Final answer:
A phylogenetic tree is a diagram that shows the evolutionary relationships among various species, based on genetic and physical traits, displaying common ancestors and suggesting the evolutionary lineage over time.
Step-by-step explanation:
A phylogenetic tree is a diagram that illustrates the evolutionary relationships among different biological species. This scientific tool represents a hypothesis of the evolutionary past that depicts how species are related to each other through common ancestors, which are shown as nodes, and the branches indicating the lineage. The length of each branch in the tree corresponds to the time period since an evolutionary split occurred, suggesting the relative time scale of diversifications.
Phylogenetic trees are constructed based on similarities and differences in genetic or physical traits or both, and they serve as a visual representation of phylogeny, or the evolutionary history and connections among organisms. The tree is composed of nodes and branches, with nodes representing ancestors and branches representing the divergences that led to the formation of new species. The length of each branch reflects the time elapsed since the split.