This isn't explained by mutation - it would still occur in absense of mutation.
This isn't explained by drift - it would still occur in absense of drift.
This isn't explained by recombination - it would still occur in absense of recombination.
This isn't explained by heredity. Heredity is needed for natural selection to work, but it isn't the only thing that is needed.
Well, then what is this physical process that acts on an organism that can explain the occurance or disappearance of traits that these other processes can not?
The organism itself is the physical process. The biological processes of the organism determines how able that organism is at reproduction.
The biological processes of the organism are determined by its traits. Traits that hinder the organisms ability to replicate will tend to not be passed on and will reduce in number. Traits that aid the organisms ability to replicate will end up being present in more organisms.