In the late eighteenth century, a typhoon swept through the Pacific atoll of Pingelap, leaving approximately 20 survivors. A large percentage of the present-day inhabitants of Pingelap are color blind. One can conclude, therefore, that the population experienced a .

Genetic bottle neck

Explanation:

Genetic bottle neck is defined as an evolutionary event during which a population is drastically reduced to to a significantly smaller size within a short period of time.

A genetic bottleneck can result from various events such as natural disaster, hunting of a species to a point of extinction or habitat destruction to cause the death of large number of organism.

In the given situation a typhoon which is a type of natural disaster caused the population to reduce to a size of  20 individuals. Then we find that the allele frequencies were greatly changed  and the allele for colorblindness became established.Hence, a large population of present day inhabitant are color blind.

So we can say that the population experienced a genetic bottle neck.

answer: grassland biomes are closer to the equator and receive more rain.

grasslands are biomes that are dominated by grasses rather shrubs and trees. savanna are biomes that exhibit grasses, shrubs and small tree as vegetation. grasslands are located near the equator of the earth. these are found in north america. savanna biomes are found in africa, south america, australia and india. grassland exhibit moderate climatic conditions, it receives   amount of rainfall higher than savanna.   therefore, savanna exhibit dry and hot climatic conditions.