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For nearly 30 years, biologists have documented a striking pattern of intra-species genetic divergence on the Baja California peninsula in dozens of disparate species. Evolutionary theory predicts that when such a pattern is shared among species the cause is extrinsic (e.g., environmental, climatic, physiographic, geological). The leading hypothesis within biological literature has been that genetic divergence was facilitated by flooding across the central peninsula by a seaway between ~3-1 Ma, resulting in separation of northern and southern populations. However, new detailed geologic mapping from the Baja GeoGenomics consortium reveals evidence for continuous terrestrial environments during the last ~30 Myr in a ≥40-km-wide ~E-W region of the central peninsula that straddles the modern-day crest, conclusively refuting the seaway hypothesis. Through integration of tectonic, volcanic, and sedimentological evidence with genomic (DNA) and gene expression (RNA) data for plants and animals, we are developing a new working model for Earth-life evolution on the peninsula over the last ~5 Myr. In this model, rift-related uplift drives the growth and dissection of topography, causing increased microenvironmental heterogeneity that populations differentially adapted to in the north and south. This is evidenced by widespread, statistically significant niche divergence in populations between northern and southern Baja in 21 studied taxa. This pattern is supported by strong differences in gene expression in northern and southern populations of two lizard species, particularly in genes relating to metabolism, which may indicate different diet or energy requirements between the regions. Habitats in the north and south then shifted due to glacial and interglacial periods, indicated by hindcasting the estimated niche conditions of those 21 taxa. With ongoing analyses, we expect to find genomic signatures of differential natural selection and adaptation within these species due in part to monsoon-driven rainfall differences. The significance of this work is twofold: it demonstrates the importance of incorporating geological data into evolutionary hypotheses and it cautions how mis-assigning cause-effect relationships in individual Earth-life systems can bias our fundamental understanding of how Earth processes shape biological evolution writ large. 

Abstract. Recent research on fold-switching metamorphic proteins has revealed some notable exceptions to Anfinsen's hypothesis of protein folding. We have previously described how a single point mutation can enable a well-folded protein domain, one of the two PAS (Per-ARNT-Sim) domains of the human ARNT (aryl hydrocarbon receptor nuclear translocator) protein, to interconvert between two conformers related by a slip of an internal β strand. Using this protein as a test case, we advance the concept of a “fragile fold”, a protein fold that can reversibly rearrange into another fold that differs by a substantial number of hydrogen bonds, entailing reorganization of single secondary structure elements to more drastic changes seen in metamorphic proteins. Here we use a battery of biophysical tests to examine several factors affecting the equilibrium between the two conformations of the switching ARNT PAS-B Y456T protein. Of note is that we find that factors which impact the HI loop preceding the shifted Iβ strand affect both the equilibrium levels of the two conformers and the denatured state which links them in the interconversion process. Finally, we describe small molecules that selectively bind to and stabilize the wild-type conformation of ARNT PAS-B. These studies form a toolkit for studying fragile protein folds and could enable ways to modulate the biological functions of such fragile folds, both in natural and engineered proteins. 

The need to train sustainability scientists and engineers to address the complex problems of our world has never been more apparent. We organized an interdisciplinary team of instructors from universities in the states of Maine, New Hampshire, and Rhode Island who designed, taught, and assessed a multi-university course to develop the core competencies necessary for advancing sustainability solutions. Lessons from the course translate across sustainability contexts, but our specific focus was on the issues and trade-offs associated with dams. Dams provide numerous water, energy, and cultural services to society while exacting an ecological toll that disrupts the flow of water, fish, and sediment in rivers. Like many natural resource management challenges, effective dam decisions require collaboration among diverse stakeholders and disciplines. We linked key sustainability principles and practices related to interdisciplinarity, stakeholder engagement, and problem-solving to student learning outcomes that are generalizable beyond our dam-specific context. Students and instructors co-created class activities to build capacity for interdisciplinary collaboration and encourage student leadership and creativity. Assessment results show that students responded positively to activities related to stakeholder engagement and interdisciplinary collaboration, particularly when practicing nested discussion and intrapersonal reflection. These activities helped broaden students’ perspectives on sustainability problems and built greater capacity for constructive communication and student leadership.