Relict species: a relict concept?

• We assess relict species as potentially biased samples of taxonomic groups because all of their close relatives went extinct.
• Relicts are diverse, either old or young species that show or do not show ancestral states in terms of characters or spatial distribution.
• Therefore, they should not be used a priori to assert phenotypic/genotypic conservatism or biota permanence.
• Relicts inform us about extinction/diversification processes and can be ranked of very high value for conservation biology, being the only surviving representatives of large groups that are mainly extinct.

Relict species have always beguiled evolutionary biologists and biogeographers, who often view them as fascinating ‘living fossils’ or remnants of old times. Consequently, they are believed to provide interesting and important information on a vanished past and are used to understand the evolution of clades and biotas. The information that relicts provide can, however, be misleading and overemphasised when it is not remembered that they belong to groups or biotas that are mostly extinct. For example, relict species imply regional extinctions and, for this reason, they cannot simultaneously provide evidence of local biota permanence. Here we consider carefully misconceptions about relict species and highlight more clearly their evolutionary and biogeographical significance.