Monday, September 24, 2007

Evidence of Evolution by Natural Selection

Dear Mrs. Foglia's Favorite Class Ever,

Today we reviewed many parts of evolution! One thing we talked about was the anatomical record which is made of homologous structures. These are when organisms have the same structure that performs different functions. For example we saw the same structure in a human, cat, whale, and bat. Another example we saw was emryological development. We saw how cells for a fish made gills. No humans do not have gills, but we have the same cells that serve for a different purpose in our body.



The opposite of homologous structures are analogous structures. These structures have similar external form, and functions. These structures also have different origin, and internal structure. The best way to explain this would be don't judge a book by it cover. The organisms may look similar on the outside but inside are very different.


Another topic discussed in class to help us understand natural selection was peppered moths. We saw percents of dark vs. light moths. This was an example of industrial melanism. Industrial because it was caused by huge industries. Melanism because the brown color in all animals is called melanin. When pollution was low, and lichen existed on trees light colored moths made up 95% of the population. Instead when factories created soot covered trees, and killed lichen dark moths blended better with their surroundings. Then in the mid 1900s clean air laws went into affect, and as a result light moths made up most of the population. This is an example of natural selection, because depending on successful traits such as color helped moths to have a high survival rate and reproduce. The moths who fit their surroundings best could escape predators.




I found this youtube video on evolution and it is weird to say the least!






The sherpa for tom. will be Kim

1 comment:

Rui Monteiro said...

People are blind by Natural Selection exclusivity. Fight the Status Quo and its Natural Selection exclusivity! See why here: http://nature-sucks.blogspot.com/