---
_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:
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- '30294507'
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creator: dernst
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file_name: 2018_PeerJ_Bertl.pdf
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oa: 1
oa_version: Published Version
pmid: 1
publication: PeerJ
publication_status: published
publisher: PeerJ
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quality_controlled: '1'
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title: Can secondary contact following range expansion be distinguished from barriers
to gene flow?
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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: '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:
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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: 2025-05-28T11:57:06Z
day: '21'
ddc:
- '576'
degree_awarded: PhD
department:
- _id: NiBa
doi: 10.15479/AT:ISTA:th_963
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language:
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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: '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:
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- '000426219600025'
intvolume: ' 208'
isi: 1
issue: '3'
language:
- iso: eng
main_file_link:
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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: '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: 2025-05-28T11:42:51Z
day: '01'
department:
- _id: NiBa
doi: 10.1534/genetics.116.196220
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issue: '3'
language:
- iso: eng
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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'
...