Incongruence between cpDNA and nrITS trees indicates extensive hybridization within <i>Eupersicaria</i> (Polygonaceae)

TitleIncongruence between cpDNA and nrITS trees indicates extensive hybridization within Eupersicaria (Polygonaceae)
Publication TypeJournal Article
Year of Publication2008
AuthorsKim S-T, Donoghue MJ
JournalAmerican Journal of Botany
Pagination1122 - 1135
Keywordsallopolyploidy, cpDNA, Eupersicaria, hybridization, incongruence tests ITS, Persicaria, PLANT SCIENCES, Polygonaceae, Polygonum

Interspecific hybridization followed by polyploidization appears to have played a major role in plant diversification, but quantifying the contribution of this mechanism to diversification within taxonomically complex clades remains difficult. Incongruence among gene trees can provide critical insights, especially when combined with data on chromosome numbers, morphology, and geography. To further test our previous hypothesis on hybrid speciation in Persicaria (Polygonaceae), we performed molecular phylogenetic studies using three cpDNA regions and nuclear ITS sequences, with an emphasis on sampling within section Eupersicaria. Our analyses revealed major conflicts between the combined cpDNA tree and the nrITS tree; a variety of incongruence tests rejected stochastic error as the cause of incongruence in most cases. On the basis of our tree incongruence results and information on chromosome numbers, we hypothesize that the origin of 10 polyploid species involved interspecific hybridiz