Multilevel Selection in the Margins: A Review of Its Representation in Undergraduate Biology Textbooks.

Multilevel selection (MLS) is a foundational framework that expands the concept of natural selection beyond the traditional focus on individuals or genes to larger units, like groups. Despite strong empirical support and applications in a broad range of biological fields, MLS, often referred to as group selection, has a controversial history, which has impeded its wide use and led to incorrect inferences on the sources and strength of selection. Here, we explore how MLS is currently presented to undergraduate biology students by analyzing the content of nine commonly used Evolutionary Biology and Animal Behavior textbooks. We ask whether and how the textbooks describe MLS-as part of the toolbox of evolutionary theory, as a controversial topic, or not at all. Using qualitative textual analysis and descriptive statistics, we found that MLS was mentioned in all of the textbooks analyzed, although usually only in the context of the evolution of social behavior. MLS was generally dismissed as unimportant when compared to individual selection and given less space and fewer examples than kin selection. We highlight the value of a more accurate presentation of MLS and present suggestions for teaching MLS in undergraduate courses based on empirically supported practices in biology education.