GP - Fitness & Breeding

In my previous previous blog 'An Overview of Genetic Programming', I went over the general idea of genetic programming. In its basis, GP is testing certain smaller programs, determining whether they are "fit" based on a model of natural selection, and then breeding those programs. There are various ways of  breeding/creating new programs from the old one; Let's look at that in more depth:

Reproduction: The computer literally reproduces the program - i.e. creates a duplicate of it - and copies it to the new population.
Crossover: The computer takes two programs(that have passed the fitness test) and creates a new offspring program by recombining randomly chosen parts from those two selected programs.
Mutation: the computer takes an existing 'fit' program randomly, and changes a chosen part of it.
Lastly,
Architecture-altering operations: in this case, the computer chooses an architecture-altering operation from an available list of operations and applies it to one selected program , hence creating the new offspring program for the new population

References:
http://geneticprogramming.com/tutorial/

Image References:
http://previews.123rf.com/images/iqoncept/iqoncept0905/iqoncept090500016/4813642-An-illustration-of-a-DNA-double-helix-with-one-highlighted-in-red-Stock-Illustration.jpg