Resolving Gnetum Evolutionary History

Abstract

Gnetums are non-flowering seed plants of the tropics. This group of about 30 species has long been fascinating to botanists because it shares some distinctive morphological characteristics with flowering plants. Both the relationships of the group to other seed plants and the relationships of the Gnetum species to one another are poorly understood. With that in mind, we focused our work on using molecular techniques to generate a phylogenetic tree for the genus Gnetum. We created libraries of total genomic DNA, used the libraries to produce millions of 101 base-pair single end sequencing reads using Illumina technology, and then used bioinformatics to identify and assemble the chloroplast genome. Thus far, we have assembled the chloroplast genomes for 10 species of Gnetum. The resulting data set, composed of 77,567 shared nucleotide positions, was analyzed using Maximum Parsimony and Maximum Likelihood models. In both of these models, the confidence level for most nodes is very high, and the trees show clades consistent with biogeography, New World Taxa separate from Old World Taxa. In the future, we would like to add additional species to our current model to further elucidate the relationships and evolutionary history of this genus