Biogeographers have long been puzzled with the way plants and animals in the Pacific islands are highly distinct from their counterparts in nearby continents. In fact, Ferdinand Magellan’s chronicler Antonio Pigafetta had already observed during his voyage to the Philippines in 1521 the biological contrast of the Philippines and the Moluccas islands of Indonesia.

“We have this so-called Wallace Line, a faunal boundary line drawn in 1859 by the British naturalist Alfred Russel Wallace to delineate the Southeast Asian and Australian fauna,” UPLB MNH researcher David Emmanuel M. General expounded during an interview.

The Wallace line runs through Indonesia, between Borneo and Sulawesi (Celebes), and through the Lombok Strait between Bali and Lombok. The vertebrates and plants on either side of the Wallace Line are distinctly different because they cannot easily spread over vast oceans.

But an extensive team of researchers worldwide which included General recently found that a specific group of insects, the Carpenter Ants Camponotus maculatus (Fabricius, 1782), are able to colonize other areas coming from their origins far better than other fauna. Carpenter ants are common ants considered as household pests, burrowing tunnels under wooden structures of homes.

According to General, insects are able to cross these faunal lines. “Camponotus queens are presumably strong fliers and can probably disperse from Southeast Asia, through the Philippines, and from Australia,” he added.

To see how these ants colonized the region, the researchers employed molecular phylogenetics to analyze mitochondrial and nuclear DNA from hundreds of Camponotus specimens worldwide. Their findings were recently published in the scientific journal Cladistics.

The research team included in their findings that Carpenter ants have been able to colonize the Philippines and other areas on both sides of the Wallace Line despite the oceanic distance. “In fact, we were able to see that these ants were able to come from various sources and colonize the Philippines at least twice in the past,” General said.

According also to General, Philippine species of Camponotus were recovered in two robust clades or monophyletic groups, indicating that there are probably two different colonization routes. “One route seems to be northward from Celebes while the other route is from Australia via the oceanic islands,” he explained.

The researchers were able to conclude that the colonization patterns of insects do not necessarily parallel that of vertebrates and plants. “These patterns have enabled insects to easily evolve compared to flora and other fauna,” General said.

“Insects, throughout history, have remained the most diverse group of terrestrial organisms in the world because of their unique and many ways of dispersal,” he added.

 For more technical information, refer to:

Clouse, R. M., Janda, M., Blanchard, B., Sharma, P., Hoffmann, B. D., Andersen, A. N., Czekanski-Moir, J. E., Krushelnycky, P., Rabeling, C., Wilson, E. O., Economo, E. P., Sarnat, E. M., General, D. M., Alpert, G. D. and Wheeler, W. C. (2014), Molecular phylogeny of Indo-Pacific carpenter ants (Hymenoptera: Formicidae, Camponotus) reveals waves of dispersal and colonization from diverse source areas. Cladistics. doi: 10.1111/cla.12099

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