University of Oulu

Roles of demography and natural selection in molecular evolution of trees, focus on Pinus sylvestris

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Author: Pyhäjärvi, Tanja1
Organizations: 1University of Oulu, Faculty of Science, Department of Biology
Format: ebook
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.4 MB)
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Language: English
Published: 2008
Publish Date: 2008-04-01
Thesis type: Doctoral Dissertation
Defence Note: Academic dissertation to be presented, with the assent of the Faculty of Science of the University of Oulu, for public defence in Kuusamonsali (Auditorium YB210), Linnanmaa, on April 11th, 2008, at 12 noon
Reviewer: Research Associate Professor Thomas Bataillon
Professor Craig Primmer


Natural selection, mutation, recombination, demographic history and chance all have a role in evolution. In natural populations, the outcome of these forces is seen as adaptations, differences between geographic varieties, and as genetic diversity in populations—both at the phenotypic and molecular levels. In this thesis I wanted to examine the roles of the evolutionary forces shaping molecular genetic diversity in trees, with emphasis on a boreal conifer, Scots pine (Pinus sylvestris).

Phylogeographic history and past population size changes have a dominant role in molecular diversity of P. sylvestris. The effect of the Last Glacial Maximum (37 000–16 000) was observed in the distribution of mitochondrial DNA variation. In contrast, nuclear DNA was not much affected by the last glacial period. Instead, more ancient demographic events that took place millions of years ago can still be observed in the variation of P. sylvestris nuclear DNA.

Not much evidence of positive natural selection was found in pines or trees in general. This is in contrast to strong natural selection that is observed at the phenotypic level. Positive selection is difficult to prove, especially when the genome is still affected by demographic history. Mutation–drift equilibrium may rarely be reached in tree populations.

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Series: Acta Universitatis Ouluensis. A, Scientiae rerum naturalium
ISSN-E: 1796-220X
ISBN: 978-951-42-8768-8
ISBN Print: 978-951-42-8767-1
Issue: 506
Copyright information: © University of Oulu, 2008. This publication is copyrighted. You may download, display and print it for your own personal use. Commercial use is prohibited.