The impact of fossils on the Evolutionary Distinctiveness and conservation status of the Australian lungfish

Abstract

The recognition of phylogenetic information for evaluating conservation priorities has stressed the importance of basal taxa. The ''Evolutionary Distinctiveness'' index (ED) is a species-specific index that includes branch length expressed as an absolute value measured in millions of years that can be applied to a single terminal taxon in a phylogeny. The ED depends on the tree pattern, i.e. of a cladogram included into a time-scale. When calculated for the Australian lungfish (Neoceratodus forsteri), a threatened dipnoan that occurs naturally only in southeast Queensland, the ED index shows variable value according to the chosen tree. On the basis of a recently proposed phylogeny including a new fossil find from the Early Cretaceous of Thailand, the ED value reaches the highest value for piscine sarcopterygians, and for all vertebrates, and thus reinforces the ''originality'' of this fish. This example points out the importance of fossils in the resolution of phylogenies and beyond, in the calculation of indexes supporting conservation decisions.