"Cichlid fish are among the most spectacular examples of rapid speciation and adaptive radiation, which makes them an excellent model system for the study of mechanisms of speciation and evolution. The hotspots of cichlid diversity are the large East African lakes, which contain hundreds of endemic species. Neotropical cichlids are less species rich, but often offer better and simpler scenarios to study very recent speciation events. A good model system of a small scale and extremely recent radiation are cichlids from the Cuatro Cienegas valley, in the Chihuahuan desert in Mexico. Fish so far assigned to the species Herichthys minckleyi have evolved during the last few thousand years and have developed an array of trophic and body shape morphologies in parallel in several isolated ponds. This has raised the hypothesis that in fact several recently formed species might be coexisting in these ponds. However, lack of concerted genetic studies mean this species complex remains an unsolved evolutionary mystery. I plan to study the reproductive isolation of the incipient species using a comprehensive approach combining morphological and ecological characterization of the different species both in the laboratory and in captivity, and molecular markers distributed across the entire genome (SNP markers obtained using the most recent parallel sequencing technologies). I aim to understand the geographic setting and the mechanisms driving speciation, and the extent of parallel evolution causing similar eco-morphological outcomes in independent settings."