The number post-reproductive age group will decline in number in a population pyramid.
<h3>What is a population?</h3>
A population is a group of organisms of the same same specie living in a defined area of a given habitat.
A population pyramid shows the number of organisms of age groups in a population.
The post-productive age group is characterized by individuals that are too old to have children.
Since they are too old to have children, the post-reproductive age group will decline in number.
Learn more about population at: brainly.com/question/25896797
Answer:
When starfish were removed from their environment, the species richness of that area went down. This was because the starfish ate the mussels, and when the starfish were removed, the mussels became abundant and preyed on many of the other species.
This experiment showed that the starfish were a keystone species. A keystone species is a species that has a low biomass but a large impact on the community they are living in.
If those are the only answers i would say mutualism