Wallacea & Endemic Species (Maluku Islands)

A map of Wallacea (Wikipedia)

Wallacea is a place populated by mostly Indonesian Islands which are alienated from Asian and Australian continental shelves due to volcanic formation and movement of plate tectonics which shows the deep-water straits were always present (Bellwood, p. 175). The name is after Alfred Russel Wallace who was a naturalist that outlined the contrasts of mammals and bird faunas on each side of the line. This geographical location is important to early Southeast Asian history because it holds a big amount of endemic species which is an essential addition to the comprehensive mega-biodiversity of the Indonesian archipelago. The purpose of this blog is to explore the islands of Wallacea and the endemic species which makes the islands important in structure and biography (Bellwood, p. 175).

Wallacea Volcano and distribution of Islands (Betchart Expeditions)

Wallacea holds three islands known as the Lesser Sundas, Maluku, and the Sulawesi subregion. The origin of these islands are due to a volcanic arc which was made in the subduction zone located where the Indo-Australian and Philippine plates join together. In the Maluku islands the North and South vary in their geological features. The islands in the North started by the volcanic activity in the Pacific and moved along New Guinea. While in the South the islands began from fragments of the Australian region (Carstensen, p. 739). The eastern border is called Lydekker’s Line and the Wallace Line represents the Western area. The middle region is personified by the Weber Line at this point is where the equal representation of both fauna and flora from Asia and Australia. 

Mammal and Bird Faunas 

Of the many endemic species the island of Maluka holds fauna species with similarities to the endemic anoa. Faunas were not widely discovered during Wallace’s time compared to his discovery of over 20 species of birds; we now have knowledge of six times more species. Wallace used this available data as “zoogeographic boundaries” between Australian and Asia (Mayra, p.1). This boundary line was easily acknowledged by others as an acceptable borderline. The conclusion he had come to was due to the different species that were not available on both islands.  Such as tigers, squirrels, and other mammals were prevalent in Bali but not found in Lombok. Due to this Wallace was able to publish his ideas that Lombok and Makassar Straits are where the boundary lies between Asian and Australian zones (Mayra, p. 3).

The islands of Wallacea are so interesting due to the split between the two zones, Australia and Asia. However, most of the animal and plant species originated from Asia. West Indies is comparable to Wallacea as both the regions are modular and split up into four biographical modules (Carstensen, p. 739).

References 

Bellwood, Peter. The Prehistory of Island Southeast Asia: A Multidisciplinary Review of Recent

Research, Journal of World Prehistory, Vol 1, No 3, 2004.

Carstensen, Daniel W., et al. “Biogeographical Modules and Island Roles: a Comparison of Wallacea and the West Indies.” Journal of Biogeography, vol. 39, no. 4, 2012.

Mayr, Ernst. “Wallace's Line in the Light of Recent Zoogeographic Studies.” The Quarterly Review of Biology, vol. 19, no. 1, 1944, pp. 1–14. JSTOR, www.jstor.org/stable/2808563. 

“Wallacea.” Wikipedia, Wikimedia Foundation, Accessed Foundation, Accessed January 212, 2021, https://en.wikipedia.org/wiki/Wallacea.