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Phylogeny and biogeography of Juglans (Juglandaceae) based on matK and ITS sequence data
Author(s) -
Stanford Alice M.,
Harden Rachel,
Parks Clifford R.
Publication year - 2000
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.2307/2656895
Subject(s) - biology , monophyly , juglans , juglandaceae , maximum parsimony , genus , ribosomal dna , botany , chloroplast dna , spacer dna , phylogenetic tree , evolutionary biology , clade , genetics , gene
We investigated phylogenetic and biogeographic relationships within Juglans (walnuts), a Tertiary disjunct genus, using 15 species of Juglans and related (Juglandaceae) outgroups. The relationships were analyzed using nucleotide sequences of the chloroplast gene matK and its flanking spacers and of the internal transcribed spacers (ITS) and 5.8S gene of the nuclear ribosomal DNA. The DNA sequences provided 246 informative characters for parsimony analysis. ITS data supported as monophyletic groups the four generic sections, Cardiocaryon, Dioscaryon, Rhysocaryon , and Trachycaryon. Within Rhysocaryon , the temperate black walnuts and the tropical black walnuts were supported as monophyletic groups. When the two data sets were combined, J. cinerea was nested within Cardiocaryon. Combined analysis with published nuclear DNA restriction site data placed J. cinerea in a monophyletic group with Cardiocaryon. These analyses consistently supported Juglans as a monophyletic group and as the sister group to the genus Pterocarya. The results of this work are consistent with the known geological history of Juglans. The fossil record suggests that the butternuts had evolved by the early Oligocene in North America. The presence of butternuts in Eurasia could be the result of migration from North America to Eurasia during the warming trend of the mid Oligocene.