A population of ants exists in the isolated habitat of File Drawer on Anna's table. They filled the niche of eating papers, ink and irrtating humans.
Today, a strong artificial selection pressure was applied to the population. Like all artificial selection, the end result is beneficial to Man and the rate of change in allele frequency in the population gene pool is much more rapid than natural selection can bring about. This is a directional selection favouring those ants that display a phenotype that allows them to survive in the presence of the selection pressure, which is Liquid Detergent.
Since there is no pre-existing mutation in the population that created a beneficial allele that allows the ants to be resistant to liquid detergent, all the ants were killed by the application of this selection pressure. This illustrates the importance of genetic diversity in a population, for now one can reasonably assume that there was no variation at the "soap resistance" gene locus, if such a locus ever existed. Hence, no ants are selected for in this exercise, no ants survived to reach reproductive maturity and no ants were able to pass on their alleles to their offspring.
If one or two ants survived, the population would have gone through a genetic bottleneck. The subsequent generations would have even less genetic diversity.
It is also interesting to note that the population on Anna's table is an isolated population. Perhaps Founder's Effect might apply to this population as they have obviously colonized the file drawer from another, faraway region. Interestingly, since physical reproductive isolating mechanisms are in place, had we left them alone, over time the population may have evolved enough to form a new species.
In English:
We found ants on Anna's table. We sprayed liquid detergent on them. All died.
This post is also published at theonlinebioblog.
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