title: Natural hybridization and introgression between Ligularia cymbulifera and L. tongolensis (Asteraceae, Senecioneae) in four different locations.
abstract: Natural hybridization has been considered to represent an important factor influencing the high diversity of the genus Ligularia Cass. in the Hengduan Mountains, China. Natural hybridization has been confirmed to occur frequently in Ligularia. To date, however, it has been demonstrated only within a single population. In this paper, we present evidence of natural hybridization in Ligularia from four different locations. The internal transcribed spacer (ITS) region of the nuclear ribosomal DNA and three chloroplast intergenic spacers (trnK-rps16, trnL-rpl32 and trnQ-5'rps16) of 149 accessions of putative hybrids and their putative parents (L. cymbulifera and L. tongolensis) were analyzed for evidence of hybridization. The ITS data clearly distinguished two putative parental species and sympatric L. vellerea and supported the hypothesis that those morphological intermediates were products of natural hybridization between L. cymbulifera and L. tongolensis. Moreover, several identified morphological parents were actual introgressed products. Because of hybridization and introgression, chloroplast DNA sequences generated a poorly resolved network. The present results indicate that varying degrees of hybridization and introgression occur differently depending on the habitat context. We conclude that gene flow caused by natural hybridization in Ligularia indeed plays an important role in the species diversity.
authors.affiliation: Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, P. R. China; University of Chinese Academy of Sciences, Beijing, P. R. China.
authors.forename: Jiaojun
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of Chemistry, Rikkyo University, Tokyo, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kuroda
authors.affiliation: Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, P. R. China.
authors.forename: Xun
authors.initials: X
authors.lastname: Gong
mesh_terms: D019659:Asteraceae / Q000145:classification / Q000166:cytology / Q000235:genetics*; D002467:Cell Nucleus / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D006824:Hybridization, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D018744:DNA, Plant; D021903:DNA, Ribosomal Spacer