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In the footsteps of Wallace

Posted on 16-09-2012 by Redactie

Well start off with a decayed wooden pole. The photo next to this text was taken by my friend Mustafa Abdul Rahman (Bob, for friends), an evolutionary biologist at Universiti Malaysia Sarawak in Malaysian Borneo. It looks like any old piece of wood, but if you knew that this is the last remnant of the bungalow of the King of Sarawak where the 19th-century naturalist Alfred Russel Wallace stayed in 1855, a biologists heart will skip a beat. For Wallace is, with Darwin, the founder of evolutionary biology. And one of the first foundations he laid was a short paper entitled On the law which has regulated the introduction of new species (the paper later became known as The Sarawak Law). He wrote that article in Borneo (though in one of the Kings other bungalows) and it was published in the journal The Annals and Magazine of Natural History.

Theory of evolution In that paper, Wallace describes how species that resemble one another usually tend to occur in one anothers vicinity. And, he suggested, this implies that one species arises from anotherin other words, evolution. Only a few years later Wallace (independently from Darwin) discovered the process of natural selection, but there, in that royal bungalow he had already formed in his mind an image of nature in which some sort of evolutionary processrather than divine creationwas the cause for new species.

Mountain snails and land snails With our expedition we step in Wallaces footsteps. Although we will not be lounging in any regal accommodations, we will be studying closely related species in Borneospecies that adhere to the Sarawak Law and occur in the close vicinity of related species. The kind of evolution were speaking of is adaptation to mountain tops: on the summits of Borneos mountainous heartland, lots of animal and plant species occur that are endemic and only occur there at great elevationand nowhere else on earth. At the same time, other species, closely related to those montane endemics, occur more widespread in the lowlands.

Mountain snail

Mountain snail

Land snail

Land snail

Take, for example, the mountain snail Everettia corrugata , which one can only find above 3,000 meters on Borneos tallest peak, Mount Kinabalu. Two other, closely related species are E. consul and E. subconsul . These are more widespread all over the lowlands of northern Borneo. The question is whether the mountain species has descended from the lowlandinhabiting species, or the other way around. This is one of the questions we hope to be solving.

Wallace himself never set foot on Borneo again. After criss-crossing Southeast Asia for many years, in 1862 he landed in England again, where he became a rather successful writer, essayist and scientist. His book The Malay Archipelago became a bestseller, but besides he also wrote books on evolution, biogeography, antivaccinationism and spiritism (the latter much to the grief of his more rational friend Darwin). He died in 1913, and the hundredth anniversary of his death will indubitably be cause for much remembrance next year.

Dr. Menno Schilthuizen , expedition leader

Logo Scientific American The English expedition blog can also be followed on Scientific American