Lesson 3 Essay Questions:
1- Compare and contrast directional selection and disruptive selection, and provide an example of each.
Directional selection occurs when one extreme of a trait is favored and the distribution curve shifts in that direction. An example of this is the human struggle with malaria. The mosquito Anopheles transmits the disease. A new drug for the disease and a insecticide for the mosquito was created. But over the years they became resistant to it and multiplied, shifting the distribution curve toward the resistant type of parasite. Disruptive selection is where any two extremes of a trait are favored over any intermediate phenotype. For example, British land snails are found in low vegetation areas. The thrushes feed on snails with dark shells and in the forest they feed on snails with light banded shells. So each phenotype adapted to their environment. (Mader & Windelspecht, 2012)
2- Many pathogenic bacteria species are becoming resistant to antibiotics. Explain how such adaptations can develop through the process of natural selection. (Hint: Relate this example to the conditions that are necessary for natural selection to occur.)
Natural selection is the process that results in adaptation of a population to the environment. This is what happens with antibiotic resistant bacteria. When antibiotic is administered, some bacteria may survive because they are genetically resistant. This bacteria will pass on their genes to the next generation. As a result, the number of resistant bacteria keeps increasing. This is the result of Natural selection, individuals that are better adapted to their environment are more likely to reproduce and their offspring will make up a greater proportion of the next generation. (Mader & Windelspecht, 2012)
3- What are the major evolutionary trends that developed among major vertebrate groups,