Final answer:
Species closely related in a phylogenetic tree will have a high percentage of genetic similarity, typically above 97%, indicating a recent common ancestor. This is reflected in a phylogenetic tree where species with more genetic similarities, like species D and E, are depicted closer together than they are to other species like A and B.
Step-by-step explanation:
When determining whether organisms are closely related or different species based on phylogenetic relationships, one of the strongest arguments is the genetic homology between the organisms. Specifically, if their DNA sequences are highly similar, it suggests a close evolutionary relationship. The criterion often used is a certain percentage of genetic similarity. In the context of the question, if two organisms have DNA sequences that are more than 97% similar, they are typically considered to be closely related. Phylogenetic relationships are concerned with the relative times in the past that species shared common ancestors, rather than just similarities or differences in appearance or habitat.
Using genetic analysis on species A, B, D, and E, a scientist would likely find that species D and E share more genetic similarities with each other than with species A and B. This suggests that D and E have a more recent common ancestor compared to their relationship with A and B. This type of analysis helps to construct a phylogenetic tree, which depicts the evolutionary relationships between species based on such genetic data.