Paleoendemic

Paleoendemic refers to a species or lineage that is confined to a small geographic area today, but represents a relic of a much wider distribution in the geological past. In contrast to neoendemics, which arise through recent speciation and often have restricted ranges, paleoendemics retain the genetic and morphological signatures of ancient lineages that once occurred across larger regions. The geographic pattern is typically the result of long-term persistence in refugia—stable habitats such as isolated mountains, plateaus, or islands—while surrounding regions underwent climatic or geological changes, extinction, or competitive replacement.

Examples commonly cited include the tuatara (Sphenodon) of New Zealand, and Ginkgo biloba in China, as well as other relict plant lineages in temperate or tropical refugia. Paleoendemics are often rare, with small population sizes and restricted distributions, making them vulnerable to habitat loss, climate change, and stochastic events. Their study helps illuminate historical biogeography and the responses of lineages to past environmental shifts, while also highlighting the conservation value of refugial habitats.

Notes: Some authors distinguish paleoendemism from related concepts such as relics or living fossils; the term is used in biogeography and ecology but definitions can vary.