Scatter a handful of volcanic peaks and limestone slabs across the Caribbean, strand a small green lizard on each, and wait. On Guadeloupe, evolution has been running that experiment for a very long time. Here is where the results live.
For most of the twentieth century, scientists saw one species here: Anolis marmoratus, the Guadeloupe anole. But it never looked like one species. On the wet slopes of Basse-Terre the males are grass-green. Elsewhere they come spotted like a giraffe, streaked in blue, or washed in gold. In 1964 the herpetologist James Lazell named a string of new subspecies, many of them pinned to a single coastline or a single island.
Genetics has since caught up with what the lizards were saying all along. Several of those island forms are now treated as full species of their own. Each one stranded on a separate island, cut off by open water that a small tree lizard does not cross, drifted down its own evolutionary road.
A channel only a few kilometres wide can be as much of a wall as a mountain range.
Charles Darwin had his finches. The Caribbean has its anoles: roughly 150 species spread across the Greater and Lesser Antilles, and biologists study them for the same reason. Islands are natural replicate experiments. Put the same starting lizard on a wet volcano, a dry limestone plateau and a windswept rock, and you can watch what changes and what doesn't.
ANOLE-WATCH refreshes these records every week from the Global Biodiversity Information Facility. The next layer is the view from orbit: Sentinel-2 satellite imagery classifying forest, scrub and bare ground on every islet, so we can ask what kind of world each of these lizards has been shaped by.