In DepthEvolution

Hybrids spawned Lake Victoria's rich fish diversity

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Science  10 Aug 2018:
Vol. 361, Issue 6402, pp. 539
DOI: 10.1126/science.361.6402.539

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Summary

The world's largest tropical lake, Lake Victoria in Africa, has seen some 500 species of cichlids in only about 15,000 years, a diversification so fast it has baffled biologists for decades. Now, researchers have evidence that ancient dallying between species from two watersheds led to very genetically diverse hybrids that could adapt in many ways to a new life in this lake. Increasing evidence has shown that hybridization, once considered detrimental, can boost a species's evolutionary potential. Suspecting that might be the case in these fish, researchers sequenced hundreds of cichlid genomes, built family trees, and compared the genomes of fish throughout that part of Africa. They discovered that parts of cichlid genomes have been mixed and matched in different ways through time, with various descendants being repeatedly separated and reunited as lakes and rivers dry up and refill. These hybrids had extensive genetic diversity that fueled rapid speciation.