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Multiple Choice
In a phylogenetic tree, which organism is considered to have the longest evolutionary history?
A
The organism located at the base (root) of the tree
B
The organism at the tip of the most recently diverged branch
C
The organism with the most branches leading to it
D
The organism that shares a node with the greatest number of other organisms
Verified step by step guidance
1
Understand the structure of a phylogenetic tree: A phylogenetic tree is a diagram that represents evolutionary relationships among organisms. The base (root) of the tree represents the common ancestor of all organisms in the tree, while the tips represent the most recently evolved organisms.
Identify the concept of evolutionary history: In this context, evolutionary history refers to the amount of time an organism's lineage has existed since diverging from a common ancestor.
Analyze the base (root) of the tree: The organism at the root of the tree represents the common ancestor of all organisms in the tree. However, this does not mean it has the longest evolutionary history, as it is an ancestral form, not a currently existing organism.
Evaluate the tips of the branches: The organisms at the tips of the most recently diverged branches are the most recently evolved and do not have the longest evolutionary history.
Consider the number of branches or nodes: The number of branches or shared nodes does not directly correlate with the length of evolutionary history. Instead, the organism with the longest evolutionary history is the one whose lineage has persisted the longest without diverging significantly, often represented by a branch that extends farthest from the root without splitting.