oa_version: Published Version page: '146' publication_identifier: issn: - 2663-337X publication_status: published publisher: Institute of Science and Technology Austria publist_id: '7713' pubrep_id: '963' related_material: record: - id: '563' relation: part_of_dissertation status: public - id: '1074' relation: part_of_dissertation status: public status: public supervisor: - first_name: Nicholas H full_name: Barton, Nicholas H id: 4880FE40-F248-11E8-B48F-1D18A9856A87 last_name: Barton orcid: 0000-0002-8548-5240 title: Inferring recent demography from spatial genetic structure tmp: image: /images/cc_by_nc.png legal_code_url: https://creativecommons.org/licenses/by-nc/4.0/legalcode name: Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) short: CC BY-NC (4.0) type: dissertation user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 year: '2018' ... --- _id: '33' abstract: - lang: eng text: Secondary contact is the reestablishment of gene flow between sister populations that have diverged. For instance, at the end of the Quaternary glaciations in Europe, secondary contact occurred during the northward expansion of the populations which had found refugia in the southern peninsulas. With the advent of multi-locus markers, secondary contact can be investigated using various molecular signatures including gradients of allele frequency, admixture clines, and local increase of genetic differentiation. We use coalescent simulations to investigate if molecular data provide enough information to distinguish between secondary contact following range expansion and an alternative evolutionary scenario consisting of a barrier to gene flow in an isolation-by-distance model. We find that an excess of linkage disequilibrium and of genetic diversity at the suture zone is a unique signature of secondary contact. We also find that the directionality index ψ, which was proposed to study range expansion, is informative to distinguish between the two hypotheses. However, although evidence for secondary contact is usually conveyed by statistics related to admixture coefficients, we find that they can be confounded by isolation-by-distance. We recommend to account for the spatial repartition of individuals when investigating secondary contact in order to better reflect the complex spatio-temporal evolution of populations and species. acknowledgement: 'Johanna Bertl was supported by the Vienna Graduate School of Population Genetics (Austrian Science Fund (FWF): W1225-B20) and worked on this project while employed at the Department of Statistics and Operations Research, University of Vienna, Austria. This article was developed in the framework of the Grenoble Alpes Data Institute, which is supported by the French National Research Agency under the “Investissments d’avenir” program (ANR-15-IDEX-02).' article_number: e5325 article_processing_charge: No author: - first_name: Johanna full_name: Bertl, Johanna last_name: Bertl - first_name: Harald full_name: Ringbauer, Harald id: 417FCFF4-F248-11E8-B48F-1D18A9856A87 last_name: Ringbauer orcid: 0000-0002-4884-9682 - first_name: Michaël full_name: Blum, Michaël last_name: Blum citation: ama: Bertl J, Ringbauer H, Blum M. Can secondary contact following range expansion be distinguished from barriers to gene flow? PeerJ. 2018;2018(10). doi:10.7717/peerj.5325 apa: Bertl, J., Ringbauer, H., & Blum, M. (2018). Can secondary contact following range expansion be distinguished from barriers to gene flow? PeerJ. PeerJ. https://doi.org/10.7717/peerj.5325 chicago: Bertl, Johanna, Harald Ringbauer, and Michaël Blum. “Can Secondary Contact Following Range Expansion Be Distinguished from Barriers to Gene Flow?” PeerJ. PeerJ, 2018. https://doi.org/10.7717/peerj.5325. ieee: J. Bertl, H. Ringbauer, and M. Blum, “Can secondary contact following range expansion be distinguished from barriers to gene flow?,” PeerJ, vol. 2018, no. 10. PeerJ, 2018. ista: Bertl J, Ringbauer H, Blum M. 2018. Can secondary contact following range expansion be distinguished from barriers to gene flow? PeerJ. 2018(10), e5325. mla: Bertl, Johanna, et al. “Can Secondary Contact Following Range Expansion Be Distinguished from Barriers to Gene Flow?” PeerJ, vol. 2018, no. 10, e5325, PeerJ, 2018, doi:10.7717/peerj.5325. short: J. Bertl, H. Ringbauer, M. Blum, PeerJ 2018 (2018). date_created: 2018-12-11T11:44:16Z date_published: 2018-10-01T00:00:00Z date_updated: 2023-10-17T12:24:43Z day: '01' ddc: - '576' department: - _id: NiBa doi: 10.7717/peerj.5325 external_id: isi: - '000447204400001' pmid: - '30294507' file: - access_level: open_access checksum: 3334886c4b39678db4c4b74299ca14ba content_type: application/pdf creator: dernst date_created: 2018-12-17T10:46:06Z date_updated: 2020-07-14T12:46:06Z file_id: '5692' file_name: 2018_PeerJ_Bertl.pdf file_size: 1328344 relation: main_file file_date_updated: 2020-07-14T12:46:06Z has_accepted_license: '1' intvolume: ' 2018' isi: 1 issue: '10' language: - iso: eng month: '10' oa: 1 oa_version: Published Version pmid: 1 publication: PeerJ publication_status: published publisher: PeerJ publist_id: '8022' quality_controlled: '1' scopus_import: '1' status: public title: Can secondary contact following range expansion be distinguished from barriers to 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: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 2018 year: '2018' ... --- _id: '1074' abstract: - lang: eng text: Recently it has become feasible to detect long blocks of nearly identical sequence shared between pairs of genomes. These IBD blocks are direct traces of recent coalescence events and, as such, contain ample signal to infer recent demography. Here, we examine sharing of such blocks in two-dimensional populations with local migration. Using a diffusion approximation to trace genetic ancestry, we derive analytical formulae for patterns of isolation by distance of IBD blocks, which can also incorporate recent population density changes. We introduce an inference scheme that uses a composite likelihood approach to fit these formulae. We then extensively evaluate our theory and inference method on a range of scenarios using simulated data. We first validate the diffusion approximation by showing that the theoretical results closely match the simulated block sharing patterns. We then demonstrate that our inference scheme can accurately and robustly infer dispersal rate and effective density, as well as bounds on recent dynamics of population density. To demonstrate an application, we use our estimation scheme to explore the fit of a diffusion model to Eastern European samples in the POPRES data set. We show that ancestry diffusing with a rate of σ ≈ 50–100 km/√gen during the last centuries, combined with accelerating population growth, can explain the observed exponential decay of block sharing with increasing pairwise sample distance. article_processing_charge: No author: - first_name: Harald full_name: Ringbauer, Harald id: 417FCFF4-F248-11E8-B48F-1D18A9856A87 last_name: Ringbauer orcid: 0000-0002-4884-9682 - first_name: Graham full_name: Coop, Graham last_name: Coop - first_name: Nicholas H full_name: Barton, Nicholas H id: 4880FE40-F248-11E8-B48F-1D18A9856A87 last_name: Barton orcid: 0000-0002-8548-5240 citation: ama: Ringbauer H, Coop G, Barton NH. Inferring recent demography from isolation by distance of long shared sequence blocks. Genetics. 2017;205(3):1335-1351. doi:10.1534/genetics.116.196220 apa: Ringbauer, H., Coop, G., & Barton, N. H. (2017). Inferring recent demography from isolation by distance of long shared sequence blocks. Genetics. Genetics Society of America. https://doi.org/10.1534/genetics.116.196220 chicago: Ringbauer, Harald, Graham Coop, and Nicholas H Barton. “Inferring Recent Demography from Isolation by Distance of Long Shared Sequence Blocks.” Genetics. Genetics Society of America, 2017. https://doi.org/10.1534/genetics.116.196220. ieee: H. Ringbauer, G. Coop, and N. H. Barton, “Inferring recent demography from isolation by distance of long shared sequence blocks,” Genetics, vol. 205, no. 3. Genetics Society of America, pp. 1335–1351, 2017. ista: Ringbauer H, Coop G, Barton NH. 2017. Inferring recent demography from isolation by distance of long shared sequence blocks. Genetics. 205(3), 1335–1351. mla: Ringbauer, Harald, et al. “Inferring Recent Demography from Isolation by Distance of Long Shared Sequence Blocks.” Genetics, vol. 205, no. 3, Genetics Society of America, 2017, pp. 1335–51, doi:10.1534/genetics.116.196220. short: H. Ringbauer, G. Coop, N.H. Barton, Genetics 205 (2017) 1335–1351. date_created: 2018-12-11T11:50:00Z date_published: 2017-03-01T00:00:00Z date_updated: 2023-09-20T12:00:56Z day: '01' department: - _id: NiBa doi: 10.1534/genetics.116.196220 ec_funded: 1 external_id: isi: - '000395807200023' intvolume: ' 205' isi: 1 issue: '3' language: - iso: eng main_file_link: - open_access: '1' url: http://www.biorxiv.org/content/early/2016/09/23/076810 month: '03' oa: 1 oa_version: Preprint page: 1335 - 1351 project: - _id: 25B07788-B435-11E9-9278-68D0E5697425 call_identifier: FP7 grant_number: '250152' name: Limits to selection in biology and in evolutionary computation publication: Genetics publication_identifier: issn: - '00166731' publication_status: published publisher: Genetics Society of America publist_id: '6307' quality_controlled: '1' related_material: record: - id: '200' relation: dissertation_contains status: public scopus_import: '1' status: public title: Inferring recent demography from isolation by distance of long shared sequence blocks type: journal_article user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 205 year: '2017' ...