In artificial selection, humans produce new varieties of organisms from wild-type ones. The process draws on the ideas of natural selection, taking advantage of existing genetic diversity, but altering trait distribution at a much faster rate.
For example, in a plant like rapeseed, Brassica rapus, two lines can be selected for different levels of trichomes—the number of protuberances, or hairiness.
The number of trichomes on a plant leaf can naturally vary. Individuals with different amounts—on the extreme ends—can be separated, interbred, and examined after subsequent generations.
To begin the experiment, healthy plants of the same age are obtained to make up Generation 1. The number of trichomes are counted on the petiole of the lowest leaf across several plants.
Two different lines are then created by selecting the top and bottom 10% of the plants from the trichome count: the “high hairiness” and the “low hairiness” lines, respectively.
All of the plants are kept in a well-lit area and well-watered until they develop flowers, typically at around 14 days old.
When the plants produce fully-developed flowers, a pollination wand or paintbrush is used to gently rub against the anther and stigma of one plant’s flowers. The pollen is then transferred inside each flower of every other plant in the same selection line. The process is repeated until all plants have been pollinated.
Following a one-month growing period, the plants should have produced mature seed pods that can be removed once they begin to turn yellow. After removing them, the seeds are collected, planted, and allowed to grow for two weeks.
Finally, the trichomes from this Generation 2 can be counted and recorded for analysis. To analyze the trichome leaf variations, frequency graphs can be generated to compare means between the plant lines and generations.