Biodiversity Conservation and Phylogenetic Systematics

Volume 14 of the series Topics in Biodiversity and Conservation pp 99-115

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What Is the Meaning of Extreme Phylogenetic Diversity? The Case of Phylogenetic Relict Species

  • Philippe GrandcolasAffiliated withInstitut de Systématique, Evolution, Biodiversité, ISYEB – UMR 7205 CNRS MNHN UPMC EPHE, Muséum National d’Histoire Naturelle, Sorbonne Universités Email author 
  • , Steven A. TrewickAffiliated withEcology Group, Institute of Agriculture and Environment, Massey University


A relict is a species that remains from a group largely extinct. It can be identified according both to a phylogenetic analysis and to a fossil record of extinction. Conserving a relict species will amount to conserve the unique representative of a particular phylogenetic group and its combination of potentially original characters, thus lots of phylogenetic diversity. However, the focus on these original characters, often seen as archaic or primitive, commonly brought erroneous ideas. Actually, relict species are not necessarily old within their group and they can show as much genetic diversity as any species. A phylogenetic relict species can be geographically or climatically restricted or not. Empirical studies have often shown that relicts are at particular risks of extinction. The term relict should not be used for putting a misleading emphasis on remnant or isolated populations. In conclusion, relict species are extreme cases of phylogenetic diversity, often endangered and with high symbolic value, of important value for conservation.


Geological extinction Genetic diversity Species age Endemism Remnant