Final answer:
A phylogenetic tree is a diagram used by biologists to illustrate the evolutionary relationships among species, where nodes represent ancestors and branches signify the passage of time since divergence.
Step-by-step explanation:
An illustration constructed by a biologist to represent the evolutionary relationships between species and shared ancestors is called a phylogenetic tree. A phylogenetic tree is a diagram that displays how different organisms are related to one another through common ancestors. The structure consists of nodes and branches, where internal nodes represent the ancestors at points where a divergence is thought to have occurred, leading to the formation of new species. The branch lengths indicate the amount of time that has passed since these speciation events took place. In essence, a phylogenetic tree is a hypothesis concerning the evolutionary connections among species, based on genetic or physical similarities and differences.
A phylogenetic tree is a diagram that represents the evolutionary relationships between species and shared ancestors. It is constructed by biologists to show how species are related to each other through common ancestors. The tree is composed of nodes and branches, where the internal nodes represent ancestors and the branches represent the time elapsed since the split. The length of the branches in the tree is proportional to the time elapsed.