Jacobs, Sarah , Hufford, Larry .
A phylogenetic analysis of Hydrangea using plastid and ITS data.
Hydrangea (Hydrangeaceae: Hydrangeae) as treated in McClintock's monograph and most other taxonomic studies is paraphyletic and nested within it are the genera Broussaisia, Decumaria, Dichroa, Pileostegia, Platycrater and Schizophragma. Our goal has been to increase taxon sampling and molecular markers in a phylogenetic study of Hydrangeae to test for evolutionary relationships in Hydrangea. We have sampled plastid (accD-psa1, matK, and psbA-trnH) and nuclear ribosomal (ITS) DNA sequences for phylogeny reconstruction. Our study has included over 40 accessions of Hydrangeae to more fully represent species diversity, morphological variation, and the geographical distribution of the tribe. We tested for congruence of phylogenetic signal in the plastid and nuclear sequences and found no hard incongruence. Parsimony and maximum likelihood reconstructions of phylogenetic data recover several major lineages in Hydrangea, and these correspond to clades recovered earlier based only on matK sequences, including the following: the macrophylla clade (composed of Broussaisia, Dichroa, H. chinensis, H. chungii, H. hirta, H. luteo-venosa, H. macrophylla, H. scandens, and H. serrata), the anomala clade (composed of H. anomala and Hydrangea section Cornidia), the aspera clade (composed of H. aspera, H. caudatifolia, H. longipes, and H. sargentiana), and the schizophragma clade (composed of Schizophragma, Pileostegia, and Decumaria). Additionally, we recovered a clade centered on H. paniculata and H. heteromalla, which was predicted by earlier studies of morphology and SSRs, that also included H. bretschneideri and H. xanthoneura. Platycrater is consistently associated with H. involucrata and H. strigosa although the monophyly of this group receives little support. Placement of Hydrangea arborescens and H. quercifolia remains uncertain. Support was particularly weak for most of the more basal nodes of the Hydrangea clade.
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1 - Washington State University, School of Biological Sciences, PO Box 644236, Pullman, WA, 99164-4236, USA
2 - Washington State University, School of Biological Sciences, Po Box 644236, Pullman, Washington, 99164-4236, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Cottonwood D/Snowbird Center
Date: Monday, July 27th, 2009
Time: 8:00 AM