Early cichlid diversification led to their success in deep parts of lake victoria

A collaborative team of biologists from Swiss and Tanzanian institutions recently made a fascinating discovery about the success of cichlid fish in Lake Victoria. Their findings, published in the journal Nature, centered on an analysis of sediment cores extracted from the lake. Martin Genner, from the University of Bristol, has also provided insights into the team’s work in a News & Views piece within the same journal issue.

Lake Victoria, Africa’s largest lake in terms of surface area, formed around 17,000 years ago. Over time, it has expanded both in size and depth, becoming home to a rich diversity of fish species, including over 500 species of cichlids. This study delved into the lake’s history by examining sediment cores from different areas.

The researchers unearthed an impressive 7,623 fish tooth fossils, spanning the lake’s history from its inception. This treasure trove of fossils allowed them to construct a timeline of fish evolution in Lake Victoria. Initially, when the lake was shallow, it was inhabited by catfish, cichlids, and carp-like cyprinoids. However, as the lake deepened, most fish species stuck to the shallows. Notably, cichlids stood out as the exception, as they ventured into deeper waters and underwent diversification, securing their success.

The team’s intriguing hypothesis suggests that cichlids thrived not because they were the first inhabitants of the lake but due to their genetic predisposition to adapt after its formation. They displayed greater ecological versatility, boasting evolved jaws and a remarkable ability to hybridize with other cichlid species. These advantageous characteristics enabled them to flourish in the lake’s deeper regions.

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