Genome complexity; epigenetics: Lamarck is back (Introduction)

by David Turell , Friday, August 31, 2018, 19:18 (2277 days ago) @ dhw

QUOTE: The second kind of epigenetic change causes unforeseen modification to an organism without altering the genetic coding for specific genes, but it also passes on these changes. It can cause change ranging from minor to profound, and can be heritable. “Lamarckian” change is where something encountered in its environment, and not necessarily expected in the life of an organism, causes chemical changes to the DNA through the addition of tiny molecules, or through a shape change of the scaffolding that holds the twisted DNA molecules in specific shapes. Other kinds of epigenetic change can also be caused by the actions of small RNA molecules responding to some kind of external environmental change. Peter Ward, “Why the Earth Has Fewer Species Than We Think”

DAVID: This fits Tony's idea about species.

dhw: It fits the idea that environmental change is the trigger for organismal change, whether adaptation or innovation. I see no hint of advance planning here, or of new organisms suddenly appearing out of nowhere.

DAVID: Advanced planning has evidence in a huge gap like the Cambrian Explosion. No explanation as yet for the Cambrian animals who appear out of nowhere.

dhw: You claimed that Lamarckian change, as quoted above, fitted Tony’s ideas about species. These include advance planning and new organisms appearing out of nowhere. I have simply pointed out that Lamarckian change, as quoted above, makes no mention of advance planning or of new organisms coming out of nowhere. So how does it fit Tony's ideas about species?

Ward's point is some species are really Lamarckian adaptations of existing species and therefore not a new species. Tony's 'staged advances' from existing forms is simply a similar thought pattern I think. The evidence for advanced planning lies in the Cambrian gap in phenotypes.