title: Molecular Evidence for the Hybrid Origin of Ilex dabieshanensis (Aquifoliaceae).
abstract: Ilex, the largest genus of dioecious woody plants, is a good study system to assess the role of hybridization in speciation and evolution. Ilex dabieshanensis, a tree endemic to Dabieshan Mountains region, was initially described as a new species. Based on morphological intermediacy and sympatric distribution with its putative parental species, I. cornuta and I. latifolia, we proposed it as a natural hybrid between them. In this study, we sequenced one chloroplast intergenic spacer (trnH-psbA) and two nuclear genes (gapC and nepGS) in I. dabieshanensis and its putative parental species to test the hybrid origin hypothesis. Our results showed that there were one to two differentially fixed sequence differences between I. cornuta and I. latifolia at the two nuclear genes. Twelve of the 14 individuals of I. dabieshanensis exhibited additivity in chromatograms on these differentially fixed sites at both nuclear genes, and the remaining two exhibited additivity in chromatograms on the fixed site at only the nepGS gene. Except one haplotype of I. cornuta at the nepGS gene, all of the haplotypes of I. cornuta at the two nuclear genes were well separated from those of I. latifolia, and most haplotypes of I. dabieshanensis were shared with those of I. cornuta and I. latifolia. Phylogenetic analysis of these haplotypes was largely consistent with haplotype network analysis. I. cornuta and I. latifolia differed by two nucleotide substitutions in the chloroplast intergenic spacer, and 12 individuals of I. dabieshanensis had the same sequences as I. latifolia, while the remaining two were identical with I. cornuta. The molecular data provide convincing evidence for the hybrid origin of I. dabieshanensis and asymmetrical direction of hybridization. One haplotype of I. cornuta at the nepGS gene was nested with those of I. latifolia, indicating introgression to I. cornuta.
authors.affiliation: Shunde Polytechnic, Foshan 528333, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Shi
authors.affiliation: Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing 210014, China.
authors.forename: Naiwei
authors.initials: N
authors.lastname: Li
authors.affiliation: State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, Sun Yat-sen University, Guangzhou 510275, China.
authors.forename: Shuqiong
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, Sun Yat-sen University, Guangzhou 510275, China.
authors.forename: Yubing
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, Sun Yat-sen University, Guangzhou 510275, China.
authors.forename: Weijie
authors.initials: W
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, Sun Yat-sen University, Guangzhou 510275, China.
authors.forename: Yuchen
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China.
authors.forename: Yongpeng
authors.initials: Y
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, Sun Yat-sen University, Guangzhou 510275, China.
authors.forename: Renchao
authors.initials: R
authors.lastname: Zhou
mesh_terms: D002467:Cell Nucleus / Q000235:genetics; D002736:Chloroplasts / Q000235:genetics; D017343:Genes, Plant; D006239:Haplotypes; D030017:Ilex / Q000145:classification / Q000235:genetics*; D010802:Phylogeny