Islands have been privileged laboratories to catch evolution red-handed.
The archipelago of the Azores is one such laboratory. It is isolated, it has groups of islands, of different ages, and its “finches” are endemic terrestrial molluscs.
Apparently without known visual predators, with plenty of food and moisture, the colourful zonitids of the endemic subgenus Drouetia Gude, 1911 in a way left evolution’s imagination freely at work, thus rendering less obvious the usual justifications of the survival of the fittest. Distributed throughout the archipelago, their diversity appears to be linked to the geological history of each island, thus illustrating the various steps of the shaping of a species.
This is the story of the unfolding search for the process driving the speciation of Drouetia. The underlying hypothesis is that speciation of Drouetia is a living example of punctuated equilibrium.