1. Explain why species that overlap a great deal in their fundamental niches have a high probability of competing. Now explain why species that overlap a great deal in their realized niches and live in the same area, probably do not compete significantly.

Explanation:

The fundamental niche is the set of conditions in which organisms are required to survive and reproduce themselves. The realized niche is the set of conditions which organisms actually use as a preference after interaction with other species.  

In the fundamental niche the organisms blend with the environment for example, if there are few resources available for survival, the members of the distinct species are likely to compete for those resources.

In the realized niche the organisms, if suffering from lack of resources, they may switch to another niche to prevent suffering and competition with other species. For example, they may change the food preference, or habitat.  

that scientist would be robert hooke