I think WWF mostly tries to protect creatures that are made extinct by Human actions (Hunting, Pollution, etc.).
Which I don't think is really natural selection.
They should be helping prevent these animals from being extinct because they aren't dying of natural causes, they are dying because of human actions, and because of this the world's ecosystem gets all messed up.
And even if the WWF does protect the animals, natural selection is still going on because the WWF protects these animals in shelters/zoo's so basically these animals aren't involved in the ecosystem anymore.
And when they only find like 2 remaining survivors, the animals sometimes won't even mate with each other.
Also, natural selection doesn't have to be one species being extinct.
For instance, giraffes have longer necks because the giraffes with shorter necks couldn't find mating partners as easily (their mating rituals involve males hitting each other with their necks). Or tallgrass plants in the midwest are usually like up to your face, but in mountains and other high terrains, they are short since the harsh weather/winds destroy the higher tallgrass so the short ones only survive, and therefore the next generation of tallgrass will all be short. (Thank you Bio 101)
I think WWF should only be protecting the Animals that we make extinct, because they are throwing off nature.
Because everything will get extinct, even us humans, it's just a part of nature.