Gain in Student Understanding of the Role of Random Variation in Evolution Following Teaching Intervention Based on Luria-Delbruck Experiment

Abstract

Undergraduate students in introductory biology classes are typically saddled with pre-existing popular beliefs that impede their ability to learn about biological evolution. One of the most common misconceptions about evolution is that the environment causes advantageous mutations, rather than the correct view that mutations occur randomly and the environment only selects for mutants with advantageous traits. In this study, a significant gain in student understanding of the role of randomness in evolution was observed after students participated in an inquiry-based pedagogical intervention based on the Luria-Delbruck experiment. Questionnaires with isomorphic questions regarding environmental selection among random mutants were administered to study participants (N = 82) in five separate sections of a sophomore-level microbiology class before and after the teaching intervention. Demographic data on each participant was also collected, in a way that preserved anonymity. Repeated measures analysis showed that post-test scores were significantly higher than pre-test scores with regard to the questions about evolution (F(1, 77) = 25.913, p < 0.001). Participants’ pre-existing beliefs about evolution had no significant effect on gain in understanding of this concept. This study indicates that conducting and discussing an experiment about phage resistance in E. coli may improve student understanding of the role of stochastic events in evolution more broadly, as post-test answers showed that students were able to apply the lesson of the Luria-Delbruck experiment to other organisms subjected to other kinds of selection.

Biological Principles and Threshold Concepts for Understanding Natural Selection

“…There are indications that threshold concepts include abstract concepts that are not necessarily specific to natural selection, but vital for grasping its principles, and these concepts must be pointed out in parallel with the key concepts of natural selection. Concepts that may hinder the learning of natural selection include temporal scale (Catley and Novick 2009;Cheek 2012), spatial scale (Kalinowski et al 2010), probability, and randomness (Garvin-Doxas and Klymkowsky 2008; Mead and Scott 2010;Robson and Burns 2011). Ross et al (2010) have also proposed several biological concepts that they distinguish from being only biological concepts because they concern more fundamental and general aspects of natural science.…”

“…Following reports of students' difficulties by various authors, we concluded that probability and randomness are threshold concepts for understanding natural selection (e.g., Mead and Scott 2010;Robson and Burns 2011). These difficulties appear to be rooted in deep-seated misconceptions about random processes, which may lead people (inter alia) to interpret unusual coincidences as paranormal because they misunderstand the probability of their occurring by chance (Paola 2002).…”

Evolving germs – Antibiotic resistance and natural selection in education and public communication

“…Thus, bacteria provide teachers with an opportunity to demonstrate evolutionary processes in large populations within a school laboratory in real time (Elena & Lenski, 2003;Smith et al, 2015). Researchers have found that these kinds of laboratory set-ups are associated with the successful teaching of evolution (Krist & Showsh, 2007;Delpech, 2009;Robson & Burns, 2011;Serafini & Matthews, 2009), although exact reasons for increased student scores when learning about evolution through bacterial contexts still remain to be explained.…”

“…Among these are that mutations are always harmful (Cho, Kahle & Nordland, 1985) and that evolution is driven by the needs of an organism (Bizzo, 1994). Consequently, Robson and Burns (2011) found interventions that directly target students' understanding of randomness in mutations to enhance learning and comprehension.…”

“…This step (called pawing) involves the initial identification of key components and patterns (Ryan & Bernard, 2003). Three of the authors then independently conducted an inductive coding procedure focusing on pupils' statements regarding the subject matter (antibiotic resistance and/or evolution) and how they referred to the animation (Graneheim & Lundman, 2004;Robson, 2011). During this step, codes were inductively created and labeled with a memo.…”