Evolution

Darwin's evolution theory vs Lamarck's

Darwin believed that organisms all adapted to their environment, and that even those of the same specie were all different. He thought that those variations between species that helped them adapt to their environment was what helped them survive and reproduce, then their offspring will reproduce as well. As for the weak, they will eventually die off. ex: Elephants used to have short trunks, while others had longer trunks which helped them reach food easier. Eventually those with shorted trunks died off and only those with longer trunks reproduced. Natural selection

Lamarck believed that if an organism changes during life in order to adapt to its environment, its changes are passed on to its offspring. He believed change was made by want or need. He also believed that organs not being used will eventually vanish, for example the human appendix.  ex: Elephants used to all have short trunks and when there was no food or water that they could reach, they stretched their trunk to reach it; therefore their offspring had longer trunk. Inheritance 

They both however believed that evolution consisted of organisms adapting to their environment by changing.

*We believe Darwin's theory. Why? Well, because a body builder won't produce a baby that is born a body builder right away. The offspring will have to work to be fit and built.

Natural selection

"survival of the fittest"

Individuals even within the same specie are different. Organisms may produce more offspring than their environment can support which leads to competing for resources. Individuals that cope with the challenges presented by their environment leave more offspring than those less suited. 

To sum it all up it was basically Darwin's idea that only the strong will survive and reproduce, while the weak will eventually die off. 

ex #1: Variation in traits may lead to green beetles and brown beetles on a tree. The green beetles are more visible therefore the birds will spot them first and eat them. The brown ones are not so easily seen or eaten, therefore they will reproduce and eventually there will only be brown beetles. 

ex #2: Fish lay thousands or millions of eggs. Within the population of eggs, there will be variations. Some may differ in color, fin and tail size, and speed. An egg that grows to be a fast fish with a skin color that allows it to blend in with its environment is more likely to survive and not be eaten than a slow fish with more obvious coloring. Eventually the more suited fish will reproduce and the weak ones will die off, causing a change in the specie.

Evidence of evolution

Fossils: for example, intermediate forms. They reveal gradual modification of species over time.

Geographic distribution of species: for example, similar animals in different locations. They reveal different lines of evolutionary descent 

Homologous body structures: for example, different mature forms develop from same embryonic tissue. They reveal species are descended from common ancestors.

Similarities in early development: for example, the order and pattern of development in vertebrate embryos. They reveal vertebrates share a common ancestry.