Scientists have used genetic analysis to confirm the identity of crocodiles that once roamed the Seychelles, solving a 250-year-old mystery. These reptiles, thought to have vanished by the mid-1800s, were not a unique species but rather the westernmost population of the saltwater crocodile (Crocodylus porosus).
Historical accounts from early explorers detailed crocodiles as a common sight in the Seychelles. However, after permanent settlers arrived in 1770, the crocodile population rapidly declined and was completely exterminated within about 50 years. Researchers from Germany and the Seychelles investigated the evolutionary history of these lost reptiles by comparing DNA from modern saltwater crocodiles with genetic material from historical museum specimens, including rare samples from the extinct Seychelles population.
The genetic findings confirmed a previous theory based on the crocodiles' physical appearance, showing that the Seychelles animals were closely related to saltwater crocodiles living thousands of kilometers away. This supports the idea that crocodiles are capable of crossing vast distances.
Saltwater crocodiles are uniquely adapted to life at sea, possessing specialized salt glands that allow them to survive extended periods in saltwater. This ability has facilitated their spread across extensive coastlines and remote islands. Experts suggest that the founding population in the Seychelles likely drifted at least 3,000 kilometers across the Indian Ocean from other populations, possibly traveling with ocean currents over generations.
"The founders of the Seychelles population must have drifted at least 3,000 kilometers across the Indian Ocean to reach the remote archipelago, perhaps even much further," stated reptile expert Frank Glaw of the Bavarian State Collections of Natural History, a senior author of the study. The genetic patterns indicate that saltwater crocodile populations have historically remained connected over long distances, highlighting the species' remarkable mobility.
Before the Seychelles population was lost, the saltwater crocodile boasted an even wider range, stretching over 12,000 kilometers from Vanuatu in the Pacific Ocean to the Seychelles in the Indian Ocean, making it one of the most widely distributed reptiles on Earth.
