Systematics Section / ASPT
Fine, Nichole L. Y. , Raubeson, Linda A. .
A phylogenetic study of Podocarpaceae.
We are gathering DNA sequence data to support phylogenetic hypotheses for the Southern-Hemisphere Conifer family Podocarpaceae. Results from others’ phylogenetic work in this family, using nuclear (18S and ITS2) and chloroplast (rbcL and trnL-F intron/spacer) sequences, have been incongruent, leaving relationships within the family a matter of debate. We are sequencing two regions -- a mitochondrial intron in nad5 and the chloroplast genes, atpB and atpE. The nad5 marker has been used by others to generate a family-level phylogeny in Pinaceae, and the atpB marker has been used in numerous other studies, but neither has been investigated in Podocarpaceae. To date, we have collected nad5 and atpB/E sequence data for twelve podocarp taxa as well as two members of the Araucariaceae (to serve as outgroups). So far we have only analyzed these data under maximum parsimony criteria and both the nad5 and the atpB/E data support single most parsimonious trees. Both agree with the previous chloroplast and ITS data, but not with 18S data, in placing our taxa Podocarpus matudai, Podocarpus milanjianus, Nageia nagi, Dacrydium cupressinum, and Dacrydium xanthandrum in one derived clade of ((Podocarpus) Nageia) (Dacrydium)). Similarly our results, like the rbcL data but unlike the other data, suggest that Phyllocladus is not basal in the family and thus should not be segregated as Phyllocladaceae. Finally, our current trees are incongruent both to each other and to the results of each of the earlier studies in the placement of Microstrobos, Microcachrys, and Saxegothaea as well as in the exact relationships of some basal taxa. Thus portions of the phylogeny remain uncertain. Currently, we are sequencing more taxa for both markers and plan further analyses. In addition, we are working to characterize the distribution of chloroplast DNA inversions within Podocarpaceae so that those characters can be added to our analyses.
1 - Central Washington University, Department of Biological Sciences, MS 7537, Ellensburg, Washington, 98926-7537, USA
Presentation Type: Poster
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM