Image Caption
When a lineage splits (speciation), it is represented as branching on a phylogeny. When a speciation event occurs, a single ancestral lineage gives rise to two or more daughter lineages.
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This image is part of a series:
![A phylogeny. Descendants are numbered 1, 2, 3, and 4 at the top. The very bottom of the phylogeny shows the ancestor. The top of the phylogeny shows recent species. The lower down a phylogeny, the further in the past the species is.](https://evolution.berkeley.edu/wp-content/uploads/2021/10/understanding_phylos_Understanding-phylo1-350x350.png)
Understanding phylogenies (1 of 4)
Understanding a phylogeny is a lot like reading a family tree. The root of the tree represents the ancestral lineage, and the tips of the branches represent the descendents of…![A phylogeny with descendents A, B, and C. A shares a speciation event with B and C. B shares a speciation event with C. There is a dotted line moving from the bottom of the phylogeny towards the speciation event of B and C; this represents the shared history of B and C. The line leading to B is green, representing the unique history of B. The line leading to C is blue, representing the unique history of C.](https://evolution.berkeley.edu/wp-content/uploads/2021/10/understanding_phylos_unique-history-350x350.png)
Understanding phylogenies (3 of 4)
Phylogenies trace patterns of shared ancestry between lineages. Each lineage has a part of its history that is unique to it alone and parts that are shared with other lineages.![Shows the same phylogeny of A, B, and C as the previous one. The point representing the speciation event of A and B&C also represent the common ancestor of A, B, and C. The point showing the speciation event of B and C also represents the common ancestor of B and C. A point along the line to C represents a unique ancestor of C.](https://evolution.berkeley.edu/wp-content/uploads/2021/10/understanding_phylos_unique-ancestor-350x350.png)