96 scenario.
The Mystery of the Genome Furthermore, because of high levels of reproductive
noise, we must honestly use a relatively low correlation coefficient when calculating the probability that a superior phenotype will reproduce.
Perhaps 50% of reproductive failure is
independent of phenotype (Figure 8b). The third level of noise – gametic sampling - There is a third level of genetic noise. This is the statistical variation associated with small population sizes. If you toss a coin many times, you will predictably get about 50% heads and 50% tails. However, if you toss the coin just 10 times, there is a good chance you will not get 50/50. You may get 60/40 or 70/30, or you might even get 100% heads. The frequency of each possible outcome is readily predicted by using probability charts. This same type of statistical variation occurs when a gene or nucleotide is segregating within a population. In very large populations, gene segregations tend to be highly predictable, but in smaller populations gene frequency will fluctuate very significantly, and in a random manner – just like a series of coin tosses. Such statistical fluctuations result in what is called genetic drift – which means gene frequencies can change - regardless of the presence or absence of selection. This simple probability element of fluctuating gene frequencies is well studied. Classically, population geneticists have dealt with genetic noise only on the level of this last type of noise - probability fluctuations. This particular type of genetic noise, which I am going to call gametic sampling, is very sensitive to population size. In small populations random genetic drift is very strong and can override the effects of even substantial mutations. This is why the small populations of endangered species are especially subject to what