Island gigantism

Size comparison of the giant gymnure (moonrat) Deinogalerix from the Late Miocene of Gargano, Italy, with a European hedgehog.

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

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

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)
Red-toothed shrews
Sardinian giant shrew Asoriculus similis Sardinia and Corsica Extinct (Holocene)
Sicilian giant shrew Asoriculus burgioi Sicily Extinct (Early Pleistocene)

Deinogalerix		 Deinogalerix spp. Gargano Island Extinct (Late Miocene)
Moon rats

Rodents

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)
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]

Gargano giant hamster		 Hattomys gargantua Gargano Island Extinct

St Kilda field mouse		 Apodemus sylvaticus hirtensis St Kilda Least Concern
Wood mouse		 MR ≈ 2 [13]

Hensel's field mouse		 Rhagamys orthodon Corsica and Sardinia Extinct (After 1300 BC)

Tenerife giant rat		 Canariomys bravoi Tenerife Extinct (Late Pleistocene) African rufous-nosed rats

Gran Canaria giant rat		 Canariomys tamarani Gran Canaria Extinct (before AD 1500)
Formentera black-tailed garden dormouse Eliomys quercinus ophiusae Formentera Rare (Introduced by humans)[14]
Garden dormouse and
other Leithiinae dormice

Balearic giant dormice		 Hypnomys spp. Mallorca & Menorca Extinct (Holocene)
Leithia melitensis
Leithia melitensis
Sicilian-Maltese giant dormice		 Leithia cartei Sicily and Malta Extinct
Leithia melitensis

Orkney vole		 Microtus arvalis orcadensis Orkney Islands Vulnerable
Common vole and
other meadow voles

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)
House mouse

Flores giant rat		 Papagomys armandvillei Flores Near Threatened
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)
North American deer mouse

Gargano giant dormouse		 Stertomys laticrestatus[17] Gargano Island Extinct
Glirinae dormice

Lagomorphs

Example Binomial name Native range Current status Continental relative

Minorcan giant lagomorph		 Nuralagus rex Minorca Extinct (Middle Pliocene) Alilepus (?)

Trischizolagus (?)
Prolagus imperialis Gargano Island Extinct
Pikas

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)
Cheracebus
Haitian monkey Insulacebus toussaintiana Southwestern Haiti Extinct

Cuban monkeys		 Paralouatta marianae[18]

P. varonai[18]		 Cuba Extinct (Pleistocene)
Jamaican monkey Xenothrix mcgregori Jamaica Extinct

Gorilla lemur		 Archaeoindris fontoynontii Central Madagascar Extinct (c. 350 BC)
Lorisoids

Baboon lemurs		 Archaeolemur spp.

Hadropithecus spp.		 Madagascar Extinct (before AD 1280)

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)

Carnivorans

Example Binomial name Native range Current status Continental relative

Sardinian giant otter		 Megalenhydris barbaricina Sardinia Extinct (Late Pleistocene)
Otters

Fossa		 Cryptoprocta ferox Madagascar Vulnerable
Mongooses

Giant fossa		 Cryptoprocta spelaea Madagascar Extinct (before AD 1400)

Birds

Stem birds

Example Binomial name Native range Current status Continental relative

Balaur		 B. bondoc Hateg Island Extinct (Late Cretaceous)
Jeholornis[19]

Gargantuavis		 G. philohinos Ibero-Armorican Island Extinct (Late Cretaceous)
Patagopteryx (?)

Ratites

Example Binomial name Native range Current status Continental relative

Kiwis		 Apterygidae New Zealand Variable Proapteryx[b]

Greater elephant birds		 Aepyornithidae
 Madagascar Extinct (c. AD 1700)

Lesser elephant birds		 Mullerornithidae Madagascar Extinct (c. AD 1260)

Giant moas		 Dinornithidae
 New Zealand Extinct (c. AD 1450)
Tinamous

Lesser moas		 Emeidae New Zealand Extinct (c. AD 1460)

Upland moas		 Megalapterygidae New Zealand Extinct (c. AD 1300)

Waterfowl

Example Binomial name Native range Current status Continental relative
New Zealand musk duck Biziura delautouri New Zealand Extinct (after AD 1500)
Australian musk duck

New Zealand geese		 Cnemiornis calcitrans

C. gracilis		 New Zealand Extinct
Cape Barren goose

Garganornis		 G. ballmanni Gargano and Scontrone islands Extinct (Late Miocene)
Geese[21]

Turtle-jawed moa-nalo		 Chelychelynechen quassus Kauai Extinct (c. AD 1000)
Dabbling ducks

Small-billed moa-nalo		 Ptaiochen pau Maui Extinct (c. AD 1000)

Large-billed moa-nalo		 Thambetochen chauliodous Maui Nui Extinct (c. AD 1000)

O'ahu moa-nalo		 Thambetochen xanion O'ahu Extinct (c. AD 1000)

Giant swan		 Cygnus falconeri Sicily and Malta Extinct (Middle Pleistocene)
Mute swan
Scarlett's duck Malacorhynchus scarletti New Zealand Extinct (after AD 1500)
Pink-eared duck

Pangalliformes

Example Binomial name Native range Current status Continental relative
Pile-builder megapode Megapodius molistructor New Caledonia and Tonga Extinct (c. 1500 BC)
Scrubfowl
Megavitiornis Megavitiornis altirostris Fiji Extinct
Galliformes

Sylviornis		 Sylviornis neocaledoniae New Caledonia and Isle of Pines Extinct

Gruiformes

Example Binomial name Native range Current status Continental relative

Red rail		 Aphanapteryx bonasia Mauritius Extinct (c. AD 1700)
Rails

Hawkins' rail		 Diaphanapteryx hawkinsi Chatham Islands Extinct (c. AD 1900)

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

South Island takahē		 Porphyrio hochstetteri South Island, New Zealand Endangered

North Island takahē		 Porphyrio mantelli North Island, New Zealand Extinct (before AD 1900)

Adzebills		 Aptornis defossor

A. otidiformis		 New Zealand Extinct
Madagascar flufftail[22]

Chatham coot		 Fulica chathamensis Chatham Islands Extinct (after AD 1500)
Red-knobbed coot
and other coots

Mascarene coot		 Fulica newtonii Mauritius and Réunion Extinct (c. AD 1700)
New Zealand coot Fulica prisca New Zealand Extinct (after AD 1280)

Réunion swamphen		 Porphyrio coerulescens Plaine des Cafres, Réunion Extinct (c. AD 1730)
Purple swamphens

Pigeons

Example Binomial name Native range Current status Continental relative

Viti Levu giant pigeon		 Natunaornis gigoura Viti Levu, Fiji Extinct
Crowned pigeons
Kanaka pigeon Caloenas canacorum New Caledonia Extinct (c. 500 BC)
Nicobar pigeon

Rodrigues solitaire		 Pezophaps solitaria Rodrigues Extinct (before AD 1778)

Dodo		 Raphus cucullatus Mauritius Extinct (c. AD 1662)

Birds of prey

Example Binomial name Native range Current status Continental relative
Liko Cave golden eagle Aquila chrysaetos simurgh Crete Extinct (Late Pleistocene)
Golden eagle
Giant crab-hawk[23] Buteogallus borrasi Cuba Extinct
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
Caracaras
Eyles' harrier Circus eylesi New Zealand Extinct (c. AD 1000)
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

Philippine eagle		 Pithecophaga jefferyi Philippines Critically endangered
Bateleur[24]

Parrots

Example Binomial name Native range Current status Continental relative

Hercules parrot		 Heracles inexpectatus New Zealand Extinct (Miocene)
Other parrots

Kakapo		 Strigops habroptilus New Zealand Critically Endangered

Broad-billed parrot		 Lophopsittacus mauritianus Mauritius Extinct (c. AD 1680)
Psittaculine parrots

Owls

Example Binomial name Native range Current status Continental relative

Cretan owl		 Athene cretensis Crete Extinct (Pleistocene)
Little owl

Cuban giant owls		 Ornimegalonyx spp. Cuba Extinct (Pleistocene)
Wood owls

Greater Gargano giant owl		 Tyto gigantea Gargano Island Extinct (Late Miocene)
Barn owls

Andros Island barn owl		 Tyto pollens Andros Island, Bahamas Extinct (before AD 1600)

Rivero's barn owl		 Tyto riveroi Cuba Extinct

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)
Australian owlet-nightjar

New Caledonian owlet-nightjar		 Aegotheles savesi New Caledonia Critically endangered

Passeriforms

Example Binomial name Native range Current status Continental relative

Chatham raven		 Corvus moriorum Chatham Islands Extinct New Zealand raven

Long-legged bunting		 Emberiza alcoveri Tenerife Extinct (after AD 1)
Cabanis's bunting
Giant nukupu'u Hemignathus vorpalis Hawaii Extinct (after AD 1000)
Finches
Tasmanian superb fairywren Malurus cyaneus cyaneus Tasmania Least Concern
Superb fairywren
Kangaroo Island superb fairywren Malurus cyaneus ashbyi Kangaroo Island Least Concern
Stout-legged wren Pachyplichas yaldwyni South Island of New Zealand Extinct
Other passeriforms

St Kilda wren		 Troglodytes troglodytes hirtensis St Kilda, Scotland Unknown
Eurasian wren

Capricorn silvereye		 Zosterops lateralis chlorocephalus Capricorn and Bunker Group of the Australian Great Barrier Reef Unknown
Silvereye

Reptiles

Pterosaurs

Example Binomial name Native range Current status Continental relative

Hatzegopteryx		 H. thambema Hateg Island Extinct (Late Cretaceous)
Quetzalcoatlus

Iguanids

Example Binomial name Native range Current status Continental relative Insular / mainland
length or mass ratio

Tongan giant iguana[25]		 Brachylophus gibbonsi Tonga Extinct (c. 800 BC)
South American
iguanas

Fijian giant iguana [26]		 Lapitiguana impensa Fiji Extinct (c. 1000 BC)

Angel Island chuckwalla		 Sauromalus hispidus Isla Ángel de la Guarda, Baja California Near Threatened Peninsular chuckwalla MR ≈ 5 [27]

San Esteban chuckwalla		 Sauromalus varius San Esteban Island, Baja California Endangered MR ≈ 5 [27]

Geckos

Example Binomial name Native range Current status Continental relative Insular / mainland
length or mass ratio

Delcourt's giant gekko		 Gigarcanum delcourti New Caledonia Extinct (c. AD 1870)
Diplodactylid geckos		 LR ≈ 6.75 [c]

New Caledonian giant gecko		 Rhacodactylus leachianus New Caledonia Least Concern LR ≈ 4.4 [d]
MR ≈ 60 [e]

Rodrigues giant day gecko		 Phelsuma gigas Rodrigues Extinct (c. AD 1850)
Day geckos

Skinks

Example Binomial name Native range Current status Continental relative

Vaillant's mabuya		 Chioninia vaillanti Cape Verde Endangered
Mainland mabuyine skinks

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
Mainland eugongyline skinks
Kishinoue's giant skink Plestiodon kishinouyei Miyako Islands and Yaeyama Islands, Japan Vulnerable
Asian Plestiodon spp.

Wall lizards

Example Binomial name Native range Current status Continental relative
La Palma giant lizard Gallotia auaritae La Palma Critically endangered
Mediterranean sandrunner lizards

La Gomera giant lizard		 Gallotia bravoana Gomera Critically endangered

Tenerife giant lizard[31]		 Gallotia goliath Tenerife Extinct (c. AD 1500)

El Hierro giant lizard		 Gallotia simonyi El Hierro Critically endangered

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
Speckled rattlesnake
Tadanae-jima striped snake population[32] Elaphe quadrivirgata Tadanae-jima island off Tokyo Unknown
Japanese striped snake

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
Isla Cerralvo long-nosed snake Rhinocheilus lecontei etheridgei Jacques Cousteau Island off Baja California Sur Unknown
Long-nosed snake

Dubious examples

Komodo dragon (Lesser Sundas)
Galápagos giant tortoise
  • 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.

Amphibians

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
African reed frogs
Palm forest tree frog Leptopelis palmatus[41] Príncipe Island Vulnerable
Red tree frog		 LR ≈ 1.2 [f]
Giant Fiji ground frog Platymantis megabotoniviti[44] Viti Levu, Fiji Extinct
Asian platymantines
São Tomé giant grass frog Ptychadena newtoni[41] São Tomé Island Endangered
Mascarene grass frog

Arthropods

Example Binomial name Native range Current status Continental relative

Coconut crab		 Birgus latro Indian Ocean islands
and Polynesia[45]		 Vulnerable
Coenobita hermit crabs

Giant weta		 Deinacrida spp. New Zealand Variable
South African king crickets
Giant pseudoscorpion[46] Garypus titanius Boatswain Bird Island Critically Endangered
Garypoids

Hissing cockroaches		 Gromphadorhini spp. Madagascar Unknown
Blaberids

Saint Helena earwig		 Labidura herculeana Saint Helena Extinct (c. AD 1967)
Shore earwig

Wallace's giant bee		 Megachile pluto North Moluccas Vulnerable
Callomegachile

Megalara		 Megalara garuda Mekongga Mountains,
Sulawesi		 Unknown
Crabronine wasps

Madagascan
giant pill-millipedes		 Microsphaerotherium spp.

Sphaeromimus spp.

Zoosphaerium spp.		 Madagascar Unknown
Indian giant pill-millipedes
(Arthrosphaera)

Orsonwelles		 Orsonwelles spp. Hawaii Unknown
Money spiders

Conant's giant Nihoa tree cricket		 Thaumatogryllus conanti Nihoa Unknown
Tree crickets

Giant Fijian long-horned beetle[47]		 Xixuthrus heros Viti Levu, Fiji Endangered
Australasian Xixuthrus
Taveuni beetle Xixuthrus terribilis Taveuni, Fiji Unknown

Gastropods

Example Binomial name Native range Current status Continental relative

Kauri land snails		 Paryphanta spp.

Powelliphanta spp.		 New Zealand Near Threatened
Other rhytidids

Flora

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

Campbell Island carrot		 Anisotome latifolia Campbell and Auckland Islands Unknown
Apiaceae

Ross lily		 Bulbinella rossii Campbell and Auckland Islands Naturally Uncommon
New Zealand Maori lily

Chatham Islands korokio[49][50]		 Corokia macrocarpa Chatham Islands Unknown
New Zealand korokio[51]

Black-eyed daisy		 Damnamenia vernicosa Auckland and Campbell Islands Naturally Uncommon
Astereae

Cucumber tree[52]		 Dendrosicyos socotranus Socotra Vulnerable
Gourds

Coco de mer[53][52]		 Lodoicea maldivica Seychelles Endangered
Borassoid palms
Pleurophyllum criniferum Antipodes, Auckland and Campbell Islands Unknown
Cineraria

Silver-leaf daisy		 Pleurophyllum hookeri Macquarie Island, Auckland and Campbell Islands Unknown

Campbell Island daisy		 Pleurophyllum speciosum Campbell and Auckland Islands Naturally Uncommon

Macquarie Island cabbage		 Stilbocarpa polaris Macquarie Island and New Zealand subantarctic islands Vulnerable
Araliaceae

See also

Notes

  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]

References

  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.
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External links

  • PBS NOVA: Why Do Islands Breed Giants (And Sometimes Dwarfs)?
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