In a tree that shows the amount of evolution, what does a shorter branch length indicate?

• A. Earlier branching events.
• B. Fewer genetic changes.
• C. Extinction events.
• D. Shorter time periods.

Answer: (B)

Verified step by step guidance

1. Understand that a phylogenetic tree is a diagram that represents evolutionary relationships among various biological species based on similarities and differences in their physical or genetic characteristics.
2. Recognize that branch lengths in a phylogenetic tree can represent different things, such as the amount of genetic change or the time elapsed since the last common ancestor.
3. Consider that shorter branch lengths typically indicate fewer genetic changes have occurred since the last common ancestor of the species represented by that branch.
4. Differentiate between the concepts of genetic change and time; while they can be related, shorter branches specifically suggest fewer genetic changes rather than shorter time periods.
5. Conclude that in the context of a phylogenetic tree, shorter branch lengths are indicative of fewer genetic changes, rather than earlier branching events, extinction events, or shorter time periods.