A KIMBERLEY CORNUCOPIA

A rich diversity of snails in north-west Western Australia is sublime evidence of evolution in action.

- VICTORIA LAURIE

JUST AS NATURALIST Charles Darwin famously observed that the Galápagos archipelago's finch species differed from island to island (see page 98), the snails in an area of the Kimberley region in WA have evolved in response to distinct and isolated environments on islands and in remnant rainforest patches. The landscapes where they occur-in Wunambal Gaambera Country in the Kimberley's north-west-are arguably more dramatic and remote than the Galápagos's finch habitat. They're in a rugged, rock-strewn region 500km north-east of Broome, accessible only by four-wheel-drive. In the Dry, intrepid travellers along the Gibb River Road here make a side-trip to see the spectacular Punamii-Uunpuu (Mitchell Falls). Offshore, boat owners and luxury yachts are familiar with only a few of the hundreds of islands, resembling small jewels in an azure sea, that form the area's Bonaparte Archipelago.

The region is already renowned for its high diversity of mammal species, including the world's tiniest marsupial the monjon. Yet, for every different mammal here, there are dozens of snail species, and although smaller and perhaps less charismatic, they're just as scientifically important. Many of the snail species survive in very restricted habitats. Some are unique to their own small rainforest patch or, in the case of offshore locations, found only in a single spot on a particular island.

It's the remarkable land snail diversity that has prompted this part of the Kimberley region to be placed on the National Heritage List. Most of the rare snails are members of the Camaenidae family - known for its remarkable diversity related to lifestyle. Embedded in their varied shell shapes, DNA, and even genitalia, is a story of adaptation - of evolution by natural selection.