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Biologists aim to explain patterns of growth, reproduction, and ageing that characterize life histories, yet we are just beginning to understand the proximate mechanisms that generate this diversity. Existing research in this area has focused on telomeres but has generally overlooked the telomere’s most direct mediator, the shelterin protein complex. Shelterin proteins physically interact with the telomere to shape its shortening and repair. They also regulate metabolism and immune function, suggesting a potential role in life history variation in the wild. However, research on shelterin proteins is uncommon outside of biomolecular work. Intraspecific analyses can play an important role in resolving these unknowns because they reveal subtle variation in life history within and among populations. Here, we assessed ecogeographic variation in shelterin protein abundance across eight populations of tree swallow (Tachycineta bicolor) with previously documented variation in environmental and life history traits. Using blood gene expression of four shelterin proteins in 12-day old nestlings, we tested the hypothesis that shelterin protein gene expression varies latitudinally and in relation to both telomere length and life history. Shelterin protein gene expression differed among populations and tracked non-linear variation in latitude: nestlings from mid-latitudes expressed nearly double the shelterin mRNA on average than those at more northern and southern sites. However, telomere length was not significantly related to latitude. We next assessed whether telomere length and shelterin protein gene expression correlate with 12-day old body mass and wing length, two proxies of nestling growth linked to future fecundity and survival. We found that body mass and wing length correlated more strongly (and significantly) with shelterin protein gene expression than with telomere length. These results highlight telomere regulatory shelterin proteins as potential mediators of life history variation among populations. Together with existing research linking shelterin proteins and life history variation within populations, these ecogeographic patterns underscore the need for continued integration of ecology, evolution, and telomere biology, which together will advance understanding of the drivers of life history variation in nature. 

Problem-based learning (PBL) is gaining momentum in engineering education as a student-centered teaching approach that engages students in problems that mirror realities of practice. While the goal of this pedagogical approach is to more authentically prepare and train students for success in the field, it can be both challenging and frustrating for faculty to effectively implement. In this research paper, the opinions of faculty experts from aerospace engineering and PBL are considered. Data were collected through two structured focus groups to identify areas deemed critical for the transition of an introductory, second-year aerospace engineering course to PBL at an R1 university on the East Coast of the United States. Four different dimensions of PBL integration were considered: design, learning objectives, implementation/facilitation, and assessment. Through a thematic analysis of focus group transcripts, results showed that while the experts identified many areas that were critical to consider during this transition, there are important areas of divergence among the expert groups. In fact, areas of distinct opposition were exposed. This study highlights the importance of considering feedback from both content/technical experts and pedagogical design experts during the development and integration of PBL and lays the groundwork for further exploration of if and how consensus between these two groups can be found to support improved curriculum development. 

This full paper is focused on research into how educators might use concept mapping to explore and design learning experiences in a problem-based learning environment. Attempts to incorporate more open-ended, ill-structured experiences have increased but are challenging for faculty to implement because there are no systematic methods or approaches that support the educator in designing these learning experiences. In the reported work, we present an exploratory study toward a systematic approach for comparing and manipulating problems. The approach combines concept mapping with Jonassen’s characterization of problems and the forms of knowledge required to solve them. We explore manipulation pathways for a problem that can be pursued by an instructor who is interested in impacting the dimensions of structuredness and complexity. We compare similarities and differences among two problems taken from introductory aerospace engineering courses. We consider manipulation of structuredness and complexity and the change propagation in forms of knowledge and solution pathways.