Different genes code for two different forms of stickleback fish.
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Courtesy of Zina Deretsky, National Science Foundation

Fish Adapting to a Changing World
News story originally written on October 8, 2008

Scientists have been studying stickleback fish to learn more about how animals cope with changes in their environment. Some stickleback fish live in the ocean while others live in freshwater. Thatís a big difference in environment.

There are two main ways that the stickleback fish and other animals cope when their environment changes. The fish in the new environment can change the way they live their lives. There is another way they change too. Over many years and many generations of fish, the whole population of fish can adapt to the new conditions through the process of microevolution. This changes the amounts of genes in the gene pool. And genes are what make the fish look like fish.

Oceanic stickleback fish have bony plates and spines for protection. These plates help the fish survive attacks by birds and other predators. Freshwater stickleback fish usually donít have the plates, and sometimes the spines. This difference is due to microevolution. It can happen very rapidly, sometimes in only dozens of years. Thatís fast for evolution.

Of course, it is not up to an individual fish whether it grows plates and spines.† It is coded in a fishís genes. Scientists have been studying the genes of the stickleback fish to learn which genes allow fish to develop plates. They have found that fish that had certain genes grew plates. Fish that had different genes instead did not grow plates.

Last modified February 6, 2009 by Lisa Gardiner.

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