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The geosciences continue to grapple with the exclusion of Black, Indigenous, Latinx, and other students of Color. These patterns can be understood in the discipline’s roots in colonialism and extractivism. Furthermore, training of the scientific process as objective and race-neutral results in scientists who do not recognize how science can perpetuate inequities in society. Using a U.S. university biogeography course as a case study, we describe an innovative framework for teaching equity through a critical historical lens that interrogates: 1) biases in the processes and forms of knowledge production, legitimization, and exclusion; 2) the source of inequities in representation in the discipline; and 3) how societal benefits and harms of scientific practices are felt disproportionately demographically and geographically. Students were encouraged to critically analyze the historical context of scientific theories and their proponents and challenge assumptions about the representativeness of data supporting those theories into the present day. Engaging with these questions broadened students’ understanding of changing paradigms in the field and of links between colonialism and modern science. We provide recommendations for instructors seeking to use similar approaches to enhance student learning. 

ABSTRACT Herbivores must overcome a variety of plant defenses, including coping with plant secondary compounds (PSCs). To help detoxify these defensive chemicals, several insect herbivores are known to harbor gut microbiota with the metabolic capacity to degrade PSCs. Leaf-cutter ants are generalist herbivores, obtaining sustenance from specialized fungus gardens that act as external digestive systems and which degrade the diverse collection of plants foraged by the ants. There is in vitro evidence that certain PSCs harm Leucoagaricus gongylophorus , the fungal cultivar of leaf-cutter ants, suggesting a role for the Proteobacteria -dominant bacterial community present within fungus gardens. In this study, we investigated the ability of symbiotic bacteria present within fungus gardens of leaf-cutter ants to degrade PSCs. We cultured fungus garden bacteria, sequenced the genomes of 42 isolates, and identified genes involved in PSC degradation, including genes encoding cytochrome P450 enzymes and genes in geraniol, cumate, cinnamate, and α-pinene/limonene degradation pathways. Using metatranscriptomic analysis, we showed that some of these degradation genes are expressed in situ . Most of the bacterial isolates grew unhindered in the presence of PSCs and, using gas chromatography-mass spectrometry (GC-MS), we determined that isolates from the genera Bacillus , Burkholderia , Enterobacter , Klebsiella , and Pseudomonas degrade α-pinene, β-caryophyllene, or linalool. Using a headspace sampler, we show that subcolonies of fungus gardens reduced α-pinene and linalool over a 36-h period, while L. gongylophorus strains alone reduced only linalool. Overall, our results reveal that the bacterial communities in fungus gardens play a pivotal role in alleviating the effect of PSCs on the leaf-cutter ant system. IMPORTANCE Leaf-cutter ants are dominant neotropical herbivores capable of deriving energy from a wide range of plant substrates. The success of leaf-cutter ants is largely due to their external gut, composed of key microbial symbionts, specifically, the fungal mutualist L. gongylophorus and a consistent bacterial community. Both symbionts are known to have critical roles in extracting energy from plant material, yet comparatively little is known about their roles in the detoxification of plant secondary compounds. In this study, we assessed if the bacterial communities associated with leaf-cutter ant fungus gardens can degrade harmful plant chemicals. We identify plant secondary compound detoxification in leaf-cutter ant gardens as a process that depends on the degradative potential of both the bacterial community and L. gongylophorus . Our findings suggest that the fungus garden and its associated microbial community influence the generalist foraging abilities of the ants, underscoring the importance of microbial symbionts in plant substrate suitability for herbivores. 

Abstract A paradigm in the plant defence literature is that defending against herbivores comes at a cost to growth, resulting in a growth–defence trade‐off. However, while there is strong evidence for growth–defence trade‐offs across species, evidence is mixed within species.Several mechanisms can account for this equivocal support within species, but teasing them apart requires examining growth–defence relationships both within and among populations, an approach seldom employed.We examined correlations between plant biomass (growth) and terpene production (defence) within and among populations ofMonarda fistulosa, a perennial herb. We sampled populations from Montana and Wisconsin, regions that differ in resource availability characterized by different summer precipitation and associated abiotic conditions that influence plant productivity.We found negative, neutral and positive growth–defence correlations, depending on the scale examined. Negative correlations occurred across populations originating from divergent regions, positive correlations occurred across populations originating from within the high‐resource region and neutral correlations were found within single populations.Collectively, these results challenge the general expectation of ubiquitous trade‐offs and support emerging views that resource availability (as it affects productivity) shapes the evolution of defence at different scales. A freePlain Language Summarycan be found within the Supporting Information of this article.