Pleistocene Rewilding

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Pleistocene Rewilding promotes the reintroduction of descendants of Pleistocene megafauna, or their close ecological equivalents. Toward the end of the Pleistocene era, between roughly 13,000 to 10,000 years ago, nearly all megafauna of South, Central, North America and Europe had dwindled toward extinction. With the loss of the large herbivores and predator species, niches important for ecosystem functioning were left unoccupied.[1] In the words of the biologist Tim Flannery, "ever since the extinction of the megafauna 13,000 years ago, the continent has had a seriously unbalanced fauna", which meant that e.g. managers of national parks have to resort to culling to keep the population of ungulates under control.[2]

Paul Martin, the originator of the Pleistocene rewilding idea, claims that present ecological communities in North America do not function appropriately in the absence of megafauna because much of the native flora and fauna evolved under the influence of large mammals.[3] Pleistocene rewilding is an extension of the conservation practice of "rewilding," which involves reintroducing species to areas where they became extinct in recent history (hundreds of years ago, or even less).[4] The fact that Pleistocene rewilding is based upon the dynamics of ecosystems many thousands of years ago lends it a grander breadth, but also makes it much more controversial than rewilding as presently practiced.

Contents

[edit] Ecological and Evolutionary Implications

Research shows that species interactions play a pivotal role in conservation efforts. Thus communities where species evolved in response to Pleistocene megafauna but now lack large mammals could be in danger of collapse.[5][6] This idea is supported by the significant impacts that extant megafauna have on the communities they occupy (given that most living megafauna are threatened or endangered). If implemented, Pleistocene rewilding could “serve as additional refugia to help preserve that evolutionary potential” of megafauna.[5][6][7] Therefore, reintroducing megafauna to North America could preserve today’s megafauna while filling ecological niches that have been vacant since the Pleistocene.[8]

[edit] Prospective Taxa for Reintroduction

The Pleistocene rewilding project aims at the promotion of extant fauna and the reintroduction of extinct genera in the south-western states of the USA. The first step of reintroduction is that of native fauna. The Bolson tortoise was a species of tortoise which was widespread in the Pleistocene era and was common in the Holocene up until very recent. Its reintroduction from northern Mexico will prove to be a vital step in order to recreate the soils humidity present in the Pleistocene in order to support grassland and extant shrubland. This is necessary in order to provide the habitat required for the herbivores set for reintroduction. The first priority will be for the continued and encouraged support for the fauna already present in the region.

- The Pronghorn antelope, which is extant in most of the US southwest after almost becoming extinct, is an obvious candidate for the revival of the ancient ecosystem as it endemic to the region, which once supported massive numbers of this species and other now-extinct relatives in the same genus. It is expected to occupy the more arid and mountainous ecosystems within the assigned area.

- The Plains bison is a major icon of American wildlife and was present in their millions during the Pleistocene and up until white settlers drove them to near-extinction in the late 19th century. The Bison has made a miraculous recovery in many regions of its former range and is involved in several local rewilding projects across the Midwest.

- Bighorn sheep along with Mountain goat are already present in the surrounding mountainous areas and will therefore should not pose as a problem in the rewilding of the more mountainous areas of the rewilding site. Reintroduction of extant species of deer to the more forested areas of the region is also very beneficial for the ecosystems they occupy, providing rich nutrients for the forested regions and help maintain them. These species include the White-tailed deer and Mule deer.

- Herbivorous species considered beneficial for the regional ecosystems include the collared peccary, a species of New World wild pig which was abundant in the Pleistocene in the form of many species. Although these species such as the Flat-headed Peccary and Long-nosed Peccary are extinct their relatives still survive in Central and South America.

- The horse which is today extant as the mustang is, in fact, not a native species but was introduced by the Spanish in the 15th century. The history of horse evolution however as a whole did actually originate in North America. The horse is therefore indigenous to the region, something the fossil record proves. The Pleistocene grasslands of North America was the birthplace of the modern horse and therefore the wild horse (the only remaining species of wild/non-domesticated horse) is very much a part of the prairie ecosystem, grazing alongside bison. The plains were home to a type of equid that resembled a zebra called the Hagerman Horse, which will be represented by Plains zebra or Grevy's zebra introduced into the Great Plains from Africa as part of the project. The mountainous region was also once home to the Yukon Wild Ass, which today is extinct, but its close relative, the Onager survives in central Asia today and can be reintroduced to boost biodiversity in the more arid regions of the rewilding area.

- Alongside the wild ass, inhabiting the drier regions were once the Camels which also evolved in North America. Living proof of this is the existence of camelids in South America in the form of the Guanaco and Vicuna(and their domesticated forms the Llama and Alpaca). North America therefore links the South American camelids with those of the Old World (the Dromedary and Bactrian camel) Pleistocene rewilding therefore suggests that the closest relatives of the North American species of camel (Yesterday's Camel) to be reintroduced. The best candidates would be the dromedary for the arid desert regions and the guanaco or vicuna in the arid mountain regions. But there has been some suggestions on breeding and rewilding the fertile hybrid camelids, Cama.

- During the Pleistocene there existed several species of Tapir in North America (California tapir and Florida tapir respectively). They all went extinct at the end of the Pleistocene but their relatives survived in South America. The mountain tapir will be an excellent choice for rewilding the regions more humid areas such as along lakes and rivers (the mountain tapir being the only non-tropical species of tapir left).

- During the Pleistocene vast populations of Proboscideans lived in North America such as the Columbian mammoth the Imperial Mammoth and the American mastodon. The mastodons all went extinct at the end of the Pleistocene, as did the mammoths of North America. However there still survives a not too distant relative of the mammoth, the Asian elephant. It now only resides tropical south-eastern Asia but the fossil record shows it was once much more widespread, living in temperate northern China as well as the Middle East, an area bearing ecological similarity with that of the south western portion of the US. The Asian elephant is therefore a good candidate for the Pleistocene rewilding project and would probably best be suited occupying the same humid areas as the Tapir as well as the dense forest regions (causing soil regeneration and controlling the spread of forests). Meanwhile the African elephant may be the best extant candidate to refill the niche left empty with the extinction of the mastodon.[2]

- During the Pleistocene North American as well as Central and South America were populated with a group of large animals which came to the north following the Great American Interchange. Today all these species of ground sloth and glyptodon are extinct with only a few smaller species surviving in the Andes and on Caribbean Islands into historic times. Their close relatives, the tree sloths and armadillos, are a remnant of this once diverse group of mammals. The reintroduction of armadillos such as the nine-banded armadillo and the giant armadillo are examples of regeneration of soils in the arid and prairie regions of the rewilding project. Other relative such as the giant anteater have also been proposed.

- Pleistocene America boasted a wide variety of dangerous carnivores, most of which are extinct today, such as the massive short-faced bear, saber-toothed cat, Homotherium, the American lion, dire wolf, American cheetah and also possible the aptly named terror bird. Some carnivores and omnivores did however survive the end of the Pleistocene and were widespread in North America until Europeans arrived such as grizzly bear, mountain lion, jaguar, grey wolf, red wolf, bobcat and coyote.


[edit] Recreating a lost ecosystem

In order for a functioning and balanced ecosystem to exist there must be carnivores that prey on the herbivores.

In the mountains, the reintroduction of the mountain lion is necessary to keep mountainous herbivores such as the camelids, asses and mountain goats under control.

In the forest surrounding them the reintroduction of the jaguar (which once roamed much of south western America until very recently) will control the populations of animals such as deer, tapirs and peccary. Alongside the jaguar will be the grizzly bear, an omnivore which was once distributed across the vastness of North America but now present in the far north of the US and much of Western and North Western Canada. Also in the heavily forested areas, the Siberian tiger and Dhole will be introduced to control the populations of deer, wild asses, camels, bighorns, and mountain goats.

In the arid regions the Old World Cheetah could be reintroduced to control the population of Pronghorn antelope which in actual fact is the fastest running herbivore on earth. The reason it can run so fast is because it was once hunted by the American cheetah. The American cheetah was however more closely related to the Mountain Lion but evolved in a similar way to the Old World cheetah, a perfect example of convergent evolution.

Reintroduced into its ancient environment, the grey wolf will spread out across all the ecosystems and compete for prey with all the other predators. The grey wolf may once again be seen hunting camels in the arid regions and bison on the grassy prairies of the Great Plains.

The last, and perhaps most controversial aspect of the rewilding project, is that of the reintroduction of lions to the American southwest. Whilst many consider the lion to be a strictly African species, this is far from the truth. The lion was in fact one of the most widespread of all megafauna and certainly of that of carnivores. The lion once ranged from Africa, through Pleistocene Europe and Asia, across Beringia and down through North America to Argentina in South America. A relict remnant of that distribution across the world is still found in India, where the Asiatic lion still survives in a small sanctuary in the Gir forest. In Europe and northern Asia it existed as the cave lion and in the Americas as the American lion. The American lion once hunted in prides across the grasslands of Pleistocene North America taking down Bison and Wild horses as their African equivalents take down wildebeest and zebra. The reintroduction of lions is however only the end of a long line of reintroductions and will only having realistic prospects of happening if all goes well with the others first.

The Pleistocene parks idea was first suggested for Arctic and South American ecosystems, but less publicized.[5][9] Mauro Galetti suggested that several plant species in South America lost their major megafauna seed dispersers in the end of the Pleistocene.[5] Secondary seed dispersal, water and indigenous people were responsible for maintaining the seed dispersal process in the last 10,000 years.[8][10] Therefore, the rewilding South American savannas will establish a lost seed dispersal services and also control unburned vegetation (due to the lack of megaherbivores). Brazilian savannas burn and release tons of carbon dioxide to the atmosphere yearly. Asian elephants, horses, llamas and other large mammals can be used to control the fires in some cases.

[edit] Implementation

The reintroduction of Bolson Tortoise, equids (see Mustang and Burro) and camelids (Dromedary) has already begun. Muskoxen roam areas of Europe and Asia last grazed during the heyday of Rome, and bison herds thrive in subarctic Canada and Alaska. To date, however, there are no active plans to reintroduce more exotic megafauna such as elephants, cheetahs or lions due to the controversial nature of these reintroductions.

The Southwestern United States and the Brazilian savanna are the most suitable parts of North and South America where the Pleistocene rewilding could be implemented. Besides fencing off large land tracts, a natural setting would be maintained in which predator and prey dynamics would take their course uninterrupted.[5] The long term plan is for an “ecological history park encompassing thousands of square miles in economically depressed parts of the Great Plains.”[6]

The Bolson Tortoise will be expanding its prehistoric population and thrive in places like Texas. Feral Horses will be encouraged to breed and multiply, and along with Wild Horses will be proxies for the few extinct equids. Camelids (of the genus camelus, lama, and vicugna) will serve as proxies for the various (about 6) extinct camels in North America. The African Cheetah will serve as the American Cheetah, while the African Lion will serve as the American Lion. The Elephant species will represent the 5 species of mammoth, mastodon, and gomphothere that thrived in North America.

Other Animals that can be used for this project might include: Mountain Tapir and Baird's Tapir (formerly part of a widespread Holarctic family); Saiga Antelope (a Pleistocene resident of the Alaskan steppe, now found only in Central Asia); and Dhole (which thrived throughout North America as well as Eurasia during the Pleistocene). Evidence states that the Siberian Tiger crossed the bering strait into Alaska during the Pleistocene.

[edit] Criticism

The main criticism of the Pleistocene rewilding is that it is unrealistic to assume that communities today are functionally similar to their state 10,000 years ago. Opponents argue that there has been more than enough time for communities to evolve in the absence of megafauna, and thus the reintroduction of large mammals could thwart ecosystem dynamics and possibly cause collapse. Under this argument, the prospective taxa for reintroduction are considered exotic and could potentially harm natives of North America through invasion, disease, or other factors.[4]

Opponents of the Pleistocene rewilding present an alternative conservation program in which more recent North American natives will be reintroduced into parts of their native ranges where they went extinct in historical times.[4]


[edit] List of species proposed for the the Pleistocene Rewilding project

Expanding populations

Considered for reintroduction

Considered to be reintroduced or as ecological proxy species

[edit] Pleistocene Rewilding in Europe

This plan was not considered by Josh Donlan, yet was thought of by Jens-C. Svenning. It involves, just like Rewilding North America, creating a Pleistocene Habitat in parts of Europe[11]. Svenning claims that "Pleistocene Rewilding can be taken for consideration outside of North America." The Proxies that can be used for this project are as follows:

Expanding Populations

Still Surviving Outside Europe

  as provy for the extinct European Wild Ass Equus hydruntinus)

Introduced

[edit] See also

[edit] References

  1. ^ Janzen, Daniel H.; Paul S. Martin (1982-01-01). "Neotropical Anachronisms: The Fruits the Gomphotheres Ate" (PDF). Science 215 (4528): 19–27. doi:[[:Template:10.1126/science.215.4528.19]]. doi:DOI: 10.1126/science.215.4528.19. http://www.sciencemag.org/cgi/reprint/215/4528/19.pdf. Retrieved 2008-07-29. 
  2. ^ a b Tim Flannery (2001), The Eternal Frontier: An Ecological History of North America and its Peoples, ISBN 1-876485-72-8, pp. 344--346
  3. ^ Martin, Paul S. (2007). Twilight of the Mammoth: Ice Age Extinction and the Rewilding of America. Berkeley: UC Press. ISBN 0520252438. http://www.amazon.com/Twilight-Mammoths-Extinctions-Rewilding-Environments/dp/0520252438/ref=sr_1_1?ie=UTF8&s=books&qid=1217286333&sr=8-1. 
  4. ^ a b c Rubenstein, D.R.; D.I. Rubenstein, P.W. Sherman, T.A. Gavin (2006). "Pleistocene Park: Does re-wilding North America represent sound conservation for the 21st century?" (PDF). http://www.eeb.princeton.edu/FACULTY/Rubenstein/pdf/RubensteinDR&DI_BioCons_2006.pdf. Retrieved 2008-07-28. 
  5. ^ a b c d e Galetti, M. (2004). "Parks of the Pleistocene: Recreating the cerrado and the Pantanal with megafauna". Natureza e Conservação 2 (1): 93–100. 
  6. ^ a b c Donlan, C.J.; et al. (2006). "Pleistocene Rewilding: An Optimistic Agenda for Twenty-First Century Conservation" ([dead link] – Scholar search). The American Naturalist: 1–22. http://www.eeb.cornell.edu/donlan/PDFS/donlan_etal_2006.pdf. 
  7. ^ Pleistocene Rewilding: An Optimistic Agenda for Twenty-First Century Conservation by C. Josh Donlan,1,* Joel Berger,2,† Carl E. Bock,3,‡ Jane H. Bock,3,§ David A. Burney,4,k James A. Estes,5,# Dave Foreman,6,** Paul S. Martin,7,†† Gary W. Roemer,8,‡‡ Felisa A. Smith,9,§§ Michael E. Soulé,10,kk and Harry W. Greene1,##; vol. 168, no. 5 the american naturalist november 2006 (Pdf [1])
  8. ^ a b Donatti, C.I.; M. Galetti, M.A. Pizo, P.R. Guimarães Jr., and P. Jordano (2007), "Living in the land of ghosts: Fruit traits and the importance of large mammals as seed dispersers in the Pantanal, Brazil", in Dennis, A., Frugivory and seed dispersal: theory and applications in a changing world, Wallingford, U.K.: Commonwealth Agricultural Bureau International, pp. 104–123 
  9. ^ Zimov, Sergey A. (2005-05-06). "Pleistocene Park: Return of the Mammoth's Ecosystem". Science 308 (5723): 796–798. doi:10.1126/science.1113442. doi:DOI: 10.1126/science.1113442. http://www.sciencemag.org/cgi/content/full/308/5723/796. Retrieved 2008-07-29. |url=http://www.sciencemag.org/cgi/content/full/308/5723/796|format=|accessdate=2008-07-29 }}
  10. ^ Guimarães Jr., P.; M. Galetti and P. Jordano (2008). "Seed dispersal anachronisms: Rethinking the fruits extinct megafauna ate". PLoS ONE (In Press). 
  11. ^ Unleash the Critters - Conservationists hope to turn back the clock on Europe's wilderness by more than 11,000 years. By Christopher Werth; ENVIRONMENT - NEWSWEEK; From the magazine issue dated Apr 20, 2009

[edit] External links

Retrieved from "http://en.wikipedia.org/wiki/Pleistocene_Rewilding"
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