There is a bird named Jake and his flock is a type of bird that live by the water and are overall a large bird in many different sizes.
There was a mutation in Jake's flock to change shape and size. This made them harder to catch and can't be hunted from humans.
When the hunter came he was able to shoot down the larger bird and the ones in Jake's family that did not have the mutation were shot down.
After the hunting season the birds where able to make more offspring's. Since most of the larger birds were killed the mutated ones were able to reproduce. This is showing habitability because the offspring had the same genes their parents passed down
This is creating a reproductive advantage because since the birds are smaller they are less of a target for the hunters because it makes them harder to hit. Also the hunter does not get as much meat out of killing this bird now. They will survive and be able to reproduce.
After thousands of years almost all of Jake's original flock have been killed off and only the ones with the mutations have survived. The allele frequency has changed to where almost all of springs have the mutations.