Paleoendemism along with
neoendemism is a possible subcategory of
endemism. Paleoendemism refers to species that were formerly widespread but are now restricted to a smaller area. Neoendemism refers to species that have recently arisen, such as through divergence and reproductive isolation or through hybridization and
polyploidy in plants.
Etymology
The first part of the word, paleo, comes from the
Greek word ''palaiós, meaning "ancient".''
The second part of the word, ''endemism'' is from
New Latin ''endēmicus'', from Greek ενδήμος, ''endēmos'', "native". ''Endēmos'' is formed of ''en'' meaning "in", and ''dēmos'' meaning "the people".
Causes
Changes in climate are thought to be the driving force in creating paleoendemic species, generally due to habitat loss. Regions where the climate has remained relatively stable form
refugia which are more likely to be endemic hotspots today.
This applies to both neoendemism and paleoendemism. However, paleoendemism differs as it does not require additional factors such as barriers and ecological opportunities as it does not rely on
adaptive radiation
In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic int ...
like neoendemism does.
[ It instead relies on the instability of other regions' climate, which may limit the range of a species to a more stable region, thus turning that species paleoendemic. Limited ability for dispersal is also important in the creation of endemic species. The two terms can essentially be defined as "cradles" of new species (neoendemism), or "museums" of old species (paleoendemism).][
]
Examples
It is not always clear whether a particular species is paleoendemic or neoendemic.
Ginkgos
''Ginkgo'' is a genus of non-flowering seed plants. The scientific name is also used as the English name. The order to which it belongs, Ginkgoales, first appeared in the Permian, 270 million years ago, and is now the only living genus within t ...
are a paleoendemic genus. From the Mesozoic to the mid-Cenozoic
The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...
, these trees could be found throughout the world. However, today, they can only be found in China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
in the wild.Asplenium scolopendrium
''Asplenium scolopendrium'', commonly known as the hart's-tongue fern, is an evergreen fern in the genus ''Asplenium'' native to the Northern Hemisphere.
Description
The most striking and unusual feature of the fern is its simple, undivided fron ...
'' var. ''americanum''
*'' Gymnocladus dioicus''
*''Gaylussacia brachycera
''Gaylussacia brachycera'', commonly known as box huckleberry or box-leaved whortleberry, is a low North American shrub related to the blueberry and the other huckleberries. It is native to the east-central United States (Pennsylvania, Delaware ...
''
*''Vandenboschia boschiana
''Vandenboschia boschiana'', synonym ''Trichomanes boschianum'', the Appalachian bristle fern or Appalachian filmy fern, is a small delicate perennial leptosporangiate fern which forms colonies with long, black creeping rhizomes. The evergreen f ...
''
*'' Abies frasieri''
Paleoendemism on islands
Islands as harbors for endemic species are explained by the theory of island biogeography.[{{Cite book, url=https://press.princeton.edu/titles/7051.html, title=The Theory of Island Biogeography, publisher=Princeton University Press, access-date=2019-03-06, isbn=9780691088365, date=2001-03-18, last1=MacArthur, first1=Robert H., last2=Wilson, first2=Edward O.] However, in order to be considered a paleoendemic on an island, the species must have had a widespread distribution previously,
See also
* Relict
References
Endemism