You're very close! While "evolution" is the overall process of change in a population over time, the specific term for a change in a gene within a population over time is "genetic evolution" or "microevolution".

Here's why:

* Evolution is a broad term that encompasses changes in the genetic makeup of a population over many generations. This can involve changes in allele frequencies, the appearance of new traits, or even the emergence of new species.

* Genetic evolution or microevolution refers to the specific changes that occur at the level of genes within a population. This can be due to processes like mutation, natural selection, genetic drift, or gene flow.

So, when a gene changes within a population over time, it's a specific example of genetic evolution, which contributes to the broader process of evolution.