Stickleback Fish Research Paper

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The stickleback fish have gained much attention from evolutionary biologists because of their historic ability to adapt to conditions that were not favorable and to survive successfully in them. They are also able to give researchers insight into how evolution occurs in other organisms. The stickleback normally spawns in freshwater but lives in the salt-water ocean. Long ago when ice melted and receded, the fish were given new possible places to inhabit and they did, expanding their spawning locations to newly formed streams. Eventually, though, the streams were cut off from the sea and the once salt-water sticklebacks were faced with the problem of being stuck in freshwater with no way to get out.1 The presence of sticklebacks in freshwater lakes today shows that somehow the fish were able to still survive even though they were in unfavorable conditions. The question is: how did they do it?…show more content…
An interesting feature of this lake is that it contains no large mouth predators of the fish. Normally, the spines of the fish keep them protected from these predators, but here in Bear Paw Lake, the spines actually decrease the fitness of the fish because the dragonfly larvae living at the lake bottom prey on the fish by grabbing them by their spines. Due to natural selection, eventually the fish in the lake population lost their spines on the undersides of their bodies.1 The fish that had low fitness due to their spines were killed and unable to produce offspring while those without spines or maybe with reduced spines lived long enough to

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