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ADAPTATION TO NORTHERN CONDITIONS AT FLOWERING TIME GENES IN ARABIDOPSIS LYRATA AND ARABIDOPSIS THALIANA, ACTA UNIVERSITATIS OULUENSIS A Scientiae Rerum Naturalium 567

ISBN-13:	978-951-42-9351-1
Kieli:	englanti
Kustantaja:	Oulun yliopisto
Oppiaine:	Luonnontieteet
Painosvuosi:	2011
Sidosasu:	pehmeäkantinen
Sijainti:	Print Tietotalo
Sivumäärä:	164
Tekijät:	NIITTYVUOPIO ANNE

21.00 €

The timing growth and reproduction are critical to the fitness of plants and animals. The timingalso has an important role in local adaptation. Locally adapted plants may have different responsesto photoperiod and other environmental cues and genes or alleles behind underlying differencesmay differ between populations. The molecular genetics and physiology of flowering of the plantmolecular biology model organism Arabidopsis thaliana is being intensively studied, and thisoffers a good opportunity to study the genetic basis of flowering time variation in related non-model species. The closely related perennial species Arabidopsis lyrata provides an interestingcomparison to A.thaliana because of its different ecology, mating system and life history. The influence of sampling designs on clustering methods was analyzed using simulations andmicrosatellite data in the selfing A.thaliana. It was found that sample size has a large effect on theresulting number of clusters and sampling too few individuals per locality could lead to a severeunderestimation of the real number of subpopulations. Patterns of sequence variation in flowering time genes and association betweenpolymorphisms at FRI (and FLC) and flowering time was studied in A. thaliana and in A.lyratato find out whether the genes were responsible for flowering time differences between and withinnatural populations. In A.thaliana there was no significant association between polymorphisms atFLC and FRI and flowering time. In A.lyrata the FRI gene was polymorphic for an indelassociated with flowering time variation within two Northern European populations, suggestingthat the indel (or a linked polymorphism) was involved in flowering time variation. However, FRIdid not explain the flowering time differences between A.lyrata populations, and other loci mustbe involved. Patterns of diversity and divergence at flowering time related loci were compared against a setof random reference loci to examine the roles of selection and demography. Sequence variation inthe studied A.lyrata populations departed from the standard neutral equilibrium model and it hasbeen influenced by recent historical events, most likely bottlenecks. The level of silent andsynonymous polymorphisms in flowering time genes was highly reduced and this can be likelyexplained by selective sweeps at flowering time genes.

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