What do branches represent in a phylogenetic tree?

In a phylogenetic tree, branches play a significant role in showcasing the evolutionary relationships and divergence of species. When focusing on the correct interpretation that branches represent the timelines of species' evolution, it's important to understand how these branches visualize evolutionary history.

In essence, each branch can indicate the passage of time as lineages evolve and separate from their ancestors. The length and direction of branches can reflect periods of evolutionary change, suggesting when certain traits appeared or when species diverged from a common ancestor. Therefore, the branches effectively illustrate the narrative of how different species or groups are connected through evolutionary history and how they have changed over time.

While branches do provide insight into relatedness between taxa, the primary function in the context of a phylogenetic tree is to depict changes over time in the evolutionary process. This temporal aspect makes understanding species' timelines crucial to interpreting a phylogenetic tree correctly. Thus, the representation of branches as timelines of species' evolution is a fundamental aspect for studying evolutionary biology.