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(New page: {{CompPsy}} '''Apex predators''' (also '''alpha predators''', '''superpredators''', or '''top-level predators''') are predators that, as adults, are not normally preyed upon in the wil...)
 
 
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'''Apex predators''' (also '''alpha predators''', '''superpredators''', or '''top-level predators''') are [[predators]] that, as adults, are not normally preyed upon in the wild in significant parts of their ranges. Some can be superpredators in some environments but not in others (e.g., [[domestic cat]]s). Some species can be the end of long [[food chains]], where they have a crucial role in maintaining and determining the health of ecosystems, although some predators may be the end of a food chain having only three stages ([[grass]]→[[deer]]→[[wolf]]), but this is the bare minimum for inclusion. Some, like [[big cat]]s, [[bear]]s, [[hyena]]s, [[crocodile]]s, [[wolf|wolve]]s and large [[dog]]s, some [[shark]]s, the [[Komodo dragon]], and the [[orca]] are potential man-eaters, although most of them will avoid humans. Even those not dangerous to humans (e.g., [[owls]]) are formidable predators in their respective niches.
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'''Apex predators''' (also '''alpha predators''', '''superpredators''', or '''top-level predators''') are [[predators]] that, as adults, are not normally preyed upon in the wild by other large animals in significant parts of their range. Apex predator species are often at the end of long [[food chains]], where they have a crucial role in maintaining the health of ecosystems.
   
== Ecological role==
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==Definition==
   
The range of different apex predators may cause some confusion, as some are much larger or differently adapted than others. A predator becomes an "apex predator" when the other species living alongside it cease to consider that animal as prey, or only attempt to attack it in the most dire of situations. For instance, although killer whales (orcas) occasionally attack and, even more rarely, feed upon [[great white shark]]s, both remain apex predators because such an occurrence is sufficiently rare for it to be considered a freak event. However, orcas frequently target leopard seals as prey, making seals a regular item on the menu, and thus not apex predators (even though orcas are their only consistent predator). [[Tiger]]s/[[lion]]s and crocodiles exemplify apex predators that occasionally interact violently with one another, but don't normally risk contact with prey that might kill or cripple them. Dogs might be vulnerable to larger and more powerful predators, but in many places they are the most powerful of all predators.
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An apex predator is one that has virtually no predators of its own, residing at the top of its food chain <ref> {{cite web|url="http://www.pbs.org/kqed/oceanadventures/glossary/" |title="apex predator" |publisher=PBS}} </ref> (Note: Predation in its zoological sense is the killing and consumption of another organism, which excludes bacteria and parasites from the apex predator concept. Predation has been used in this context since 1932 <ref>{{cite web|url="http://www.etymonline.com/index.php?search=predation&searchmode=none |title="predator" |publisher=Online Etymological Dictionary }}</ref>). The apex predator concept is commonly applied in wildlife management and conservation, as well as eco-tourism. In these contexts it has been defined in terms of [[trophic levels]]. Trophic levels are "hierarchical strata of a food web characterized by organisms which are the same number of steps removed from the [[foundation species|primary producers]]."<ref>{{cite web |url=http://www.merriam-webster.com/dictionary/trophic+level
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|title=Trophic level |accessdate=2008-06-02 |publisher=Merriam-Webster Dictionary|date= }}</ref> Primary, secondary, tertiary, and higher level consumers occupy successive trophic levels. One study of marine food webs defined apex predators as greater than trophic level four.<ref>{{cite journal |last=Essington |first=Timothy E. |coauthors= Beaudreau, Anne H.; Wiedenmann, John |year=2005 |month=December |title=Fishing through marine food webs |journal= Proceedings of the National Academy of Sciences|volume=103 |issue=9 |pages=3171–3175 |url=http://www.pnas.org/cgi/reprint/0510964103v1.pdf |accessdate= 2007-11-24 |format=PDF}}</ref>
   
Such an animal as a [[river dolphin]] or the [[Baikal seal]], either of which would be ordinary prey for orcas in the open ocean, have no predators in their usual habitats. [[Venom]] is usually not adequate to make a superpredator; a [[rattlesnake]] is potential prey for [[eagle]]s, [[hawk]]s, [[cat]]s, [[kingsnake]]s, and [[Geococcyx|roadrunner]]s; the [[Cubozoa|box jellies]] and [[Portuguese Man o' War]] that could kill a human with their stings are prey for some [[sea turtle]]s.
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Food chains are often far shorter on land, with the top of the food chain limited to the third trophic level, as where such predators as the [[big cat]]s, [[crocodilian]]s, [[hyena]]s, [[wolves]], or giant constrictor snakes prey upon large herbivores. Such also applies to such omnivores as grizzly bears and [[human]]s that eat considerable vegetable material as well as much meat but are not themselves prey in most of their range.
   
The same weapons that make superpredators so formidable hunters (claws, talons, teeth, power, strength) typically make them superb defenders of themselves. Even so small a predator as the [[electric eel]] that uses electrical charge to kill small fish and crustaceans as prey can give an unpleasant shock to such an animal as a [[caiman]], [[jaguar]], [[cougar]], dog, [[giant otter]], [[anaconda]], [[egret]], or human, causing the misguided predator to seek something less troublesome.
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==Ecological role==
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:''See also [[Mesopredator release hypothesis]].''
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Apex predators affect prey species' population dynamics. Where two competing species are in an ecologically unstable relationship, apex predators tend to create stability if they prey upon both. Inter-predator relationships are also affected by apex status. Non-native fish, for example, have been known to devastate formerly dominant predators. One lake manipulation study found that when the non-native [[smallmouth bass]] was removed, [[lake trout]], the suppressed native apex predator, diversified its prey selection and increased its trophic level.<ref name="Lepak">Lepak, Jesse M., Kraft, Clifford E., and Weidel, Brian C. (March 2006). "[http://www.dnr.cornell.edu/cek7/Publications/Lepak_et_al_2006.pdf Rapid Food Web Recovery in Response to Removal of an Introduced Apex Predator]" (PDF). ''Canadian Journal of Fisheries and Aquatic Sciences'' '''63''' (3): 569-575. ISSN: 0706-652X. Retrieved on [[2008]]-[[06-03]].</ref>
   
Some ordinarily hunt singly (any cat other than the lion, [[sperm whale]], [[alligator]], [[reticulated python]], [[snapping turtle]], or any [[eagle]]); some are highly social in their hunting strategies (lions, wolves, dogs, [[dingo]]s, [[African hunting dog]]s, [[dhole]]s, orcas, [[harrier hawk]]s, and the [[driver ant]]s and [[fire ant]]s that in some niches are top predators). Dogs and humans participate in some of the most efficient teams of predators.
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Effects on wider ecosystem characteristics, such as plant [[ecology]], have been debated, but there is evidence of a significant impact by apex predators: introduced [[arctic fox]]es, for example, have been shown to turn subarctic islands from [[grassland]] into [[tundra]] through predation on [[seabird]]s.<ref>{{cite journal |last=Croll |first=D. A. |coauthors=Maron, J. L.; et al. |year= 2005|month=March |title=Introduced Predators Transform Subarctic Islands from Grassland to Tundra |journal=[[Science (magazine)|Science]] |volume=307 |issue=5717 |pages=1959 - 1961 | url=http://www.sciencemag.org/cgi/content/abstract/307/5717/1959 |accessdate= 2007-11-24 |doi=10.1126/science.1108485 }}</ref> Such wide-ranging effects on lower levels of an ecosystem are termed [[trophic cascade]]s. The removal of top-level predators—often through human agency—can radically cause (or disrupt) trophic cascades.<ref>{{cite web |last= Egan|first=Logan Zane |coauthors=Téllez, Jesús Javier |year=2005 |month=June |title=Effects of preferential primary consumer fishing on lower trophic level herbivores in the Line Islands |work=Stanford at Sea |publisher=[[Stanford University]] |url=http://stanford.sea.edu/research/EganTellez_Research_Project.pdf |accessdate= 2007-11-24 |format=PDF }}</ref><ref>{{cite journal |last=Pace |first=M. L. |coauthors=Cole, J. J.; et al. |year=1999 |month=December |title=Trophic cascades revealed in diverse ecosystems |journal=Trends in Ecology and Evolution |volume=14 |issue=12 |pages=483-488 |url= http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&list_uids=10542455&cmd=Retrieve&indexed=google |accessdate= 2007-11-24}}</ref> A commonly cited example of apex predators affecting an ecosystem is [[Yellowstone National Park]]. After the reintroduction of the [[gray wolf]] in 1995, researchers noticed drastic changes occurring in the [[Greater Yellowstone Ecosystem]]. Elk, the primary prey of the gray wolf, became less abundant and changed their behavior, freeing riparian zones from constant grazing. The respite allowed willows and aspens to grow, creating habitat for [[beaver]], [[moose]], and scores of other species. In addition to the effects on prey species, the gray wolf's presence also affected the park's [[grizzly bear]] population. The bears, emerging from hibernation, chose to scavenge off wolf kills to gain needed energy and fatten up after fasting for months. Dozens of other species have been documented scavenging off wolf kills also.
   
In addition, the status of an apex predator depends only on its surroundings, not its universal hunting ability. All species are highly attuned to their environment, and apex predators only more so. Outside of their normal context such a predator could easily become prey to unfamiliar species, like putting a Komodo dragon in the grasslands alongside lions and hyenas. A [[sea star]], [[cone shell]], [[octopus]], or a [[sea anemone]] that might have predators elsewhere might be the arch-predator of some small tide pool.
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== See also ==
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*[[List of apex predators]]
   
Humans can be viewed as the "ultimate" apex predator if one applies the food-chain definition, as humans have largely removed themselves from being preyed upon in the wild, and have used technology (especially firearms) and even other animals (dogs, horses, and elephants) to subdue, evade, and/or kill most of the wild animals that pose a threat to themselves. Certain regions of the world, mostly wilderness, are still dangerous to humans in this respect. Predators such as lions, [[leopard]]s, [[Nile crocodile]]s and [[saltwater crocodile]]s retain notoriety for being "man-eaters", as the humans they interact with possess negligible weapons in order to defend against attack. Still, by and far humans have surpassed the evolutionary limits of their bodies, resulting in safety from nearly all natural predators.
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==References==
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{{reflist}}
   
== External links ==
 
   
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{{feeding}}
== See also ==
 
*[[List of Apex Predators]]
 
   
 
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Apex predators (also alpha predators, superpredators, or top-level predators) are predators that, as adults, are not normally preyed upon in the wild by other large animals in significant parts of their range. Apex predator species are often at the end of long food chains, where they have a crucial role in maintaining the health of ecosystems.

DefinitionEdit

An apex predator is one that has virtually no predators of its own, residing at the top of its food chain [1] (Note: Predation in its zoological sense is the killing and consumption of another organism, which excludes bacteria and parasites from the apex predator concept. Predation has been used in this context since 1932 [2]). The apex predator concept is commonly applied in wildlife management and conservation, as well as eco-tourism. In these contexts it has been defined in terms of trophic levels. Trophic levels are "hierarchical strata of a food web characterized by organisms which are the same number of steps removed from the primary producers."[3] Primary, secondary, tertiary, and higher level consumers occupy successive trophic levels. One study of marine food webs defined apex predators as greater than trophic level four.[4]

Food chains are often far shorter on land, with the top of the food chain limited to the third trophic level, as where such predators as the big cats, crocodilians, hyenas, wolves, or giant constrictor snakes prey upon large herbivores. Such also applies to such omnivores as grizzly bears and humans that eat considerable vegetable material as well as much meat but are not themselves prey in most of their range.

Ecological roleEdit

See also Mesopredator release hypothesis.

Apex predators affect prey species' population dynamics. Where two competing species are in an ecologically unstable relationship, apex predators tend to create stability if they prey upon both. Inter-predator relationships are also affected by apex status. Non-native fish, for example, have been known to devastate formerly dominant predators. One lake manipulation study found that when the non-native smallmouth bass was removed, lake trout, the suppressed native apex predator, diversified its prey selection and increased its trophic level.[5]

Effects on wider ecosystem characteristics, such as plant ecology, have been debated, but there is evidence of a significant impact by apex predators: introduced arctic foxes, for example, have been shown to turn subarctic islands from grassland into tundra through predation on seabirds.[6] Such wide-ranging effects on lower levels of an ecosystem are termed trophic cascades. The removal of top-level predators—often through human agency—can radically cause (or disrupt) trophic cascades.[7][8] A commonly cited example of apex predators affecting an ecosystem is Yellowstone National Park. After the reintroduction of the gray wolf in 1995, researchers noticed drastic changes occurring in the Greater Yellowstone Ecosystem. Elk, the primary prey of the gray wolf, became less abundant and changed their behavior, freeing riparian zones from constant grazing. The respite allowed willows and aspens to grow, creating habitat for beaver, moose, and scores of other species. In addition to the effects on prey species, the gray wolf's presence also affected the park's grizzly bear population. The bears, emerging from hibernation, chose to scavenge off wolf kills to gain needed energy and fatten up after fasting for months. Dozens of other species have been documented scavenging off wolf kills also.

See also Edit

ReferencesEdit

  1. ["http://www.pbs.org/kqed/oceanadventures/glossary/" "apex predator"]. PBS.
  2. ["http://www.etymonline.com/index.php?search=predation&searchmode=none "predator"]. Online Etymological Dictionary.
  3. Trophic level. Merriam-Webster Dictionary. URL accessed on 2008-06-02.
  4. Essington, Timothy E., Beaudreau, Anne H.; Wiedenmann, John (December 2005). Fishing through marine food webs. Proceedings of the National Academy of Sciences 103 (9): 3171–3175.
  5. Lepak, Jesse M., Kraft, Clifford E., and Weidel, Brian C. (March 2006). "Rapid Food Web Recovery in Response to Removal of an Introduced Apex Predator" (PDF). Canadian Journal of Fisheries and Aquatic Sciences 63 (3): 569-575. ISSN: 0706-652X. Retrieved on 2008-06-03.
  6. Croll, D. A., Maron, J. L.; et al. (March 2005). Introduced Predators Transform Subarctic Islands from Grassland to Tundra. Science 307 (5717): 1959 - 1961.
  7. Egan, Logan Zane, Téllez, Jesús Javier (2005). Effects of preferential primary consumer fishing on lower trophic level herbivores in the Line Islands. (PDF) Stanford at Sea. Stanford University. URL accessed on 2007-11-24.
  8. Pace, M. L., Cole, J. J.; et al. (December 1999). Trophic cascades revealed in diverse ecosystems. Trends in Ecology and Evolution 14 (12): 483-488.



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