Английская Википедия:Island gigantism
Island gigantism, or insular gigantism, is a biological phenomenon in which the size of an animal species isolated on an island increases dramatically in comparison to its mainland relatives. Island gigantism is one aspect of the more general "island effect" or "Foster's rule", which posits that when mainland animals colonize islands, small species tend to evolve larger bodies, and large species tend to evolve smaller bodies (insular dwarfism). This is itself one aspect of the more general phenomenon of island syndrome which describes the differences in morphology, ecology, physiology and behaviour of insular species compared to their continental counterparts. Following the arrival of humans and associated introduced predators (dogs, cats, rats, pigs), many giant as well as other island endemics have become extinct (e.g. the dodo and Rodrigues solitaire, giant flightless pigeons related to the Nicobar pigeon). A similar size increase, as well as increased woodiness, has been observed in some insular plants such as the Mapou tree (Cyphostemma mappia) in Mauritius which is also known as the "Mauritian baobab" although it is member of the grape family (Vitaceae).
Possible causes
Large mammalian carnivores are often absent on islands because of insufficient range or difficulties in over-water dispersal. In their absence, the ecological niches for large predators may be occupied by birds, reptiles or smaller carnivorans, which can then grow to larger-than-normal size. For example, on prehistoric Gargano Island in the Miocene-Pliocene Mediterranean, on islands in the Caribbean like Cuba, and on Madagascar and New Zealand, some or all apex predators were birds like eagles, falcons and owls, including some of the largest known examples of these groups. However, birds and reptiles generally make less efficient large predators than advanced carnivorans.
Since small size usually makes it easier for herbivores to escape or hide from predators, the decreased predation pressure on islands can allow them to grow larger.[1]Шаблон:Efn Small herbivores may also benefit from the absence of competition from missing types of large herbivores.
Benefits of large size that have been suggested for island tortoises include decreased vulnerability to scarcity of food and/or water, through ability to survive for longer intervals without them, or ability to travel longer distances to obtain them. Periods of such scarcity may be a greater threat on oceanic islands than on the mainland.[2]
Thus, island gigantism is usually an evolutionary trend resulting from the removal of constraints on the size of small animals related to predation and/or competition.[3] Such constraints can operate differently depending on the size of the animal, however; for example, while small herbivores may escape predation by hiding, large herbivores may deter predators by intimidation. As a result, the complementary phenomenon of island dwarfism can also result from the removal of constraints related to predation and/or competition on the size of large herbivores.[4] In contrast, insular dwarfism among predators more commonly results from the imposition of constraints associated with the limited prey resources available on islands.[4] As opposed to island dwarfism, island gigantism is found in most major vertebrate groups and in invertebrates.
Territorialism may favor the evolution of island gigantism. A study on Anaho Island in Nevada determined that reptile species that were territorial tended to be larger on the island compared to the mainland, particularly in the smaller species. In territorial species, larger size makes individuals better able to compete to defend their territory. This gives additional impetus to evolution toward larger size in an insular population.[5]
A further means of establishing island gigantism may be a founder effect operative when larger members of a mainland population are superior in their ability to colonize islands.[6]
Island size plays a role in determining the extent of gigantism. Smaller islands generally accelerate the rate of evolution of changes in organism size, and organisms there evolve greater extremes in size.[7]
Examples
Examples of island gigantism include:
Mammals
Many rodents grow larger on islands, whereas carnivorans, proboscideans and artiodactyls usually become smaller.
Eulipotyphlans
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Balearic giant shrew | Nesiotites hidalgo | Majorca and Menorca | Extinct (3000-2000 BC) | Файл:Neomys anomalus.jpg Red-toothed shrews |
Sardinian giant shrew | Asoriculus similis | Sardinia and Corsica | Extinct (Holocene) | |
Sicilian giant shrew | Asoriculus burgioi | Sicily | Extinct (Early Pleistocene) | |
Файл:Deinogalerix Gargano fauna.jpg Deinogalerix |
Deinogalerix spp. | Gargano Island | Extinct (Late Miocene) | Файл:Hylomys suillus - Naturmuseum Senckenberg - DSC02077a.JPG Moon rats |
Rodents
Lagomorphs
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Файл:Nuralagus NTy.jpg Minorcan giant lagomorph |
Nuralagus rex | Minorca | Extinct (Middle Pliocene) | Alilepus (?) Trischizolagus (?) |
Prolagus imperialis | Gargano Island | Extinct | Файл:Ochotona pallasi.jpg Pikas | |
Файл:Prolagus3.jpg Sardinian pika |
Prolagus sardus | Corsica, Sardinia and Tavolara | Extinct (c. AD 1800) |
Primates
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Hispaniola monkey | Antillothrix bernensis | Hispaniola | Extinct (before AD 1600) | Файл:Callicebus lugens.jpg Cheracebus |
Haitian monkey | Insulacebus toussaintiana | Southwestern Haiti | Extinct | |
Файл:Paralouatta marianae skull.jpg Cuban monkeys |
Paralouatta marianae[16] P. varonai[16] |
Cuba | Extinct (Pleistocene) | |
Jamaican monkey | Xenothrix mcgregori | Jamaica | Extinct | |
Файл:Archaeoindris fontoynonti.jpg Gorilla lemur |
Archaeoindris fontoynontii | Central Madagascar | Extinct (c. 350 BC) | Файл:Galago senegalensis.jpg Lorisoids |
Файл:Archaeolemur edwardsi.jpg Baboon lemurs |
Archaeolemur spp. Hadropithecus spp. |
Madagascar | Extinct (before AD 1280) | |
Файл:Babakotia radofilai.jpg Sloth lemurs |
Babakotia spp. Palaeopropithecus spp. |
Western and Central Madagascar | Extinct (c. AD 1500) | |
Файл:Megaladapis.jpg Koala lemurs |
Megaladapis edwardsi M. grandidieri M. madagascariensis |
Madagascar | Extinct (AD 1280–1420) |
Carnivorans
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Файл:D2627 Megalenhydris.jpg Sardinian giant otter |
Megalenhydris barbaricina | Sardinia | Extinct (Late Pleistocene) | Файл:Otters at feeding time 2004 SMC.jpg Otters |
Файл:Cryptoprocta Ferox.JPG Fossa |
Cryptoprocta ferox | Madagascar | Vulnerable | Файл:Herpestes ichneumon Египетский мангуст, или фараонова крыса, или ихневмо́н.jpg Mongooses |
Файл:Fossa de les cavernes.png Giant fossa |
Cryptoprocta spelaea | Madagascar | Extinct (before AD 1400) |
Birds
Stem birds
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Файл:Balaur bondoc as avialan.jpg Balaur |
B. bondoc | Hateg Island | Extinct (Late Cretaceous) | Файл:Jeholornis mmartyniuk wiki.jpg Jeholornis[17] |
Файл:Gargantuavis philoinos femur.JPG Gargantuavis |
G. philohinos | Ibero-Armorican Island | Extinct (Late Cretaceous) | Файл:Patagopteryx deferrariisi.jpg Patagopteryx (?) |
Ratites
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Файл:Apteryx australis - Swedish Museum of Natural History - Stockholm, Sweden - DSC00615.JPG Kiwis |
Apterygidae | New Zealand | Variable | ProapteryxШаблон:Efn |
Файл:Aepyornis maximus (pajaroelfantgigante).png Greater elephant birds |
Aepyornithidae |
Madagascar | Extinct (c. AD 1700) | |
Файл:Mullerornis agilis.jpg Lesser elephant birds |
Mullerornithidae | Madagascar | Extinct (c. AD 1260) | |
Файл:Dinornis novaezealandiae.png Giant moas |
Dinornithidae |
New Zealand | Extinct (c. AD 1450) | Файл:Tinamus majorPCSL00504B.jpg Tinamous |
Файл:Euryapteryx.jpg Lesser moas |
Emeidae | New Zealand | Extinct (c. AD 1460) | |
Файл:Megalapteryx.png Upland moas |
Megalapterygidae | New Zealand | Extinct (c. AD 1300) |
Waterfowl
Pangalliformes
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Pile-builder megapode | Megapodius molistructor | New Caledonia and Tonga | Extinct (c. 1500 BC) | Файл:Megapodius reinwardt Cairns.jpg Scrubfowl |
Megavitiornis | Megavitiornis altirostris | Fiji | Extinct | Файл:Flickr - Rainbirder - Ceylon Junglefowl (Gallus lafayetii) Male.jpg Galliformes |
Файл:Sylviornis.PNG Sylviornis |
Sylviornis neocaledoniae | New Caledonia and Isle of Pines | Extinct |
Gruiformes
Pigeons
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Файл:Natunaornis gigoura e.jpg Viti Levu giant pigeon |
Natunaornis gigoura | Viti Levu, Fiji | Extinct | Файл:Western Crowned Pigeon (Goura cristata) in TMII Birdpark.jpg Crowned pigeons |
Kanaka pigeon | Caloenas canacorum | New Caledonia | Extinct (c. 500 BC) | Файл:Nicobar Pigeon 820.jpg Nicobar pigeon |
Файл:Pezophaps solitaria recreation.jpg Rodrigues solitaire |
Pezophaps solitaria | Rodrigues | Extinct (before AD 1778) | |
Файл:DodoMansur cutted.png Dodo |
Raphus cucullatus | Mauritius | Extinct (c. AD 1662) |
Birds of prey
Parrots
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Файл:Heracles inexpectatus.jpg Hercules parrot |
Heracles inexpectatus | New Zealand | Extinct (Miocene) | Файл:Horned Parakeet 3487 Copyright TP ONG.JPG Other parrots |
Файл:Strigops habroptilus 1.jpg Kakapo |
Strigops habroptilus | New Zealand | Critically Endangered | |
Файл:Lophopsittacus.jpg Broad-billed parrot |
Lophopsittacus mauritianus | Mauritius | Extinct (c. AD 1680) | Файл:Rose-ringed Parakeet (Psittacula krameri)- Female on a Neem (Azadirachta indica) tree at Hodal Iws IMG 1279.jpg Psittaculine parrots |
Owls
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Файл:Candiacervus ropalophorus.jpg Cretan owl |
Athene cretensis | Crete | Extinct (Pleistocene) | Файл:Athene noctua (portrait).jpg Little owl |
Файл:Ornimegalonyx oteroi.jpg Cuban giant owls |
Ornimegalonyx spp. | Cuba | Extinct (Pleistocene) | Файл:Strix-varia-005.jpg Wood owls |
Файл:Tyto gigantea.JPG Greater Gargano giant owl |
Tyto gigantea | Gargano Island | Extinct (Late Miocene) | Файл:Barn Owl, Canada.jpg Barn owls |
Файл:Tyto pollens hccm.jpeg Andros Island barn owl |
Tyto pollens | Andros Island, Bahamas | Extinct (before AD 1600) | |
Файл:Tyto riveroi.jpg Rivero's barn owl |
Tyto riveroi | Cuba | Extinct | |
Файл:Tyto robusta.JPG Lesser Gargano giant owl |
Tyto robusta | Gargano Island | Extinct (Early Pliocene) |
Caprimulgiformes
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
New Zealand owlet-nightjar | Aegotheles novazelandiae | New Zealand | Extinct (c. AD 1200) | Файл:Aegotheles cristatus -South Australia, Australia-8.jpg Australian owlet-nightjar |
Файл:Aegothelessavesi.jpg New Caledonian owlet-nightjar |
Aegotheles savesi | New Caledonia | Critically endangered |
Passeriforms
Reptiles
Pterosaurs
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Файл:Hatzegopteryx.png Hatzegopteryx |
H. thambema | Hateg Island | Extinct (Late Cretaceous) | Файл:Life restoration of a group of giant azhdarchids, Quetzalcoatlus northropi, foraging on a Cretaceous fern prairie.png Quetzalcoatlus |
Iguanids
Example | Binomial name | Native range | Current status | Continental relative | Insular / mainland length or mass ratio |
---|---|---|---|---|---|
Файл:Brachylophus gibbonsi.JPG Tongan giant iguana[22] |
Brachylophus gibbonsi | Tonga | Extinct (c. 800 BC) | Файл:Iguana iguana Portoviejo 01.jpg South American iguanas |
|
Файл:Lapitiguana impensa.JPG Fijian giant iguana [23] |
Lapitiguana impensa | Fiji | Extinct (c. 1000 BC) | ||
Файл:Sauromalus hispidus - Reptilium Landau.jpg Angel Island chuckwalla |
Sauromalus hispidus | Isla Ángel de la Guarda, Baja California | Near Threatened | Peninsular chuckwalla | MR ≈ 5 [24] |
Файл:San Esteban Island Chuckwalla.jpg San Esteban chuckwalla |
Sauromalus varius | San Esteban Island, Baja California | Endangered | MR ≈ 5 [24] |
Geckos
Example | Binomial name | Native range | Current status | Continental relative | Insular / mainland length or mass ratio |
---|---|---|---|---|---|
Файл:Gecko de Delcourt Hoplodactylus delcourti GLAM MHNL 2016 3742.jpg Delcourt's giant gekko |
Gigarcanum delcourti | New Caledonia | Extinct (c. AD 1870) | Файл:Oedura lesueurii 2.jpg Diplodactylid geckos |
LR ≈ 6.75 Шаблон:Efn |
Файл:Rhacodactylus leachianus.jpg New Caledonian giant gecko |
Rhacodactylus leachianus | New Caledonia | Least Concern | LR ≈ 4.4 Шаблон:Efn MR ≈ 60 Шаблон:Efn | |
Rodrigues giant day gecko |
Phelsuma gigas | Rodrigues | Extinct (c. AD 1850) | Файл:Gold dust day gecko.JPG Day geckos |
Skinks
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Файл:Mabuja3.jpg Vaillant's mabuya |
Chioninia vaillanti | Cape Verde | Endangered | Файл:Notomabuya frenata.jpg Mainland mabuyine skinks |
Файл:Macroscincus coctei003.jpg Cape Verde giant skink |
Macroscincus coctei | Cape Verde | Extinct (after AD 1900) | |
Mauritius giant skink |
Leiolopisma mauritiana | Mauritius | Extinct (after AD 1600) | Mainland eugongyline skinks |
Terror skink | Phoboscincus bocourti | Île des Pins off New Caledonia | Endangered | Файл:Skink in Aussie.jpg Mainland eugongyline skinks |
Kishinoue's giant skink | Plestiodon kishinouyei | Miyako Islands and Yaeyama Islands, Japan | Vulnerable | Файл:Five-striped Blue-tailed Skink (Plestiodon elegans) 藍尾石龍子.jpg Asian Plestiodon spp. |
Wall lizards
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
La Palma giant lizard | Gallotia auaritae | La Palma | Critically endangered | Файл:Psammodromus algirus - 01.jpg Mediterranean sandrunner lizards |
Файл:Gallotia bravoana.jpg La Gomera giant lizard |
Gallotia bravoana | Gomera | Critically endangered | |
Файл:Tenerife giant lizard restoration.jpg Tenerife giant lizard[25] |
Gallotia goliath | Tenerife | Extinct (c. AD 1500) | |
Файл:Gallotia Simonyi at Centro de recuperación del lagarto gigante..jpg El Hierro giant lizard |
Gallotia simonyi | El Hierro | Critically endangered | |
Файл:Gallotia stehlini -Gran Canaria, Canary Islands, Spain-8.jpg Gran Canaria giant lizard |
Gallotia stehlini | Gran Canaria | Least Concern |
Snakes
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Angel de la Guarda Island speckled rattlesnake | Crotalus mitchellii angelensis | Isla Ángel de la Guarda off Baja California | Least Concern | Файл:Speckled Rattlesnake (Crotalus mitchellii) (21705787199).jpg Speckled rattlesnake |
Tadanae-jima striped snake population[26] | Elaphe quadrivirgata | Tadanae-jima island off Tokyo | Unknown | Файл:Elaphe quadrivirgata.JPG Japanese striped snake |
Файл:20060306 King Island Tiger Snake.jpg Island tiger snake populations |
Notechis scutatus | Islands Mount Chappell (Tasmania); Williams, Hopkins, and the Nuyts Archipelago (all South Australia)[27] | Least Concern[28] | Файл:Tiger snake 2.jpg Tiger snake |
Isla Cerralvo long-nosed snake | Rhinocheilus lecontei etheridgei | Jacques Cousteau Island off Baja California Sur | Unknown | Файл:Rhinocheilus lecontei tessellatus.jpg Long-nosed snake |
Dubious examples
- The Komodo dragon of Flores and nearby islands, the largest extant lizard, and a similar (extinct) giant monitor lizard from Timor have been regarded as examples of giant insular carnivores. Since islands tend to offer limited food and territory, their mammalian carnivores (if present) are usually smaller than continental ones. These cases involve ectothermic carnivores on islands too small to support much mammalian competition. However, these lizards are not as large as their extinct Australian relative megalania, and it has been proposed based on fossil evidence that the ancestors of these varanids first evolved their large size in Australia and then dispersed to Indonesia.[29] If this is true, rather than being insular giants they would be viewed as examples of phyletic gigantism. Supporting this interpretation is evidence for a lizard in Pliocene India, Varanus sivalensis, comparable in size to V. komodoensis.[29] Nevertheless, given that Australia is often described as the world's largest island and that the related megalania, the largest terrestrial lizard known in the fossil record, was restricted to Australia, the perception of the largest Australasian/Indonesian lizards as insular giants may still have some validity.
- Giant tortoises in the Galápagos Islands and the Seychelles, the largest extant tortoises, as well as extinct tortoises of the Mascarenes and Canary Islands, are often considered examples of island gigantism. However, during the Pleistocene, comparably sized or larger tortoises were present in Australia (Meiolania), southern Asia (Megalochelys), Europe[30] (Titanochelon), Madagascar (Aldabrachelys), North America[31] (Hesperotestudo) and South America[32] (Chelonoidis, the same genus now found in the Galápagos[33]), and on a number of other, more accessible islands of Oceania and the Caribbean.[31] In the late Pliocene they were also present in Africa ("Geochelone" laetoliensis[34]). The present situation of large tortoises being found only on remote islands appears to reflect that these islands were discovered by humans recently and have not been heavily populated, making their tortoises less subject to overexploitation.
Amphibians
Example | Binomial name | Native range | Current status | Continental relative | Insular / mainland length or mass ratio |
---|---|---|---|---|---|
São Tomé giant tree frog | Hyperolius thomensis[35] | São Tomé Island | Endangered | Файл:Hyperolius argus Al-ReedFrogs 01.jpg African reed frogs |
|
Palm forest tree frog | Leptopelis palmatus[35] | Príncipe Island | Vulnerable | Файл:Leptopelis rufus02.jpg Red tree frog |
LR ≈ 1.2 Шаблон:Efn |
Giant Fiji ground frog | Platymantis megabotoniviti[36] | Viti Levu, Fiji | Extinct | Файл:Platymantis cagayanensis (KU 330716) from mid-elevation of Mt. Cagua - ZooKeys-266-001-g019.jpg Asian platymantines |
|
São Tomé giant grass frog | Ptychadena newtoni[35] | São Tomé Island | Endangered | Файл:Madagascar Grass Frog (Ptychadena madagascariensis), Andasibe, Madagascar (14156831413).jpg Mascarene grass frog |
Arthropods
Gastropods
Example | Binomial name | Native range | Current status | Continental relative |
---|---|---|---|---|
Файл:Powelliphanta annectens DOC 2007.jpg Kauri land snails |
Paryphanta spp. Powelliphanta spp. |
New Zealand | Near Threatened | Файл:Flat shelled snail Chatswood West.JPG Other rhytidids |
Flora
In addition to size increase, island plants may also exhibit "insular woodiness".[40] The most notable examples are the megaherbs of New Zealand's subantarctic islands.Шаблон:Citation needed Increased leaf and seed size was also reported in some island species regardless of growth form (herbaceous, bush, or tree).[41]
See also
Notes
References
External links
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ 4,0 4,1 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Freudenthal, M. (1985). Cricetidae (Rodentia) from the Neogene of Gargano (Prov. of Foggia, Italy). Rijksmuseum van Geologie en Mineralogie.
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite journal
- ↑ http://www.raco.cat/index.php/Orsis/article/viewFile/24434/24268 Шаблон:Bare URL PDF
- ↑ Шаблон:Cite journal
- ↑ 16,0 16,1 Шаблон:Cite journal
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ 24,0 24,1 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ https://www.jstage.jst.go.jp/article/hsj2000/21/1/21_1_43/_pdf Шаблон:Bare URL PDF
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite iucn
- ↑ 29,0 29,1 Шаблон:Cite journal
- ↑ Pérez-García, A., Vlachos, E., & Arribas, A. (2017). The last giant continental tortoise of Europe: A survivor in the Spanish Pleistocene site of Fonelas P-1. Palaeogeography, Palaeoclimatology, Palaeoecology, 470, 30–39.
- ↑ 31,0 31,1 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Fariña, R.A., Vizcaíno, S.F. & De Iuliis, G. (2013) Megafauna: Giant Beasts of South America. Indiana University Press, 448 pages.
- ↑ Шаблон:Cite book
- ↑ 35,0 35,1 35,2 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Neither coconut crabs nor their relatives can swim beyond the larva stage, making the adults land animals in practice. Coconut crabs can weigh over 4 kg (9 pounds); the largest hermit crabs of the related genus Coenobita, C. brevimanus of coastal Africa and Asia, only reaches 230 grams (0.5 pounds).
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ 41,0 41,1 Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ 44,0 44,1 Шаблон:Cite book
- ↑ Шаблон:Cite book