Members of the Midas cichlid group underwent sympatric speciation to produce a range of species, says new research.
The old-fashioned view of species formation, or speciation, was that new species formed in the presence of a geographical boundary, through allopatric speciation.
However, there are now many theories for a range of fishes, that the can also evolve in the absence of such boundaries via a process called sympatric speciation, but fewer living examples of how the process can occur.
Now scientists from the Department of Biology at the University of Konstanz believe they have new evidence to show that Amphilophus cichlids in the Midas cichlid genus evolved through sympatric speciation.
Their research, published in the journal Nature last month, looked at Amphilophus in Lake Apoyo, a small volcanic crater lake in Nicaragua, in which a number of related Amphilophus species are found.
It used phylogeographic data, morphometric and ecological data and population genetic data to show that the Lake's original ancestral stocks were Amphilophus citrinellus.
The data also suggest that a second species, A. zaliosus, evolved from citrinellus in the Lake to produce a more elongated fish evolved for lake-like in just 10,000 years - a remarkably short period of time for a new species to evolve.
The study also says that the two fish are reproductively isolated, so the species choose to mate with their own kind rather than with each other, and they do represent distinct species within the Amphilophus genus.
For more details see the paper: Barluenga M, Stolting KN, Salzburger W, Muschick M, Meyer A (2006) - Sympatric speciation in Nicaraguan crater lake cichlid fish. Nature. 2006 Feb 9;439 (7077):719-23.