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| While offering the usual mix of articles covering both new and old world cichlids, one theme that emerges from this month’s collection is “speciation via hybridization”. Evidence continues to mount that genetic introgression—hybridization between ‘species’—may be an important mechanism in the evolution of cichlids and other organisms. Patrick Tawil writes about Melanochromis brevis, one of a few atypical Melanochromis species that express a checkered, ‘filmnegative’ grid pattern. Tawil suspects that M. brevis may in fact be a natural hybrid between another Melanochromis species (e.g. M. heterochromis) and Pseudotropheus williamsi. He reviews the evidence for this, while also discussing the aquarium husbandry of this uncommonly kept species.
In keeping with this theme of speciation via hybridization, Martin Geerts explores the apparent role of natural hybridization in the evolution of cichlids. The evidence is mounting that hybridization amongst the cichlids of Lakes Victoria, Malawi, and even Tanganyika are responsible for what has become known as ‘reticulate evolution’ – evolution via genetic exchange (introgression). Known examples of such suspected interspecific gene flow include several species from South America including the peacock ‘basses’, Cichla species, and, of course, discus. Which leads us to my article that reviews the most recent DNA-based research attempting to answer the perennial and hotly debated question: “How many species of discus are there?” A quick summary of the situation as it stood circa 2006/2007 with the publication of competing studies by Bleher et al. (2007) and by Ready et al. (2006) is followed by more recent and more conclusive studies by the Farias/Hrbek group in 2008 and 2011 based on DNA sequencing suggesting strongly that discus comprise a single species which is in the process of speciating, but has not yet fi nished that evolutionary process: one species becoming many, caught in our current, somewhat confusing snapshot. This issue is rounded out by Ad Konings who chronicles his recent expedition to Burundi and Northern Congo. For the last 20 years the Congolese (northwestern) section of Lake Tanganyika has been inaccessible due to the ongoing extremely dangerous political situation in the Democratic Republic of Congo. In preparing a new edition of his Tanganyika cichlids book, he wanted to include underwater photos from all areas of the lake, including those from the northwestern coast. This two-part article chronicles his experiences getting to and successfully fi lming in this remote, challenging, and still dangerous (though improving) part of the lake. Finally, in “My 6 Favorite Cichlids” Oliver Lucanus, noted explorer/collector/importer of tropical fi sh whose exceptional photographs grace the discus article, shares his surprising pick of favorites. Fascinating! We conclude with our regular feature: “What’s New” by Laif DeMason. In the words of editor and author Ad Konings: “Enjoy your cichlids!” |
Wayne S. Leibel, Editor  |
