Free Essay Scientific Experiments Regarding Evolution

supermario · Uploaded by **supermario** on Aug 27, 2006

Scientific Experiments Regarding Evolution

Science has proven that evolution is the key to our adaptation patterns. Over millions of years humans, birds, reptiles, and fish have evolved to survive in their environments. This can be found in the simplest life forms as well as the most complicated life forms. Examples of this can be found in cavefish losing their eyes from nonuse and humans losing large amounts of body hair from living in warmer dwellings. Scientist have shown exactly how fast the evolutionary process can be with an experiment held on salmon in the late 1930�s.

An experiment held by biologist in the Northwest has shown how salmon, which were introduced to Lake Washington in 1937, have evolved incredibly over thirteen generations. Lake Washington basically has two environments: the beach and the river environments. The male salmon that moved to the river became more streamlined so they could swim up strong river currents better, while the females grew 10% bigger than their sister, the lake females. The females gained size aids in their nest building abilities. Both river and lake females make their nest by slamming their bodies into the lake or riverbed which leaves a nice trench to deposit their eggs into. After the eggs have been laid, they swim upstream to stir up gravel, which will drift over the eggs to form a protective blanket over them. As you can see, the size advantage of the river salmon allows her to dig deeper trenches that will protect her eggs from the stronger current and the flooding river. The lake males grew a larger hump in front of their dorsal fin. Their gained size slows them down in the river, but allows them to become better sexual competitors in the lakes.

The evolution between these salmon has caused their DNA to become genetically different. These differences in their DNA cause both females and males to look completely different. These physical differences are probably what is causing these fish not to interbreed. The physical advantages of in their own environments allow them to mate and reproduce with fish of their own kind.

Evolution can be found in all forms of life. Survival of the fittest is Mother Nature�s way of weeding out the weak. So if a species is weak and can�t adapt, they slowly die off. The dodo bird is an example an animal that wasn�t able to keep up with the times. So if you want to survive in this world, you need to be able to keep up with times.