“The question of what determines biological diversity has pestered evolutionary biologists ever since Wallace and Darwin came up with their theory of evolution,” Salzburger said. The new study doesn’t provide conclusive answers, but it does expose a possibly telling imbalance in the cichlids’ evolutionary tree. Some branches saw an abundance of species form, while others remained sparse. In those differences, the researchers spotted an intriguing relationship: The most genetically diverse cichlid species were from branches that gave rise to more species; the sparest branches held the most genetically homogenous species.”