Comments on: Genome Size, Adaptations, Constraints, Exaptations, Aptations, and so on…

By: Greg Laden

Greg Laden — Fri, 18 Jan 2008 16:38:16 +0000

I'm not sure if I follow the logic here. Are you saying that there might be pressure to make smaller cells but the only easy way to do that is to get rid of junk DNA?No, I am not saying that.I still don't see how your hypothesis leads you to claim that junk DNA is a myth.I am not making that connection, nor am I claiming that "junk DNA is a myth."

By: Larry Moran

Larry Moran — Fri, 18 Jan 2008 16:24:42 +0000

I’m not sure if I follow the logic here. Are you saying that there might be pressure to make smaller cells but the only easy way to do that is to get rid of junk DNA?How, exactly, would this work? Let’s say you have some variation in the population where there are some individuals with 1% less DNA in their genomes? Would those individuals have a significant enough selective advantage to ensure fixation of the smaller genome?Does it follow from your scenario that the bloating of the genome in our ancestors had no detrimenatl effect even though it might have led to larger cells and slower metabolic activity? If so, doesn’t that mean that the junk really is junk in most species?I still don’t see how your hypothesis leads you to claim that junk DNA is a myth.

By: Greg Laden

Greg Laden — Fri, 18 Jan 2008 12:55:34 +0000

I have always thought that both the logic and empirical support for adaptationist approaches and neutral approaches were very good but oversimplifid. This is an issue I have thought a great deal about, and I have concluded that both approaches can be accommodated, but neither is very powerful as a model for evolution.

By: TR Gregory

TR Gregory — Fri, 18 Jan 2008 12:51:03 +0000

This is indeed the nature of the issue. It is also why I don’t ascribe to either the adaptationist or neutralist camp (if such there truly be) when it comes to such a complicated topic. We are doing work on quite a number of the questions you cited, so stay tuned.