title: Genetic architecture and genomic patterns of gene flow between hybridizing species of Picea.
abstract: Hybrid zones provide an opportunity to study the effects of selection and gene flow in natural settings. We employed nuclear microsatellites (single sequence repeat (SSR)) and candidate gene single-nucleotide polymorphism markers (SNPs) to characterize the genetic architecture and patterns of interspecific gene flow in the Picea glauca × P. engelmannii hybrid zone across a broad latitudinal (40-60 degrees) and elevational (350-3500 m) range in western North America. Our results revealed a wide and complex hybrid zone with broad ancestry levels and low interspecific heterozygosity, shaped by asymmetric advanced-generation introgression, and low reproductive barriers between parental species. The clinal variation based on geographic variables, lack of concordance in clines among loci and the width of the hybrid zone points towards the maintenance of species integrity through environmental selection. Congruency between geographic and genomic clines suggests that loci with narrow clines are under strong selection, favoring either one parental species (directional selection) or their hybrids (overdominance) as a result of strong associations with climatic variables such as precipitation as snow and mean annual temperature. Cline movement due to past demographic events (evidenced by allelic richness and heterozygosity shifts from the average cline center) may explain the asymmetry in introgression and predominance of P. engelmannii found in this study. These results provide insights into the genetic architecture and fine-scale patterns of admixture, and identify loci that may be involved in reproductive barriers between the species.
authors: 1] Department of Forest and Conservation Sciences, Centre for Forest Conservation Genetics, University of British Columbia, Vancouver, BC, Canada [2] Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
authors: A
authors: A
authors: De La Torre
authors: 1] Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden [2] Umeå Plant Sciences Centre, Umeå, Sweden.
authors: P K
authors: PK
authors: Ingvarsson
authors: Department of Forest and Conservation Sciences, Centre for Forest Conservation Genetics, University of British Columbia, Vancouver, BC, Canada.
authors: S N
authors: SN
authors: Aitken
mesh_terms: D001955:British Columbia; D018744:DNA, Plant / Q000235:genetics; D019143:Evolution, Molecular; D051456:Gene Flow; D056426:Genetic Loci; D005828:Genetics, Population; D005838:Genotype; D005843:Geography; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats; D008957:Models, Genetic; D028222:Picea / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA; D015206:Southwestern United States
chemical_list: D018744:DNA, Plant