Building a Better Tree
By organizing all eukaryotic species into groups and depicting their evolution in a tree-like structure, researchers shape a better understanding of how different sets of organisms relate to one another and how they evolved. However beneficial these trees might be, there is some debate as to which genetic markers should serve as the trees’ organizing principle, as well as which method of grouping should be utilized. Tani Leigh ’12 is working with Assistant Professor of Biology Wei-Jen Chang this summer to create a new version of the eukaryotic phylogenetic tree using ribosomal proteins.
A eukaryotic tree functions as a diagram depicting how eukaryotic species have evolved. Researchers have built many different phylogenetic trees in an attempt to organize the eukaryotic family of organisms. These trees are based on different molecular sequences such as DNA and RNA as well as sequences for various proteins and structures. Current models of the eukaryotic tree have indicated that there are two overarching categories of eukaryotes, unikonts and bikonts, as well as six more specific “super groups.” Though these groups are generally-accepted in the scientific community, there remain discrepancies in how some organisms are grouped throughout many of the current phylogenetic trees. Part of Leigh’s research is to find whether her new model fits with the generally-accepted unikont-bikont theory.
Leigh’s research focuses specifically on ribosomal proteins, which are essential to the process of translating RNA into proteins. Using information from an online database, she is collecting sequences from various ribosomal proteins from 26 different eukaryotic species that span across five of the six super groups. Leigh then uses three programs to organize and present her data: the first combines and aligns the sequences, the second determines a model to use for the trees’ construction, and the third actually builds the trees from the second program’s model.
Finally, Leigh uses another program to view the trees and manipulate them for easier interpretation. From there, she evaluates the trees. Leigh explains that this is the most important part of the process because at this point she determines whether or not the tree appears accurate. If not, she repeats the entire process with combined sequences from multiple ribosomal proteins. If, after several attempts at lengthening the sequence, the tree still does not appear accurate, Leigh starts over with a different set of sequences.
While this type of work has its setbacks and can be time-consuming, Leigh enjoys the satisfaction of knowing that the more research she does, the more useful results she obtains, a pattern that is not always true in scientific research. Furthermore, Leigh believes that her findings may be useful to the scientific community as a step forward in creating a more accurate eukaryotic tree.
On campus, Leigh, a biology major with a Japanese minor, is the secretary of the Muslim Students Association and a member of the Rainbow Alliance. She also participates in HAVOC volunteering events each semester. Her other interests include learning and practicing Japanese, watching Hindi movies, and exploring new places.
Creating eukaryotic trees help provide a visual model of how different species have evolved, enhancing the general beliefs about the subject. In short, Leigh explains her project as a attempt to enhance our understanding of science: “I feel that it is our mission as the human race to discover everything there is to discover about the world, and this project is most definitely a part of that mission.”
Tani Leigh is a graduate of Ballston Spa High School in New York.