Geada López, G., K. Kamiya, and K. Harada. 2002. Phylogenetic relationships of diploxylon pines (subgenus Pinus) based on plastid sequence data. Int. J. Plant Sci. 163: 737-747.
Abstract: The plastid DNA sequences of rbcL, matK, the trnV intron, and the rpl20-rps18 spacer in 38 species of subgenus Pinus, representing all recognized subsections, were analyzed. Combined data sets of 3230 bp were used to assess relationships with maximum parsimony, neighbor joining, and maximum likelihood algorithms. Subgenus Pinus splits into two distinct lineages, corresponding to Eurasia and North America ("New World hard pines"). The Eurasian lineage differentiated into two clades: the Mediterranean pines, including the Himalayan pine P. roxburghii (subsections Canarienses, Halepenses, and Pinaster), and subsection Pinus. Two North American pines, P. tropicalis and P. resinosa, are typical members of subsection Pinus but are not closely related to each other. Subsection Contortae occupied the basal position in the "New World hard pines" followed by subsection Ponderosae. Of the remaining "New World hard pines" subsections, Attenuatae was a monophyletic group and Oocarpae, Australes, and Leiophyllae were poorly resolved. The eastern Cuban pines, P. cubensis and P. maestrensis, formed a subgroup within Australes. MatK evolved much faster than rbcL, and the noncoding regions evolved more slowly than rbcL and matK synonymous sites. The divergence times for each subsection were estimated from the rbcL sequence data calibrated by fossil data.