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Students often express Lamarckian ideas—that changes acquired during an organism’s lifetime can be inherited—when reasoning about natural selection. Researchers have described this reasoning as arising from incorrect and unproductive misconceptions. Using the theoretical tools of resource theory and data from interviews with college students, we argue that an alternative explanation for students’ apparent Lamarckian reasoning is that they are seeking to provide mechanisms that can account for trait change. Unlike canonical populationlevel mechanisms, organism-level mechanisms are grounded in plausible changes to organismal forms, physiologies, or behaviors. We found that organism-level mechanistic reasoning arose in interviews when students recognized a need for a mechanistic explanation and shifted into an epistemological framing of in-the-moment knowledge construction. Rather than interpret Lamarckian ideas as misconceptions, we argue that they can be viewed as evidence of students' generative epistemological resources for seeking and providing mechanisms. 

Activation of SARS-CoV-2 Spike deploys its fusion peptide to a membrane of the host cell to infect it. NMR in solution demonstrates that this fusion peptide transforms from intrinsic disorder in solution into a wedge-shaped structure inserted in bilayered micelles. According to NOEs and proximity to a nitroxide spin label deep in the membrane mimic, the globular fold of three helices contrasts the open, extended conformations observed in compact prefusion states. In the hydrophobic, narrow end of the wedge, helices 1 and 2 contact the fatty acyl chains of phospholipids. 50 of the resulting paramagnetic NMR relaxation enhancements and 6 lipid-protein NOEs provided ambiguous distances as collective variables (colvars) to bias and guide MD simulations. Simulations in NAMD using the CHARMM36 forcefield included colvars for 130 medium- and long-range NOEs to maintain the equilibrium structure. In the gently NMR-biased simulations, the fusion peptide maintained its insertion of helices 1 and 2 within a single leaflet while helix 3 remained exposed. A cation occasionally visited the anionic side chains in the loop joining helices 2 and 3 or at the N-terminal end of helix 1. The unoccupied leaflet is thinned and distorted opposite the fusion peptide.The thinning could be related to the fusion peptide promoting formation of the hemi-fusion intermediate in the process of viral-cell fusion. Supported by NSF Rapid award 2030473. 

Abstract Wildlife must adapt to human presence to survive in the Anthropocene, so it is critical to understand species responses to humans in different contexts. We used camera trapping as a lens to view mammal responses to changes in human activity during the COVID-19 pandemic. Across 163 species sampled in 102 projects around the world, changes in the amount and timing of animal activity varied widely. Under higher human activity, mammals were less active in undeveloped areas but unexpectedly more active in developed areas while exhibiting greater nocturnality. Carnivores were most sensitive, showing the strongest decreases in activity and greatest increases in nocturnality. Wildlife managers must consider how habituation and uneven sensitivity across species may cause fundamental differences in human–wildlife interactions along gradients of human influence.