---
_id: '14711'
abstract:
- lang: eng
text: "In nature, different species find their niche in a range of environments,
each with its unique characteristics. While some thrive in uniform (homogeneous)
landscapes where environmental conditions stay relatively consistent across space,
others traverse the complexities of spatially heterogeneous terrains. Comprehending
how species are distributed and how they interact within these landscapes holds
the key to gaining insights into their evolutionary dynamics while also informing
conservation and management strategies.\r\n\r\nFor species inhabiting heterogeneous
landscapes, when the rate of dispersal is low compared to spatial fluctuations
in selection pressure, localized adaptations may emerge. Such adaptation in response
to varying selection strengths plays an important role in the persistence of populations
in our rapidly changing world. Hence, species in nature are continuously in a
struggle to adapt to local environmental conditions, to ensure their continued
survival. Natural populations can often adapt in time scales short enough for
evolutionary changes to influence ecological dynamics and vice versa, thereby
creating a feedback between evolution and demography. The analysis of this feedback
and the relative contributions of gene flow, demography, drift, and natural selection
to genetic variation and differentiation has remained a recurring theme in evolutionary
biology. Nevertheless, the effective role of these forces in maintaining variation
and shaping patterns of diversity is not fully understood. Even in homogeneous
environments devoid of local adaptations, such understanding remains elusive.
Understanding this feedback is crucial, for example in determining the conditions
under which extinction risk can be mitigated in peripheral populations subject
to deleterious mutation accumulation at the edges of species’ ranges\r\nas well
as in highly fragmented populations.\r\n\r\nIn this thesis we explore both uniform
and spatially heterogeneous metapopulations, investigating and providing theoretical
insights into the dynamics of local adaptation in the latter and examining the
dynamics of load and extinction as well as the impact of joint ecological and
evolutionary (eco-evolutionary) dynamics in the former. The thesis is divided
into 5 chapters.\r\n\r\nChapter 1 provides a general introduction into the subject
matter, clarifying concepts and ideas used throughout the thesis. In chapter 2,
we explore how fast a species distributed across a heterogeneous landscape adapts
to changing conditions marked by alterations in carrying capacity, selection pressure,
and migration rate.\r\n\r\nIn chapter 3, we investigate how migration selection
and drift influences adaptation and the maintenance of variation in a metapopulation
with three habitats, an extension of previous models of adaptation in two habitats.
We further develop analytical approximations for the critical threshold required
for polymorphism to persist.\r\n\r\nThe focus of chapter 4 of the thesis is on
understanding the interplay between ecology and evolution as coupled processes.
We investigate how eco-evolutionary feedback between migration, selection, drift,
and demography influences eco-evolutionary outcomes in marginal populations subject
to deleterious mutation accumulation. Using simulations as well as theoretical
approximations of the coupled dynamics of population size and allele frequency,
we analyze how gene flow from a large mainland source influences genetic load
and population size on an island (i.e., in a marginal population) under genetically
realistic assumptions. Analyses of this sort are important because small isolated
populations, are repeatedly affected by complex interactions between ecological
and evolutionary processes, which can lead to their death. Understanding these
interactions can therefore provide an insight into the conditions under which
extinction risk can be mitigated in peripheral populations thus, contributing
to conservation and restoration efforts.\r\n\r\nChapter 5 extends the analysis
in chapter 4 to consider the dynamics of load (due to deleterious mutation accumulation)
and extinction risk in a metapopulation. We explore the role of gene flow, selection,
and dominance on load and extinction risk and further pinpoint critical thresholds
required for metapopulation persistence.\r\n\r\nOverall this research contributes
to our understanding of ecological and evolutionary mechanisms that shape species’
persistence in fragmented landscapes, a crucial foundation for successful conservation
efforts and biodiversity management."
acknowledged_ssus:
- _id: SSU
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Oluwafunmilola O
full_name: Olusanya, Oluwafunmilola O
id: 41AD96DC-F248-11E8-B48F-1D18A9856A87
last_name: Olusanya
orcid: 0000-0003-1971-8314
date_created: 2023-12-26T22:49:53Z
date_published: 2024-01-19T00:00:00Z
date_updated: 2025-05-26T09:05:10Z
day: '19'
ddc:
- '576'
degree_awarded: MS
department:
- _id: NiBa
- _id: GradSch
doi: 10.15479/at:ista:14711
ec_funded: 1
file:
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checksum: de179b1c6758f182ff0c70d8b38c1501
content_type: application/zip
creator: oolusany
date_created: 2024-01-03T18:30:13Z
date_updated: 2024-01-03T18:30:13Z
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creator: oolusany
date_created: 2024-01-03T18:31:34Z
date_updated: 2024-01-03T18:31:34Z
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file_date_updated: 2024-01-03T18:31:34Z
has_accepted_license: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by-nc-sa/4.0/
month: '01'
oa: 1
oa_version: Published Version
page: '183'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '665385'
name: International IST Doctoral Program
- _id: c08d3278-5a5b-11eb-8a69-fdb09b55f4b8
grant_number: P32896
name: Causes and consequences of population fragmentation
- _id: 34c872fe-11ca-11ed-8bc3-8534b82131e6
grant_number: '26380'
name: Polygenic Adaptation in a Metapopulation
publication_identifier:
issn:
- 2663 - 337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '10658'
relation: part_of_dissertation
status: public
- id: '10787'
relation: part_of_dissertation
status: public
- id: '14732'
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
- first_name: Jitka
full_name: Polechova, Jitka
last_name: Polechova
- first_name: Himani
full_name: Sachdeva, Himani
last_name: Sachdeva
title: Local adaptation, genetic load and extinction in metapopulations
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legal_code_url: https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode
name: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC
BY-NC-SA 4.0)
short: CC BY-NC-SA (4.0)
type: dissertation
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2024'
...
---
_id: '15020'
abstract:
- lang: eng
text: "This thesis consists of four distinct pieces of work within theoretical biology,
with two themes in common: the concept of optimization in biological systems,
and the use of information-theoretic tools to quantify biological stochasticity
and statistical uncertainty.\r\nChapter 2 develops a statistical framework for
studying biological systems which we believe to be optimized for a particular
utility function, such as retinal neurons conveying information about visual stimuli.
We formalize such beliefs as maximum-entropy Bayesian priors, constrained by the
expected utility. We explore how such priors aid inference of system parameters
with limited data and enable optimality hypothesis testing: is the utility higher
than by chance?\r\nChapter 3 examines the ultimate biological optimization process:
evolution by natural selection. As some individuals survive and reproduce more
successfully than others, populations evolve towards fitter genotypes and phenotypes.
We formalize this as accumulation of genetic information, and use population genetics
theory to study how much such information can be accumulated per generation and
maintained in the face of random mutation and genetic drift. We identify the population
size and fitness variance as the key quantities that control information accumulation
and maintenance.\r\nChapter 4 reuses the concept of genetic information from Chapter
3, but from a different perspective: we ask how much genetic information organisms
actually need, in particular in the context of gene regulation. For example, how
much information is needed to bind transcription factors at correct locations
within the genome? Population genetics provides us with a refined answer: with
an increasing population size, populations achieve higher fitness by maintaining
more genetic information. Moreover, regulatory parameters experience selection
pressure to optimize the fitness-information trade-off, i.e. minimize the information
needed for a given fitness. This provides an evolutionary derivation of the optimization
priors introduced in Chapter 2.\r\nChapter 5 proves an upper bound on mutual information
between a signal and a communication channel output (such as neural activity).
Mutual information is an important utility measure for biological systems, but
its practical use can be difficult due to the large dimensionality of many biological
channels. Sometimes, a lower bound on mutual information is computed by replacing
the high-dimensional channel outputs with decodes (signal estimates). Our result
provides a corresponding upper bound, provided that the decodes are the maximum
posterior estimates of the signal."
acknowledged_ssus:
- _id: ScienComp
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Michal
full_name: Hledik, Michal
id: 4171253A-F248-11E8-B48F-1D18A9856A87
last_name: Hledik
citation:
ama: Hledik M. Genetic information and biological optimization. 2024. doi:10.15479/at:ista:15020
apa: Hledik, M. (2024). Genetic information and biological optimization.
Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:15020
chicago: Hledik, Michal. “Genetic Information and Biological Optimization.” Institute
of Science and Technology Austria, 2024. https://doi.org/10.15479/at:ista:15020.
ieee: M. Hledik, “Genetic information and biological optimization,” Institute of
Science and Technology Austria, 2024.
ista: Hledik M. 2024. Genetic information and biological optimization. Institute
of Science and Technology Austria.
mla: Hledik, Michal. Genetic Information and Biological Optimization. Institute
of Science and Technology Austria, 2024, doi:10.15479/at:ista:15020.
short: M. Hledik, Genetic Information and Biological Optimization, Institute of
Science and Technology Austria, 2024.
date_created: 2024-02-23T14:02:04Z
date_published: 2024-02-23T00:00:00Z
date_updated: 2025-06-30T13:21:09Z
day: '23'
ddc:
- '576'
- '519'
department:
- _id: GradSch
- _id: NiBa
- _id: GaTk
doi: 10.15479/at:ista:15020
ec_funded: 1
file:
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checksum: b2d3da47c98d481577a4baf68944fe41
content_type: application/pdf
creator: mhledik
date_created: 2024-02-23T13:50:53Z
date_updated: 2024-02-23T13:50:53Z
file_id: '15021'
file_name: hledik thesis pdfa 2b.pdf
file_size: 7102089
relation: main_file
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content_type: application/zip
creator: mhledik
date_created: 2024-02-23T13:50:54Z
date_updated: 2024-02-23T14:20:16Z
file_id: '15022'
file_name: hledik thesis source.zip
file_size: 14014790
relation: source_file
file_date_updated: 2024-02-23T14:20:16Z
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keyword:
- Theoretical biology
- Optimality
- Evolution
- Information
language:
- iso: eng
month: '02'
oa: 1
oa_version: Published Version
page: '158'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '665385'
name: International IST Doctoral Program
- _id: 2665AAFE-B435-11E9-9278-68D0E5697425
grant_number: RGP0034/2018
name: Can evolution minimize spurious signaling crosstalk to reach optimal performance?
- _id: bd6958e0-d553-11ed-ba76-86eba6a76c00
grant_number: '101055327'
name: Understanding the evolution of continuous genomes
publication_identifier:
issn:
- 2663 - 337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '7553'
relation: part_of_dissertation
status: public
- id: '7606'
relation: part_of_dissertation
status: public
- id: '12081'
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
- first_name: Gašper
full_name: Tkačik, Gašper
id: 3D494DCA-F248-11E8-B48F-1D18A9856A87
last_name: Tkačik
orcid: 0000-0002-6699-1455
title: Genetic information and biological optimization
type: dissertation
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2024'
...
---
_id: '14651'
abstract:
- lang: eng
text: 'For self-incompatibility (SI) to be stable in a population, theory predicts
that sufficient inbreeding depression (ID) is required: the fitness of offspring
from self-mated individuals must be low enough to prevent the spread of self-compatibility
(SC). Reviews of natural plant populations have supported this theory, with SI
species generally showing high levels of ID. However, there is thought to be an
under-sampling of self-incompatible taxa in the current literature. In this thesis,
I study inbreeding depression in the SI plant species Antirrhinum majus using
both greenhouse crosses and a large collected field dataset. Additionally, the
gametophytic S-locus of A. majus is highly heterozygous and polymorphic, thus
making assembly and discovery of S-alleles very difficult. Here, 206 new alleles
of the male component SLFs are presented, along with a phylogeny showing the high
conservation with alleles from another Antirrhinum species. Lastly, selected sites
within the protein structure of SLFs are investigated, with one site in particular
highlighted as potentially being involved in the SI recognition mechanism.'
acknowledged_ssus:
- _id: ScienComp
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Louise S
full_name: Arathoon, Louise S
id: 2CFCFF98-F248-11E8-B48F-1D18A9856A87
last_name: Arathoon
orcid: 0000-0003-1771-714X
citation:
ama: Arathoon LS. Investigating inbreeding depression and the self-incompatibility
locus of Antirrhinum majus. 2023. doi:10.15479/at:ista:14651
apa: Arathoon, L. S. (2023). Investigating inbreeding depression and the self-incompatibility
locus of Antirrhinum majus. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:14651
chicago: Arathoon, Louise S. “Investigating Inbreeding Depression and the Self-Incompatibility
Locus of Antirrhinum Majus.” Institute of Science and Technology Austria, 2023.
https://doi.org/10.15479/at:ista:14651.
ieee: L. S. Arathoon, “Investigating inbreeding depression and the self-incompatibility
locus of Antirrhinum majus,” Institute of Science and Technology Austria, 2023.
ista: Arathoon LS. 2023. Investigating inbreeding depression and the self-incompatibility
locus of Antirrhinum majus. Institute of Science and Technology Austria.
mla: Arathoon, Louise S. Investigating Inbreeding Depression and the Self-Incompatibility
Locus of Antirrhinum Majus. Institute of Science and Technology Austria, 2023,
doi:10.15479/at:ista:14651.
short: L.S. Arathoon, Investigating Inbreeding Depression and the Self-Incompatibility
Locus of Antirrhinum Majus, Institute of Science and Technology Austria, 2023.
date_created: 2023-12-11T19:30:37Z
date_published: 2023-12-12T00:00:00Z
date_updated: 2023-12-22T11:04:45Z
day: '12'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: GradSch
- _id: NiBa
doi: 10.15479/at:ista:14651
ec_funded: 1
file:
- access_level: open_access
checksum: 520bdb61e95e66070e02824947d2c5fa
content_type: application/pdf
creator: larathoo
date_created: 2023-12-13T15:37:55Z
date_updated: 2023-12-13T15:37:55Z
file_id: '14684'
file_name: Phd_Thesis_LA.pdf
file_size: 34101468
relation: main_file
success: 1
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content_type: application/zip
creator: larathoo
date_created: 2023-12-13T15:42:23Z
date_updated: 2023-12-14T08:58:18Z
file_id: '14685'
file_name: Phd_Thesis_LA.zip
file_size: 31052872
relation: source_file
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checksum: 9a778c949932286f4519e1f1fca2820d
content_type: application/zip
creator: larathoo
date_created: 2023-12-11T19:24:59Z
date_updated: 2023-12-14T08:58:18Z
file_id: '14681'
file_name: Supplementary_Materials.zip
file_size: 10713896
relation: supplementary_material
file_date_updated: 2023-12-14T08:58:18Z
has_accepted_license: '1'
language:
- iso: eng
month: '12'
oa: 1
oa_version: Published Version
page: '96'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '665385'
name: International IST Doctoral Program
publication_identifier:
issn:
- 2663 - 337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '11411'
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: Investigating inbreeding depression and the self-incompatibility locus of Antirrhinum
majus
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '14058'
abstract:
- lang: eng
text: "Females and males across species are subject to divergent selective pressures
arising\r\nfrom di↵erent reproductive interests and ecological niches. This often
translates into a\r\nintricate array of sex-specific natural and sexual selection
on traits that have a shared\r\ngenetic basis between both sexes, causing a genetic
sexual conflict. The resolution of\r\nthis conflict mostly relies on the evolution
of sex-specific expression of the shared genes,\r\nleading to phenotypic sexual
dimorphism. Such sex-specific gene expression is thought\r\nto evolve via modifications
of the genetic networks ultimately linked to sex-determining\r\ntranscription
factors. Although much empirical and theoretical evidence supports this\r\nstandard
picture of the molecular basis of sexual conflict resolution, there still are
a\r\nfew open questions regarding the complex array of selective forces driving
phenotypic\r\ndi↵erentiation between the sexes, as well as the molecular mechanisms
underlying sexspecific adaptation. I address some of these open questions in my
PhD thesis.\r\nFirst, how do patterns of phenotypic sexual dimorphism vary within
populations,\r\nas a response to the temporal and spatial changes in sex-specific
selective forces? To\r\ntackle this question, I analyze the patterns of sex-specific
phenotypic variation along\r\nthree life stages and across populations spanning
the whole geographical range of Rumex\r\nhastatulus, a wind-pollinated angiosperm,
in the first Chapter of the thesis.\r\nSecond, how do gene expression patterns
lead to phenotypic dimorphism, and what\r\nare the molecular mechanisms underlying
the observed transcriptomic variation? I\r\naddress this question by examining
the sex- and tissue-specific expression variation in\r\nnewly-generated datasets
of sex-specific expression in heads and gonads of Drosophila\r\nmelanogaster.
I additionally used two complementary approaches for the study of the\r\ngenetic
basis of sex di↵erences in gene expression in the second and third Chapters of\r\nthe
thesis.\r\nThird, how does intersex correlation, thought to be one of the main
aspects constraining the ability for the two sexes to decouple, interact with
the evolution of sexual\r\ndimorphism? I develop models of sex-specific stabilizing
selection, mutation and drift\r\nto formalize common intuition regarding the patterns
of covariation between intersex\r\ncorrelation and sexual dimorphism in the fourth
Chapter of the thesis.\r\nAlltogether, the work described in this PhD thesis provides
useful insights into the\r\nlinks between genetic, transcriptomic and phenotypic
layers of sex-specific variation,\r\nand contributes to our general understanding
of the dynamics of sexual dimorphism\r\nevolution."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Gemma
full_name: Puixeu Sala, Gemma
id: 33AB266C-F248-11E8-B48F-1D18A9856A87
last_name: Puixeu Sala
orcid: 0000-0001-8330-1754
citation:
ama: 'Puixeu Sala G. The molecular basis of sexual dimorphism: Experimental and
theoretical characterization of phenotypic, transcriptomic and genetic patterns
of sex-specific adaptation. 2023. doi:10.15479/at:ista:14058'
apa: 'Puixeu Sala, G. (2023). The molecular basis of sexual dimorphism: Experimental
and theoretical characterization of phenotypic, transcriptomic and genetic patterns
of sex-specific adaptation. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:14058'
chicago: 'Puixeu Sala, Gemma. “The Molecular Basis of Sexual Dimorphism: Experimental
and Theoretical Characterization of Phenotypic, Transcriptomic and Genetic Patterns
of Sex-Specific Adaptation.” Institute of Science and Technology Austria, 2023.
https://doi.org/10.15479/at:ista:14058.'
ieee: 'G. Puixeu Sala, “The molecular basis of sexual dimorphism: Experimental and
theoretical characterization of phenotypic, transcriptomic and genetic patterns
of sex-specific adaptation,” Institute of Science and Technology Austria, 2023.'
ista: 'Puixeu Sala G. 2023. The molecular basis of sexual dimorphism: Experimental
and theoretical characterization of phenotypic, transcriptomic and genetic patterns
of sex-specific adaptation. Institute of Science and Technology Austria.'
mla: 'Puixeu Sala, Gemma. The Molecular Basis of Sexual Dimorphism: Experimental
and Theoretical Characterization of Phenotypic, Transcriptomic and Genetic Patterns
of Sex-Specific Adaptation. Institute of Science and Technology Austria, 2023,
doi:10.15479/at:ista:14058.'
short: 'G. Puixeu Sala, The Molecular Basis of Sexual Dimorphism: Experimental and
Theoretical Characterization of Phenotypic, Transcriptomic and Genetic Patterns
of Sex-Specific Adaptation, Institute of Science and Technology Austria, 2023.'
date_created: 2023-08-15T10:20:40Z
date_published: 2023-08-15T00:00:00Z
date_updated: 2023-12-13T12:15:36Z
day: '15'
ddc:
- '576'
degree_awarded: PhD
department:
- _id: GradSch
- _id: NiBa
- _id: BeVi
doi: 10.15479/at:ista:14058
ec_funded: 1
file:
- access_level: closed
checksum: 4e44e169f2724ee8c9324cd60bcc2b71
content_type: application/zip
creator: gpuixeus
date_created: 2023-08-16T18:15:17Z
date_updated: 2023-08-17T06:55:24Z
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success: 1
file_date_updated: 2023-08-18T10:47:55Z
has_accepted_license: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by/4.0/
month: '08'
oa: 1
oa_version: Published Version
page: '230'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '665385'
name: International IST Doctoral Program
- _id: 9B9DFC9E-BA93-11EA-9121-9846C619BF3A
grant_number: '25817'
name: 'Sexual conflict: resolution, constraints and biomedical implications'
publication_identifier:
isbn:
- 978-3-99078-035-0
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '9803'
relation: research_data
status: public
- id: '12933'
relation: research_data
status: public
- id: '6831'
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status: public
- id: '14077'
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
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
title: 'The molecular basis of sexual dimorphism: Experimental and theoretical characterization
of phenotypic, transcriptomic and genetic patterns of sex-specific adaptation'
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: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '12800'
abstract:
- lang: eng
text: 'The evolutionary processes that brought about today’s plethora of living
species and the many billions more ancient ones all underlie biology. Evolutionary
pathways are neither directed nor deterministic, but rather an interplay between
selection, migration, mutation, genetic drift and other environmental factors.
Hybrid zones, as natural crossing experiments, offer a great opportunity to use
cline analysis to deduce different evolutionary processes - for example, selection
strength. Theoretical cline models, largely assuming uniform distribution of individuals,
often lack the capability of incorporating population structure. Since in reality
organisms mostly live in patchy distributions and their dispersal is hardly ever
Gaussian, it is necessary to unravel the effect of these different elements of
population structure on cline parameters and shape. In this thesis, I develop
a simulation inspired by the A. majus hybrid zone of a single selected locus under
frequency dependent selection. This simulation enables us to untangle the effects
of different elements of population structure as for example a low-density center
and long-range dispersal. This thesis is therefore a first step towards theoretically
untangling the effects of different elements of population structure on cline
parameters and shape. '
alternative_title:
- ISTA Master's Thesis
article_processing_charge: No
author:
- first_name: Mara
full_name: Julseth, Mara
id: 1cf464b2-dc7d-11ea-9b2f-f9b1aa9417d1
last_name: Julseth
citation:
ama: Julseth M. The effect of local population structure on genetic variation at
selected loci in the A. majus hybrid zone. 2023. doi:10.15479/at:ista:12800
apa: Julseth, M. (2023). The effect of local population structure on genetic
variation at selected loci in the A. majus hybrid zone. Institute of Science
and Technology Austria. https://doi.org/10.15479/at:ista:12800
chicago: Julseth, Mara. “The Effect of Local Population Structure on Genetic Variation
at Selected Loci in the A. Majus Hybrid Zone.” Institute of Science and Technology
Austria, 2023. https://doi.org/10.15479/at:ista:12800.
ieee: M. Julseth, “The effect of local population structure on genetic variation
at selected loci in the A. majus hybrid zone,” Institute of Science and Technology
Austria, 2023.
ista: Julseth M. 2023. The effect of local population structure on genetic variation
at selected loci in the A. majus hybrid zone. Institute of Science and Technology
Austria.
mla: Julseth, Mara. The Effect of Local Population Structure on Genetic Variation
at Selected Loci in the A. Majus Hybrid Zone. Institute of Science and Technology
Austria, 2023, doi:10.15479/at:ista:12800.
short: M. Julseth, The Effect of Local Population Structure on Genetic Variation
at Selected Loci in the A. Majus Hybrid Zone, Institute of Science and Technology
Austria, 2023.
date_created: 2023-04-04T18:57:11Z
date_published: 2023-04-05T00:00:00Z
date_updated: 2023-06-02T22:30:05Z
day: '05'
ddc:
- '576'
degree_awarded: MS
department:
- _id: GradSch
- _id: NiBa
doi: 10.15479/at:ista:12800
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has_accepted_license: '1'
language:
- iso: eng
month: '04'
oa: 1
oa_version: Published Version
page: '21'
publication_identifier:
issn:
- 2791-4585
publication_status: published
publisher: Institute of Science and Technology Austria
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: The effect of local population structure on genetic variation at selected loci
in the A. majus hybrid zone
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '11128'
abstract:
- lang: eng
text: "Although we often see studies focusing on simple or even discrete traits
in studies of colouration,\r\nthe variation of “appearance” phenotypes found in
nature is often more complex, continuous\r\nand high-dimensional. Therefore, we
developed automated methods suitable for large datasets\r\nof genomes and images,
striving to account for their complex nature, while minimising human\r\nbias.
We used these methods on a dataset of more than 20, 000 plant SNP genomes and\r\ncorresponding
fower images from a hybrid zone of two subspecies of Antirrhinum majus with\r\ndistinctly
coloured fowers to improve our understanding of the genetic nature of the fower\r\ncolour
in our study system.\r\nFirstly, we use the advantage of large numbers of genotyped
plants to estimate the haplotypes in\r\nthe main fower colour regulating region.
We study colour- and geography-related characteristics\r\nof the estimated haplotypes
and how they connect to their relatedness. We show discrepancies\r\nfrom the expected
fower colour distributions given the genotype and identify particular\r\nhaplotypes
leading to unexpected phenotypes. We also confrm a signifcant defcit of the\r\ndouble
recessive recombinant and quite surprisingly, we show that haplotypes of the most\r\nfrequent
parental type are much less variable than others.\r\nSecondly, we introduce our
pipeline capable of processing tens of thousands of full fower\r\nimages without
human interaction and summarising each image into a set of informative scores.\r\nWe
show the compatibility of these machine-measured fower colour scores with the
previously\r\nused manual scores and study impact of external efect on the resulting
scores. Finally, we use\r\nthe machine-measured fower colour scores to ft and
examine a phenotype cline across the\r\nhybrid zone in Planoles using full fower
images as opposed to discrete, manual scores and\r\ncompare it with the genotypic
cline."
acknowledged_ssus:
- _id: ScienComp
- _id: Bio
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Lenka
full_name: Matejovicova, Lenka
id: 2DFDEC72-F248-11E8-B48F-1D18A9856A87
last_name: Matejovicova
citation:
ama: Matejovicova L. Genetic basis of flower colour as a model for adaptive evolution.
2022. doi:10.15479/at:ista:11128
apa: Matejovicova, L. (2022). Genetic basis of flower colour as a model for adaptive
evolution. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:11128
chicago: Matejovicova, Lenka. “Genetic Basis of Flower Colour as a Model for Adaptive
Evolution.” Institute of Science and Technology Austria, 2022. https://doi.org/10.15479/at:ista:11128.
ieee: L. Matejovicova, “Genetic basis of flower colour as a model for adaptive evolution,”
Institute of Science and Technology Austria, 2022.
ista: Matejovicova L. 2022. Genetic basis of flower colour as a model for adaptive
evolution. Institute of Science and Technology Austria.
mla: Matejovicova, Lenka. Genetic Basis of Flower Colour as a Model for Adaptive
Evolution. Institute of Science and Technology Austria, 2022, doi:10.15479/at:ista:11128.
short: L. Matejovicova, Genetic Basis of Flower Colour as a Model for Adaptive Evolution,
Institute of Science and Technology Austria, 2022.
date_created: 2022-04-07T08:19:54Z
date_published: 2022-04-06T00:00:00Z
date_updated: 2023-06-23T06:26:41Z
day: '06'
ddc:
- '576'
- '582'
degree_awarded: PhD
department:
- _id: GradSch
- _id: NiBa
doi: 10.15479/at:ista:11128
file:
- access_level: open_access
checksum: e9609bc4e8f8e20146fc1125fd4f1bf7
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language:
- iso: eng
month: '04'
oa: 1
oa_version: Published Version
page: '112'
publication_identifier:
isbn:
- 978-3-99078-016-9
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
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: Genetic basis of flower colour as a model for adaptive 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: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2022'
...
---
_id: '11388'
abstract:
- lang: eng
text: "In evolve and resequence experiments, a population is sequenced, subjected
to selection and\r\nthen sequenced again, so that genetic changes before and after
selection can be observed at\r\nthe genetic level. Here, I use these studies to
better understand the genetic basis of complex\r\ntraits - traits which depend
on more than a few genes.\r\nIn the first chapter, I discuss the first evolve
and resequence experiment, in which a population\r\nof mice, the so-called \"Longshanks\"
mice, were selected for tibia length while their body mass\r\nwas kept constant.
The full pedigree is known. We observed a selection response on all\r\nchromosomes
and used the infinitesimal model with linkage, a model which assumes an infinite\r\nnumber
of genes with infinitesimally small effect sizes, as a null model. Results implied
a very\r\npolygenic basis with a few loci of major effect standing out and changing
in parallel. There\r\nwas large variability between the different chromosomes
in this study, probably due to LD.\r\nIn chapter two, I go on to discuss the impact
of LD, on the variability in an allele-frequency\r\nbased summary statistic, giving
an equation based on the initial allele frequencies, average\r\npairwise LD, and
the first four moments of the haplotype block copy number distribution. I\r\ndescribe
this distribution by referring back to the founder generation. I then demonstrate\r\nhow
to infer selection via a maximum likelihood scheme on the example of a single
locus and\r\ndiscuss how to extend this to more realistic scenarios.\r\nIn chapter
three, I discuss the second evolve and resequence experiment, in which a small\r\npopulation
of Drosophila melanogaster was selected for increased pupal case size over 6\r\ngenerations.
The experiment was highly replicated with 27 lines selected within family and
a\r\nknown pedigree. We observed a phenotypic selection response of over one standard
deviation.\r\nI describe the patterns in allele frequency data, including allele
frequency changes and patterns\r\nof heterozygosity, and give ideas for future
work."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Stefanie
full_name: Belohlavy, Stefanie
id: 43FE426A-F248-11E8-B48F-1D18A9856A87
last_name: Belohlavy
orcid: 0000-0002-9849-498X
citation:
ama: Belohlavy S. The genetic basis of complex traits studied via analysis of evolve
and resequence experiments. 2022. doi:10.15479/at:ista:11388
apa: Belohlavy, S. (2022). The genetic basis of complex traits studied via analysis
of evolve and resequence experiments. Institute of Science and Technology
Austria. https://doi.org/10.15479/at:ista:11388
chicago: Belohlavy, Stefanie. “The Genetic Basis of Complex Traits Studied via Analysis
of Evolve and Resequence Experiments.” Institute of Science and Technology Austria,
2022. https://doi.org/10.15479/at:ista:11388.
ieee: S. Belohlavy, “The genetic basis of complex traits studied via analysis of
evolve and resequence experiments,” Institute of Science and Technology Austria,
2022.
ista: Belohlavy S. 2022. The genetic basis of complex traits studied via analysis
of evolve and resequence experiments. Institute of Science and Technology Austria.
mla: Belohlavy, Stefanie. The Genetic Basis of Complex Traits Studied via Analysis
of Evolve and Resequence Experiments. Institute of Science and Technology
Austria, 2022, doi:10.15479/at:ista:11388.
short: S. Belohlavy, The Genetic Basis of Complex Traits Studied via Analysis of
Evolve and Resequence Experiments, Institute of Science and Technology Austria,
2022.
date_created: 2022-05-16T16:49:18Z
date_published: 2022-05-18T00:00:00Z
date_updated: 2023-08-29T06:41:51Z
day: '18'
ddc:
- '576'
degree_awarded: PhD
department:
- _id: GradSch
- _id: NiBa
doi: 10.15479/at:ista:11388
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date_updated: 2023-05-20T22:30:03Z
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language:
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month: '05'
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page: '98'
publication_identifier:
isbn:
- 978-3-99078-018-3
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
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- id: '6713'
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: The genetic basis of complex traits studied via analysis of evolve and resequence
experiments
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: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2022'
...
---
_id: '8574'
abstract:
- lang: eng
text: "This thesis concerns itself with the interactions of evolutionary and ecological
forces and the consequences on genetic diversity and the ultimate survival of
populations. It is important to understand what signals processes \r\nleave on
the genome and what we can infer from such data, which is usually abundant but
noisy. Furthermore, understanding how and when populations adapt or go extinct
is important for practical purposes, such as the genetic management of populations,
as well as for theoretical questions, since local adaptation can be the first
step toward speciation. \r\nIn Chapter 2, we introduce the method of maximum entropy
to approximate the demographic changes of a population in a simple setting, namely
the logistic growth model with immigration. We show that this method is not only
a powerful \r\ntool in physics but can be gainfully applied in an ecological framework.
We investigate how well it approximates the real \r\nbehavior of the system, and
find that is does so, even in unexpected situations. Finally, we illustrate how
it can model changing environments.\r\nIn Chapter 3, we analyze the co-evolution
of allele frequencies and population sizes in an infinite island model.\r\nWe
give conditions under which polygenic adaptation to a rare habitat is possible.
The model we use is based on the diffusion approximation, considers eco-evolutionary
feedback mechanisms (hard selection), and treats both \r\ndrift and environmental
fluctuations explicitly. We also look at limiting scenarios, for which we derive
analytical expressions. \r\nIn Chapter 4, we present a coalescent based simulation
tool to obtain patterns of diversity in a spatially explicit subdivided population,
in which the demographic history of each subpopulation can be specified. We compare
\r\nthe results to existing predictions, and explore the relative importance of
time and space under a variety of spatial arrangements and demographic histories,
such as expansion and extinction. \r\nIn the last chapter, we give a brief outlook
to further research. "
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Eniko
full_name: Szep, Eniko
id: 485BB5A4-F248-11E8-B48F-1D18A9856A87
last_name: Szep
citation:
ama: Szep E. Local adaptation in metapopulations. 2020. doi:10.15479/AT:ISTA:8574
apa: Szep, E. (2020). Local adaptation in metapopulations. Institute of Science
and Technology Austria. https://doi.org/10.15479/AT:ISTA:8574
chicago: Szep, Eniko. “Local Adaptation in Metapopulations.” Institute of Science
and Technology Austria, 2020. https://doi.org/10.15479/AT:ISTA:8574.
ieee: E. Szep, “Local adaptation in metapopulations,” Institute of Science and Technology
Austria, 2020.
ista: Szep E. 2020. Local adaptation in metapopulations. Institute of Science and
Technology Austria.
mla: Szep, Eniko. Local Adaptation in Metapopulations. Institute of Science
and Technology Austria, 2020, doi:10.15479/AT:ISTA:8574.
short: E. Szep, Local Adaptation in Metapopulations, Institute of Science and Technology
Austria, 2020.
date_created: 2020-09-28T07:33:38Z
date_published: 2020-09-20T00:00:00Z
date_updated: 2023-09-07T13:11:39Z
day: '20'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: NiBa
doi: 10.15479/AT:ISTA:8574
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content_type: application/pdf
creator: dernst
date_created: 2020-09-28T07:25:35Z
date_updated: 2020-09-28T07:25:35Z
file_id: '8575'
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oa: 1
oa_version: Published Version
page: '158'
publication_identifier:
eissn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
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: Local adaptation in metapopulations
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2020'
...
---
_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: 2025-05-28T11:57:06Z
day: '21'
ddc:
- '576'
degree_awarded: PhD
department:
- _id: NiBa
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creator: dernst
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date_updated: 2020-07-14T12:45:23Z
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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:
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- id: '563'
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- id: '1074'
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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:
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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: '6291'
abstract:
- lang: eng
text: Bacteria and their pathogens – phages – are the most abundant living entities
on Earth. Throughout their coevolution, bacteria have evolved multiple immune
systems to overcome the ubiquitous threat from the phages. Although the molecu-
lar details of these immune systems’ functions are relatively well understood,
their epidemiological consequences for the phage-bacterial communities have been
largely neglected. In this thesis we employed both experimental and theoretical
methods to explore whether herd and social immunity may arise in bacterial popu-
lations. Using our experimental system consisting of Escherichia coli strains
with a CRISPR based immunity to the T7 phage we show that herd immunity arises
in phage-bacterial communities and that it is accentuated when the populations
are spatially structured. By fitting a mathematical model, we inferred expressions
for the herd immunity threshold and the velocity of spread of a phage epidemic
in partially resistant bacterial populations, which both depend on the bacterial
growth rate, phage burst size and phage latent period. We also investigated the
poten- tial for social immunity in Streptococcus thermophilus and its phage 2972
using a bioinformatic analysis of potentially coding short open reading frames
with a signalling signature, encoded within the CRISPR associated genes. Subsequently,
we tested one identified potentially signalling peptide and found that its addition
to a phage-challenged culture increases probability of survival of bacteria two
fold, although the results were only marginally significant. Together, these results
demonstrate that the ubiquitous arms races between bacteria and phages have further
consequences at the level of the population.
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Pavel
full_name: Payne, Pavel
id: 35F78294-F248-11E8-B48F-1D18A9856A87
last_name: Payne
orcid: 0000-0002-2711-9453
citation:
ama: Payne P. Bacterial herd and social immunity to phages. 2017.
apa: Payne, P. (2017). Bacterial herd and social immunity to phages. Institute
of Science and Technology Austria.
chicago: Payne, Pavel. “Bacterial Herd and Social Immunity to Phages.” Institute
of Science and Technology Austria, 2017.
ieee: P. Payne, “Bacterial herd and social immunity to phages,” Institute of Science
and Technology Austria, 2017.
ista: Payne P. 2017. Bacterial herd and social immunity to phages. Institute of
Science and Technology Austria.
mla: Payne, Pavel. Bacterial Herd and Social Immunity to Phages. Institute
of Science and Technology Austria, 2017.
short: P. Payne, Bacterial Herd and Social Immunity to Phages, Institute of Science
and Technology Austria, 2017.
date_created: 2019-04-09T15:16:45Z
date_published: 2017-02-01T00:00:00Z
date_updated: 2023-09-07T12:00:00Z
day: '01'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: NiBa
- _id: JoBo
file:
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checksum: a0fc5c26a89c0ea759947ffba87d0d8f
content_type: application/pdf
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date_updated: 2020-07-14T12:47:27Z
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month: '02'
oa: 1
oa_version: Published Version
page: '83'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
status: public
supervisor:
- first_name: Jonathan P
full_name: Bollback, Jonathan P
id: 2C6FA9CC-F248-11E8-B48F-1D18A9856A87
last_name: Bollback
orcid: 0000-0002-4624-4612
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
title: Bacterial herd and social immunity to phages
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2017'
...
---
_id: '1125'
abstract:
- lang: eng
text: "Natural environments are never constant but subject to spatial and temporal
change on\r\nall scales, increasingly so due to human activity. Hence, it is crucial
to understand the\r\nimpact of environmental variation on evolutionary processes.
In this thesis, I present\r\nthree topics that share the common theme of environmental
variation, yet illustrate its\r\neffect from different perspectives.\r\nFirst,
I show how a temporally fluctuating environment gives rise to second-order\r\nselection
on a modifier for stress-induced mutagenesis. Without fluctuations, when\r\npopulations
are adapted to their environment, mutation rates are minimized. I argue\r\nthat
a stress-induced mutator mechanism may only be maintained if the population is\r\nrepeatedly
subjected to diverse environmental challenges, and I outline implications of\r\nthe
presented results to antibiotic treatment strategies.\r\nSecond, I discuss my
work on the evolution of dispersal. Besides reproducing\r\nknown results about
the effect of heterogeneous habitats on dispersal, it identifies\r\nspatial changes
in dispersal type frequencies as a source for selection for increased\r\npropensities
to disperse. This concept contains effects of relatedness that are known\r\nto
promote dispersal, and I explain how it identifies other forces selecting for
dispersal\r\nand puts them on a common scale.\r\nThird, I analyse genetic variances
of phenotypic traits under multivariate stabilizing\r\nselection. For the case
of constant environments, I generalize known formulae of\r\nequilibrium variances
to multiple traits and discuss how the genetic variance of a focal\r\ntrait is
influenced by selection on background traits. I conclude by presenting ideas and\r\npreliminary
work aiming at including environmental fluctuations in the form of moving\r\ntrait
optima into the model."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Sebastian
full_name: Novak, Sebastian
id: 461468AE-F248-11E8-B48F-1D18A9856A87
last_name: Novak
orcid: 0000-0002-2519-824X
citation:
ama: Novak S. Evolutionary proccesses in variable emvironments. 2016.
apa: Novak, S. (2016). Evolutionary proccesses in variable emvironments.
Institute of Science and Technology Austria.
chicago: Novak, Sebastian. “Evolutionary Proccesses in Variable Emvironments.” Institute
of Science and Technology Austria, 2016.
ieee: S. Novak, “Evolutionary proccesses in variable emvironments,” Institute of
Science and Technology Austria, 2016.
ista: Novak S. 2016. Evolutionary proccesses in variable emvironments. Institute
of Science and Technology Austria.
mla: Novak, Sebastian. Evolutionary Proccesses in Variable Emvironments.
Institute of Science and Technology Austria, 2016.
short: S. Novak, Evolutionary Proccesses in Variable Emvironments, Institute of
Science and Technology Austria, 2016.
date_created: 2018-12-11T11:50:17Z
date_published: 2016-07-01T00:00:00Z
date_updated: 2025-05-28T11:57:05Z
day: '01'
ddc:
- '576'
degree_awarded: PhD
department:
- _id: NiBa
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language:
- iso: eng
month: '07'
oa: 1
oa_version: Published Version
page: '124'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
publist_id: '6235'
related_material:
record:
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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: Evolutionary proccesses in variable emvironments
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2016'
...
---
_id: '1131'
abstract:
- lang: eng
text: "Evolution of gene regulation is important for phenotypic evolution and diversity.
Sequence-specific binding of regulatory proteins is one of the key regulatory
mechanisms determining gene expression. Although there has been intense interest
in evolution of regulatory binding sites in the last decades, a theoretical understanding
is far from being complete. In this thesis, I aim at a better understanding of
the evolution of transcriptional regulatory binding sequences by using biophysical
and population genetic models.\r\nIn the first part of the thesis, I discuss how
to formulate the evolutionary dynamics of binding se- quences in a single isolated
binding site and in promoter/enhancer regions. I develop a theoretical framework
bridging between a thermodynamical model for transcription and a mutation-selection-drift
model for monomorphic populations. I mainly address the typical evolutionary rates,
and how they de- pend on biophysical parameters (e.g. binding length and specificity)
and population genetic parameters (e.g. population size and selection strength).\r\nIn
the second part of the thesis, I analyse empirical data for a better evolutionary
and biophysical understanding of sequence-specific binding of bacterial RNA polymerase.
First, I infer selection on regulatory and non-regulatory binding sites of RNA
polymerase in the E. coli K12 genome. Second, I infer the chemical potential of
RNA polymerase, an important but unknown physical parameter defining the threshold
energy for strong binding. Furthermore, I try to understand the relation between
the lac promoter sequence diversity and the LacZ activity variation among 20 bacterial
isolates by constructing a simple but biophysically motivated gene expression
model. Lastly, I lay out a statistical framework to predict adaptive point mutations
in de novo promoter evolution in a selection experiment."
acknowledgement: This PhD thesis may not have been completed without the help and
care I received from some peo- ple during my PhD life. I am especially grateful
to Tiago Paixao, Gasper Tkacik, Nick Barton, not only for their scientific advices
but also for their patience and support. I thank Calin Guet and Jonathan Bollback
for allowing me to “play around” in their labs and get some experience on experimental
evolution. I thank Magdalena Steinrueck and Fabienne Jesse for collaborating and
sharing their experimental data with me. I thank Johannes Jaeger for reviewing my
thesis. I thank all members of Barton group (aka bartonians) for their feedback,
and all workers of IST Austria for making the best working conditions. Lastly, I
thank two special women, Nejla Sag ̆lam and Setenay Dog ̆an, for their continuous
support and encouragement. I truly had a great chance of having right people around
me.
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Murat
full_name: Tugrul, Murat
id: 37C323C6-F248-11E8-B48F-1D18A9856A87
last_name: Tugrul
orcid: 0000-0002-8523-0758
citation:
ama: Tugrul M. Evolution of transcriptional regulatory sequences. 2016.
apa: Tugrul, M. (2016). Evolution of transcriptional regulatory sequences.
Institute of Science and Technology Austria.
chicago: Tugrul, Murat. “Evolution of Transcriptional Regulatory Sequences.” Institute
of Science and Technology Austria, 2016.
ieee: M. Tugrul, “Evolution of transcriptional regulatory sequences,” Institute
of Science and Technology Austria, 2016.
ista: Tugrul M. 2016. Evolution of transcriptional regulatory sequences. Institute
of Science and Technology Austria.
mla: Tugrul, Murat. Evolution of Transcriptional Regulatory Sequences. Institute
of Science and Technology Austria, 2016.
short: M. Tugrul, Evolution of Transcriptional Regulatory Sequences, Institute of
Science and Technology Austria, 2016.
date_created: 2018-12-11T11:50:19Z
date_published: 2016-07-01T00:00:00Z
date_updated: 2025-05-28T11:57:04Z
day: '01'
ddc:
- '576'
degree_awarded: PhD
department:
- _id: NiBa
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creator: dernst
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date_updated: 2021-02-22T11:45:20Z
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file_name: 2016_Tugrul_Thesis.pdf
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language:
- iso: eng
month: '07'
oa: 1
oa_version: Published Version
page: '89'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
publist_id: '6229'
related_material:
record:
- id: '5554'
relation: research_data
status: public
- id: '1666'
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: Evolution of transcriptional regulatory sequences
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2016'
...
---
_id: '1398'
abstract:
- lang: eng
text: Hybrid zones represent evolutionary laboratories, where recombination brings
together alleles in combinations which have not previously been tested by selection.
This provides an excellent opportunity to test the effect of molecular variation
on fitness, and how this variation is able to spread through populations in a
natural context. The snapdragon Antirrhinum majus is polymorphic in the wild for
two loci controlling the distribution of yellow and magenta floral pigments. Where
the yellow A. m. striatum and the magenta A. m. pseudomajus meet along a valley
in the Spanish Pyrenees they form a stable hybrid zone Alleles at these loci recombine
to give striking transgressive variation for flower colour. The sharp transition
in phenotype over ~1km implies strong selection maintaining the hybrid zone. An
indirect assay of pollinator visitation in the field found that pollinators forage
in a positive-frequency dependent manner on Antirrhinum, matching previous data
on fruit set. Experimental arrays and paternity analysis of wild-pollinated seeds
demonstrated assortative mating for pigmentation alleles, and that pollinator
behaviour alone is sufficient to explain this pattern. Selection by pollinators
should be sufficiently strong to maintain the hybrid zone, although other mechanisms
may be at work. At a broader scale I examined evolutionary transitions between
yellow and anthocyanin pigmentation in the tribe Antirrhinae, and found that selection
has acted strate that pollinators are a major determinant of reproductive success
and mating patterns in wild Antirrhinum.
acknowledgement: "I am indebted to many people for their support during my PhD, but
I particularly wish to thank Nick Barton for his guidance and intuition, and for
encouraging me to take the time to look beyond the immediate topic of my PhD to
understand the broader context. I am also especially grateful to David Field his
bottomless patience, invaluable advice on experimental design, analysis and scientific
writing, and for tireless work on the population surveys and genomic work without
most of my thesis could not have happened. \r\n\r\nIt has been a pleasure to work
with the combined strengths of the groups at The John Innes Centre, University of
Toulouse and IST Austria. Thanks to Enrico Coen and his group for hosting me in
Norwich in 2011 and especially for setting up the tag experiment. \r\n\r\nI thank
David Field, Desmond Bradley and Maria Clara Melo-Hurtado for organising field collections,
as well as Monique Burrus and Christophe Andalo and a large number of volunteers
for their e ff orts helping with the field work. Furthermore I thank Coline Jaworski
for providing seeds and for her input into the design of the experimental arrays,
and Matthew Couchman for maintaining the database of. \r\n\r\nIn addition to those
mentioned above, I am grateful to Melinda Pickup, Spencer Barrett, and four anonymous
reviewers for their insightful comments on sections of this manuscript. I also thank
Jana Porsche for her e ff orts in tracking down the more obscure references for
chapter 5, and Jon Bollback for his advice about the analysis. \r\n\r\nI am indebted
to Jon Ågren for his patience whilst I finished this thesis, and to Sylvia Cremer
and Magnus Nordborg for taking the time to read and evaluate the thesis given a
shorter deadline than was fair. \r\n\r\nA very positive aspect of my PhD has been
the supportive atmosphere of IST. In particular, I have come to appreciate the enormous
support from our group assistants Nicole Hotzy, Julia Asimakis, Christine Ostermann
and Jerneja Beslagic. I also thank Christian Chaloupka and Stefan Hipfinger for
their enthusiasm and readiness to help where possible in setting up our greenhouse
and experiments. "
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Thomas
full_name: Ellis, Thomas
id: 3153D6D4-F248-11E8-B48F-1D18A9856A87
last_name: Ellis
orcid: 0000-0002-8511-0254
citation:
ama: Ellis T. The role of pollinator-mediated selection in the maintenance of a
flower color polymorphism in an Antirrhinum majus hybrid zone. 2016. doi:10.15479/AT:ISTA:TH_526
apa: Ellis, T. (2016). The role of pollinator-mediated selection in the maintenance
of a flower color polymorphism in an Antirrhinum majus hybrid zone. Institute
of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:TH_526
chicago: Ellis, Thomas. “The Role of Pollinator-Mediated Selection in the Maintenance
of a Flower Color Polymorphism in an Antirrhinum Majus Hybrid Zone.” Institute
of Science and Technology Austria, 2016. https://doi.org/10.15479/AT:ISTA:TH_526 .
ieee: T. Ellis, “The role of pollinator-mediated selection in the maintenance of
a flower color polymorphism in an Antirrhinum majus hybrid zone,” Institute of
Science and Technology Austria, 2016.
ista: Ellis T. 2016. The role of pollinator-mediated selection in the maintenance
of a flower color polymorphism in an Antirrhinum majus hybrid zone. Institute
of Science and Technology Austria.
mla: Ellis, Thomas. The Role of Pollinator-Mediated Selection in the Maintenance
of a Flower Color Polymorphism in an Antirrhinum Majus Hybrid Zone. Institute
of Science and Technology Austria, 2016, doi:10.15479/AT:ISTA:TH_526 .
short: T. Ellis, The Role of Pollinator-Mediated Selection in the Maintenance of
a Flower Color Polymorphism in an Antirrhinum Majus Hybrid Zone, Institute of
Science and Technology Austria, 2016.
date_created: 2018-12-11T11:51:47Z
date_published: 2016-02-18T00:00:00Z
date_updated: 2024-02-21T13:51:39Z
day: '18'
ddc:
- '576'
degree_awarded: PhD
department:
- _id: NiBa
doi: '10.15479/AT:ISTA:TH_526 '
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publist_id: '5809'
pubrep_id: '526'
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status: public
supervisor:
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full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
title: The role of pollinator-mediated selection in the maintenance of a flower color
polymorphism in an Antirrhinum majus hybrid zone
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2016'
...