Phylogenetic diversity has become invaluable for conservation biology in the last decades, refl ecting its link to option values and to evolutionary potential. We argue that its use will continue to grow rapidly in the next decades because of the transformation of systematics with new molecular techniques and especially metagenomics. In a near future, phylogenetic diversity typically will be the very fi rst result at hand, and the great challenge of biodiversity sciences will be to preserve its link with natural history and the remainder of biological knowledge through species vouchers and names. The phylogeny availability and the very wide sampling allowed will facilitate obtaining detailed biodiversity information at local scale and considering the transition across scales -a fundamental need well highlighted in international conservation guidelines, and historically so diffi cult to achieve. All this suggests that phylogenetic diversity might be at the center of more explicit identifi cation of conservation priorities and options. For concluding, we explore an emerging local-to-regional-to-global challenge: the possibility of defi ning "planetary boundaries" for biodiversity on the basis of phylogenetic diversity.