Genomic islands of speciation separate cichlid ecomorphs in an East African crater lake

Cichlids diverge within a crater lake It is not clear how populations diversify and new species form at the genomic level, especially when they coexist in the same location. Malinsky et al. investigated how two ecomorphs of cichlid fish in a small lake in Tanzania are diversifying relative to each other. Although there is gene flow between the two forms, major regions of genetic divergence, known as genomic islands, separate the populations. Within these islands, the authors found genes likely to be associated with mate choice, supporting the idea that genetic changes related to breeding preferences are the first to diverge during speciation. Science , this issue p. 1493