Evolution Repeating Itself?

An article on Science Now talks about the evolution of the stickleback fish also know as Gasterosteus aculeatus. About 10,000 years ago ice glaciers melted and stranded many marine stickleback in freshwater water sources like lakes and streams. In these new isolated environments the fish developed traits that would benefit them in the new environment and got rid of unnecessary ones.  New information has been revealed that the changes which happen so quickly may be linked not to mutations but to the activity of some genes. Since this new information was revealed biologists may be switching the focus of studying evolution with the idea of  gene regulation in all organisms.

One of the reasons that stickleback  fish are of interest to biologists is because the species has undergone the same evolution multiple times as new stickleback fish enter freshwater areas. Because of the similarities  of all the evolution the fish have undergone  this made them a target for evolutionary biologists like David Kingsley, a evolutionary biologist at Stanford University in Palo Alto, California. His colleagues and of course himself successfully sequenced the genome of one type of stickleback from Alaska, this sequence had a high degree of accuracy. Then using the successful one they use sequence as a blueprint and sequenced 10 pairs other species. Each pair was of a ocean dweller and its freshwater counterpart. If these fish had indeed undergone repeated evolution the genome would reflect that by having super similar genome regions. There findings showed that 147 regions of the genome  were similar confirming that repeated evolution was happening at a very high rate in stickleback fish.

After that they searched the regions for genes. Which they then compared to the other fish. They believed if the genes were the same in the freshwater fish and different in the ocean dwellers then they could assume with evidence that the gene is responsible for the alteration for freshwater. They found that this was the case in only about 17% of the cases in all the regions of the genome. They also found that about 41% of the regions that no gene was present. This allowed the biologist to confirm that the changes from ocean dweller to freshwater dweller results from the regulating of genes in some area of the genome. Scientists have documented other organisms that have repeated evolution but no other organism has undergone as many times as sticklebacks going from ocean dweller to freshwater dweller.