If temperatures had dropped below freezing when I was gone last week, the impatiens in my garden would have died  If the impatiens had died, they obviously could not continue to bloom
However, since the impatiens in my garden are still in bloom today, temperatures did not drop below freezing last week
If the introduction of a new species would adversely affect some species already existing in an environment, that species should not be introduced into it. Ttherefore, since the introduction of species into new environments will result in some species in those environments being adversely affected, species should probably not be introduced into new environments.