Date of Degree Completion
Master of Science (MS)
Second Committee Member
Third Committee Member
Gnetum are non-flowering seed plants of the tropics, indigenous to South America, Africa, and Asia. This group of about 40 species is fascinating to botanists because it shares distinctive morphological characteristics with flowering plants, such as broad leaves, woody stems, and flower-like strobili. There are still questions surrounding the relationships within the genus of Gnetum. With that in mind, I focused my work on generating phylogenetic hypotheses, using two molecular data sets: a concatenation of over 60 different chloroplast genes (66,815 base pairs), and the whole chloroplast genome (128,772 base pairs). This allowed me to compare the two phylogenies and assess whether adding non-coding regions increase phylogenetic resolution. Statistical tests determined that the data were sufficient to answer questions about deep splits, and to resolve the branches within the genus. I used each of the two data sets to infer Maximum Parsimony and Maximum Likelihood phylogenetic hypotheses for 18 species of Gnetum. Confidence levels for most nodes were very high, and trees show clades consistent with biogeography. My bootstrap results suggest that the South American clade may not be the earliest diverging lineage, although statistical tests support the South American clade at the base of the Gnetum tree.
McFadden, Angela, "Resolving Gnetum Evolutionary History" (2016). All Master's Theses. 485.