Island gigantism

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
The large Haast's eagle and moa from New Zealand (both extinct)

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. A similar size increase, as well as increased woodiness, has been observed in some insular plants.

Possible causes[edit]

Diagram displaying the change in size of wētā species in two ecosystems. The size and population of wētā are affected by predation. Rats introduced on the mainland began to prey on wētā, reducing their population; wētā shrank in response. On an island isolated from predation, such as Little Barrier Island, wētā have a dense population and have grown to a massive size. Insular species of giant wētā are the only ones not facing extinction. As wētā grow over time, bird predation declines.[citation needed]

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][a] 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.[4]

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.[5] 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.[6] In contrast, insular dwarfism among predators more commonly results from the imposition of constraints associated with the limited prey resources available on islands.[6] 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.[7]

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.[8]

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.[9]


Examples of island gigantism include:


Many rodents grow larger on islands, whereas carnivorans, proboscideans and artiodactyls usually become smaller.


Example Binomial name Native range Current status Continental relative
Corsican giant shrew Asoriculus corsicanus Corsica Extinct (before 500 BC) Neomys anomalus.jpg
Red-toothed shrews
Balearic giant shrew Asoriculus hidalgo Majorca and Menorca Extinct
Sardinian giant shrew Asoriculus similis Sardinia Extinct
Deinogalerix Gargano fauna.jpg
Deinogalerix spp. Gargano Island Extinct (Late Miocene) Hylomys suillus - Naturmuseum Senckenberg - DSC02077a.JPG
Moon rats


Example Binomial name Native range Current status Continental relative Insular / mainland
length or mass ratio
Blunt-toothed giant hutia Amblyrhiza inundata Anguilla and Saint Martin Extinct (Pleistocene) Hoplomys gymnurus2.jpg
Neotropical spiny rats
Larger Jamaican giant hutia Clidomys osborni Jamaica Extinct (Late Pleistocene)
Plate-toothed giant hutia Elasmodontomys obliquus Puerto Rico Extinct (c. 1 AD)
Twisted-toothed mouse Quemisia gravis Hispaniola Extinct
Arboreal giant hutia[10] Tainotherium valei Puerto Rico Extinct
Lesser Jamaica giant hutia Xaymaca fulvopulvis Jamaica Extinct
Majorcan giant hamsters Apocricetus darderi

Tragomys macpheei
Majorca Extinct Apocricetus alberti[11]

Cricetus kormosi[12]
Hattomys gargantua Naturalis.JPG
Gargano giant hamster
Hattomys gargantua Gargano Island Extinct
St Kilda field mouse (Apodemus sylvaticus hirtensis).png
St Kilda field mouse
Apodemus sylvaticus hirtensis St Kilda Least Concern ApodemusSylvaticus.jpg
Wood mouse
MR ≈ 2 [13]
Rhagamys orthodon lower hemimandibles, Pleistocene of Corsica.jpg
Hensel's field mouse
Rhagamys orthodon Corsica and Sardinia Extinct (Late Pleistocene)
Canariomys bravoi.jpg
Tenerife giant rat
Canariomys bravoi Tenerife Extinct (Late Pleistocene) African rufous-nosed rats
Canariomys tamarani fossils.JPG
Gran Canaria giant rat
Canariomys tamarani Gran Canaria Extinct (before AD 1500)
Formentera black-tailed garden dormouse Eliomys quercinus ophiusae Formentera Rare[14] Eliomys quercinus01.jpg
Garden dormouse and
other Leithiinae dormice
Minorcan giant dormouse Hypnomys mahonensis Menorca Extinct
Majorcan giant dormouse
Hypnomys morpheus Majorca Extinct
Sicilian giant dormouse Leithia cartei Sicily Extinct
Maltese giant dormouse Leithia melitensis Malta Extinct
Topillo de las Orcadas.jpg
Orkney vole
Microtus arvalis orcadensis Orkney Islands Vulnerable Feldmaus Microtus arvalis.jpg
Common vole and
other meadow voles
Mikrotia magna Naturalis 2.JPG
Gargano giant voles
Mikrotia magna

M. maiuscula

M. parva
Gargano Island Extinct (Early Pliocene)
St Kilda house mouse
Mus musculus muralis St Kilda Extinct (c. AD 1930) Mouse white background.jpg
House mouse

Flores giant rat
Papagomys armandvillei Flores Near Threatened Rattus rattus03.jpg
North African black rat
and other true rats
Sulawesi giant rat Paruromys dominator Sulawesi Least Concern
Admiralty giant rat Rattus detentus Manus Island Unknown / Likely threatened[15]
Congreso black rat population[16] Rattus rattus Isla del Congreso Least Concern
Channel Islands deer mice Peromyscus anyapahensis

P. nesodytes
Northern Channel Islands of California Extinct (c. 6000 BC) DiGangi-Deermouse.jpg
North American deer mouse
Stertomys laticrestatus.jpg
Gargano giant dormouse
Stertomys laticrestatus[17] Gargano Island Extinct 7schlaefer.jpg
Glirinae dormice


Example Binomial name Native range Current status Continental relative
Nuralagus NTy.jpg
Minorcan giant lagomorph
Nuralagus rex Minorca Extinct (Middle Pliocene) Alilepus (?)

Trischizolagus (?)
Prolagus imperialis Gargano Island Extinct Ochotona pallasi.jpg
Sardinian pika
Prolagus sardus Corsica, Sardinia and Tavolara Extinct (c. AD 1800)


Example Binomial name Native range Current status Continental relative
Hispaniola monkey Antillothrix bernensis Hispaniola Extinct (before AD 1600) Callicebus lugens.jpg
Haitian monkey Insulacebus toussaintiana Southwestern Haiti Extinct
Paralouatta marianae skull.jpg
Cuban monkeys
Paralouatta marianae[18]

P. varonai[18]
Cuba Extinct (Pleistocene)
Jamaican monkey Xenothrix mcgregori Jamaica Extinct
Archaeoindris fontoynonti.jpg
Gorilla lemur
Archaeoindris fontoynontii Central Madagascar Extinct (c. 350 BC) Galago senegalensis.jpg
Archaeolemur edwardsi.jpg
Baboon lemurs
Archaeolemur spp.

Hadropithecus spp.
Madagascar Extinct (before AD 1280)
Babakotia radofilai.jpg
Sloth lemurs
Babakotia spp.

Palaeopropithecus spp.
Western and Central Madagascar Extinct (c. AD 1500)
Koala lemurs
Megaladapis edwardsi

M. grandidieri

M. madagascariensis
Madagascar Extinct (AD 1280–1420)


Example Binomial name Native range Current status Continental relative
D2627 Megalenhydris.jpg
Sardinian giant otter
Megalenhydris barbaricina Sardinia Extinct (Late Pleistocene) Otters at feeding time 2004 SMC.jpg
Cryptoprocta Ferox.JPG
Cryptoprocta ferox Madagascar Vulnerable Herpestes ichneumon Египетский мангуст, или фараонова крыса, или ихневмо́н.jpg
Fossa de les cavernes.png
Giant fossa
Cryptoprocta spelaea Madagascar Extinct (before AD 1400)


Stem birds[edit]

Example Binomial name Native range Current status Continental relative
Balaur bondoc as avialan.jpg
B. bondoc Hateg Island Extinct (Late Cretaceous) Jeholornis mmartyniuk wiki.jpg
Gargantuavis philoinos femur.JPG
G. philohinos Ibero-Armorican Island Extinct (Late Cretaceous) Patagopteryx deferrariisi.jpg
Patagopteryx (?)


Example Binomial name Native range Current status Continental relative
Apteryx australis - Swedish Museum of Natural History - Stockholm, Sweden - DSC00615.JPG
Apteryx spp. New Zealand Variable Proapteryx[b]
Aepyornis maximus.jpg
Greater elephant birds
Aepyornis hildebrandti

A. maximus

Vorombe titan
Madagascar Extinct (c. AD 1000)
Mullerornis agilis.jpg
Lesser elephant birds
Mullerornis spp. Madagascar Extinct (c. AD 1260)
Dinornithidae SIZE 01.png
Anomalopteryx didiformis

Dinornis spp.

Emeus crassus

Euryapteryx spp.

Megalapteryx didinus

Pachyornis spp.
New Zealand Extinct (before AD 1445) Tinamus majorPCSL00504B.jpg


Example Binomial name Native range Current status Continental relative
New Zealand musk duck Biziura delautouri New Zealand Extinct (after AD 1500) Biziura lobata - Sandford.jpg
Australian musk duck
New Zealand geese
Cnemiornis calcitrans

C. gracilis
New Zealand Extinct Cereopsis novaehollandiae 2.jpg
Cape Barren goose
Garganornis ballmanni (reconstruction by Stefano Maugeri).jpg
G. ballmanni Gargano and Scontrone islands Extinct (Late Miocene) Greylag Goose - St James's Park, London - Nov 2006.jpg
Turtle-jawed moa-nalo
Chelychelynechen quassus Kauai Extinct (c. AD 1000) Pacific Black Duck (Anas superciliosa) RWD2.jpg
Dabbling ducks
Moa Nalo Maui Nui.JPG
Small-billed moa-nalo
Ptaiochen pau Maui Extinct (c. AD 1000)
Moa Nalo Maui Nui.JPG
Large-billed moa-nalo
Thambetochen chauliodous Maui Nui Extinct (c. AD 1000)
Thambetochen xanion.jpg
O'ahu moa-nalo
Thambetochen xanion O'ahu Extinct (c. AD 1000)
Cygnus falconeri giant swan .jpg
Giant swan
Cygnus falconeri Sicily and Malta Extinct (Middle Pleistocene) Mute swan Vrhnika.jpg
Mute swan
Scarlett's duck Malacorhynchus scarletti New Zealand Extinct (after AD 1500) Malacorhynchus membranaceus -Central Park Zoo, New York, USA-8a.jpg
Pink-eared duck


Example Binomial name Native range Current status Continental relative
Pile-builder megapode Megapodius molistructor New Caledonia and Tonga Extinct (c. 1500 BC) Megapodius reinwardt Cairns.jpg
Megavitiornis Megavitiornis altirostris Fiji Extinct Flickr - Rainbirder - Ceylon Junglefowl (Gallus lafayetii) Male.jpg
Sylviornis neocaledoniae New Caledonia and Isle of Pines Extinct


Example Binomial name Native range Current status Continental relative
Red rail
Aphanapteryx bonasia Mauritius Extinct (c. AD 1700) Rallus caerulescens00.jpg
Hawkins's rail.jpg
Hawkins' rail
Diaphanapteryx hawkinsi Chatham Islands Extinct (c. AD 1900)
Nesotrochis debooyi.jpg
Antillean cave rail
Nesotrochis debooyi Puerto Rico and Virgin Islands Extinct
Cuban cave rail Nesotrochis picapicensis Cuba Extinct
Haitian cave rail Nesotrochis steganinos Hispaniola Extinct
Porphyrio hochstetteri -Tiritiri Matangi Island-8b-3c.jpg
South Island takahē
Porphyrio hochstetteri South Island, New Zealand Endangered
North Island Takahē.jpg
North Island takahē
Porphyrio mantelli North Island, New Zealand Extinct (before AD 1900)
Aptornis BW.jpg
Aptornis defossor

A. otidiformis
New Zealand Extinct CorethruraInsularisKeulemans.jpg
Madagascar flufftail[22]
Fulica chathamensis 1 1896.jpg
Chatham coot
Fulica chathamensis Chatham Islands Extinct (after AD 1500) Red-knobbed coot (Fulica cristata) non-breeding.jpg
Red-knobbed coot
and other coots
Fulica newtoni.jpg
Mascarene coot
Fulica newtonii Mauritius and Réunion Extinct (c. AD 1700)
New Zealand coot Fulica prisca New Zealand Extinct (after AD 1280)
Porphyrio coerulescens.png
Réunion swamphen
Porphyrio coerulescens Plaine des Cafres, Réunion Extinct (c. AD 1730) African Purple Swamphen.jpg
Purple swamphens


Example Binomial name Native range Current status Continental relative
Natunaornis gigoura e.jpg
Viti Levu giant pigeon
Natunaornis gigoura Viti Levu, Fiji Extinct Western Crowned Pigeon (Goura cristata) in TMII Birdpark.jpg
Crowned pigeons
Kanaka pigeon Caloenas canacorum New Caledonia Extinct (c. 500 BC) Nicobar Pigeon 820.jpg
Nicobar pigeon
Pezophaps solitaria recreation.jpg
Rodrigues solitaire
Pezophaps solitaria Rodrigues Extinct (before AD 1778)
DodoMansur cutted.png
Raphus cucullatus Mauritius Extinct (c. AD 1662)

Birds of prey[edit]

Example Binomial name Native range Current status Continental relative
Liko Cave golden eagle Aquila chrysaetos simurgh Crete Extinct (Late Pleistocene) GoldenEagle-Nova.jpg
Golden eagle
Giant crab-hawk[23] Buteogallus borrasi Cuba Extinct Buteogallus urubitinga NBII.jpg
Great black hawk
and other hawks
Giant hawk Gigantohierax sp. Cuba Extinct
Titan-hawk Titanohierax gloveralleni Cuba, Hispaniola and the Bahamas Extinct
Jamaican caracara Caracara tellustris Jamaica Extinct Crested Caracara JCB.jpg
Eyles' harrier Circus eylesi New Zealand Extinct (c. AD 1000) Circus approximans - Peter Murrel.jpg
Swamp harrier
Gargano Island eagles Garganoaetus freudenthali

G. murivorus
Gargano Island Extinct (Late Miocene) Aquila delphinensis
Haast's eagle
Hieraaetus moorei New Zealand Extinct (c. AD 1400) Little Eagle flight gore jun06.jpg
Little eagle
Philippine eagle 2.jpg
Philippine eagle
Pithecophaga jefferyi Philippines Critically endangered Gaukler-01.jpg


Example Binomial name Native range Current status Continental relative
Heracles inexpectatus.jpg
Hercules parrot
Heracles inexpectatus New Zealand Extinct (Miocene) Horned Parakeet 3487 Copyright TP ONG.JPG
Other parrots
Strigops habroptilus 1.jpg
Strigops habroptilus New Zealand Critically Endangered
Broad-billed parrot
Lophopsittacus mauritianus Mauritius Extinct (c. AD 1680) Rose-ringed Parakeet (Psittacula krameri)- Female on a Neem (Azadirachta indica) tree at Hodal Iws IMG 1279.jpg
Psittaculine parrots


Example Binomial name Native range Current status Continental relative
Candiacervus ropalophorus.jpg
Cretan owl
Athene cretensis Crete Extinct (Pleistocene) Athene noctua (portrait).jpg
Little owl
Ornimegalonyx oteroi.jpg
Cuban giant owls
Ornimegalonyx spp. Cuba Extinct (Pleistocene) Strix-varia-005.jpg
Wood owls
Tyto gigantea.JPG
Greater Gargano giant owl
Tyto gigantea Gargano Island Extinct (Late Miocene) Barn Owl, Canada.jpg
Barn owls
Tyto pollens hccm.jpeg
Andros Island barn owl
Tyto pollens Andros Island, Bahamas Extinct (before AD 1600)
Tyto riveroi.jpg
Rivero's barn owl
Tyto riveroi Cuba Extinct
Tyto robusta.JPG
Lesser Gargano giant owl
Tyto robusta Gargano Island Extinct (Early Pliocene)


Example Binomial name Native range Current status Continental relative
New Zealand owlet-nightjar Aegotheles novazelandiae New Zealand Extinct (c. AD 1200) Aegotheles cristatus -South Australia, Australia-8.jpg
Australian owlet-nightjar
New Caledonian owlet-nightjar
Aegotheles savesi New Caledonia Critically endangered


Example Binomial name Native range Current status Continental relative
NovitatesZoologicae18 Pl02 Corvus moriorum.png
Chatham raven
Corvus moriorum Chatham Islands Extinct New Zealand raven
Emberiza alcoveri.jpg
Long-legged bunting
Emberiza alcoveri Tenerife Extinct (after AD 1) Emberiza cabanisi cognominata, Menongue, Birding Weto, a.jpg
Cabanis's bunting
Giant nukupu'u Hemignathus vorpalis Hawaii Extinct (after AD 1000) Red-mantled Rosefinch - Almaty - Kazakistan S4E4053 (23051167291).jpg
Tasmanian superb fairywren Malurus cyaneus cyaneus Tasmania Least Concern Male and female superb fairy wren.jpg
Superb fairywren
Kangaroo Island superb fairywren Malurus cyaneus ashbyi Kangaroo Island Least Concern
Stout-legged wren Pachyplichas yaldwyni South Island of New Zealand Extinct Cobb's Wren.png
Other passeriforms
Ibis (1885) (14565465039).jpg
St Kilda wren
Troglodytes troglodytes hirtensis St Kilda, Scotland Unknown Ein neugieriger Zaunkönig.jpg
Eurasian wren
Silvereye, Capricorn.JPG
Capricorn silvereye
Zosterops lateralis chlorocephalus Capricorn and Bunker Group of the Australian Great Barrier Reef Unknown Silvereye Jan 2010.jpg



Example Binomial name Native range Current status Continental relative
H. thambema Hateg Island Extinct (Late Cretaceous) Life restoration of a group of giant azhdarchids, Quetzalcoatlus northropi, foraging on a Cretaceous fern prairie.png


Example Binomial name Native range Current status Continental relative Insular / mainland
length or mass ratio
Brachylophus gibbonsi.JPG
Tongan giant iguana[25]
Brachylophus gibbonsi Tonga Extinct (c. 800 BC) Iguana iguana Portoviejo 01.jpg
South American
Lapitiguana impensa.JPG
Fijian giant iguana [26]
Lapitiguana impensa Fiji Extinct (c. 1000 BC)
Sauromalus hispidus - Reptilium Landau.jpg
Angel Island chuckwalla
Sauromalus hispidus Isla Ángel de la Guarda, Baja California Near Threatened Peninsular chuckwalla MR ≈ 5 [27]
San Esteban Island Chuckwalla.jpg
San Esteban chuckwalla
Sauromalus varius San Esteban Island, Baja California Endangered MR ≈ 5 [27]


Example Binomial name Native range Current status Continental relative Insular / mainland
length or mass ratio
Gecko de Delcourt Hoplodactylus delcourti GLAM MHNL 2016 3742.jpg
Delcourt's giant gekko
Hoplodactylus delcourti New Zealand Extinct (c. AD 1870) Oedura lesueurii 2.jpg
Diplodactylid geckos
LR ≈ 6.75 [c]
Rhacodactylus leachianus.jpg
New Caledonian giant gecko
Rhacodactylus leachianus New Caledonia Least Concern LR ≈ 4.4 [d]
MR ≈ 60 [e]
Phelsuma gigas - Giant Rodrigues Gecko - extinct 2.jpg
Rodrigues giant day gecko
Phelsuma gigas Rodrigues Extinct (c. AD 1850) Gold dust day gecko.JPG
Day geckos


Example Binomial name Native range Current status Continental relative
Vaillant's mabuya
Chioninia vaillanti Cape Verde Endangered Notomabuya frenata.jpg
Mainland mabuyine skinks
Macroscincus coctei003.jpg
Cape Verde giant skink
Macroscincus coctei Cape Verde Extinct (after AD 1900)
Leiolopisma mauritiana - memorial model - Ile aux Aigrettes.jpg
Mauritius giant skink
Leiolopisma mauritiana Mauritius Extinct (after AD 1600) Mainland eugongyline skinks
Terror skink Phoboscincus bocourti Île des Pins off New Caledonia Endangered Skink in Aussie.jpg
Mainland eugongyline skinks
Kishinoue's giant skink Plestiodon kishinouyei Miyako Islands and Yaeyama Islands, Japan Vulnerable Five-striped Blue-tailed Skink (Plestiodon elegans) 藍尾石龍子.jpg
Asian Plestiodon spp.

Wall lizards[edit]

Example Binomial name Native range Current status Continental relative
La Palma giant lizard Gallotia auaritae La Palma Critically endangered Psammodromus algirus - 01.jpg
Mediterranean sandrunner lizards
Gallotia bravoana.jpg
La Gomera giant lizard
Gallotia bravoana Gomera Critically endangered
Tenerife giant lizard restoration.jpg
Tenerife giant lizard[31]
Gallotia goliath Tenerife Extinct (c. AD 1500)
Gallotia Simonyi at Centro de recuperación del lagarto gigante..jpg
El Hierro giant lizard
Gallotia simonyi El Hierro Critically endangered
Gallotia stehlini -Gran Canaria, Canary Islands, Spain-8.jpg
Gran Canaria giant lizard
Gallotia stehlini Gran Canaria Least Concern

Monitor Lizards[edit]

Example Binomial name Native range Current Status Continential relative
Komodo Dragon (01).jpgKomodo dragon Varanus komodoensis Eastern Lesser Sunda Islands Endangered Lace Monitor in Tamborine National Park, Cedar Creek Falls, Queensland, Australia.jpgLace monitor


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 Speckled Rattlesnake (Crotalus mitchellii) (21705787199).jpg
Speckled rattlesnake
Tadanae-jima striped snake population[32] Elaphe quadrivirgata Tadanae-jima island off Tokyo Unknown Elaphe quadrivirgata.JPG
Japanese striped snake
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)[33] Least Concern[34] Tiger snake 2.jpg
Tiger snake
Isla Cerralvo long-nosed snake Rhinocheilus lecontei etheridgei Jacques Cousteau Island off Baja California Sur Unknown Rhinocheilus lecontei tessellatus.jpg
Long-nosed snake

Dubious examples[edit]

  • 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.[35] 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.[35] 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[36] (Titanochelon), Madagascar (Aldabrachelys), North America[37] (Hesperotestudo) and South America[38] (Chelonoidis, the same genus now found in the Galápagos[39]), and on a number of other, more accessible islands of Oceania and the Caribbean.[37] In the late Pliocene they were also present in Africa ("Geochelone" laetoliensis[40]). 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.


Example Binomial name Native range Current status Continental relative Insular / mainland
length or mass ratio
São Tomé giant tree frog Hyperolius thomensis[41] São Tomé Island Endangered Hyperolius argus Al-ReedFrogs 01.jpg
African reed frogs
Palm forest tree frog Leptopelis palmatus[41] Príncipe Island Vulnerable Leptopelis rufus02.jpg
Red tree frog
LR ≈ 1.2 [f]
Giant Fiji ground frog Platymantis megabotoniviti[44] Viti Levu, Fiji Extinct Platymantis cagayanensis (KU 330716) from mid-elevation of Mt. Cagua - ZooKeys-266-001-g019.jpg
Asian platymantines
São Tomé giant grass frog Ptychadena newtoni[41] São Tomé Island Endangered Madagascar Grass Frog (Ptychadena madagascariensis), Andasibe, Madagascar (14156831413).jpg
Mascarene grass frog


Example Binomial name Native range Current status Continental relative
Birgus latro (Bora-Bora).jpg
Coconut crab
Birgus latro Indian Ocean islands
and Polynesia[45]
Vulnerable Purple hermit crab in can.jpg
Coenobita hermit crabs
Giant wētā
Deinacrida spp. New Zealand Variable ParktownPrawn.jpg
South African king crickets
Giant pseudoscorpion[46] Garypus titanius Boatswain Bird Island Critically Endangered Serianus bolivianus.jpg
Madagascar hissing cockroaches
Gromphadorhina spp. Madagascar Least Concern CockroachSwartbos.jpg
Labidura herculeana.jpg
Saint Helena earwig
Labidura herculeana Saint Helena Extinct (c. AD 1967) Labidura riparia.jpg
Shore earwig
Stavenn Megachile pluto.jpg
Wallace's giant bee
Megachile pluto North Moluccas Vulnerable Megachilidae. Chalicodoma sensu lato male. Likely subgenus Callomegachile. - Flickr - gailhampshire.jpg
Megalara garuda male.png
Megalara garuda Mekongga Mountains,
Unknown Wasp August 2012-2.jpg
Crabronine wasps
Sphaeromimus andohahela.jpg
giant pill-millipedes
Microsphaerotherium spp.

Sphaeromimus spp.

Zoosphaerium spp.
Madagascar Unknown Giant pill millipede-2-bsi-yercaud-salem-India.JPG
Indian giant pill-millipedes
Orsonwelles malus (Simon, 1900).jpg
Orsonwelles spp. Hawaii Unknown Labulla thoracica 02.JPG
Money spiders
Conants Giant.jpg
Conant's giant Nihoa tree cricket
Thaumatogryllus conanti Nihoa Unknown Neoxabea bipunctata - Two-spotted Tree Cricket (30874429898).jpg
Tree crickets
Taveuni longhorn beetle.jpg
Giant Fijian long-horned beetle[47]
Xixuthrus heros Viti Levu, Fiji Vulnerable Longhorn Beetle (Xixuthrus microcerus) (8756596643).jpg
Australasian Xixuthrus
Taveuni beetle Xixuthrus terribilis Taveuni, Fiji Unknown


Example Binomial name Native range Current status Continental relative
Powelliphanta annectens DOC 2007.jpg
Kauri land snails
Paryphanta spp.

Powelliphanta spp.
New Zealand Near Threatened Flat shelled snail Chatswood West.JPG
Other rhytidids


In addition to size increase, island plants may also exhibit "insular woodiness".[48] The most notable examples are the megaherbs of New Zealand's subantarctic islands.[citation needed] Increased leaf and seed size was also reported in some island species regardless of growth form (herbaceous, bush, or tree).[49]

Example Binomial name Native range Current status Continental relative
Anisotome latifolia.jpg
Campbell Island carrot
Anisotome latifolia Campbell and Auckland Islands Unknown Angelica archangelica (1118596627).jpg
Bulbinella rossi and Australasian pipit.jpg
Ross lily
Bulbinella rossii Campbell and Auckland Islands Naturally Uncommon Bulbinella hookeri kz01.jpg
New Zealand Maori lily
Corokia macrocarpa kz04.jpg
Chatham Islands korokio[49][50]
Corokia macrocarpa Chatham Islands Unknown Corokia cotoneaster growing beside the track into Te Toto Gorge, Raglan, New Zealand.jpg
New Zealand korokio[51]
Flora Antarctica Plate XXVI.XXVII.jpg
Black-eyed daisy
Damnamenia vernicosa Auckland and Campbell Islands Naturally Uncommon Erigeron Glaucus.jpg
Cucumber tree (6407165121).jpg
Cucumber tree[52]
Dendrosicyos socotranus Socotra Vulnerable Cucumis sativus 0001.JPG
Lodoicea Maldivica B.jpg
Coco de mer[53][52]
Lodoicea maldivica Seychelles Endangered Atakora-Borassus aethiopum (4).jpg
Borassoid palms
Flora Antarctica Plate XXIV.XXV.jpg Pleurophyllum criniferum Antipodes, Auckland and Campbell Islands Unknown Cineraria geifolia 28092003 Afrique du sud.jpg
Pleurophyllum hookeri.jpg
Silver-leaf daisy
Pleurophyllum hookeri Macquarie Island, Auckland and Campbell Islands Unknown
Pleurophyllum speciosum (1).jpg
Campbell Island daisy
Pleurophyllum speciosum Campbell and Auckland Islands Naturally Uncommon
Chatham Islands nikau[49]
Rhopalostylis aff. sapida Chatham Islands Unknown Nikau Palme 01.jpg
Stilbocarpa polaris.jpg
Macquarie Island cabbage
Stilbocarpa polaris Macquarie Island and New Zealand subantarctic islands Vulnerable Aralia spinosa, Georgia, USA.jpg

See also[edit]


  1. ^ The reduction in predation on islands often also leads to tamer behavior of island prey species, a trend that has been analyzed in lizards.[2][3]
  2. ^ The earliest known New Zealand kiwi ancestor, a presumed recent arrival from Australia.[20]
  3. ^ Based on the estimated total length of H. delcourti, ~23.6 in,[28] and the average length of a member of Diplodactylus, the most species-rich genus of Australian diplodactylid geckos, ~3.5 in.[29]
  4. ^ Based on the average total length of the larger subspecies, R. l. leachianus, ~15.5 in,[30] and the average length of a member of Diplodactylus, the most species-rich genus of Australian diplodactylid geckos, ~3.5 in.[29]
  5. ^ Based on the average mass of the larger subspecies, R. l. leachianus, ~240 g,[30] with the average weight of a member of Diplodactylus, the most species-rich genus of Australian diplodactylid geckos, ~4 g.[29]
  6. ^ Based on the average female snout to vent length (SVL) of L. palmatus, ~96 mm,[42] with the average female SVL of L. rufus, ~80 mm.[43]


  1. ^ Herczeg, G. B.; Gonda, A. L.; Merilä, J. (2009-07-16). "Evolution of Gigantism in Nine-Spined Sticklebacks". Evolution. 63 (12): 3190–3200. doi:10.1111/j.1558-5646.2009.00781.x. PMID 19624722. S2CID 205782326.
  2. ^ Cooper, W. E.; Pyron, R. A.; Garland, T. (2014-01-08). "Island tameness: Living on islands reduces flight initiation distance". Proceedings of the Royal Society B: Biological Sciences. 281 (1777): 20133019. doi:10.1098/rspb.2013.3019. PMC 3896029. PMID 24403345.
  3. ^ Yong, E. (2014-01-08). "Islands make animals tamer". Nature. doi:10.1038/nature.2014.14462. S2CID 183158746.
  4. ^ Jaffe, A. L.; Slater, G. J.; Alfaro, M. E. (2011-01-26). "The evolution of island gigantism and body size variation in tortoises and turtles". Biology Letters. 7 (4): 558–561. doi:10.1098/rsbl.2010.1084. PMC 3130210. PMID 21270022.
  5. ^ Barahona, F.; Evans, S.E.; Mateo, J.A.; Garcia-Marquez, M.; Lopez-Jurado, L.F. (March 2000). "Endemism, Gigantism and Extinction in Island Lizards: The Genus Gallotia on the Canary Islands". Journal of Zoology. 250 (3): 373–388. doi:10.1017/s0952836900003101. hdl:10553/19918.
  6. ^ a b Raia, P.; Meiri, S. (August 2006). "The island rule in large mammals: paleontology meets ecology". Evolution. 60 (8): 1731–1742. doi:10.1111/j.0014-3820.2006.tb00516.x. PMID 17017072. S2CID 26853128.
  7. ^ Keehn, J. E.; Nieto, N. C.; Tracy, C. R.; Gienger, C. M.; Feldman, C. R. (2013-08-27). "Evolution on a desert island: Body size divergence between the reptiles of Nevada's Anaho Island and the mainland around Pyramid Lake". Journal of Zoology. 291 (4): 269–278. doi:10.1111/jzo.12066.
  8. ^ Lomolino, M. V. (2005-09-05). "Body size evolution in insular vertebrates: generality of the island rule". Journal of Biogeography. 32 (10): 1683–1699. doi:10.1111/j.1365-2699.2005.01314.x. hdl:2027.42/146565.
  9. ^ Filin, I.; Ziv, Y. (2004). "New Theory of Insular Evolution: Unifying the Loss of Dispersability and Body-mass Change" (PDF). Evolutionary Ecology Research. 6: 115–124.
  10. ^ Turvey, S. T. (2006). "A new genus and species of giant hutia (Tainotherium valei) from the Quaternary of Puerto Rico: an extinct arboreal quadruped?". Journal of Zoology. 270 (4): 585–594. doi:10.1111/j.1469-7998.2006.00170.x.
  11. ^ Torres-Roig, E.; Agustí, J.; Bover, P.; Alcover, J.A. (2017). "A new giant cricetine from the basal Pliocene of Mallorca (Balearic Islands, western Mediterranean): biostratigraphic nexus with continental mammal zones". Historical Biology. 31 (5): 559–573. doi:10.1080/08912963.2017.1377194. S2CID 135302585.
  12. ^ Freudenthal, M. (1985). Cricetidae (Rodentia) from the Neogene of Gargano (Prov. of Foggia, Italy). Rijksmuseum van Geologie en Mineralogie.
  13. ^ "St Kilda's 'super-sized' field mice studied". BBC. 2010-09-03. Retrieved 2020-03-02.
  14. ^ "Error" (PDF).
  15. ^ Timm, R. M.; Weijola, V.; Aplin, K. P.; Donnellan, S. C.; Flannery, T. F.; Thomson, V.; Pine, R. H. (2016-04-12). "A new species of Rattus (Rodentia: Muridae) from Manus Island, Papua New Guinea". Journal of Mammalogy. 97 (3): 861–878. doi:10.1093/jmammal/gyw034.
  16. ^[bare URL PDF]
  17. ^ Daams, R.; Freudenthal, M. (1985). "Stertomys laticrestatus, a new glirid (dormice, Rodentia) from the insular fauna of Gargano (Prov. of Foggia, Italy)". Scripta Geologica. 77: 21–27.
  18. ^ a b MacPhee, R.D.E., Iturralde-Vinent, M.A., and Gaffney, E.S. (February 2003). "Domo de Zaza, an Early Miocene Vertebrate Locality in South-Central Cuba, with Notes on the Tectonic Evolution of Puerto Rico and the Mona Passage". American Museum Novitates (3394): 1–42. doi:10.1206/0003-0082(2003)394<0001:DDZAEM>2.0.CO;2. hdl:2246/2820.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  19. ^ "Late Cretaceous Animals of Romania's Haţeg Island--a More Complex View".
  20. ^ Worthy, Trevor H.; et al. (2013). Miocene fossils show that kiwi (Apteryx, Apterygidae) are probably not phyletic dwarves (PDF). Paleornithological Research 2013, Proceedings of the 8th International Meeting of the Society of Avian Paleontology and Evolution. Retrieved 16 September 2017.
  21. ^ Pavia, M.; Meijer, H. J. M.; Rossi, M. A.; Göhlich, U. B. (2017-01-11). "The extreme insular adaptation of Garganornis ballmanni Meijer, 2014: a giant Anseriformes of the Neogene of the Mediterranean Basin". Royal Society Open Science. 4 (1): 160722. Bibcode:2017RSOS....460722P. doi:10.1098/rsos.160722. PMC 5319340. PMID 28280574.
  22. ^ "African Origins for the Enigmatic Adzebill".
  23. ^ Naish, Darren (2008-01-28). "Titan-hawks and other super-raptors". Tetrapod Zoology blog. ScienceBlogs LLC. Retrieved 2011-03-02.
  24. ^ Lerner, Heather R.L.; Mindell, David P. (2005). "Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA". Molecular Phylogenetics and Evolution. 37 (2): 327–346. doi:10.1016/j.ympev.2005.04.010. PMID 15925523.
  25. ^ Pregill, G. K.; Steadman, D. W. (March 2004). "South Pacific Iguanas: Human Impacts and a New Species". Journal of Herpetology. 38 (1): 15–21. doi:10.1670/73-03A. JSTOR 1566081. S2CID 85627049.
  26. ^ Pregill, G. K.; Worthy, T. H. (March 2003). "A New Iguanid Lizard (Squamata, Iguanidae) from the Lare Quaternary of Fiji, Southwest Pacific". Herpetologica. 59 (1): 57–67. doi:10.1655/0018-0831(2003)059[0057:ANILSI]2.0.CO;2. ISSN 0018-0831.
  27. ^ a b Petren, K.; Case, T.J. (1997). "A Phylogenetic Analysis of Body Size Evolution and Biogeography in Chuckwallas (Sauromalus) and Other Iguanines". Evolution. 51 (1): 206–219. doi:10.1111/j.1558-5646.1997.tb02402.x. PMID 28568786. S2CID 22032248.
  28. ^ Wilson, K.-J. (2004). Flight of the Huia: Ecology and Conservation of New Zealand's Frogs, Reptiles, Birds and Mammals. Canterbury University Press. ISBN 0-908812-52-3. OCLC 937349394.
  29. ^ a b c Stewart, C. (9 May 2014). "Diplodactylus Geckos of Australia". Retrieved 2020-02-29.
  30. ^ a b Bergman, J.; Hamper, R. (2016). "New Caledonian Giant Gecko Care Sheet". Retrieved 2020-02-29.
  31. ^ Maca-Meyer, N.; Carranza, S.; Rando, J. C.; Arnold, E. N.; Cabrera, V. M. (2003-12-01). "Status and relationships of the extinct giant Canary Island lizard Gallotia goliath (Reptilia: Lacertidae), assessed using ancient mtDNA from its mummified remains" (PDF). Biological Journal of the Linnean Society. 80 (4): 659–670. doi:10.1111/j.1095-8312.2003.00265.x. Retrieved 2010-04-03.
  32. ^[bare URL PDF]
  33. ^ Keogh, J. S.; Scott, I. A. W.; Hayes, C. (January 2005). "Rapid and repeated origin of insular gigantism and dwarfism in Australian tiger snakes". Evolution. 59 (1): 226–233. doi:10.1111/j.0014-3820.2005.tb00909.x. PMID 15792242. S2CID 58524.
  34. ^ Michael, D.; Clemann, N.; Robertson, P. (2018). "Notechis scutatus". IUCN Red List of Threatened Species. 2018: e.T169687A83767147. Retrieved 19 December 2019.
  35. ^ a b Hocknull, S.A.; Piper, P.J.; van den Bergh, G.D.; Due, R.A.; Morwood, M.J.; Kurniawan, I. (2009). "Dragon's Paradise Lost: Palaeobiogeography, Evolution and Extinction of the Largest-Ever Terrestrial Lizards (Varanidae)". PLOS ONE. 4 (9): e7241. Bibcode:2009PLoSO...4.7241H. doi:10.1371/journal.pone.0007241. PMC 2748693. PMID 19789642.
  36. ^ 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.
  37. ^ a b Hansen, D. M.; Donlan, C. J.; Griffiths, C. J.; Campbell, K. J. (April 2010). "Ecological history and latent conservation potential: large and giant tortoises as a model for taxon substitutions" (PDF). Ecography. 33 (2): 272–284. doi:10.1111/j.1600-0587.2010.06305.x. Retrieved 2012-03-02.
  38. ^ Cione, A. L.; Tonni, E. P.; Soibelzon, L. (2003). "The Broken Zig-Zag: Late Cenozoic large mammal and tortoise extinction in South America". Rev. Mus. Argentino Cienc. Nat. N.S. 5 (1): 1–19. doi:10.22179/REVMACN.5.26. ISSN 1514-5158.
  39. ^ Fariña, R.A., Vizcaíno, S.F. & De Iuliis, G. (2013) Megafauna: Giant Beasts of South America. Indiana University Press, 448 pages.
  40. ^ Harrison, T. (2011). "Tortoises (Chelonii, Testudinidae)". Paleontology and Geology of Laetoli: Human Evolution in Context, Vol. 2: Fossil Hominins and the Associated Fauna. Vertebrate Paleobiology and Paleoanthropology. Springer Science+Business Media. pp. 479–503. doi:10.1007/978-90-481-9962-4_17. ISBN 978-90-481-9961-7.
  41. ^ a b c Measey, G.J.; Vences, M.; Drewes, R.C.; Chiari, Y.; Melo, M.; Bourles, B. (2006). "Freshwater paths across the ocean: molecular phylogeny of the frog Ptychadena newtoni gives insights into amphibian colonization of oceanic islands". Journal of Biogeography. 34 (1): 7–20. doi:10.1111/j.1365-2699.2006.01589.x.
  42. ^ "Leptopelis palmatus". University of California, Berkeley. 2008. Retrieved 29 February 2020.
  43. ^ "Leptopelis rufus". University of California, Berkeley. 2008. Retrieved 29 February 2020.
  44. ^ Worthy, T.H. (2001). "A New Species of Platymantis (Anura: Ranidae) from Quaternary Deposits On Viti Levu, Fiji". Palaeontology. 44 (4): 665–680. doi:10.1111/1475-4983.00197.
  45. ^ 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).
  46. ^ "Ascension Island Biodiversity Action Plan: Garypus titanius species action plan" (PDF). Georgetown, Ascension Island: Ascension Island Government Conservation Department. 2015-02-26. Retrieved 2019-09-11.
  47. ^ Keppel, Gunnar; Lowe, Andrew J.; Possingham, Hugh P. (2009). "Changing perspectives on the biogeography of the tropical South Pacific: influences of dispersal, vicariance and extinction". Journal of Biogeography. 36 (6): 1035–1054. doi:10.1111/j.1365-2699.2009.02095.x. ISSN 0305-0270.
  48. ^ Bowen, Lizabeth; Vuren, Dirk Van (1997). "Insular Endemic Plants Lack Defenses Against Herbivores". Conservation Biology. 11 (5): 1249–1254. doi:10.1046/j.1523-1739.1997.96368.x. ISSN 0888-8892.
  49. ^ a b c "Small islands breed big seeds".
  50. ^ "Website Not Available".
  51. ^ "T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network - Corokia cotoneaster (Korokio)".
  52. ^ a b Burns, K.C. (May 2019). Evolution in Isolation: The Search for an Island Syndrome in Plants. Cambridge University Press. doi:10.1017/9781108379953. ISBN 978-1108379953. OCLC 1105218367. S2CID 186536407.
  53. ^ Proctor, J. (1984). "Vegetation of the granitic islands of the Seychelles". In Stoddart, D. R. (ed.). Biogeography and Ecology of the Seychelles Islands. W. Junk. ISBN 978-90-6193-881-1. OCLC 906429733.

External links[edit]