Abstract Detail

Colloquia: Emerging Results from Studies of Gymnosperms on the Tree of Life II

Braukmann, Thomas [1], Kuzmina, Maria [2], Stefanovic, Sasa [3].

Structural changes in the plastid genome of gymnosperms support the “gnepine” hypothesis.

One of the most challenging questions impeding the resolution of seed plant phylogeny is the placement of Gnetales, a highly divergent group of gymnosperms. Ascertaining its phylogenetic placement is problematic due to a combination of high taxonomic sampling error, saturation at nucleotide sites, and high rate variation across sites and clades. Additionally, conflicting signal within and among sequences used to reconstruct phylogenies support different hypotheses. However, molecular evidence is not limited only to sequence data; it also includes rare structural genomic characters that can be utilized as informative markers for resolving phylogenetic relationships. Currently available results from sequenced plastid genomes have revealed several potential markers that can be exploited to choose among alternative phylogenetic hypotheses, but the extent of the distribution of the characters has not been fully surveyed. Using slot-blot hybridization and sequence data approaches, a suite of potential characters, including the losses of genes and introns from plastid and mitochondrial genomes as well as distribution of amino acid indels, were surveyed across an extensive sample containing 70 out of 85 gymnosperm genera. Our results indicate that these structural markers are compatible with an affinity of Gnetales to conifers. In particular, the concerted loss of all plastid ndh genes supports the contentious“gnepine” hypothesis.

Broader Impacts:

1 - University of Toronto at Mississauga, Department of Biology, 3359 Mississauga Rd N, Mississauga, ON, L5L1C6, Canada
2 - University of Guelph, Biodiversity Institute of Ontario, 50 Stone Rd E, Guelph, ON, N1G 2W1, Canada
3 - University of Toronto at Mississauga, Biology, 3359 Mississauga Rd N, Mississauga, Ontario, L5L1C6, Canada

Keywords:
seed plant phylogeny
Gnetales
Conifers.

Presentation Type: Symposium or Colloquium Presentation
Session: C2
Location: Ballroom C/Convention Center
Date: Monday, August 2nd, 2010
Time: 1:30 PM
Number: C2003
Abstract ID:287