Dispersal To The Indonesian Islands Biology Essay

The Varanus Komodoensis, normally referred to as the Komodo Dragon is a species found on the Indonesian islands. These islands include: Komodo Island, West Flores, Rintja ( most shack on these three islands ) , Padar, and Nusa Mbarapu. They are besides found on islands near Indonesia including the lesser Sunda, Bali and West Timor ( Quammen 137 ) . They are endemic to most of these islands. There are about 3,000-5,000 V. Komodoensis ‘ on the Earth ( Harlow et al. 339 ) . V. Komodoensis is of import to keep population control within their islands. Varanids, normally known as proctor lizards, foremost appeared in southeast Asia, and so Australia when the two continents collided about 15 million old ages ago. The V. Komodoensis was so thought to germinate and colonise on Indonesia, when Australia and Indonesia were closer than they are today due to Continental impetus ( Auffenberg 77-80 ) . The V. Komodoensis can digest biomes of tropical Savannah woods, unfastened lowland home ground, beaches, and dry river bottoms ( ibid 15 ) . The restricted scope of the V. Komodoensis, the largest carnivore to be so restricted, is still a subject of argument. This and their dispersion and scope on the Indonesian ( and surrounded islands ) will be discussed in this paper.

Dispersion to the Indonesian Islands

The Varanids genus foremost appeared in Asia at least 90 million old ages ago when the dinosaur epoch was stoping. This genus so continued to colonise South East Asia and finally made their manner to Australia ( Pianka 402 ) . This was possible because they travelled to Australia before Continental impetus separated these two continents further apart than they were 15 million old ages ago. About two million old ages subsequently, it is thought that a 2nd line of descent spread through Indonesia, which included the V. Komodoensis. Like the old colonisation between Asia and Australia, Indonesian islands and Australia were thought to hold come into contact during the Miocene therefore nearer together at the clip doing this passage to the islands possible ( shorter distance to travel ) ( Auffenberg 45-46 ) . It is besides thought that the line of descent formed in Indonesia when sea degrees were low, therefore doing it possible for them to swim and colonise the islands, which were besides closer together before floating apart. Furthermore, the sea degrees were thought to lift up once more after this travel from Australia therefore insulating the species to the islands and accounting for their low dispersion rates throughout the universe ( ibid. ) . The big size of the V. Komodoensis was thought to be due in portion to their evolutionary history of big varanids ( Pianka 401 ) but chiefly to their deficiency of marauders, doing them an vertex species, and their position as a “ specialist huntsman ” of the pigmy elephants in which a big size would be necessary in runing such a big species ( Stegodon ) ( ibid 39 ) .

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Challenging claims of reaching to Indonesian islands

While the impression is that the 2nd line of descent of Varanus species, including the V. Komodoensis, evolved in Indonesia, this impression was disputed by a squad of Australian scientists, led by paleontologist Scott Hocknull. Hocknull argued that the V. Komodoensis really attained its giantism from its evolutionary traits ( Meiri et al. 96 ) passed down from V. salvadorii, V. varius and Varanus prisca. Thus the morphology of the V. Komodoensis is non usual to its genus ; instead it was passed down its evolutionary tree ( Hocknull 1-2 ) . The scientists besides argued that the V. Komodoensis really evolved in Australia before going to Indonesia. The survey indicates that “ the dodo record suggests that elephantine varanids evolved independently on mainland Asia and the island-continent of Australia during the Pliocene. This is because many dodos were found on Australia that appeared to be indistinguishable to V. Komodoensis in size and do up. They appear to hold evolved along with many other big lizards around 3-4 million old ages ago ( ibid. 10 ) .

This conflicting information may be due to the fact that the V. Komodoensis was non discovered until 1910. Their isolation made it hard to be studied prior to this clip, so the research about their history is comparatively limited.

Distribution on the Indonesian Islands

Before the Indonesian islands and environing islands experient impetus, they were reasonably close together, if non attached. At this clip the V. Komodoensis were able to scatter across the land, which so turned into assorted islands. The V. Komodoensis can digest biomes of tropical Savannah woods, unfastened lowland home ground, beaches, dry river bottoms. Indonesian islands tend to be tropical and hot, therefore suited for the V. Komodoensis ( Auffenberg 15 ) . Younger komodo firedrakes stay in trees to avoid predation from older komodo firedrakes that eat immature firedrakes. As they grow older they go to anchor degree and Hunt for larger mammals ( Jessop et al. 465 ) . Since V. Komodoensis eat about any species, including their ain, they can be found on any portion of the island looking for nutrient. A map of the firedrakes ‘ nests can bespeak where they are normally found, as seen in Figure 1 ( Jessop et al. 465 ) .

Figure 1 Black points indicate nests of V. Komodoensis throughout Komodo National Park on Komodo Island ( Jessop et al. 465 ) . Movement and scrounging largely occurs during showery seasons when it is less humid and the weaker quarries are out ( i.e. little lizards, rats, cervid ) . They occupy the full island of Komodo and certain countries of the other islands ( i.e. they occupy 400 square kilometers of Flores ) . The V. Komodoensis can digest temperatures runing from 65-107 grades Fahrenheit ( Harlow et al. 3 ) .

Survival mechanisms

The indigenousness of the V. Komodoensis is due to its isolation and stableness ( Cox and Moore 90 ) . The V. Komodoensis is an apex marauder. They have basically no life menaces on the islands. This may account for their ability to keep their big size and ability to last despite such low distribution ( Meiri et al. 90 ) . Poaching and natural catastrophes are basically the lone menaces of extinction of the species. They are responsible for population control of herbivores in their home ground. Without the V. Komdoensis, the herbivores they eat would rule the ecosystem, who would in bend eat up all the works life and cause extinction to the workss on the islands. The V. Komodoensis ‘ ability to run and kill makes it highly prone to survival. They besides have a slow metamorphosis so they can travel without eating for hebdomads. Their ability to modulate their organic structure temperature by sitting in the Sun if they are cold, or seek shadiness in order to chill themselves down allows them to digest the conditions of the islands at any clip of twelvemonth ( Harlow et al. 340 ) . V. Komodoensis ‘ are besides first-class swimmers so they can swim short distances to the assorted islands that they inhabit for assorted grounds, i.e. nutrient, temperature penchant, etc. These grounds all explain their indigenousness and their adaptability to such a limited distribution of merely a few stray islands ( Auffenberg 126 ) .


The V. Komodoensis is really limited in distribution. They are found on Indonesian islands and the environing 1s ( Quammen 137 ) . Their ability to efficaciously run and digest the conditions that they live in, twelvemonth unit of ammunition, makes them likely to last for a long clip despite their low population. Explanations for their isolation include their migration to the Indonesian islands early on and the lifting sea degrees once they already arrived there ( Pianka 402 ) . There has been controversy about their development occurred. It has been normally accepted that they evolved, through a 2nd line of descent, on the Indonesian islands. However a survey led by Scott Hocknull found that they might hold really evolved on Australia, aboard other Varnsus ‘ , before geting to the islands ( Hocknull 1-2 ) . There is besides no clear reply sing their limited distribution to merely choose islands. V. Komodoensis were discovered comparatively late in human history ( 1910 ) which may explicate the elusiveness about their development and their limited distribution, despite their big size. The V. Komodoensis are limited in figure but because of their position of an apex marauder, biome tolerance and authorities protection ( from poaching, selling tegument ) , they should go on to boom.


Auffenberg, Walter. The Behavioral Ecology of the Komodo Monitor. Gainesville: Universityes of Florida, 1981.

Cox, Christopher Barry, and Peter D. Moore. Biogeography: An Ecological and Evolutionary Approach 7th ed.. Oxford: Blackwell Publishing, 2005.

Harlow, Henry J. , Deni Purwandana, Tim S. Jessop, and John A. Phillips. “ Size-Related Differences in the Thermoregulatory Habits of Free-Ranging Komodo Dragons. ” International Journal of Zoology 2010 ( 2010 ) : 1-9.

Hocknull, Scott, Philip J. Piper, Gert D. Van Den Bergh, and Rokus Awe Due. “ Dragon ‘s Eden Lost: Palaeobiogeography, Evolution and Extinction of the Largest-Ever Terrestrial Lizards. ” PLOS One 4.9 ( 2009 ) : 1-15.

Jessop, T. , and Joanna Sumner. “ Distribution, Use and Selection of Nest Type by Komodo Dragons. ” Biological Conservation 117.5 ( 2004 ) : 463-70.

Meiri, Shai, Pasquale Raia, and Albert B. Phillimore. “ Murdering Dragons: Limited Evidence for Unusual Body Size Evolution on Islands. ” Journal of Biogeography ( 2010 ) : 89-100.

Pianka, Eric R. “ Evolution of Body Size: Varanid Lizards as a Model System. ” The American Naturalist 146.3 ( 1995 ) : 398-414.

Quammen, David. The Song of the Dodo: Island Biogeography in an Age of Extinctions. New York: Simon & A ; Schuster, 1997.


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