This style is used to show information about the fossil record of the species shown but makes it difficult to identify relationships. The blobby tree shown here depicts the relationships among ants, flies, butterflies, and beetles, and has a timescale. This diagram has the following basic features:
- An arrow showing that evolutionary time flows from the bottom root of the tree (earlier times) towards the top tips (more recent times).
- A root at the bottom from which the other branches emanate. The root represents the ancestor that all the lineages on the tree have in common.
- A branching pattern. The tree shown here depicts a root with ants, then flies and butterflies, and then beetles splitting off. The branching pattern represents evolutionary relationships. It tells you how closely related different groups are. However, this tree makes it difficult to identify details of the branching pattern. All the insect groups here are related to one another, but it is hard to know exactly how.
- Branching points. Branching points represent the ancestor that all the lineages whose branches join at that point have in common. Three branching points on the tree are highlighted. However, this tree makes it difficult to identify branching points.
- Tips. Tips represent groups of organisms. On the tree, the icons depicting ants, flies, butterflies, and beetles are each highlighted. Here, each tip is a major group of insects.
Buttons at the bottom are labeled “advanced tree features” and “animated video.” A button at the top is labeled “select a tree.”
This style is used to show information about the fossil record of the species shown but makes it difficult to identify relationships. The blobby tree shown here depicts the relationships among four unspecified groups of organisms. The tree has a vertical timescale running from 200 million years ago at the root of the tree to 0 million years ago at the top of the tree. This diagram has the following advanced features:
- Highlighted group or name on a lineage. “Name of group” is boxed, highlighted, and appears on an upper branch and the lower trunk of the tree. When a name is written on or near lineages, it indicates that those lineages belong to the same named group. However, this tree sometimes has multiple named groups shown within the same branch, making it hard to understand the relationships among those groups.
- Varying branch width. The top part of the tree, which has branches of varying widths, is highlighted. Varying branch width usually indicates the diversity of that lineage. Wider branches indicate greater diversity.
- Varying branch length with timescale. A set of related branches on the tree are highlighted. Varying branch length with a timescale indicates when different lineages split or extinction events occurred.
- Bold vertical lines. Three bold vertical rectangles positioned on different branches of the tree are highlighted. Bars placed on lineages usually indicate the time period over which fossils from that lineage are known.
- Differently colored branches. Two terminal lineages and the branching point at which they meet are colored red, in contrast to the rest of the tree. This usually indicates that a particular feature evolved and was inherited by the highlighted lineages. It can also mean that the highlighted branches share the same name.
Buttons at the bottom are labeled “basic tree features” and “animated video.” A button at the top is labeled “select a tree.”
An animated video shows these different styles of branching diagram morphing into another. Each diagram depicts the relationships among ants, flies, butterflies, and beetles. All evolutionary trees, no matter what they look like, represent the same thing: evolutionary relationships.
Buttons at the bottom are labeled “basic tree features” and “advanced tree features.” A button at the top is labeled “select a tree.”