why are phylogenies important
Phylogenetic diversity takes those lengths to give you an idea of how evolutionarily diverse the fauna in your ecosystem is and to give conservation people priorities. For example, long branches mean that you have basal taxa which are more important to conserve because they originated earlier and thus have more information about evolution to give. On the other hand, very short branches tell us that these species are very new, possibly the result of an adaptive radiation and are also in need of protection.