title: Revisiting a classic case of introgression: hybridization and gene flow in Californian sunflowers.
abstract: During invasion, colonizing species can hybridize with native species, potentially swamping out native genomes. However, theory predicts that introgression will often be biased into the invading species. Thus, empirical estimates of gene flow between native and invasive species are important to quantify the actual threat of hybridization with invasive species. One classic example of introgression occurs in California, where Helianthus bolanderi was thought to be a hybrid between the serpentine endemic Helianthus exilis and the congeneric invader Helianthus annuus. We used genotyping by sequencing to look for signals of introgression and population structure. We find that H. bolanderi and H. exilis form one genetic clade, with weak population structure that is associated with geographic location rather than soil composition and likely represent a single species, not two. Additionally, while our results confirmed early molecular analysis and failed to support the hybrid origin of H. bolanderi, we did find evidence for introgression mainly into the invader H. annuus, as predicted by theory.
authors: Department of Botany and Biodiversity Research Centre, University of British Columbia, University Blvd, Vancouver, BC, V6T 1Z4, Canada.
authors: Gregory L
authors: GL
authors: Owens
authors: Department of Botany and Biodiversity Research Centre, University of British Columbia, University Blvd, Vancouver, BC, V6T 1Z4, Canada.
authors: Gregory J
authors: GJ
authors: Baute
authors: Department of Botany and Biodiversity Research Centre, University of British Columbia, University Blvd, Vancouver, BC, V6T 1Z4, Canada.|Department of Biology, Indiana University, Bloomington, IN, 47405, USA.
authors: Loren H
authors: LH
authors: Rieseberg
mesh_terms: D002140:California; D018744:DNA, Plant / Q000235:genetics; D051456:Gene Flow; D005828:Genetics, Population; D060005:Genotyping Techniques; D006368:Helianthus / Q000145:classification / Q000235:genetics*; D006824:Hybridization, Genetic; D058865:Introduced Species; D008957:Models, Genetic; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant
keywords: angiosperms; gene flow; hybridization; invasive species; phylogeography; population genetics-empirical