"We knew there were two different species but we didn't know how that came about." "These fish meet each other all the time and really live in the same spot," he said. The fact that the two different cichlid fish species live side by side is puzzling, he said. Scientists also generally believe that originating a new species requires geographical isolation – such as two continents drifting apart. Cichlids are an important model for evolutionary biologists because no other group of vertebrates has split into so many species – about 2,000 – so quickly, Seehausen said.
"The split of one species into two was initiated by adaptation of the sensory system, in this case the eyes, to the local environment," he said. The cichlids – pronounced "sick-lids" – evolved to improve their ability to see food and predators at different depths, and this also affected the way they saw colours and attracted mates, said Seehausen, who led the study published in the journal Nature. Ole Seehausen, an evolutionary biologist at the institute on the shores of Lake Lucerne, and his team found that some colourful cichlid fish in Africa's Lake Victoria formed a new species by adapting their vision, showing that geographical isolation is not essential for divergence. Researchers at the Swiss Federal Institute of Aquatic Science and Technology found that females more attuned to blue will choose a metallic blue mate, while those better able to see red will prefer a bright red male.
A study of brightly coloured fish has now shown that this has less to do with aesthetics than with the sensitivity of female eyes, which varies as a result of adaptation to the environment. In many species the male's mating fortunes are decided by looking impressive. This content was published on OctoOctominutes
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