Actually, it really does fall under all definitions of "natural selection", ...
... even if we, as humans, have learned to manipulate nature for an (unfair?) advantage
Those species that live in deserts and die, die due to lack of food growing/to grow ...
... same with Those that live in deserts here
... they can't grow or survive, they populate more, and have less
... it really IS "natural selection"
I know, there's arguable variation on the thought-process for this ...
... I'm sure Emp'll "set me straight"