In biology, a
refugium
(plural:
refugia
) is a location which supports an isolated or
relict
population
of a once more widespread species. This isolation (
allopatry
) can be due to climatic changes, geography, or human activities such as
deforestation
and overhunting.
Present examples of refugial animal species are the
mountain gorilla
, isolated to specific mountains in central Africa, and the
Australian sea lion
, isolated to specific breeding beaches along the south-west coast of Australia, due to humans taking so many of their number as game. This resulting isolation, in many cases, can be seen as only a temporary state; however, some refugia may be longstanding, thereby having many
endemic species
, not found elsewhere, which survive as relict populations. The
Indo-Pacific Warm Pool
has been proposed to be a longstanding refugium, based on the discovery of the "living fossil" of a marine
dinoflagellate
called
Dapsilidinium pastielsii
, currently found in the Indo-Pacific Warm Pool only.
[1]
For plants,
anthropogenic climate change
propels scientific interest in identifying refugial species that were isolated into small or
disjunct
ranges during glacial episodes of the
Pleistocene
, yet whose ability to expand their ranges during the warmth of
interglacial
periods (such as the
Holocene
) was apparently limited or precluded by
topographic
,
streamflow
, or
habitat
barriers
[2]
[3]
[4]
?or by the extinction of
coevolved animal dispersers
.
[5]
The concern is that ongoing warming trends will expose them to
extirpation
or
extinction
in the decades ahead.
[6]
[7]
In
anthropology
,
refugia
often refers specifically to
Last Glacial Maximum refugia
, where some ancestral human populations may have been forced back to
glacial refugia
(similar small isolated pockets on the face of the continental
ice sheets
) during the
last glacial period
. Going from west to east, suggested examples include the
Franco-Cantabrian region
(in northern
Iberia
), the
Italian
and
Balkan
peninsulas, the
Ukrainian LGM refuge
, and the
Bering Land Bridge
. Archaeological and genetic data suggest that the source populations of Paleolithic humans survived the glacial maxima (including the
Last Glacial Maximum
) in sparsely wooded areas and dispersed through areas of high primary productivity while avoiding dense
forest cover
.
[8]
Glacial refugia, where human populations found refuge during the last glacial period, may have played a crucial role in shaping the emergence and diversification of the language families that exist in the world today.
[9]
More recently,
refugia
has been used to refer to areas that could offer relative climate stability in the face of modern
climate change
.
[10]
Speciation
[
edit
]
As an example of a locale refugia study,
Jurgen Haffer
first proposed the concept of refugia to explain the
biological diversity
of bird populations in the
Amazonian river basin
. Haffer suggested that climatic change in the late
Pleistocene
led to reduced reservoirs of habitable forests in which populations become allopatric. Over time, that led to
speciation
: populations of the same species that found themselves in different refugia evolved differently, creating
parapatric
sister-species
. As the Pleistocene ended, the arid conditions gave way to the present humid rainforest environment, reconnecting the refugia.
Scholars have since expanded the idea of this mode of speciation and used it to explain population patterns in other areas of the world, such as
Africa
,
Eurasia
, and
North America
. Theoretically, current biogeographical patterns can be used to infer past refugia: if several unrelated species follow concurrent
range
patterns, the area may have been a refugium. Moreover, the current distribution of
species
with narrow ecological requirements tend to be associated with the spatial position of glacial refugia.
[11]
Simple environment examples of temperature
[
edit
]
One can provide a simple explanation of refugia involving core temperatures and exposure to sunlight. In the
northern hemisphere
, north-facing sites on hills or mountains, and places at higher elevations count as
cold sites
. The reverse are sun- or heat-exposed, lower-elevation, south-facing sites:
hot sites
. (The opposite directions apply in the
southern hemisphere
.) Each site becomes a refugium, one as a "cold-surviving refugium" and the other as a "hot-surviving refugium". Canyons with deep hidden areas (the opposite of hillsides, mountains, mesas, etc. or other exposed areas) lead to these separate types of refugia.
A concept not often referenced is that of "sweepstakes colonization":
[12]
[13]
when a dramatic ecological event occurs, for example a meteor strike, and global, multiyear effects occur. The sweepstake-winning species happens to already be living in a fortunate site, and their environment is rendered even more advantageous, as opposed to the "losing" species, which immediately fails to reproduce.
[12]
[13]
Past climate change refugia
[
edit
]
Ecological understanding and geographic identification of climate refugia that remained significant strongholds for plant and animal survival during the extremes of past cooling and warming episodes largely pertain to the
Quaternary glaciation
cycles during the past several million years, especially in the
Northern Hemisphere
. A number of defining characteristics of past refugia are prevalent, including "an area where distinct genetic lineages have persisted through a series of Tertiary or Quaternary climate fluctuations owing to special, buffering environmental characteristics", "a geographical region that a species inhabits during the period of a glacial/interglacial cycle that represents the species' maximum contraction in geographical range," and "areas where local populations of a species can persist through periods of unfavorable regional climate."
[14]
Future climate change refugia
[
edit
]
In
systematic conservation planning
, the term
refugium
has been used to define areas that could be used in
protected area
development to protect species from
climate change
.
[10]
The term has been used alternatively to refer to areas with stable habitats or stable climates.
[10]
More specifically, the term
in situ
refugium is used to refer to areas that will allow species that exist in an area to remain there even as conditions change, whereas
ex situ
refugium refers to an area into which
species distributions
can move to in response to climate change.
[10]
Sites that offer
in situ
refugia are also called
resilient sites
in which species will continue to have what they need to survive even as climate changes.
[15]
One study found with downscaled
climate models
that areas near the coast are predicted to experience overall less warming than areas toward the interior of the US
State of Washington
.
[16]
Other research has found that
old-growth forests
are particularly insulated from climatic changes due to evaporative cooling effects from
evapotranspiration
and their ability to retain moisture.
[17]
The same study found that such effects in the
Pacific Northwest
would create important refugia for bird species. A review of refugia-focused conservation strategy in the
Klamath-Siskiyou Ecoregion
found that, in addition to old-growth forest, the northern aspects of hillslopes and deep gorges would provide relatively cool areas for wildlife and
seeps
or
bogs
surrounded by mature and old-growth forests would continue to supply moisture even as water availability decreases.
[18]
Beginning in 2010 the concept of
geodiversity
(a term used previously in efforts to preserve scientifically important geological features) entered into the literature of
conservation biologists
as a potential way to identify climate change refugia and as a surrogate (in other words, a proxy used when planning for protected areas) for biodiversity.
[19]
[20]
[21]
While the language to describe this mode of conservation planning hadn't fully developed until recently, the use of geophysical diversity in conservation planning goes back at least as far as the work by Hunter and others in 1988,
[22]
and Richard Cowling and his colleagues in
South Africa
also used "spatial features" as surrogates for
ecological
processes in establishing conservation areas in the late 1990s and early 2000s.
[23]
[24]
The most recent efforts have used the idea of
land facets
(also referred to as
geophysical settings
,
enduring features
, or
geophysical stages
[15]
), which are unique combinations of
topographical features
(such as slope steepness, slope direction, and
elevation
) and
soil
composition, to quantify physical features.
[20]
The density of these facets, in turn, is used as a measure of geodiversity.
[21]
[15]
Because geodiversity has been shown to be correlated with biodiversity,
[2]
even as species move in response to climate change, protected areas with high geodiversity may continue to protect biodiversity as
niches
get filled by the influx of species from neighboring areas.
[15]
Highly geodiverse protected areas may also allow for the movement of species within the area from one land facet or elevation to another.
[15]
Conservation scientists, however, emphasize that the use of refugia to plan for climate change is not a substitute for fine-scale (more localized) and traditional approaches to conservation, as individual species and
ecosystems
will need to be protected where they exist in the present.
[2]
[25]
They also emphasize that responding to climate change in conservation is not a substitute for actually limiting the causes of climate change.
[2]
See also
[
edit
]
Notes
[
edit
]
- ^
Mertens KN, Takano Y, Head MJ, Matsuoka K (2014).
"Living fossils in the Indo-Pacific warm pool: A refuge for thermophilic dinoflagellates during glaciations"
(PDF)
.
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.
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Bibcode
:
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.
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:
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.
S2CID
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. Archived from
the original
(PDF)
on 2020-02-15.
- ^
a
b
c
d
Davis, Margaret B (October 1989).
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(PDF)
.
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.
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- ^
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"Special Reviews: Range shifts and adaptive responses to Quaternary climate change"
.
Science
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.
PMID
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- ^
Petit, Remy J; et al. (August 2004).
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.
Forest Ecology and Management
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197
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doi
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.
- ^
Svenning, Jens-Christian; Skov, Flemming (2007).
"Ice age legacies in the geographical distribution of tree species richness in Europe"
.
Global Ecology and Biogeography
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:
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.
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.
- ^
Seliger, Benjamin J; McGill, Brian J; Svenning, Jens-Christian; Gill, Jacqueline L (November 2020).
"Widespread underfilling of the potential ranges of North American trees"
.
Journal of Biogeography
.
48
(2): 359?371.
doi
:
10.1111/jbi.14001
.
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.
- ^
Manes, Stella; et al. (2021).
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.
Biological Conservation
.
257
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.
doi
:
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.
S2CID
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.
- ^
Gavashelishvili A, Tarkhnishvili D (2016). "Biomes and human distribution during the last ice age".
Global Ecology and Biogeography
.
25
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:
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.
doi
:
10.1111/geb.12437
.
- ^
Gavashelishvili, A; et al. (2023), "The time and place of origin of South Caucasian languages: insights into past human societies, ecosystems and human population genetics",
Scientific Reports
,
13
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:
10.1038/s41598-023-45500-w
,
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- ^
a
b
c
d
Ashcroft MB (2010).
"Identifying refugia from climate change"
.
Journal of Biogeography
.
37
(8): 1407?1413.
Bibcode
:
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.
doi
:
10.1111/j.1365-2699.2010.02300.x
.
S2CID
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.
- ^
Tarkhnishvili D (2011).
"Palaeoclimatic models help to understand current distribution of Caucasian forest species"
.
Biological Journal of the Linnean Society
.
105
: 231?248.
doi
:
10.1111/j.1095-8312.2011.01788.x
.
- ^
a
b
Petit RJ, Hu FS, Dick CW (June 2008).
"Forests of the past: a window to future changes"
(PDF)
.
Science
.
320
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Bibcode
:
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.
doi
:
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.
hdl
:
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.
PMID
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.
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.
- ^
a
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"Gulf of Guinea Islands Biodiversity Project"
. California Academy of Sciences
. Retrieved
26 April
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.
- ^
Tang, Cindy Q (2018).
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(PDF)
.
Nature Communications
.
9
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Bibcode
:
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.
doi
:
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.
PMC
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.
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- ^
a
b
c
d
e
"Climate Change Resilience in the Pacific Northwest"
.
conservationgateway.org
. Retrieved
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.
- ^
"Washington Wildlife Habitat Connectivity Working Group"
. Retrieved
2019-03-19
.
- ^
Betts MG, Phalan B, Frey SJ, Rousseau JS, Yang Z (April 2018).
"Old-growth forests buffer climate-sensitive bird populations from warming"
.
Diversity and Distributions
.
24
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doi
:
10.1111/ddi.12688
.
- ^
Olson D, DellaSala DA, Noss RF, Strittholt JR, Kass J, Koopman ME, Allnutt TF (January 2012). "Climate Change Refugia for Biodiversity in the Klamath-Siskiyou Ecoregion".
Natural Areas Journal
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.
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.
- ^
Anderson MG, Ferree CE (July 2010).
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.
PLOS ONE
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5
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:
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doi
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.
PMC
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- ^
a
b
Beier P, Brost B (June 2010). "Use of land facets to plan for climate change: conserving the arenas, not the actors".
Conservation Biology
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"Unepscs.org"
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.
References
[
edit
]
Look up
refugium
in Wiktionary, the free dictionary.