Rapid evolution or epigenetics? (Introduction)

by dhw, Wednesday, February 23, 2011, 14:04 (5001 days ago) @ David Turell

BBella has been asking some searching questions about the Cambrian debate, and as they tie in with David's post about rapid evolution, I'm combining both threads.
 
DAVID: We know that evolution can be rapid, when dangers confront a species. The NY Times has an article which discusses the 50 year change in an endangered fish in the Hudson river from PCB contamination. A block of six bases was deleted from one gene to accomplish the feat. The mechanism for the gene change is not known.-http://green.blogs.nytimes.com/2011/02/18/speedy-evolution-indeed/-The article goes out of its way to specify that a rare genetic mutation allowed the species to thrive, and although this is a clear example of adaptation and natural selection at work, it's an equally clear example of evolution preserving the status quo. The Atlantic tomcod remained an Atlantic tomcod. At the risk of boring everyone to tears, let me reiterate that adaptation is not the same as innovation, i.e. the survival of a species does not lead to new species. This brings us to the next pointAVID: A new entry in the Cambrian debate. Plankton caused the huge jump in oxygen in the atmosphere:-http://wattsupwiththat.com/ 2/22/11-BBELLA: I read this article and it seems to say that upheavals in the earths crust (volcanic activity/earthquakes?) is what created the increase in plankton that caused more oxygen. Does this then mean when we have earthquakes and volcanic activity now more oxygen is a by-product? We sure could use more O2!-A lovely observation! What interests me, though, is that everyone seems to be concerned about what caused the jump in oxygen. Is anyone asking how a jump in oxygen could result in new species? On the not unreasonable assumption that each generation descends from the preceding generation, and bearing in mind the example of the Atlantic tomcod (or Darwin's finches if you like), why should changes in the atmosphere result in existing creatures changing into different creatures? In other words, what evidence is there that micro-evolution can, even over millions of years, lead to macro-evolution? Epigenetics may explain the former, but it certainly doesn't explain the latter. As always, I'm not questioning whether evolution happened. I'm asking for help in understanding the innovations that led to speciation.