title: Disentangling the roles of history and local selection in shaping clinal variation of allele frequencies and gene expression in Norway spruce (Picea abies).
abstract: Understanding the genetic basis of local adaptation is challenging due to the subtle balance among conflicting evolutionary forces that are involved in its establishment and maintenance. One system with which to tease apart these difficulties is clines in adaptive characters. Here we analyzed genetic and phenotypic variation in bud set, a highly heritable and adaptive trait, among 18 populations of Norway spruce (Picea abies), arrayed along a latitudinal gradient ranging from 47°N to 68°N. We confirmed that variation in bud set is strongly clinal, using a subset of five populations. Genotypes for 137 single-nucleotide polymorphisms (SNPs) chosen from 18 candidate genes putatively affecting bud set and 308 control SNPs chosen from 264 random genes were analyzed for patterns of genetic structure and correlation to environment. Population genetic structure was low (F(ST) = 0.05), but latitudinal patterns were apparent among Scandinavian populations. Hence, part of the observed clinal variation should be attributable to population demography. Conditional on patterns of genetic structure, there was enrichment of SNPs within candidate genes for correlations with latitude. Twenty-nine SNPs were also outliers with respect to F(ST). The enrichment for clinal variation at SNPs within candidate genes (i.e., SNPs in PaGI, PaPhyP, PaPhyN, PaPRR7, and PaFTL2) indicated that local selection in the 18 populations, and/or selection in the ancestral populations from which they were recently derived, shaped the observed cline. Validation of these genes using expression studies also revealed that PaFTL2 expression is significantly associated with latitude, thereby confirming the central role played by this gene in the control of phenology in plants.
authors.affiliation: Department of Ecology and Genetics, Evolutionary Biology Center, Uppsala University, 752 36 Uppsala, Sweden.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Thomas
authors.initials: T
authors.lastname: Källman
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Ma
authors.forename: Niclas
authors.initials: N
authors.lastname: Gyllenstrand
authors.forename: Giusi
authors.initials: G
authors.lastname: Zaina
authors.forename: Michele
authors.initials: M
authors.lastname: Morgante
authors.forename: Jean
authors.initials: J
authors.lastname: Bousquet
authors.forename: Andrew
authors.initials: A
authors.lastname: Eckert
authors.forename: Jill
authors.initials: J
authors.lastname: Wegrzyn
authors.forename: David
authors.initials: D
authors.lastname: Neale
authors.forename: Ulf
authors.initials: U
authors.lastname: Lagercrantz
authors.forename: Martin
authors.initials: M
authors.lastname: Lascoux
mesh_terms: D001499:Bayes Theorem; D055669:Ecological and Environmental Phenomena; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D005787:Gene Frequency / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics*; D016014:Linear Models; D015810:Linkage Disequilibrium / Q000235:genetics; D028222:Picea / Q000235:genetics*; D018520:Plant Shoots / Q000235:genetics; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D012641:Selection, Genetic / Q000235:genetics*