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
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of large animals evolving or having a reduced body size when their population's range is limited to a small environment, primarily islands. This natural process is disti ...
). This is itself one aspect of the more general phenomenon of
island syndrome
Island syndrome describes the differences in morphology, ecology, physiology and behaviour of insular species compared to their continental counterparts. These differences evolve due to the different ecological pressures affecting insular specie ...
which describes the differences in
morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
*Morphology (archaeology), study of the shapes or forms of artifacts
*Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...
,
ecology
Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...
,
physiology
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
and
behaviour
Behavior (American English) or behaviour (British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as wel ...
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
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
. A similar size increase, as well as increased woodiness, has been observed in some insular plants.
Possible causes
![Island Gigantism- A Growing Projection](https://upload.wikimedia.org/wikipedia/commons/8/83/Island_Gigantism-_A_Growing_Projection.png)
Large mammalian carnivores are often absent on islands because of insufficient range or difficulties in
over-water dispersal. In their absence, the
ecological niche
In ecology, a niche is the match of a species to a specific environmental condition.
Three variants of ecological niche are described by
It describes how an organism or population responds to the distribution of resources and competitors (for ...
s 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
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
-
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58[Mediterranean
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...](_blank)
, on islands in the
Caribbean
The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...
like
Cuba
Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...
, and on
Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
and
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
, some or all
apex predator
An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own.
Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...
s were birds like
eagle
Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...
s,
falcon
Falcons () are birds of prey in the genus ''Falco'', which includes about 40 species. Falcons are widely distributed on all continents of the world except Antarctica, though closely related raptors did occur there in the Eocene.
Adult falcons ...
s and
owl
Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...
s, including some of the largest known examples of these groups. However, birds and reptiles generally make less efficient large predators than advanced
carnivora
Carnivora is a Clade, monophyletic order of Placentalia, placental mammals consisting of the most recent common ancestor of all felidae, cat-like and canidae, dog-like animals, and all descendants of that ancestor. Members of this group are f ...
ns.
Since small size usually makes it easier for
herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s to escape or hide from predators, the decreased predation pressure on islands can allow them to grow larger.
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.
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.
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
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of large animals evolving or having a reduced body size when their population's range is limited to a small environment, primarily islands. This natural process is disti ...
can also result from the removal of constraints related to predation and/or competition on the size of large herbivores.
In contrast, insular dwarfism among predators more commonly results from the imposition of constraints associated with the limited prey resources available on islands.
As opposed to island dwarfism, island gigantism is found in most major
vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
groups and in
invertebrates
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
.
Territorialism
Territorialism can refer to:
* Animal territorialism, the animal behavior of defending a geographical area from intruders
* Environmental territorialism, a stance toward threats posed toward individuals, communities or nations by environmental even ...
may favor the evolution of island gigantism. A study on
Anaho Island
Anaho Island is a rocky island in Pyramid Lake, and located on the Pyramid Lake Indian Reservation, Washoe County, in the U.S. state of Nevada.
Geography
Anaho Island is a little more than long from north to south, and also from east to west a ...
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.
A further means of establishing island gigantism may be a
founder effect
In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1942, using ...
operative when larger members of a mainland population are superior in their ability to colonize islands.
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.
Examples
Examples of island gigantism include:
Mammals
Many rodents grow larger on islands, whereas
carnivora
Carnivora is a Clade, monophyletic order of Placentalia, placental mammals consisting of the most recent common ancestor of all felidae, cat-like and canidae, dog-like animals, and all descendants of that ancestor. Members of this group are f ...
ns,
proboscidea
The Proboscidea (; , ) are a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. From ...
ns and
artiodactyl
The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing poster ...
s usually become smaller.
Eulipotyphla
Eulipotyphla (, which means "truly fat and blind") is an order of mammals suggested by molecular methods of phylogenetic reconstruction, which includes the laurasiatherian members of the now-invalid polyphyletic order Lipotyphla, but not the afr ...
ns
Rodent
Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...
s
Lagomorph
The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (hares and rabbits) and the Ochotonidae (pikas). The name of the order is derived from the Ancient Greek ''lagos'' (Î»Î±Î³Ï ...
s
Primates
Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...
Carnivora
Carnivora is a Clade, monophyletic order of Placentalia, placental mammals consisting of the most recent common ancestor of all felidae, cat-like and canidae, dog-like animals, and all descendants of that ancestor. Members of this group are f ...
ns
Birds
Stem birds
Ratites
A ratite () is any of a diverse group of flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites.
The systematics o ...
Waterfowl
Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which in ...
Pangalliformes
Pangalliformes is the scientific name of a provisional clade of birds within the group Galloanserae. It is defined as all birds more closely related to chickens than to ducks, and includes all modern chickens, turkeys, pheasants, and megapodes, ...
Gruiformes
The Gruiformes are an order (biology), order containing a considerable number of living and extinct bird family (biology), families, with a widespread geographical diversity. Gruiform means "crane-like".
Traditionally, a number of wading and t ...
Pigeons
Columbidae () is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with short necks and short slender bills that in some species feature fleshy ceres. They primarily ...
Birds of prey
Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predators ...
Parrot
Parrots, also known as psittacines (), are birds of the roughly 398 species in 92 genera comprising the order Psittaciformes (), found mostly in tropical and subtropical regions. The order is subdivided into three superfamilies: the Psittacoid ...
s
Owl
Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...
s
Caprimulgiformes
Nightjars are medium-sized nocturnal or crepuscular birds in the family Caprimulgidae and order Caprimulgiformes, characterised by long wings, short legs, and very short bills. They are sometimes called goatsuckers, due to the ancient folk tal ...
Passeriform
A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...
s
Reptiles
Pterosaur
Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...
s
Iguanid
The Iguanidae is a family of lizards composed of the iguanas, chuckwallas, and their prehistoric relatives, including the widespread green iguana.
Taxonomy
Iguanidae is thought to be the sister group to the collared lizards (family Crotaphy ...
s
Gecko
Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates throughout the world. They range from .
Geckos ar ...
s
Skink
Skinks are lizards belonging to the family Scincidae, a family in the infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one of the most diverse families of lizards. Ski ...
s
Wall lizards
Monitor Lizards
Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are recogn ...
Snake
Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...
s
Dubious examples
![Galapagos giant tortoise Geochelone elephantopus](https://upload.wikimedia.org/wikipedia/commons/4/42/Galapagos_giant_tortoise_Geochelone_elephantopus.jpg)
* The
Komodo dragon
The Komodo dragon (''Varanus komodoensis''), also known as the Komodo monitor, is a member of the monitor lizard family Varanidae that is endemic to the Indonesian islands of Komodo, Rinca, Flores, and Gili Motang. It is the largest extant ...
of
Flores
Flores is one of the Lesser Sunda Islands, a group of islands in the eastern half of Indonesia. Including the Komodo Islands off its west coast (but excluding the Solor Archipelago to the east of Flores), the land area is 15,530.58 km2, and th ...
and nearby islands, the largest extant lizard, and a similar (extinct) giant
monitor lizard
Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are recogn ...
from
Timor
Timor is an island at the southern end of Maritime Southeast Asia, in the north of the Timor Sea. The island is East Timor–Indonesia border, divided between the sovereign states of East Timor on the eastern part and Indonesia on the western p ...
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
An ectotherm (from the Greek () "outside" and () "heat") is an organism in which internal physiological sources of heat are of relatively small or of quite negligible importance in controlling body temperature.Davenport, John. Animal Life a ...
carnivores on islands too small to support much
mammalian
Mammals () are a group of vertebrate animals constituting the class (biology), class Mammalia (), characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk for feeding (nursing) their young, a ...
competition. However, these lizards are not as large as their extinct Australian relative
megalania
Megalania (''Varanus priscus'') is an extinct species of giant monitor lizard, part of the megafaunal assemblage that inhabited Australia during the Pleistocene. It is the largest terrestrial lizard known to have existed, reaching an estimated ...
, 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.
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''.
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 tortoise
Giant tortoises are any of several species of various large land tortoises, which include a number of extinct species, as well as two extant species with multiple subspecies formerly common on the islands of the western Indian Ocean and on the ...
s in the
Galápagos Islands
The Galápagos Islands (Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuador ...
and the
Seychelles
Seychelles (, ; ), officially the Republic of Seychelles (french: link=no, République des Seychelles; Creole: ''La Repiblik Sesel''), is an archipelagic state consisting of 115 islands in the Indian Ocean. Its capital and largest city, V ...
, the largest extant tortoises, as well as extinct tortoises of the
Mascarenes
The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of the islands belonging to the Republic of Mauritius as well as the French department of Réunion. Their ...
and
Canary Islands
The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...
, are often considered examples of island gigantism. However, during the Pleistocene, comparably sized or larger tortoises were present in
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
(''
Meiolania
''Meiolania'' ("small roamer") is an extinct genus of meiolaniid stem-turtle native to Australasia from the Middle Miocene to Late Pleistocene and possibly Holocene. It is best known from fossils found on Lord Howe Island, though fossils are know ...
''), southern
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
(''
Megalochelys
''Megalochelys'' ("great turtle") is an extinct genus of cryptodiran tortoises that lived from the Miocene to Pleistocene. They are noted for their giant size, which is among the largest of any known testudine, with a maximum carapace length ove ...
''),
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
(''Titanochelon''), Madagascar (''
Aldabrachelys
''Aldabrachelys'' is the recognised genus for the Seychelles and Madagascan radiations of giant tortoises, including the Aldabra giant tortoise (''Aldabrachelys gigantea'').
Naming
This name is problematic in that the type specimen is actually r ...
''),
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
(''
Hesperotestudo
''Hesperotestudo'' ("Western turtle") is an extinct genus of tortoise native to North and Central America from the Oligocene to the Late Pleistocene. Species of ''Hesperotesudo'' varied widely in size, with the largest unnamed species from El Sal ...
'') and
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
(''
Chelonoidis
''Chelonoidis'' is a genus of turtles in the tortoise family erected by Leopold Fitzinger in 1835.
They are found in South America and the Galápagos Islands, and formerly had a wide distribution in the West Indies.
The multiple subspecies of t ...
'', the same genus now found in the Galápagos
[Fariña, R.A., VizcaÃno, S.F. & De Iuliis, G. (2013) ''Megafauna: Giant Beasts of South America.'' Indiana University Press, 448 pages.]), and on a number of other, more accessible islands of
Oceania
Oceania (, , ) is a region, geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern Hemisphere, Eastern and Western Hemisphere, Western hemispheres, Oceania is estimated to have a land area of ...
and the
Caribbean
The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...
.
In the late Pliocene they were also present in Africa ("''
Geochelone
''Geochelone'' is a genus of tortoises.
''Geochelone'' tortoises, which are also known as typical tortoises or terrestrial turtles, can be found in southern Asia. They primarily eat plants. Species
The genus consists of two extant species:
A n ...
''" ''laetoliensis''
). 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
Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term app ...
.
Amphibians
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbore ...
Arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
s
Gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
s
Flora
In addition to size increase, island plants may also exhibit "insular woodiness".
The most notable examples are the
megaherb
Megaherbs are a group of herbaceous wildflowers growing in the New Zealand subantarctic islands and on the other subantarctic islands. They are characterised by their great size, with huge leaves and very large and often unusually coloured flowers ...
s of
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
's
subantarctic islands. Increased leaf and seed size was also reported in some island species regardless of growth form (herbaceous,
bush
Bush commonly refers to:
* Shrub, a small or medium woody plant
Bush, Bushes, or the bush may also refer to:
People
* Bush (surname), including any of several people with that name
**Bush family, a prominent American family that includes:
*** ...
, or
tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
).
See also
*
Deep-sea gigantism
In zoology, deep-sea gigantism or abyssal gigantism is the tendency for species of invertebrates and other deep-sea dwelling animals to be larger than their shallower-water relatives across a large taxonomic range. Proposed explanations for thi ...
*
Island tameness
Island tameness is the tendency of many populations and species of animals living on isolated islands to lose their wariness of potential predators, particularly of large animals. The term is partly synonymous with ecological naïveté, which also ...
*
Insular dwarfism
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of large animals evolving or having a reduced body size when their population's range is limited to a small environment, primarily islands. This natural process is disti ...
*
Megafauna
In terrestrial zoology, the megafauna (from Greek μÎγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common threshold ...
*
Pleistocene extinctions
The Quaternary period (from 2.588 ± 0.005 million years ago to the present) has seen the extinctions of numerous predominantly megafaunal species, which have resulted in a collapse in faunal density and diversity and the extinction of key ecolog ...
Notes
References
External links
PBS NOVA: Why Do Islands Breed Giants (And Sometimes Dwarfs)?
{{DEFAULTSORT:Island Gigantism
Animal size
Evolutionary biology concepts
Giantism
Gigantism ( el, γίγας, ''gÃgas'', "giant", plural γίγαντες, ''gÃgantes''), also known as giantism, is a condition characterized by excessive growth and height significantly above average. In humans, this condition is caused by ove ...