Which of the following ecologists proposed the 'rivet popper' hypothesis?

Identify the full form of $IUCN$.

How many species of birds are found in Colombia?

Given below are two statements.
Statement-$I$: Genetic diversity is the diversity in the number and type of genes as well as chromosomes present in the same species and variations in the genes and their alleles.
Statement-$II$: Species diversity deals with the variety of species as well as the number of individuals of different species observed in an area.
In light of the above statements,select the correct answer from the options given below.

How many species of Amphibians are present in the Amazonian rain forest in South America?

Assertion : Diversity observed in the entire geographical area is called gamma diversity.
Reason : Biodiversity decreases from high altitude to low altitude.