The Biogeography of the Malay Archipelego

Alfred Wallace explored the Malay Archipelego between 1854-1862, collecting over 125,000 specimens of mammals, birds, reptiles, insects, and molluscs that he sent back to England.  The majority of these species were unknown to science then.  He knew about Darwin’s Theory of Evolution before a reluctant Darwin  published his Origin of Species.  Darwin was a high society gentleman, hesitant to publish his provocative theory, but Wallace wholeheartedly endorsed his theory from evidence he gathered on his natural history expeditions, and he was going to begin discussing Darwinism in his own scientific papers.  This prodded Darwin into finally publishing his theory.  Alfred Wallace, who was more of a working class guy, didn’t care what old fuddy duds thought about the new theory.  He deserves as much credit as Darwin for introducing the fundamental framework of all biological science, but he is relatively unknown by comparison.

Alfred Wallace discovered an interesting faunal partition in the Malay Archipelego, a geographical area including hundreds of islands extending for 4000 miles.  The birds and mammals on the western islands resemble Asian species, while those on the eastern islands resemble Australian species.  He noted the seas between islands with similar species of wildlife were shallow enough for ships to anchor.  He correctly came to the conclusion that formerly a landbridge once connected eastern islands to Australia, and another landbridge connected western islands to Asia.  The islands of Bali and Lombock are adjacent with only a few miles separating them, yet the avifauna on the 2 islands differs in the extreme.  Not coincidentally, the depth of the sea between the 2 precluded the possibility they were ever joined.  The most common birds on Bali–yellow breasted weavers, black grasshopper thrushes, rosy barbets, and 3-toed woodpeckers–were of Asian origins and totally absent on Lombock, while the 2 most common birds on Lombock–white cockatoos and honeysuckers–were of Australian affinities and were absent on Bali.

Map of the Malay archipelego.  During Ice Ages sea level fell.  Some of the islands were connected to Asia via a landbridge, while others were connected to Australia.  The present day flora and fauna on the islands that were connected to Asia show affinities to that continent, while the eastern islands have flora and fauna with Australian affinities.

Western Malaysian islands host Asian species of wildlife such as elephant, rhino, buffalo, deer, pig, tapir, macaque, orangutan, cats, dogs, and rodents.  None of these mammals were native to eastern islands, though deer, pig, and macaque have been introduced by man to some of them.  Possums, and in New Guinea, tree kangaroos are the only native mammals on the eastern islands other than bats.  Even the bird life between the 2 groups of islands is in contrast.  Of course, shorebird species common to both are found, but the upland species are quite different.  Woodpeckers and pheasants, common birds on western islands, are unknown on eastern islands.  Conversely, the eastern islands have unique species of birds not found anywhere else on earth aside from Australia.  Cockatoos, cassowaries, brush-tongued lories, moundbuilders, honeysuckers, and birds of paradise are some of the birds with Australian affinities, not found on western islands.

image 634 of Buff-necked Woodpecker

The red buffed woodpecker (Meiglyptes tukki.)  Woodpeckers are common on the Asian side of the Malay Archipelego but are absent from the Australian side–evidence of 2 separate landbridges during the Ice Ages.  Despite their ability of flight, forest birds rarely fly over ocean barriers.

The black banded squirrel (Callosciurus orestes).  Squirrels are common on the islands that were once connected to Asia, but are absent from islands once connected to Australia.

Sulphur-crested Cockatoo

The Sulphur Crested cockatoo (Cacatua galerita), a bird with Australian affinities found on eastern islands of the archipelego. 

File:Ailurops ursinus Naemundung 2 North Sulawesi.jpg

The Sulawesi cuscus–a type of possum with Australian affinities.  Possums are the only native mammals found on the eastern islands of the archipelego, other than bats.  Tree kangaroos are found on New Guinea.

During the Pleistocene it would have been possible to see completely different fauna with just a short boat trip from the Asian landbridge to the Australian landbridge.  Yet, that narrow strip of ocean was enough to block back and forth colonization between the 2 continents.  Even most forest birds that could potentially fly the distance never did.  It was and is like 2 different worlds.

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I’ve spent the past month reading Alfred Wallace’s The Malay Archipelego.  He was a remarkable naturalist with amazing persistence and knowledge, able to discern the difference between thousands of species of insects and birds.  To collect new specimens, he took perilous boat journeys to islands located far from western “civilization,” and endured numerous hardships.  Many times his crew consisted of unreliable natives, but the malaria, sores, tormenting insects, and inconsistent food supply were reliable.  It seems like his sailboats were always going against contrary winds.  It’s hard to believe he was able to endure this for 8 years.

His values definitely differed from modern day sensibilities.  He was racist, believing Europeans were a superior race.  He assumed whenever he arrived on an island that he was entitled to get whatever he wanted. On one occasion he convinced the chief of a village to let him have temporary occupancy of a house, forcing the people who  lived there to move out.  (I must note that he did compensate the family with beads, knives, cloth, etc.) Then he wondered why the natives in that village were unfriendly to him.  Most natives in other locations were friendly.

The way he collected specimens would also disturb the modern naturalist.  He shot birds and mammals and stuck their carcasses in alcohol to preserve them.  Shooting beautiful birds simply to collect them for scientific knowledge was bad enough, but he also had no reservations about shooting orangutans.  To me, this is like shooting your neighbor so he can be displayed in a museum.  One time, he accidentally captured an orangutan baby after he killed its mother.  Though he noticed the baby ape behaved much like a human baby, it didn’t stop him from killing more orangutans.  He murdered 18 orangutans in all.  According to our modern values, this is just disgusting.  Some of the animals did get revenge on people then.  Wallace mentioned that tigers killed an average of 100 people a year in Singapore during the mid-19th century.  Today, there are no tigers anywhere close to Singapore.

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2 Responses to “The Biogeography of the Malay Archipelego”

  1. James Robert Smith Says:

    Most of the naturalists of his era had no problems with shooting any animal for any reason that could in the slightest way have been considered “research”. One of my favorite wildlife writers of the early 20th Century, Ernest Thompson Seton, would not hesitate to shoot some animals to examine the contents of their stomach, just to satisfy his scientific curiosity.

  2. markgelbart Says:

    Audubon is another one who shot every bird he could.

    Seems heartless to me.

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