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dc.contributor.author
Pålsson, Aksel
dc.contributor.supervisor
Widmer, Alex
dc.contributor.supervisor
Fior, Simone
dc.contributor.supervisor
Alexander, Jake
dc.contributor.supervisor
Karrenberg, Sophie
dc.contributor.supervisor
Hiscock, Simon
dc.date.accessioned
2023-06-02T11:46:23Z
dc.date.available
2023-06-01T22:26:47Z
dc.date.available
2023-06-02T11:46:23Z
dc.date.issued
2023
dc.identifier.uri
http://hdl.handle.net/20.500.11850/614700
dc.identifier.doi
10.3929/ethz-b-000614700
dc.description.abstract
Divergent selection pressures imposed by contrasting environmental conditions at opposite ends of environmental gradients can drive the evolution of populations that are adapted to local conditions. Elevational gradients in the Alps coincide with steep climatic gradients where plant populations experience divergent selection within a limited geographic scale. This feature makes alpine plants with a broad elevational range ideal for the study of evolution of local adaptation. In this thesis, we aimed to unravel the evolution of distinct locally adapted ecotypes of alpine carnations (Dianthus spp., Caryophyllaceae) in response to climate driven selection imposed by contrasting elevational habitats. As a study system, we used two perennial systems with an elevational distribution ranging from the colline to alpine belts in central Europe, D. carthusianorum and D. sylvestris. We used populations from low and high elevation growing in long-term reciprocal transplant experiments to study the evolutionary processes underlying ecotype formation by investigating performance across multiple fitness components and life stages of the perennial life cycle. Experiments for D. sylvestris were further combined with phenotypic selection analyses and a genome-wide association study based on a transplant of recombinant F2 crosses, which were used to examine the both contribution of divergent traits to adaptation and the fitness effect of alleles underlying these traits. In chapter I, we first tested for local adaptation in D. carthusianorum by using data on performance in individual fitness components measured over a period of three years in the reciprocal transplant experiment. We found evidence of genotype by environment (GxE) interactions and fitness advantages of the local ecotype, though with extensive variation at different stages of the life cycle. We thus performed a complementary seedling recruitment experiment and integrated fitness over the course of the experiment through matrix population models. Population growth rates showed a strong signal of local adaptation in both elevational environments and further provided evidence of alternate life-history traits as determinants of plant fitness. The low elevation environment caused the local plants to express a faster life cycle characterized by high investment in early reproduction. Contrarily, fitness of the local plants in the high elevation ecotype was driven primarily by survival. The high elevation plants also reproduced more in the foreign environment, which caused them to exceed their physiological limit of resource allocation to reproduction and suffer a cost in terms of reduced post reproductive survival. Chapter I shows how selection imposed at the extremes of an elevational gradient drove ecotype formation in a perennial plant, highlighting the influence of trade-offs and phenotypic plasticity of life history traits as determinants of population performance under different environmental conditions. In chapter II, we explored how selection acting through different fitness components of the perennial life cycle has driven ecotype formation in D. sylvestris, and we dissected the contribution of divergent traits to this process. Populations of D. sylvestris persisted in high elevation refugia during the Last Glacial Maximum and have subsequently colonized low elevation habitats. We combined phenotypic and fitness data collected in a reciprocal transplant experiment over five years with phenotypic selection analyses on F2 crosses to unravel the contributions of adaptive traits to the responses to the contrasting environmental conditions and associated selection regimes. Our results revealed a strong genetic basis for plant size, plant height and flowering time, associated with elevational adaptation. The high elevation environment favored a conservative life history strategy characterized by a long life span and limited investment in reproduction. Consistently, selection acted towards early flowering to ensure completion of the reproductive cycle in the short alpine summer season. In contrast, the warmer low elevation environment favored a life history strategy characterized by high investment in early reproduction at the expense of a shorter life cycle, and thus plants achieving large size and maximized fecundity. Our results show that colonization of the warmer low elevation habitats proceeded through a shift in both phenotypic and life history traits linked to resource allocation in a high-energy environment with a longer reproductive season. In chapter III, we leveraged results from chapter II to uncover the fitness effect of alleles underlying the traits that contributed to the adaptive divergence between the low and high elevation populations of D. sylvestris. We performed genome-wide association analyses and identified a polygenic genetic architecture underlying the studied adaptive traits. We found examples of both antagonistic pleiotropy and conditional neutrality describing the fitness effects of allelic variation at these loci. By dissecting separate fitness components, we revealed that alleles underlying successful reproduction at high elevation had a negative effect on fecundity, while this relationship turned positive at low elevation. These results suggest that the trade-off in resource allocation indicated in chapter II is accompanied by congruent signals at the level of the underlying genetic variants.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.subject
natural selection
en_US
dc.subject
local adaptation
en_US
dc.subject
ecotype divergence
en_US
dc.subject
life history traits
en_US
dc.subject
transplant experiment
en_US
dc.subject
fitness trade‐off
en_US
dc.subject
genetic trade-offs
en_US
dc.title
Uncovering the evolution of elevational ecotypes in Alpine carnations
en_US
dc.type
Doctoral Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
dc.date.published
2023-06-02
ethz.size
166 p.
en_US
ethz.code.ddc
DDC - DDC::5 - Science::500 - Natural sciences
en_US
ethz.grant
Genomics of adaptation in the context of a rapid plant radiation
en_US
ethz.grant
Ecological Genomics of Plant Adaptation
en_US
ethz.identifier.diss
29194
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02720 - Institut für Integrative Biologie / Institute of Integrative Biology::03706 - Widmer, Alexander / Widmer, Alexander
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02720 - Institut für Integrative Biologie / Institute of Integrative Biology::03706 - Widmer, Alexander / Widmer, Alexander
en_US
ethz.grant.agreementno
160123
ethz.grant.agreementno
182675
ethz.grant.fundername
SNF
ethz.grant.fundername
SNF
ethz.grant.funderDoi
10.13039/501100001711
ethz.grant.funderDoi
10.13039/501100001711
ethz.grant.program
Projekte Lebenswissenschaften
ethz.grant.program
Projekte Lebenswissenschaften
ethz.date.deposited
2023-06-01T22:26:47Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
ethz.date.embargoend
2024-06-02
ethz.rosetta.installDate
2023-06-02T11:46:24Z
ethz.rosetta.lastUpdated
2024-02-02T23:53:35Z
ethz.rosetta.exportRequired
true
ethz.rosetta.versionExported
true
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