This model simulates the coloration evolution of a fish population influenced by various factors. You can create a boundary to divide the population, differentiate the environment, as well as adjust various factors, and then observe what happens to the fish color distribution over time.
Grades: 9-12, College Introductory Biology;
NGSS standards: HS-LS4-5
Press on the "setup" button, then press on "run/pause" button to run the simulation.
When the simulation starts, you should see a population of fish swimming in a lake, represented by a dark blue background. The fish are given a random age from 0 to 9. Each fish executes the same set of behavioral rules: 1) moving, 2) growth and death, 3) reproduction, and 4) survival.
Rule 1-Moving: Fish swims in the simulated lake. When fish encounters a boundary, it resets its direction and moves away.
Rule 2-Growth and death: Fish's age increases every hypothetic year. The fish older than 20 disappear from the simulation; namely, they die.
Rule 3-Reproduction: In each "year," each female RANDOMLY chooses a male from the adjacent area as the mate and reproduces offspring. Most of the offspring fish's color is the average of their parents. In a chance determined by the slider "mutation-rate," a mutant is produced with either a lighter or darker color in comparison with the average parent color. The female preference is controlled by "strength-of-preference." The higher is the preference strength, the more does the female prefers a male with a color similar to her.
Rule 4-Survival: In this module, the more different is the fish color from the background, the more likely is it to become prey. The slider "number-of-visual-predators" enables you to adjust the strength of predation pressure.
Rule 5-Overpopulation: The maximum capacity of the lake is determined by the slider "max-lake-capacity." If the number of fish exceeds the maximum, every fish has a 50% chance of dying regardless of its gender, age, or color.
How can you use the model to simulate allopatric speciation?
How can you use the model to simulate sympatric speciation?
This module is made by Dr. Lin Xiang at University of Kentucky, Lexington, KY. If you mention this model in a publication, we ask that you include the citations below.
Xiang, L. (2017). Speciation mechanisms. Department of STEM Education, University of Kentucky, Lexington, KY.
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