A scientist studied a population of gorillas in central Africa for one year. During this time, four gorillas were born and one orphaned gorilla joined the group. Two older gorillas died and three males left the population to find mates.
The calculated population growth was (zero, positive, or negative) , indicating that the population (was growing, was shrinking, had not net change).

the population of unionid mussels in the hudson river decreased after zebra mussels were introduced. zebra mussels, a nonnative species, competed with the unionid mussels for food. the zebra mussels were able to outcompete the unionid mussels, allowing the zebra mussel population to increase dramatically over six years. the unionid mussel population decreased due to a lack of food.

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