Relict (biology)
In
Definition
A relict (or relic) plant or animal is a
When a relict is representative of taxa found in the fossil record, and yet is still living, such an organism is sometimes referred to as a living fossil. However, a relict need not be currently living. An evolutionary relict is any organism that was characteristic of the flora or fauna of one age and that persisted into a later age, with the later age being characterized by newly evolved flora or fauna significantly different from those that came before.
Examples
A notable example is the thylacine of Tasmania, a relict marsupial carnivore that survived into modern times on an island, whereas the rest of its species on mainland Australia had gone extinct between 3000 and 2000 years ago.[3]
Another example is Omma, a genus of beetle with a fossil record extending back over 200 million years to the Late Triassic and found worldwide during the Jurassic and Cretaceous, now confined to a single living species in Australia. Another relict from the Triassic is Pholadomya, a common clam genus during the Mesozoic, now confined to a single rare species in the Caribbean.
An example from the fossil record would be a specimen of
An example of divergent evolution creating relicts is found in the shrews of the islands off the coast of Alaska, namely the
In
While the extirpation of a geographically disjunct population of a relict species may be of regional conservation concern, outright extinction at the species level may occur in this century of rapid climate change if geographic range occupied by a relict species has already contracted to the degree that it is narrowly endemic. For this reason, the traditional conservation tool of translocation has recently been reframed as assisted migration of narrowly endemic, critically endangered species that are already (or soon expected) to experience climate change beyond their levels of tolerance.[7] Two examples of critically endangered relict species for which assisted migration projects are already underway are the western swamp tortoise of Australia and a subcanopy conifer tree in the United States called Florida Torreya.[8]
A well-studied botanical example of a relictual taxon is Ginkgo biloba, the last living representative of Ginkgoales that is restricted to China in the wild. Ginkgo trees had a diverse and widespread northern distribution during the Mesozoic, but are not known from the fossil record after the Pliocene other than G. biloba.[9][10]
The Saimaa ringed seal (Phoca hispida saimensis) is an endemic subspecies, a relict of last ice age that lives only in Finland in the landlocked and fragmented Saimaa freshwater lake complex.[11] Nowadays the population has less than 400 individuals, which poses a threat to its survival.[12]
Another example is the relict leopard frog once found throughout Nevada, Arizona, Utah, and Colorado, but now only found at Lake Mead National Recreation Area in Nevada and Arizona.
Relevance
The concept of relictualism is useful in understanding the ecology and
Studies have been done on relict populations in isolated mountain and valley habitats in western North America, where the
So-called "relics of cultivation"[15] are plant species that were grown in the past for various purposes (medicinal, food, dyes, etc.), but are no longer utilized. They are naturalized and can be found at archaeological sites.
See also
References
- ISBN 9783540921608.
- JSTOR 2399690.
- ^ ISBN 978-0-684-82712-4.
- ISBN 978-0-253-34733-6.
- ^ ISBN 978-1-56098-845-8.
- Guardian Unlimited. Retrieved 9 April 2011.
- PMID 21411178.
- ^ Dalrymple, Sarah (16 July 2021). "Why climate change is forcing conservationists to be more ambitious: by moving threatened species to pastures new". The Conversation. Retrieved 26 July 2022.
- S2CID 4342303.
- ^ Julie Jalalpour; Matt Malkin; Peter Poon; Liz Rehrmann; Jerry Yu (1997). "Ginkgoales: Fossil Record". University of California, Berkeley. Retrieved 3 June 2008.
- S2CID 25621332.
- ^ "Saimaa Ringed Seal". WWF Finland. Retrieved 2019-01-30.
- ISBN 978-0-395-51174-9.
- ISBN 978-0-226-31763-2.