Denise S. Pope

Testing function of fiddler crab claw waving by manipulating social context

Abstract Many territorial advertisement signals are thought to be dual-function signals, directed to both rival male and receptive female conspecifics. However, few studies have tested this assumption by examining whether in fact both sexes are likely to elicit signaling behavior from territorial males. In this study, I experimentally manipulated the social context of male sand fiddler crabs (Uca pugilator) to investigate the effect of different audiences on the performance of the claw-waving display, a territorial signal that is often presumed to be directed to both males and females. To test whether males perform this signal to both audiences, I measured the frequency of waving behavior by focal males when housed in field enclosures alone, with only males, with only females, or with both males and females. Focal males waved at a low frequency when alone, and the presence of males had no effect on their level of waving. However, in the presence of females, focal males showed a significantly higher level of waving, whether or not males were also present. In addition, there was no association between fighting and waving behavior. This experiment provides evidence that from the perspective of the signaling male, the claw-waving display of U. pugilator is not a dual-function signal but rather is primarily directed to receptive females.

Observing populations and testing predictions about genetic drift in a computer simulation improves college students’ conceptual understanding

BackgroundEvolution is a difficult subject for students, with well-documented confusion about natural selection, tree thinking, and genetic drift among other topics. Here we investigate the effect of a simulation-based module about the conservation of black-footed ferrets, a module designed with pedagogical approaches that have been demonstrated to be effective, for teaching genetic drift. We compared performance on the Genetic Drift Inventory (GeDI) of students who completed the module and students who were in classes that used other methods for teaching genetic drift.ResultsStudents in 19 courses using the simulation-based module improved their understanding of genetic drift significantly after completing the Ferrets module, as measured by the GeDI. Students in five control courses actually performed significantly worse on the GeDI after instruction. The lower scores in the control courses were driven by a decrease in these students’ understanding of key concepts.ConclusionsThe Ferrets module appears to be an effective way to teach genetic drift. In the control courses, students’ progress in understanding genetic drift may pass through a stage where their understanding of key concepts is worse than it was prior to instruction. However, students who learned genetic drift in courses that used the Ferrets module showed a more rapid increase in their understanding of key concepts related to genetic drift. This result suggests that the paths that students can take to move from novice to expert understanding may be more varied than was previously predicted.

Testing the effectiveness of two natural selection simulations in the context of a large-enrollment undergraduate laboratory class

BackgroundSimulations can be an active and engaging way for students to learn about natural selection, and many have been developed, including both physical and virtual simulations. In this study we assessed the student experience of, and learning from, two natural selection simulations, one physical and one virtual, in a large enrollment introductory biology lab course. We assigned students to treatments (the physical or virtual simulation activity) by section and assessed their understanding of natural selection using a multiple-choice pre-/post-test and short-answer responses on a post-lab assignment. We assessed student experience of the activities through structured observations and an affective survey.ResultsStudents in both treatments showed increased understanding of natural selection after completing the simulation activity, but there were no differences between treatments in learning gains on the pre-/post-test, or in the prevalence of concepts and misconceptions in written answers. On a survey of self-reported enjoyment they rated the physical activity significantly higher than the virtual activity. In classroom observations of student behavior, we found significant differences in the distribution of behaviors between treatments, including a higher frequency of off-task behavior during the physical activity.ConclusionsOur results suggest that both simulations are valuable active learning tools to aid students’ understanding of natural selection, so decisions about which simulation to use in a given class, and how to best implement it, can be motivated by contextual factors.