(Sexual Swimmers)

5 Mate Preference

Three genes affect phenotypic features which come into play in times of mate choice:

head color
color shift from head to consecutive segments in all limbs
favorite color in a potential mate

The first two genes control the coloration of the swimmer. Colors include the six primary and secondary colors of a painter's color wheel: red, orange, yellow, green, blue, and violet (violet being followed by red, in cyclical fashion). They are stored as consecutive integers in the model. An algorithm was designed which is not meant to model any particular biological scheme for animal coloration, but simply to generate phenotypic variety from a small number of genes. Coloration is determined by the following algorithm (expressed in C language).
     for (L=1; L<=num_limbs; L++)
      {
       c = head_color;
       for (S=1; S<=num_segments; S++)
        {
         c = c + color_shift;
         segment(L)(S)color = red + ((int)(c*(float)(violet-red)) % (violet-red));
        }
       }
where c is a positive real number, and head_color and color_shift are positive real numbers, determined by gene values. These two genes control the making a large variety of color patterns in swimmers, including solid colors.

The "favorite color" gene comes into affect when a swimmer is looking for an ideal mate. When sizing up the potential mates within its view, it chooses one who exhibits the largest amount of its favorite color, and, to a lesser extent, the two adjacent colors on the color wheel. For instance, a red-loving swimmer will tend to choose mates having lots of red, violet, and orange. Red would have twice the "strength" as violet or orange, in enticing this swimmer's lust. Swimmers exhibiting none of these colors would not be chosen by the red-loving swimmer.

Amount, not percentage of favorite color in a mate is perceived. Thus, more limbs can potentially have a larger effect - the expectation is that sexual selection can have an effect on the evolution of body size.


6 The Physics of Motion

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