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Multiple Choice
In a cladogram, what does each branch point (node) represent?
A
A unique trait found only in one species
B
A common ancestor shared by the descendant lineages
C
The geographic location where a species was discovered
D
The time at which a species became extinct
Verified step by step guidance
1
Understand the concept of a cladogram: A cladogram is a diagram used in evolutionary biology to show relationships among organisms. It represents hypotheses about the evolutionary history of species.
Identify the significance of branch points (nodes): In a cladogram, each branch point or node represents a divergence event where a single lineage splits into two or more descendant lineages.
Clarify the meaning of a common ancestor: The node signifies a common ancestor shared by all the descendant lineages that branch out from that point. This ancestor is inferred based on shared traits among the descendants.
Eliminate incorrect options: A unique trait found only in one species is not represented by a node; it is typically shown as a derived characteristic along a branch. Geographic location and extinction time are unrelated to the function of nodes in a cladogram.
Conclude the correct interpretation: Each node in a cladogram represents a common ancestor shared by the descendant lineages, which is the correct answer to the problem.