A virus killed most of the blue-footed ducks in Japan reducing the population from 9,000 to 900. In an effort to help preserve the species, 50 blue-footed ducks were trapped and used to start a new population in England. Eventually the two blue-footed duck populations could no longer successfully interbreed. This event would best be described as -

Speciation

Explanation:

When the virus reduced the population of the blue-footed a new population of the same bird trapped in England can no longer interbreed. This event can be described as speciation.

Speciation is the process by which a new species with a different character from the parent trait is formed during evolution. Speciation can occur as a result of the absence of an organism from its population for a long time. This is basically how new species are produced and these organisms find it difficult to reproduce with each other after speciation.

The geographic isolation caused the speciation that the blue-footed ducks encountered

explanation:

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.