Natural Selection (Evolution)

by dhw, Sunday, August 07, 2011, 16:16 (4856 days ago) @ xeno6696

PART ONE
Matt, I have split this post into two, but please read both before considering a response, as they are interlinked. I would greatly welcome comments from others on this subject, as evolution is such a key topic for all of us.
 
Matt's definition of NS is: "the process by which an organism undergoes environmental pressure and responds to that pressure in its genotype". He has been taught that NS is "the ENTIRE process", which I take to mean the entire process of evolution. I object to any attempt that makes NS and evolution synonymous, as this is a device used by some atheist scientists to ridicule sceptics. NS is scientifically proven, whereas many other aspects of evolution are not. For instance, I pointed out that your definition does not cover "innovations such as sex, flight, sight (i.e. totally new organs, which I would associate with macro-evolution)", and you have ignored this in your response. (N.B. I believe evolution happened, and acknowledge that we cannot make clear distinctions between adaptations and innovations, but the complex mechanisms that lead to NS are the area of contention. That is why they need to be given their own terminology.) My contention, then, is that NS is only part of the process ... namely that which follows adaptations and innovations, and ensures that they survive. Your definition only covers adaptation and doesn't even mention survival. If anything, it corresponds to a definition of epigenetics that I found on Google (I'm afraid I lost the reference):-"an epigenetic trait is a stably inherited phenotype resulting from changes in a chromosome without alterations in the DNA sequence." Shilatifard and colleagues have also proposed three categories of signals that operate in the establishment of a stably heritable epigenetic state. The first is a signal from the environment, the second is a responding signal in the cell that specifies the affected chromosomal location, and the third is a sustaining signal that perpetuates the chromatin change in subsequent generations."-Are you, then, arguing that evolution IS epigenetics IS Natural Selection?
 
MATT: dhw, I guess I misinterpreted your desire... if you don't care to have direct quotes...-You had wasted an hour looking in vain for quotes to prove that "professional scientists" no longer used the Darwinian definition of NS. Do by all means keep searching if you wish. Meanwhile, here are two of several similar definitions of NS googled at random:-Wikipedia: the process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations. 
 
biologyon line: A process in nature in which organisms possessing certain genotypic characteristics that make them better adjusted to an environment tend to survive, reproduce, increase in number or frequency, and therefore, are able to transmit and perpetuate their essential genotypic qualities to succeeding generations. - N.B. In all the current definitions I found, and in all my many reference books, the organisms already have/possess the beneficial traits. -I agree with almost everything in the remainder of this section of your post, except where you continue to make NS synonymous with evolution, and so I will comment only where necessary.
 
MATT: So... Natural Selection isn't JUST what gets left behind, you NEED to look at the entire process, and I think that's why I was taught Natural Selection as the ENTIRE process, and not the pared-down version I see you and David using.
 
NS is an ongoing process: whatever is selected will also be subject to changing environments etc., and so every adaptation and innovation (stage one) will be followed by NS (stage 2) ad infinitum. But adaptation is adaptation and NS is NS, and although they are interdependent, they are not the same thing. The entire process is evolution. See Part Two.