William C. Beckerson
CourseSource
Abstract: While adaptation by means of natural selection is a widely understood biological phenomenon in today’s scientific community, it was not the only hypothesis of its time seeking to explain the inheritance of traits. In the 19th century, Charles Darwin and Alfred Russel Wallace postulated that descent with modification is the result of environmental factors selecting for preexisting characteristics within a population by killing off individuals less suited for survival in those conditions (natural selection); however, the French naturalist Jean-Baptiste Lamarck had an alternative line of reasoning. He proposed that change over time was instead caused by the subtle acquisition of new characteristics by individuals exposed to adverse environmental pressures, which were then passed down by the parents to their offspring. While countless research endeavors of the 20th century have supported the theory put forth by Darwin and Wallace (e.g., homologous structures in the fossil record, similar development of animal embryos, and genetic similarity between all organisms), the subtle differences between their community-based explanation and Lamarck’s individualistic views can be hard for students to understand, particularly if they have preexisting religious or political views contrary to the topic. To help overcome the misinformed mindset of “evolution is just a theory”, this lesson plan provides educators with a microbiology experiment that can be used to demonstrate the process of Darwinian evolution in real-time using replica plating to showcase the evolution of antibiotic resistance. Educators can thus use this exercise to provide students with concrete evidence of natural selection and explain how evolution applies to their everyday lives.
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