To try and settle the debate, Scholz and his team examined sediment records from the lake covering 1.3 million years. They found that over this period the water levels dropped by more than 200 metres around 24 times.
Forced diversification

These dramatic changes would have changed the habitat, says Scholz, as less water in the lake would shift the rocky shoreline inwards, alter the pH and salt levels of the water, and even separate the lake into smaller ones. This would ultimately force the fish to adapt to the new conditions and diversify.