What Is Natural Selection?

When looking through the notebook trying to find the subjects that I wanted to talk about I found two topics that I thought were the most interesting and that I understood the most. The first chapter that I thought was the most interesting to me was natural selection. I think it’s really interesting because it is so prevalent in our lives. There are two different parts of natural selection. There is natural selection itself and then there is also non-adaptive evolution. Natural selection deals with the change of allele frequencies because of the change in the environment. The allele frequencies give us an indication of how much variation there is in a population. A population wants more variation because it allows the population to deal

The first one is directional selection. This type of natural selection moves the allele frequency of the population in one direction. An example of this is moth coloration. The moths that were darker color were able to live because they blended in with the trees unlike the brightly colored moths, therefore, directional selection occurred because it allele frequency was changed but only to one side. The second type is stabilizing selection. This selection moves the allele frequency to the middle. An example of this is human birth weight. If a baby is to big it can have damaging effects on the mother, however if the baby is to small the baby may not live. The final type is diversifying selection. This is when the allele frequency is on the both ends of the phenotype scale. An example of this is birds and their beaks. There are advantages to both large and small beaks but the beaks that were medium size were not able to

If we don’t have antibiotics all bacteria reproduce at a similar rate. With the antibiotic the non-resistant individuals die but there is an increase in the resistant alleles. The genetic diversity is generated by rapid reproduction which because there is an increase rate of mutations which creates new alleles. It is also generated because bacteria can share DNA through gene transfer and they are also able to pick up DNA from the environment. This creates a threat to us because currently scientists have discovered at least one bacteria strain with resistance to each of the current