Polyploid speciation inHedera (Araliaceae): Phylogenetic and biogeographic insights based on chromosome counts and ITS sequences |
| |
Authors: | Pablo Vargas Hugh A McAllister Cynthia Morton Stephen L Jury Mike J Wilkinson |
| |
Institution: | (1) Department of Botany, Plant Sciences Laboratories, University of Reading, RG6 6AS, United Kingdom;(2) University of Liverpool Botanic Garden, L64 4AY Ness, Neston, Cheshire, United Kingdom;(3) Present address: Real Jardín Botánico, CSIC, Plaza de Murillo 2, E-28014, Madrid Spain |
| |
Abstract: | Variation in chromosome number and internal transcribed sequences (ITS) of nrDNA is used to infer phylogenetic relationships of a wide range ofHedera species. Polyploidy was found to be frequent inHedera, with diploid, tetraploid, hexaploid and octoploid populations being detected. Nucleotide additivity occurs in the ITS sequences of one tetraploid (H. hibernica) and two hexaploid species (H. maderensis, H. pastuchovii), suggesting that all three species originated by allopolyploidisation. ITS sequence polymorphism and nucleotide characters may indicate the presence of an ancient genome persistent only in some allopolyploid species. Phylogenetic analyses of ITS sequence data reveal two lineages ofHedera: one containing all sequences belonging to extant diploids plus the tetraploidH. algeriensis, and a second that includes this ancient ITS type and others exclusive to several polyploid species. The origin of the polyploids is evaluated on the basis of morphology, chromosome counts, ITS sequence polymorphism, and phylogenetic analyses. Reconstruction of reticulate evolution inHedera agrees with two allopolyploid areas on both sides of the Mediterranean basin. Morphological, molecular and cytological evidence also suggests an active dispersal ofHedera populations that may account for three independent introductions in Macaronesia. |
| |
Keywords: | Araliaceae Hedera Chromosome counts polyploidy ITS sequences polymorphism concerted evolution phylogenetic analyses biogeography |
本文献已被 SpringerLink 等数据库收录! |
|