Learn on PengiAmplify Science (California) Grade 8Chapter 3: Identifying Related Species

Lesson 1: Evolutionary Trees

Key Idea.

Section 1

Reading the Nodes (Time)

Key Idea

In an evolutionary tree, the vertical position of the branching point (node) represents time.

  • A node near the top represents a recent split (a recent common ancestor).
  • A node near the bottom represents an ancient split (a distant common ancestor).

Section 2

Determining Relatedness

Key Idea

"Who is more closely related?" is the most common question. The rule is: Look for the Most Recent Common Ancestor.

A whale is more closely related to a hippo than to a cow. Why? Because the "Whale-Hippo" ancestor lived more recently than the "Whale-Cow" ancestor.

Lesson overview

Expand to review the lesson summary and core properties.

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Section 1

Reading the Nodes (Time)

Key Idea

In an evolutionary tree, the vertical position of the branching point (node) represents time.

  • A node near the top represents a recent split (a recent common ancestor).
  • A node near the bottom represents an ancient split (a distant common ancestor).

Section 2

Determining Relatedness

Key Idea

"Who is more closely related?" is the most common question. The rule is: Look for the Most Recent Common Ancestor.

A whale is more closely related to a hippo than to a cow. Why? Because the "Whale-Hippo" ancestor lived more recently than the "Whale-Cow" ancestor.