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Genetic structure, gene flow and local adaptation in the interior spruce hybrid zone De La Torre Cuba, Amanda Rosa Maria
Abstract
Natural hybrid zones provide a great opportunity to study the evolutionary relationships between closely related species. I have combined ten microsatellites (SSR) and 311 single nucleotide polymorphism (SNP) markers with quantitative data to investigate the genetic structure, interspecific gene flow and adaptation of the economically and ecologically important Picea glauca (white spruce) x P. engelmannii (Engelmann spruce) hybrid zone in western North America. Climate modelling and paleoclimate analysis was used to study the historical evolutionary relationships between hybridizing species; and to predict future patterns of genetic variation in the zone. This modelling suggests these species may have been in contact for as long as 21,000 years. Current levels of admixture and introgression are extensive, as suggested by both the SSR and SNP analyses, with populations showing elevational and latitudinal unimodal clines in admixture. Hybrids occupy intermediate environments in the zone and show a higher genetic contribution from Engelmann spruce than from white spruce on average. Despite a long history of interspecific gene flow, pure species and hybrids are adapted to different environments. Results of the quantitative analysis based on long-term data on growth and survival, as well as bud phenology and cold hardiness, indicate that the white x Engelmann spruce hybrid zone is maintained by adaptation to the length of growing seasons and the persistence of the snowpack (exogenous selection), in which hybrids are fitter than pure species in intermediate environments, fitting the "Bounded hybrid superiority" model of hybrid zone maintenance. I identified 12 outlier SNPs among the 311 SNPs; these were genes responsible for carbohydrate metabolism, signal transduction and transcription factors. These results have significant implications for forest management and breeding of spruce species in British Columbia, where this species complex is managed as one species without considering the complexity in population structure and adaptive differences between pure species and hybrids.
Item Metadata
Title |
Genetic structure, gene flow and local adaptation in the interior spruce hybrid zone
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2012
|
Description |
Natural hybrid zones provide a great opportunity to study the evolutionary relationships
between closely related species. I have combined ten microsatellites (SSR) and 311 single
nucleotide polymorphism (SNP) markers with quantitative data to investigate the genetic
structure, interspecific gene flow and adaptation of the economically and ecologically important
Picea glauca (white spruce) x P. engelmannii (Engelmann spruce) hybrid zone in western
North America. Climate modelling and paleoclimate analysis was used to study the historical
evolutionary relationships between hybridizing species; and to predict future patterns of genetic
variation in the zone. This modelling suggests these species may have been in contact for as
long as 21,000 years. Current levels of admixture and introgression are extensive, as
suggested by both the SSR and SNP analyses, with populations showing elevational and
latitudinal unimodal clines in admixture. Hybrids occupy intermediate environments in the zone
and show a higher genetic contribution from Engelmann spruce than from white spruce on
average. Despite a long history of interspecific gene flow, pure species and hybrids are
adapted to different environments. Results of the quantitative analysis based on long-term data
on growth and survival, as well as bud phenology and cold hardiness, indicate that the white x
Engelmann spruce hybrid zone is maintained by adaptation to the length of growing seasons
and the persistence of the snowpack (exogenous selection), in which hybrids are fitter than
pure species in intermediate environments, fitting the "Bounded hybrid superiority" model of hybrid zone maintenance. I identified 12 outlier SNPs among the 311 SNPs; these were genes
responsible for carbohydrate metabolism, signal transduction and transcription factors. These
results have significant implications for forest management and breeding of spruce species in
British Columbia, where this species complex is managed as one species without considering
the complexity in population structure and adaptive differences between pure species and
hybrids.
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Genre | |
Type | |
Language |
eng
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Date Available |
2012-10-31
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0072709
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2012-05
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International