What are some examples of selective pressures?

What is a cordon and where is it found

Explain how ancient whale fossils found in eqypt are believed to support the theory of evolution.

Legumes, a type of plant, require rhizobia, a type of soil bacteria, to survive since these organisms fix nitrogen during photosynthesis. rhizobia use the legumes for food. what would most likely happen to the legume population if rhizobia suddenly became extinct?