Abstract

Given the current accelerating extinction rates, an increasing number of species-based conservation strategies have emerged because of the public interest in helping save particular species by funding rescue actions.
Although public interest has focused mainly on well-studied, charismatic species, conservation scientists have developed tools to help prioritize species conservation from a more objective perspective, preserving ecosystem functioning and human well-being for future generations. For that purpose, species-centered biodiversity in- dicators that account not only for the extinction risk of a species but also for its evolutionary and/or functional distinctiveness have been developed. A species is considered irreplaceable and distinctive if it is isolated on the phylogenetic tree and/or if it has distinct traits, especially functional traits that determine the species’ effects on ecosystems. The quantitative values representing extinction risk and distinctiveness of species have often been multiplied to define a quantitative conservation priority score. However, there is a plethora of ways to combine several conservation criteria into a single quantitative priority score, and the product of this multiplication is one such possibility. Each possible way of combining extinction risk and distinctiveness provides a different point of view on which of these should prevail to set conservation priorities. We set up an axiomatic framework on how a species’ distinctiveness could be combined with its extinction risk via a tool used to define conservation prior- ities. By doing so, we show that further work is still needed to better communicate biodiversity indicators to the public and ensure an informed choice of indicators.

Keywords:

Indicator Ecosystem functioning Evolutionary history EDGE of existence Single-species management.