What is the Difference Between UPGMA and Neighbor Joining Tree?

The key difference between UPGMA (Unweighted Pair Group Method with Arithmetic Mean) and Neighbor Joining Tree lies in the type of phylogenetic tree each method constructs and their reliability.

• UPGMA is an agglomerative hierarchical clustering method based on the average linkage method. It produces a rooted phylogenetic tree and assumes equal rates of evolution. This method was developed by Sokal and Michener in 1958. However, UPGMA has a major drawback due to its assumption of the same evolutionary rate on all lineages.
• Neighbor Joining Tree is a more reliable method than UPGMA. It produces an unrooted phylogenetic tree and allows unequal rates of evolution, with branch lengths proportional to the amount of change. This method was developed to address the limitations of UPGMA, such as its assumption of constant evolutionary rates.

In summary, UPGMA constructs rooted trees and assumes equal evolutionary rates, while Neighbor Joining Tree constructs unrooted trees and allows for unequal evolutionary rates. Neighbor Joining Tree is considered a more reliable method than UPGMA.

Comparative Table: UPGMA vs Neighbor Joining Tree

UPGMA (Unweighted Pair Group Method with Arithmetic Mean) and Neighbor Joining are two different methods for constructing phylogenetic trees. Here is a table summarizing the differences between the two methods:

Both methods use clustering techniques and require the use of mathematical algorithms to interpret the phylogenetic tree. UPGMA is a simpler method that groups organisms based on their least evolutionary distance and calculates the arithmetic mean of these groups to determine new splits. Neighbor Joining, on the other hand, constantly updates the pairwise distances between all nodes in the tree based on the addition of a new node, reflecting their most recent common ancestor. Neighbor Joining is considered more reliable than UPGMA and does not assume a constant rate of evolution.