Select an incorrect statement with respect to biodiversity.

Which one of the following reasons is proposed for the greater species diversity in tropical environments compared to temperate ones?

For frugivorous birds and mammals in the tropical forests of different continents,the slope is found to have the value of

Why do the tropics have greater biological diversity?

What is/are the correct explanations for higher diversity in tropical areas in comparison to temperate areas?
$I$. There are no unfavourable seasons in the tropics
$II$. Less solar energy is available in the tropics
$III$. Rate of extinction is low in the tropics
$IV$. Resource availability is higher in the tropics
Choose the correct option.

The observation that "within a region, species richness increases with increasing exploratory area, but only up to a limit" was made by which scientist?