Genomics of explosive adaptive radiation

Our newest paper on the ecological and genomic basis of the explosive adaptive radiation of the Lake Victoria haplochromine cichlids has been published today in Nature! In this work led by Matt McGee and Sam Borstein, we found that in a large phylogeny containing all described cichlids, speciation rates in most of the cichlid family are not unusually high compared to other taxa, but a few lineages living in large, young lakes, show extremely high rates of speciation. These increases in speciation rates are associated with the absence of large predators, even though this cannot explain why some lineages show explosive speciation in the same area others don’t.

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We sequenced the genomes of 100 haplochromine cichlid species from the fastest explosive adaptive radiation in Lake Victoria, East Africa, that unfolded in the last 15,000 years. We found that the Lake Victoria haplochromines have an exceptional genomic potential in the form of hundreds of ancient haplotypes with insertion or deletion polymorphisms, many of them associated with ecological niches they exploit and originating from hybridization between distant lineages. Our results suggest that the combination of ecological opportunity in a newly formed lake without large predators, strong sexual selection and exceptional genomic potential together led to the huge adaptive radiation of Lake Victoria cichids within the blink of an eye.

Another digest of the story can be read in the Eawag News and I hope you enjoy the full story in our paper (e-mail me for a copy!).

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