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Phoenix666 [soylentnews.org] writes:

Cichlid fish from a tiny volcanic crater lake in Africa [phys.org] have been caught in the act of sympatric speciation, whereby a new species evolves when there is no geographic barrier to physically separate the new species from the old. The study, led by the Wellcome Trust Sanger Institute and co-authored by the University of Bristol, is published today in Science.

Scientists studied the whole-genome sequences of 146 small fish [phys.org] in the 700m-wide Lake Massoko in Tanzania in order to answer two of the most debated questions in evolutionary biology: is sympatric speciation possible and, if so, what are the genetic and physical traits that drive this form of evolution (sexual attraction or specialisation in lifestyle, diet or other ecological factors)?

Senior author, Professor George Turner of the School of Biological Sciences, Bangor University said: "The idea of sympatric speciation has divided evolutionary opinion for a long time. It has been difficult to substantiate that new species can arise when genetic variations can be exchanged easily between the two evolving groups. But we have caught this form of evolution in the act by identifying two different forms of cichlid fish [phys.org] that are separating from each other within a lake that is only 700m wide."

Cichlid fish are a valuable model of evolution. In nearby Lake Malawi, many hundreds of cichlid species have been found, differentiated by size, shape, colour, feeding habits and ecological preferences such as living towards the surface of the lake or at the bottom. Because of this vast diversity the lake is known as 'Darwin's Pond'. In contrast Lake Massoko is 'Darwin's puddle': a much simpler place with many fewer species and fewer factors to drive speciation.

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