A, B and C are the events that will cause an ecological disturbance.
Rationale:
A. Introduction of a new species: When a new specie is introduced, it increases the competition in ecosystem with the native species for food, water, space and shelter. This affects the reproductive success of the native species and thus the dynamics of ecosystem.
B. Climate change: Climate change is different from a simple change of weather. The best example would be of Antarctica where the ice is melting fast due to the global warming. The native species find it harder to adapt to the warm temperatures.
C. Late spring snowstorm: Spring is the season where the plants grow and animals shed their fur. When snowstorms occur in this season they harm these plants and animals that live there.
<span>The mechanism that affected the gene pool of the immigrants that entered the United States through Ellis Island from 1892 to 1954 is B. gene flow. Gene flow is the transfer of genes or alleles from one population to another. The migration of millions of individuals from countries across the Atlantic Ocean to the United States is responsible for the changes in the gene pool of the immigrants.</span>
It reduces the amount of harmful rays released by the sun and It increases the levels of carbon dioxide in the air.
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