You have dominant genes (brown eyes) and recessive genes (green eyes)
In order for a child to be born with brown eyes only one parent needs to have brown eyes. Having green eyes is recessive so either both parents need to have green eyes or neither of them needs to have them. But if one parent has green eyes and the other has brown eyes, then the brown eyed gene will almost always dominate the green eyed one.
A population decrease in primary producers would affect the ecosystem negatively because everyone who ate the primary consumers would have a lack of food.
