There is an organism halfway up a branch in a branching diagram and a different organism at the tip of the branch what can you infer about these organisms

The organism halfway up is the evolutionary ancestor of the one at the top of the branch. The one halfway up shares some characteristics with the one on the top. Hence the connection in the diagram.

Explanation:

A branching tree diagram is a set of groups within groups, with the organisms at the bottom having the fewest shared characteristics and the ones at the top having the most.