DNA Similarity and Evolutionary Relationships

More distantly related species have had more time elapse since they shared a common ancestor; therefore, they have had more time for mutations to accumulate in their DNA. Closely related species have had little time to accumulate mutations since their last common ancestor, so their DNA sequences are much more similar.

More closely related species (top panel) tend to share more anatomical features and similar DNA sequences than more distantly related species (bottom panel).

There are two panels with two animals in each. The top panel shows two different lizard species. The bottom panel shows a snake and a lizard.