Strategies for assessing what biology majors know about nonadaptive evolution
Evolution instruction has traditionally concentrated on improving students’ understanding of natural selection. This tradition overlooks the paradigm shift that began 35 years ago when Gould and Lewontin highlighted the limitations of an “adaptationist programme.” Evolutionary researchers now widely acknowledge that nonadaptive processes are essential components to understand completely the richness of evolution. To align evolution instruction with evolutionary research, we have developed three concept inventories that can be used to measure effectiveness at teaching nonadaptive evolution: the GeDI for genetic drift; the DCI for dominance relationships in allelic pairs; and the EvoDevoCI for evo-devo. A subset of questions within each of these concept inventories tests whether and how students conflate the target concepts with three common misconceptions about natural selection: overreliance on natural selection as an explanation for evolution; teleological thinking; and essentialism. We analyzed student performance on these nonadaptive evolution concept inventories to determine whether their responses to questions that included answer choices with these natural selection misconceptions was related to their overall performance.
The results for the GeDI and DCI seem to indicate that a better understanding of nonadaptive evolution is associated with a better understanding of natural selection. However, student performance on the subset of questions in the EvoDevoCI with distractors containing misconceptions about natural selection was the same, regardless of student understanding of evo-devo overall. This result may be due to the fact that students encounter genetic drift and dominance relationships repeatedly in a curriculum, but are typically exposed to evo-devo occasionally in isolated, advanced courses. It may also be due to the format of the EvoDevoCI, in which the wrong answer choices were at times written to include words that testwise students tend to use to eliminate wrong answer choices, such as absolutes like only or always. The combined results from the GeDI, DCI, and EvoDevoCI lead us to propose that we can improve instruction by more explicitly including nonadaptive evolutionary mechanisms, interleaving our teaching about natural selection with teaching about other evolutionary mechanisms. This shift in teaching would parallel a shift that began in evolutionary research 35 years ago with Gould and Lewontin’s critique of the adaptationist programme.