title: Phylogeny and evolutionary histories of Pyrus L. revealed by phylogenetic trees and networks based on data from multiple DNA sequences.
abstract: Reconstructing the phylogeny of Pyrus has been difficult due to the wide distribution of the genus and lack of informative data. In this study, we collected 110 accessions representing 25 Pyrus species and constructed both phylogenetic trees and phylogenetic networks based on multiple DNA sequence datasets. Phylogenetic trees based on both cpDNA and nuclear LFY2int2-N (LN) data resulted in poor resolution, especially, only five primary species were monophyletic in the LN tree. A phylogenetic network of LN suggested that reticulation caused by hybridization is one of the major evolutionary processes for Pyrus species. Polytomies of the gene trees and star-like structure of cpDNA networks suggested rapid radiation is another major evolutionary process, especially for the occidental species. Pyrus calleryana and P. regelii were the earliest diverged Pyrus species. Two North African species, P. cordata, P. spinosa and P. betulaefolia were descendent of primitive stock Pyrus species and still share some common molecular characters. Southwestern China, where a large number of P. pashia populations are found, is probably the most important diversification center of Pyrus. More accessions and nuclear genes are needed for further understanding the evolutionary histories of Pyrus.
authors.affiliation: Department of Horticulture, The State Agricultural Ministry Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Hangzhou, Zhejiang 310058, China; Institute of Horticulture and Landscape, College of Ecology, Lishui University, Lishui, Zhejiang 323000, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Department of Horticulture, The State Agricultural Ministry Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Hangzhou, Zhejiang 310058, China.
authors.forename: Danying
authors.initials: D
authors.lastname: Cai
authors.affiliation: Department of Plant Sciences, University of California, Mail Stop 2, Davis, CA 95616-8780, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Potter
authors.affiliation: National Clonal Germplasm Repository, USDA-ARS, Corvallis, OR 97333, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Postman
authors.affiliation: Department of Horticulture, The State Agricultural Ministry Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Hangzhou, Zhejiang 310058, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Horticulture, The State Agricultural Ministry Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Hangzhou, Zhejiang 310058, China. Electronic address: ywteng@zju.edu.cn.
authors.forename: Yuanwen
authors.initials: Y
authors.lastname: Teng
mesh_terms: D001499:Bayes Theorem; D005075:Biological Evolution; D002681:China; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D006239:Haplotypes; D006824:Hybridization, Genetic; D010802:Phylogeny; D031989:Pyrus / Q000145:classification* / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast; D018744:DNA, Plant
keywords: DNA sequences; Phylogenetic network; Pyrus; Rapid radiation; Reticulation