Question

Evolution is such a heated topic in various social circles. However, we do have proof of microevolution and speciation. Furthermore, we as humans use the process of artificial selection to create lots of new plant and animal species for a wide variety of reasons. In this discussion, take a stance regarding the theory of evolution. Rules of discussion:

Answer 1

For the present discussion, I will assume the following stance : Evolution doesn't necessarily have to be slow.

Below are the supporting points :

1. In case of Darwinian Finches, a recent report came out of a study of just 20 years of plain observation which stated that the beak sizes of measured Finches fluctuated with the availability of seed grains. This points to the fact that evolution can occur ove short periods.

2. Rapid evolution of Darwinian Finches is now thought to be a product of epigenetics (DNA methylation patterns) rather than mutation. In contrast to mutation events, epigenetic modifications are more frequent, do not affect the stability of gene expression and are adaptable.

3. Rapid evolution can also be seen in cases of microorganism such as bacteria which mutate very quickly. The reason behind these are two - a) random mutation envents and b) mutations events trigerred due to environmental response. The reason that bacteria, virus, etc. mutate very quickly is to escape the highly specific and efficienty defense system of the hosts. In addition, these mutation events are tolerated by the microorganisms since they are not able to affect normal processes.

4. Rapid evolution can occur as a result of several DNA replication errors by chance . This leads to production of mutant phenotypes which if naturally selected may lead to quicker evolution.

5. In case of small populations or populations which experience a genetic bottleneck , the genetic makeup of future offsprings are determined by the little available genes of founder populations. So when a population is small, the probability of a mutation enjoying natural selection is high and thus may lead to quicker evolution and speciation.

6. Genetic drift , also called sampling error, can lead to fixation of alleles rapidly in small populations. Thus when a mutation arises in small population, its probability of the mutated gene or phenotype becoming fixed is high. This may lead to faster evolution.

7. In case of African elephants, the size of the tusks and the abundance of tuskless males have significantly increased in the past 50 years due to hunting pressure. Due to hunting of tusked elephants, their probability of reproducing decreased thus leading to a selection pressure against tusked elephants. This too is an example of faster evolution.