Hello,

On day one, I tell my students: to get a good answer, always give context, and always list what you have done to answer the question yourself. In short, don't ask for answers unless your question includes a list of all your failed attempts at the answer :)

So, your question needs to be refined. The "interpretation" of a tree (or any scientific result / output / inference etc) is always in relation to the context of your hypothesis, or at least the context of what question is being addressed.

In the specific case of a phylogenetic tree, interpretation might be regarding

• how relationships compare with biological plausibility,
• how relationships compare with other experiments,
• how confidence values for nodes relate to the type of data and the method through which it was analysed,
• the length of the branches on the tree, given knowledge on evolutionary change, molecular evolution, substitution rate, or any other aspect of the phylogenetics,
• where the placement of the root is and what that means for the rest of the tree; whether the tree was rooted through a priori designation, or methodological inference.
• and many other aspects, for example whether time can be quantified from the tree, what kinds of biases might be influencing results, and, as mentioned, how it fits with a generalised picture of the question at hand.

So, to understand what you want to know, you need to provide context. What is the question? What are the OTUs (operational taxonomic units; are they species? genes? gene families? etc?)? What are the confidence metrics (bootstraps? posterior probabilities? Bremer values?)?

Best wishes.