In this Age of Extinction, we must prioritize the species we want to conserve. Conservation programs use different metrics for species prioritization, but more work is needed linking these metrics to particular aspects of biodiversity value. Here, I focus on the species-specific conservation metric of Evolutionary Distinctness (ED) designed to identify species with few close relatives. I first explore the relationship between ED and a presumed valuable attribute, the average rarity of traits. Using simulations, I find high degrees of association between ED and trait rarity; however unlike another metric of isolation (Average Pairwise Distance) this ability decreases as higher gamma clades are sampled. I then examine, under different scenarios of extinction, how well ED captures a related touted value, total phylogenetic diversity (PD). I find a very strong correlation between PD and ED across all surveyed trees. Overall, ED is not perfect, but shows some promise as a simple conservation metric, capturing at least two related measures of biodiversity value
