What means genetic change in living things over time?

It actually refers to the genetic traits, which change during time, because if you stop to think about it, surely, dogs 400 years ago were not the same as the dogs we see today since they have had changes in their genetic sequences, which adapted them to live better and even new species have appeared (or simply have been "made" which even so, depends on a genetic change).

Hope it helped,

BioTeacher101

a community that experiences major changes undergoes progress