How new species arise in the sea

How can a species split into several new species if they still live close to each other and are able to interbreed? Using a group of Caribbean reef fishes as a model system, a team of scientists has found that natural selection can couple the evolution of genes for vision and color pattern.

Is there any reason to think that neutral evolution could not in principle cause this same result?

The Lake Victoria Cichlids are an interesting example of this. Sympatric speciation driven by sexual selection produced hundreds of species within a single lake. The really interesting (and sad) thing is that due to increased turbidity from runoff and pollution these separate species are unable to recognize one another and are hybridizing, which results in loss of species in the lake. They have lost nearly 1/2 of the species so far.