examples of symbiosis.

Predator/Prey- A predator is an organism that eats another organism. The prey is the organism which the predator eats. Some examples of predator and prey are lion and zebra, bear and fish, and fox and rabbit. 

 

Parasitism- Parasitism is a type of non mutual relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. 

Mutualism- Mutualism is the way two organisms of different species biologically interact in a relationship in which each individual derives a fitness benefit (i.e., increased or improved reproductive output).

Commensalism- In ecology, commensalism is a class of relationship between two organisms where one organism benefits but the other is neutral (there is no harm or benefit).

 references: http://science.jrank.org/pages/1641/Commensalism.html
http://en.wikipedia.org/wiki/Mutualism_%28biology%29
http://en.wikipedia.org/wiki/Parasitism
http://necsi.edu/projects/evolution/co-evolution/pred-prey/co-evolution_predator.html

food web.

 

Producers: tree

Primary Consumers: goat, mouse

Secondary Consumers: owl, wildcat, rabbit, snake

Tertiary Consumers: jackal, wildcat, kite, lion

Scavengers: none

Decomposers: none

references: http://www.vtaide.com/png/foodchains.htm

how geographic distribution can support evolution.

The existence of similar but unrelated species was a puzzle to Darwin. Later, he realized that similar animals in different locations were the product of different lines of evolutionary descent.
For example, the beaver and the capybara are similar species that inhabit similar environments of North America and South America. The South American coypu also shares many characteristics with the North American muskrat.

 references: http://en.wikipedia.org/wiki/Evolution

http://wiki.answers.com/Q/What_is_Geographical_distribution

natural selection.

Natural selection is a normal process resulting in the evolution of organisms best adapted to the environment. The relation between Natural Selection and Mutations are very simple. Let's say a Giraffe has a small neck and his food is on a tree. It will cause him to keep reaching as far as he can, if the giraffe and its future generations continue to do this process, their necks will start to extend due to evolution which can affect the phenotypes of the Giraffes which will change the genotypes of the future generations so they will be able to have long necks.

 
Expatation is the shift in a function of a trait during evolution. Like, a trait can evolve because of one function, but subsequently it may come to serve another.

references:  www.unknownworlds.com/ns/
evolution.berkeley.edu/evolibrary/article/evo_25
en.wikipedia.org/wiki/Exaptation