Systematics Section / ASPT
Syring, John V. , Farrrell, Kathleen , Businský, Roman , Cronn, RC , Liston, Aaron .
Widespread Genealogical Nonmonophyly in Species of Pinus Subgenus Strobus.
PHYLOGENETIC relationships among Pinus species from subgenus Strobus remain unresolved despite combined efforts based on nrITS and cpDNA. To provide greater resolution among these taxa, a 900-bp intron from a Late Embryogenesis Abundant (LEA)-like gene (IFG8612) was sequenced from 39 pine species, with two or more alleles representing 33 species. Nineteen of 33 species exhibited allelic nonmonphyly in the strict consensus tree, and 10 deviated significantly from allelic monophyly based on topology incongruence tests. Intraspecific nucleotide diversity ranged from 0.0 – 0.0211, and analysis of variance shows that nucleotide diversity was strongly associated (P<0.0001) with the degree of species monophyly. While species nonmonophyly complicates phylogenetic interpretations, this nuclear locus offers greater topological support than previously observed for cpDNA or nrITS. Lacking evidence for hybridization, recombination, or imperfect taxonomy, we feel that incomplete lineage sorting remains the best explanation for the polymorphisms shared among species. Depending on the species, coalescent expectations indicate that reciprocal monophyly will be more likely than paraphyly in 1.71 to 24.0 × 106 years, and that complete genome wide coalescence in these species may require up to 76.3 × 106 years. The absence of allelic coalescence is a severe constraint in the application of phylogenetic methods in Pinus, and taxa sharing similar life history traits with Pinus are likely to show species nonmonophyly using nuclear markers.
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1 - Oregon State University, Department of Botany & Plant Pathology, 2082 Cordley Hall, Corvallis, Oregon, 97331-2902, USA
2 - Silva Tarouca Research Institute for Landscape and Ornamental Gardenin, Průhonice, , Czech Republic
3 - USDA Forest Service, Forest Genetics, Pacific Nothwest Research Station, 3200 SW Jefferson Way, Corvallis, Oregon, 97331, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 144/Performing Arts Center
Date: Tuesday, August 1st, 2006
Time: 9:15 AM