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When is a shrub a tree?

October 8, 2015

With the characteristics described in my “Plant Competition” post, I can loosely model grass, shrubs, and trees by height and width. There is no out and out “that’s a tree” variable in the genetics and so we come to a problem: how do you prevent grass from mating with trees? Genetic algorithms rely on being able to select the highest fitness members of a population, but what if the two most successful members are exceedingly different phenotypically?

As it stands, I only have two phenotypic chromosomes that could make mating undesirable: width and height. The simplest answer is prevent mating between plants that differ in these categories too much.

Many plants are asexual, which is no fun in terms of genetic algorithms which rely on crossover of genes between partners; I’ve excluded them. Without flowering or fruit, there is no real mechanism for non asexual mating, so I have to rely on an abstracted mechanism. I’m flirting with the idea of seeds that land on the same plot have a chance of mating. Though, that’s kind of arbitrary. Right now, the only genetic change occurs through mutation.

Fitness is also hard to determine numerically, as the simulation does not have structured population creation, reproduction, and fitness determination steps, since plants reproduce at different rates. Simply existing in abundance is fitness enough.

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