Genetic recycling drives the diversification of cichlid fishes in Lake Victoria, says Joana Meier

Science magazine has published a paper by Branco Weiss Fellow Joana Meier as lead author. The paper demonstrates that the extraordinary diversity of cichlid fishes in Africa’s Lake Victoria – where 500 species of fish emerged in just 16,000 years – was made possible by “genetic recycling”: new species evolved and adapted to a multitude of food and habitats not from new mutations, but pre-existing genetic variants that got mixed and matched into many different species.

Dr. Meier and her multinational team with researchers from the Swiss water research institute Eawag, the University of Bern, the University of Cambridge and the Wellcome Sanger Institute compared genomes of 464 present-day cichlid fish species from Lake Victoria and the wider Great African Lakes region. They could show that hybridization – where two different species interbreed and generate large genetic variation by combining their genes – enabled cichlids to do so well. Lake Victoria was completely dry 20,000-16,000 years ago. While the species diversity that existed in Lake Victoria prior to the dry period went extinct, some cichlid populations likely survived in swamp refugia. Each of those populations would have retained different genetic variants of the original species diversity and when the lake refilled, their joint genetic variation allowed very fast adaptation and species diversification. The research team also identified unique genetic variants that spurred this process, thus providing important insights into the genetic basis of adaptive evolution and diversification.

Read the paper in Science magazine

Read the news on the Wellcome Sanger Institute’s website

Read the news on the EAWAG website