Evolution

Evolution plays a pervasive role in shaping the form and function of all biological molecules and organisms

Students should be able to explain and apply the core concepts underlying the theory of evolution, including the process of natural selection and its molecular basis, and evidence supporting the theory of evolution.

The learning goals below are categorized as introductory A, intermediate B and upper C.

1. The significance of evolution

Evolution is genetic change within a population over time. Understanding evolutionary processes and the supporting evidence is an integral part of the molecular life sciences. It explains many present day issues, such as crop availability and pesticide resistance in agriculture, vaccine and drug development in medicine and regulatory mechanisms in cellular, developmental and behavioral biology.

Associated learning goals

• Students should be able to describe evolution as genetic change in a population over time. A
• Students should be able to analyze preexisting and novel data and relate the findings in light of evolution. B
• Students should be able to relate evolution to concepts in biochemistry and molecular biology. C

2. Mechanisms of evolution

Many mechanisms may drive evolution. These include mutation, migration (gene flow), genetic drift (chance changes from generation to generation) and natural selection.

Associated learning goals

• Students should be able to explain how mechanisms of evolution cause variation within a population. A
• Students should be able to distinguish between random and nonrandom evolutionary processes. B
• Students should be able to demonstrate their understanding of the mechanisms of evolution to relevant issues, such as antibiotic resistance, the occurrence of genetic disorders or cancer therapeutics. C

3. Natural selection is a key evolutionary mechanism

Evolution by natural selection results from differential reproductive success, where individuals with certain heritable traits are more successful. The fitness of an individual and its genotype is directly determined by its relative reproductive success. The fittest individuals will pass their genes to more offspring, driving the evolution of the population. In this way, the population becomes better-suited (adapted) to its environment. Multiple lines of evidence support evolution by natural selection, including the fossil record, homologies and direct observation in laboratory and field studies.

Associated learning goals

• Students should be able to describe the process of natural selection. A
• Students should be able distinguish between individual fitness and adaptation of populations. B
• Students should be able to explain how selection of phenotypes affects genotype transmission. B
• Students should be able to synthesize and evaluate supporting evidence for the theory of natural selection. C

4. The molecular basis of evolution

Organismal traits are determined at the genetic and epigenetic level. Molecular modifications at these levels may determine the RNA and protein expression patterns in a cell, influencing the phenotype of the organism. Genetic modifications can also arise from the acquisition of new genetic material via processes such as horizontal gene transfer, endosymbiosis and viral vector transfer. Transmission of these heritable alterations may lead to changes in the genetic composition of a population, thereby driving evolution.

Associated learning goals

• Students should be able to explain how cells can acquire new genetic material. A
• Students should be able to explain how mutations and epigenetic changes influence gene expression, structure and function of gene products and the fitness of an organism. B
• Using genetic information, students should be able to categorize organisms and establish phylogenetic relationships. C