5.6 [ Speciation, Rate of Evolution, Macroevolution ]

     Natural selection leaves the strongest to survive, so the species with the favorable trait survives with the unfavorable trait dies. With only the desired traits to survive in the environment survive, some believe this is classified as a new species. This process is called speciation which is the formation of a new species, this is carried out by allopatric speciation which happens in three steps.

1) A physical barrier separates the species into two or more groups isolated from one another. A physical barrier is some change in the environment, an example would be a construction site on a river sperating the two sides.

2) Natural selection influences the environments in different ways because of the separation between the two or more and because of this species evolve in different ways.

3) Eventually, the two environments would have separated so much that the species that were split because of the physical barrier can no longer breed and have become separate species.

5.5 [ Mutations, Sexual Reporduction ]

5.4 [ Theorys of Evolution, Natural Selection ]

     In the 1800's the first theory of evolution was thought up by Jean-Baptiste Lamarck. He came up with a theory called spontaneous generation where species were continually being created from non living matter. Lamarck's theory on evolution was the traits of the parents that they gradually over time gained would be transfer to there offspring. For example if a adult dalmation had all black spots and and is tall and muscular from stretching and running a lot. Then its offspring would be tall muscular and have black spots. However this theory also has many flaws such as missing limbs scars or any other disfiguration were not passed onto the offspring. Lamarckism or inheritance of acquired characteristics was immediately discredited. 

 

     The next theory of evolution was proposed by Charles Darwin in 1858. On his voyage to the Galapagos islands he studied birds. Most notably a bird called a finch, he noticed different variations between the finches. For example a long skinny beak was meant for getting bugs out of trees, bigger wider beaks were made for crushing its food. Although for Darwin's theory to work four things must be present in the environment. Overpopulation, variation, competition and survival of the fittest. Once all the criteria are meet the species will start to adapt to there new environment by mutation in order to survive.

http://www.biology-online.org/2/11_natural_selection.htm

http://ts3.mm.bing.net/images/thumbnail.aspx

http://en.wikipedia.org/wiki/Darwin%27s_finches

Ritter, B., Burley, K., & Fraser, D. (2007). Chapter 5 Evolution. Nelson. (Original work published 2007)