The evolutionary tree is drawn to scale, with branch lengths in units representing the number of amino acids substituted per site. (journals.plos.org)
We now have a more complete structure, including meaningful branch lengths, which are proxies for the periods of time between specific branching events.» (sciencedaily.com)
Surprisingly, when they placed the real plants on the graph according to their actual nutrient travel distances and total branch lengths, the plants fell almost perfectly on the Pareto curve, meaning that plants» networks of branches are finding the best balance between cost and performance for their particular environment. (salk.edu)