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Evolutionary history of P urple cone spruce ( P icea purpurea ) in the Q inghai– T ibet P lateau: homoploid hybrid origin and P leistocene expansion
Author(s) -
Sun Yongshuai,
Abbott Richard J.,
Li Lili,
Li Long,
Zou Jiabin,
Liu Jianquan
Publication year - 2014
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.12599
Subject(s) - biology , introgression , phylogenetic tree , evolutionary biology , mitochondrial dna , nuclear dna , genetics , gene
Hybridization and introgression can play an important role in speciation. Here, we examine their roles in the origin and evolution of P icea purpurea , a diploid spruce species occurring on the Q inghai– T ibet P lateau ( QTP ). Phylogenetic relationships and ecological differences between this species and its relatives, P . schrenkiana, P . likiangensis and P . wilsonii, are unclear. To clarify them, we surveyed sequence variation within and between them for 11 nuclear loci, three chloroplast (cp) and two mitochondrial (mt) DNA fragments, and examined their ecological requirements using ecological niche modelling. Initial analyses based on 11 nuclear loci rejected a close relationship between P . schrenkiana and P . purpurea . BP & P tests and ecological niche modelling indicated substantial divergence between the remaining three species and supported the species status of P . purpurea, which contained many private alleles as expected for a well‐established species. Sequence variation for cp DNA and mt DNA suggested a close relationship between P . purpurea and P . wilsonii , while variation at the nuclear se1364 gene suggested P . purpurea was more closely related to P . likiangensis . Analyses of genetic divergence, Bayesian clustering and model comparison using approximate B ayesian computation ( ABC ) of nuclear (nr) DNA variation all supported the hypothesis that P . purpurea originated by homoploid hybrid speciation from P . wilsonii and P . likiangensis . The ABC analysis dated the origin of P . purpurea at the P leistocene, and the estimated hybrid parameter indicated that 69% of its nuclear composition was contributed by P . likiangensis and 31% by P . wilsonii . Our results further suggested that during or immediately following its formation, P . purpurea was subject to organelle DNA introgression from P . wilsonii such that it came to possess both mt DNA and cp DNA of P . wilsonii . The estimated parameters indicated that following its origin, P . purpurea underwent an expansion during/after the largest P leistocene glaciation recorded for the QTP .