Open Mike: Cornell OBI Conference Chapter 14—“Using Numerical Simulation to Test the “Mutation-Count” Hypothesis” —Discussion excerpt

To facilitate discussion, we are publishing the abstracts and conclusions/summaries/Introduction excerpts of the 24 papers from the Cornell Conference on the Origin of Biological Information here at Uncommon Descent, with cumulative links to previous papers at the bottom of each page. You can get from anywhere to anywhere in the system.

Note: A blow-by-blow account of the difficulties that the authors experienced from Darwin lobby attempts to censor the book by denying it publication with Springer are detailed here. Fortunately, the uproar resulted in an opportunity for readers like yourself to read the book online. That said, the hard cover version is now shipping.

The Conclusion of “Using Numerical Simulation to Test the “Mutation-Count” Hypothesis” by Wesley H. Brewer, John R. Baumgardner, John C. Sanford:

It is widely understood that probability selection is what is generally happening in nature. Truncation selection is the type of artificial selection employed consciously by plant and animal breeders, and is not generally applicable to natural populations (truncation selection seems to primarily be invoked for natural populations only when the MCM is deemed desirable).

However, it is significant to note that given uniform mutation effects and probability selection, as the population approaches zero mean fitness (extinction), we often observe clear evidence of the MCM effect, and this can slow or even stop mutation accumulation. This effect is weakly evident in Figure 2. But this special phenomenon actually helps prove the point, because what is happening as the population approaches extinction is that selection is forced from probability selection into a type of truncation selection. This actually helps demonstrate that some form of truncation is required to activate the MCM. In this particular case, as the population’s mean fitness approaches zero, many individuals have a fitness of zero or less, and they are hence unconditionally removed from the population (truncation).

When selection regimes are employed that are intermediate between probability selection and truncation selection (partial truncation), with mutation effects still being equal and with no environmental variance, there is still a strong MCM effect—which can either slow or halt mutation accumulation (Figure 2). Low levels of environmental variation can interfere with the MCM effect under partial truncation, but cannot by itself negate it (Figure 2). However, higher levels of environmental variation can strongly interfere with the MCM effect (Figure 2), most especially in the case of full truncation selection (not shown).

Although it is instructive to model uniform mutation effects on fitness, we know that mutation fitness effects are never uniform, and are actually extremely variable in all living systems. Therefore we tested how effective the MCM might be, given a distribution of mutation effects which was intermediate between a totally uniform fitness effect and a realistic distribution for higher organisms. We did this by doing experiments using a Weibull distribution of mutation fitness effects having a higher than normal minimal fitness effect (.00001). This is 3,000 times greater than what we consider reasonable (i.e., the inverse of the functional genome size).

In a large genome, there should be many mutation effects smaller than one is a million or even one in a billion. Even in free-living bacteria, deleterious mutation effects should minimally range down to .00001. We did a series of experiments using this more limited range of mutation effects. Given this distribution, the mutations that were accumulating only ranged from .001 to .00001 o(just one to two orders of magnitude). We found that even given this relatively narrow range of accumulating fitness effects, mutation accumulation and fitness decline could not be halted, even under full truncation selection (Figure 3). Some non-linearityof mutation accumulation and fitness decline is evident early in these runs, but in all four experiments these rates eventually became very linear. Mutation accumulation and fitness decline then progressed at constant rates all the way to population collapse just prior to extinction, regardless of whether selection was full truncation, strong truncation, weak truncation, or probability selection. The selection mode merely affected the time to extinction (Figure 3). More.

Open Mike: Origin of Biological Information conference: Origin of life studies flatlined

Open Mike: Cornell OBI Conference— Can you answer these conundrums about information?

Open Mike: Cornell OBI Conference—Is a new definition of information needed for biology? (Chapter 2)

Open Mike: Cornell OBI Conference—New definition of information proposed: Universal Information (Chapter 2)

Open Mike: Cornell OBI Conference—Chapter Three, Dembski, Ewert, and Marks on the true cost of a successful search

Open Mike: Cornell OBI Conference—Chapter Three on the true cost of a successful search—Conservation of information

Open Mike: Cornell OBI Conference—Chapter Four: Pragmatic Information

Open Mike: Cornell OBI Conference—Chapter Four, Pragmatic information: Conclusion

Open Mike: Cornell OBI Conference Chapter Five Abstract

Open Mike: Cornell OBI Conference Chapter Five – Basener on limits of chaos – Conclusion

Open Mike: Cornell OBI Conference Chapter Six – Ewert et all on the Tierra evolution program – Abstract

Open Mike: Cornell OBI Conference Chapter Six – Ewert et all on the Tierra evolution program – Conclusion

Open Mike: Cornell OBI Conference Chapter 7—Probability of Beneficial Mutation— Abstract

Open Mike: Cornell OBI Conference Chapter 7—Probability of Beneficial Mutation— Conclusion

Open Mike: Cornell OBI Conference Chapter 8—Entropy, Evolution and Open Systems—Abstract

Open Mike: Cornell OBI Conference Chapter 8—Entropy, Evolution and Open Systems—Conclusion

Open Mike: Cornell OBI Conference Chapter 9—Information and Thermodynamics in Living Systems—Abstract

Open Mike: Cornell OBI Conference Chapter 9—Information and Thermodynamics in Living Systems—Conclusion

Open Mike: Cornell OBI Conference Chapter 10—Biological Information and Genetic Theory: Introductory Comments—Abstract

Open Mike: Cornell OBI Conference Chapter 10—Biological Information and Genetic Theory: Introductory Comments— Excerpt

Open Mike: Cornell OBI Conference Chapter 11—Not Junk After All—Abstract

Open Mike: Cornell OBI Conference Chapter 11—Not Junk After All—Conclusion

Open Mike: Cornell OBI Conference Chapter 12—“Can Purifying Natural Selection Preserve Biological Information?”—Abstract

Open Mike: Cornell OBI Conference Chapter 12——“Can Purifying Natural Selection Preserve Biological Information?”—Excerpt

Open Mike: Cornell OBI Conference Chapter 13—“Selection Threshold Severely Constrains Capture of Beneficial Mutations”— Abstract

Open Mike: Cornell OBI Conference Chapter 13—“Selection Threshold Severely Constrains Capture of Beneficial Mutations”—Concluding Comments excerpt

Open Mike: Cornell OBI Conference Chapter 14—“Using Numerical Simulation to Test the “Mutation-Count” Hypothesis”—Abstract

One Reply to “Open Mike: Cornell OBI Conference Chapter 14—“Using Numerical Simulation to Test the “Mutation-Count” Hypothesis” —Discussion excerpt”

1. 1
selvaRajan says:

It is really unfortunate that instead of fostering healthy debate with respect for peer view point, scientists are indulging in such despicable behavior. What it also suggests is that the Darwinist have very little faith in their own theory and know it will not stand the test of any scientific criticism