Constructing Plant Phylogeny Based on Morphological Characteristics and Molecular Data
Phylogeny is the study of evolutionary relationships among groups of living and extinct organisms on earth (Campbell et al., 2011). To show evolutionary relationships, a phylogenetic tree (a visual representation of the lineages among organisms) is constructed. All phylogenetic trees are hypotheses that are to be tested, modified, and tested again. One type of tree, known as a rooted tree, contains a root, nodes, branches, and clades (Figure 1). The root of the tree represents a common ancestor from which all the organisms in the group are derived. Within the tree are several nodes, representing a branching point for a taxonomic unit (such as phylum, genus, or species). Branches, the lines that extend from nodes, establish how closely related one group is to the other; the shorter the line, the more closely related the groups. Groups sharing a node share a common ancestor and make up a clade. The purpose of this experiment is to analyze the similarities and differences that exist between two phylogenetic trees for different types of land plants: morphological tree and molecular data tree. The ribulose bisphosphate carboxylase (Rubisco) protein is essential to carbon fixation in photosynthesis and is found in green algae (charophytes) and all land plants (Campbell et al., 2011). The gene sequence for the large subunit (rbcL) of the Rubisco protein has been isolated from a large variety of algae and plants. We hypothesize that the phylogenetic tree based on morphology and life cycle features would be an accurate depiction of land plant phylogeny based on molecular data from the nucleotide sequences of rbcL. Methods
We used two different methods to analyze the relationships among land plants. First, we gathered information on morphology by observing key traits and reading the life cycles of certain groups of plants in the laboratory. The traits...
Cited: Campbell, N.A., Reece, J.B., Morgan, J.G., and Carter, M.E.B. 2011. Molecular Phylogeny of Plants. In Symbiosis, The Pearson Custom Library for the Biological Sciences. Pearson Learning Solutions, Boston MA pp. 266-273.
Please join StudyMode to read the full document