Evolution of Mimetism, v.2.0

This short video illustrates the artificial evolution of mimetism in a population of lizards. Each (RGB) component of the lizards' color was represented as an 8-bit "gene" (haploid), which resulted in each lizard being represented by its 24-bit "genome". In the video we can see four lizards sampled from the population, and the decrease of the population's average "visibility" against the background. As a measure of this visibility the distance between the RGB vectors of the lizards and the average color of the background was used. The evolutionary process was modeled as a very, very simple genetic algorithm: 1) An initial population of 200 lizards (with random colors) was assumed to exist; 2) This population was subject to mortality: 30% of the population died randomly (e.g., due to disease, starvation, accidents, etc.) and, starting at generation 25, the 20% worst (less-fit) also perished (e.g., introduction of a new predator in the environment) 3) The surviving lizards were allowed to mate (with randomly selected partners), generating a number of offspring equal to the initial size of the population, and then died off; The offspring are generated through genetic recombination of their parents' "genomes", and are subject to mutations (the probability of a mutation happening at a given point was set as 1 in 1000) 4) The cycle then continues from step 2. After a certain time the background pattern changes (simulating a sudden environmental change). It can be seen that, as the selective pressure starts pulling in a different direction, the average color of the population tends to follow after a few generations. This little simulation is intended only to illustrate the ability of very simple evolutionary systems to produce a population with good mimetism characteristics. In the next ones I intend to include characteristics such as: - diploidy and dominance; - gender; - generation gaps (lizards living and reproducing across multiple generations) Suggestions and comments are welcome.

Category:

Education

Tags:

• Evol
• calangos