Systematics Section / ASPT
Gernandt, David S. , Zerón-Flores, Omar , González -Garibaldi, Delia E. , Vázquez-Vera, Federico , Márquez, Juan , Pinero, Daniel , Liston, Aaron .
Systematics and biogeography of Pinus subsection Cembroides.
Pinus subsection Cembroides is a monophyletic group comprised of approximately 11 species distributed in Mexico and the western United States. The only "pinyon pine" species outside of subsection Cembroides is P. nelsonii from the Sierra Madre Oriental of Mexico. Together, subsection Cembroides, P. nelsonii (subsection Nelsoniae), and the bristlecone and foxtail pines (subsection Balfourianae) of the western United States form a clade we recognize as section Parrya. A published sequence matrix from three cpDNA genes (matK, rbcL and rpl16) for section Parrya was expanded to include three cpDNA spacers (trnL-F, rpl20-rps18, and atpB-rbcL). The expanded matrix improves the resolution of subsection Cembroides with respect to previous cpDNA and nuclear ITS region phylogenies. Three morphologically divergent pinyons with limited distributions in Mexico, P. maximartinezii, P. pinceana, and P. rzedowskii, form a clade at the base of the pinyons. In a more derived position, P. monophylla and P. quadrifolia of the western United States and Baja California form a sister group which is in turn the sister group of a clade comprised of four poorly-resolved lineages: 1) P. culminicola and P. johannis (including P. discolor), 2) P. cembroides and its subspecies, 3) P. remota (including P. catarinae), and 4) P. edulis and P. californiarum. Its unique cpDNA haplotype together with differences in morphology suggest that P. californiarum may be a valid species; although cpDNA sequences indicate a close relationship with P. edulis, morphology, secondary metabolites, and potential hybridization complicate its taxonomic status. For a more complete picture of cpDNA haplotype diversity in subsection Cembroides, additional population sampling is needed, particularly in the Sierra Madre Occidental, and southern Arizona, New Mexico, and Texas.
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1 - Universidad Autonoma del Estado de Hidalgo, Centro de Investigaciones Biologicas, AP 1-69, Plaza Juarez, Pachuca, Hidalgo, 42001, Mexico
2 - Universidad Nacional Autonoma de Mexico, Instituto de Ecologia, Ciudad Universitaria, A.P. 70-275, Mexico, D.F., 04510, Mexico
3 - Oregon State University, Department of Botany & Plant Pathology, 2082 Cordley Hall, Corvallis, Oregon, 97331-2902, USA
Presentation Type: Oral Paper
Date: Tuesday, August 16th, 2005
Time: 8:15 AM