Microevolution is a change in gene frequency in a population. Suppose you sample a beetle population this year, and determine that 80% of the genes in the population are for green coloration and 20% of them are for brown coloration. You go back the next year, repeat the procedure, and find a new ratio: 60% green genes to 40% brown genes. You have detected a microevolutionary pattern: a change in gene frequency. A change in gene frequency over time means that the population has evolved.
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