[dnautics]

> Over the extremely long run regions of the genome that have no biological function should disappear, no?

I think the only argument you can make is that 'eventually a neutral deletion would delete it' but I don't think we have a sense of what the timescale of that should be, and anyways, that isn't 'natural selection', unless you have some sort of argument that there is some intrinsic burden to maintaining DNA. If there is such a burden, it's very low, and probably doesn't affect the reproductive fitness of most organisms (esp. not higher organisms).

I think maybe for a really small organism, like on the order of Mycoplasma, or viruses, the carrying extra base pairs burden can be real, but this is not a general rule across biology.

[panabee]

hypothesis: one purpose of "junk" DNA is to guard against viral disruption of coding regions.

even if they serve no purpose except to fill space, the added base pairs create "decoy" areas of DNA and decrease the likelihood of random mutations affecting vital functions.