---
_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
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creator: oolusany
date_created: 2024-01-03T18:30:13Z
date_updated: 2024-01-03T18:30:13Z
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oa_version: Published Version
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grant_number: '665385'
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grant_number: P32896
name: Causes and consequences of population fragmentation
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grant_number: '26380'
name: Polygenic Adaptation in a Metapopulation
publication_identifier:
issn:
- 2663 - 337X
publication_status: published
publisher: Institute of Science and Technology Austria
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relation: part_of_dissertation
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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
- 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
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...
---
_id: '14732'
abstract:
- lang: eng
text: 'Fragmented landscapes pose a significant threat to the persistence of species
as they are highly susceptible to heightened risk of extinction due to the combined
effects of genetic and demographic factors such as genetic drift and demographic
stochasticity. This paper explores the intricate interplay between genetic load
and extinction risk within metapopulations with a focus on understanding the impact
of eco-evolutionary feedback mechanisms. We distinguish between two models of
selection: soft selection, characterised by subpopulations maintaining carrying
capacity despite load, and hard selection, where load can significantly affect
population size. Within the soft selection framework, we investigate the impact
of gene flow on genetic load at a single locus, while also considering the effect
of selection strength and dominance coefficient. We subsequently build on this
to examine how gene flow influences both population size and load under hard selection
as well as identify critical thresholds for metapopulation persistence. Our analysis
employs the diffusion, semi-deterministic and effective migration approximations.
Our findings reveal that under soft selection, even modest levels of migration
can significantly alleviate the burden of load. In sharp contrast, with hard selection,
a much higher degree of gene flow is required to mitigate load and prevent the
collapse of the metapopulation. Overall, this study sheds light into the crucial
role migration plays in shaping the dynamics of genetic load and extinction risk
in fragmented landscapes, offering valuable insights for conservation strategies
and the preservation of diversity in a changing world.'
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
- first_name: Kseniia
full_name: Khudiakova, Kseniia
id: 4E6DC800-AE37-11E9-AC72-31CAE5697425
last_name: Khudiakova
orcid: 0000-0002-6246-1465
- first_name: Himani
full_name: Sachdeva, Himani
id: 42377A0A-F248-11E8-B48F-1D18A9856A87
last_name: Sachdeva
citation:
ama: Olusanya OO, Khudiakova K, Sachdeva H. Genetic load, eco-evolutionary feedback
and extinction in a metapopulation. bioRxiv. doi:10.1101/2023.12.02.569702
apa: Olusanya, O. O., Khudiakova, K., & Sachdeva, H. (n.d.). Genetic load, eco-evolutionary
feedback and extinction in a metapopulation. bioRxiv. https://doi.org/10.1101/2023.12.02.569702
chicago: Olusanya, Oluwafunmilola O, Kseniia Khudiakova, and Himani Sachdeva. “Genetic
Load, Eco-Evolutionary Feedback and Extinction in a Metapopulation.” BioRxiv,
n.d. https://doi.org/10.1101/2023.12.02.569702.
ieee: O. O. Olusanya, K. Khudiakova, and H. Sachdeva, “Genetic load, eco-evolutionary
feedback and extinction in a metapopulation,” bioRxiv. .
ista: Olusanya OO, Khudiakova K, Sachdeva H. Genetic load, eco-evolutionary feedback
and extinction in a metapopulation. bioRxiv, 10.1101/2023.12.02.569702.
mla: Olusanya, Oluwafunmilola O., et al. “Genetic Load, Eco-Evolutionary Feedback
and Extinction in a Metapopulation.” BioRxiv, doi:10.1101/2023.12.02.569702.
short: O.O. Olusanya, K. Khudiakova, H. Sachdeva, BioRxiv (n.d.).
date_created: 2024-01-04T09:35:54Z
date_published: 2023-12-04T00:00:00Z
date_updated: 2025-05-26T09:05:10Z
day: '04'
department:
- _id: NiBa
- _id: JaMa
doi: 10.1101/2023.12.02.569702
language:
- iso: eng
license: https://creativecommons.org/licenses/by-nc-nd/4.0/
main_file_link:
- open_access: '1'
url: https://www.biorxiv.org/content/10.1101/2023.12.02.569702v1
month: '12'
oa: 1
oa_version: Preprint
project:
- _id: c08d3278-5a5b-11eb-8a69-fdb09b55f4b8
grant_number: P32896
name: Causes and consequences of population fragmentation
- _id: 34d33d68-11ca-11ed-8bc3-ec13763c0ca8
grant_number: '26293'
name: The impact of deleterious mutations on small populations
- _id: 34c872fe-11ca-11ed-8bc3-8534b82131e6
grant_number: '26380'
name: Polygenic Adaptation in a Metapopulation
publication: bioRxiv
publication_status: submitted
related_material:
record:
- id: '14711'
relation: dissertation_contains
status: public
status: public
title: Genetic load, eco-evolutionary feedback and extinction in a metapopulation
tmp:
image: /images/cc_by_nc_nd.png
legal_code_url: https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode
name: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
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short: CC BY-NC-ND (4.0)
type: preprint
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
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...