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Fish stocking has been utilized for over a century to offset extirpations or declines in abundance of many native species. These historical declines and hatchery contributions have led to uncertainty surrounding whether many contemporary populations are native, introgressed with hatchery sources, or entirely of hatchery origin. Such uncertainty is problematic for the conservation of native biodiversity as it hampers management agencies' ability to prioritize the conservation of indigenous locally adapted populations. Fortunately, genetic and genomic tools have allowed researchers to investigate these questions, often through the use of clustering or assignment approaches that are predicated on identifiable and consistent divergence between native populations and hatchery sources. Here, we apply these methods to restriction-site associated DNA (RAD) data from 643 brook trout (Salvelinus fontinalis) originating from 13 wild populations and an exogenous hatchery strain to investigate the extent of historical extirpations, hatchery contributions, and processes affecting population structure in a small area of the previously unglaciated Driftless Area of Wisconsin, USA. The results from these analyses suggest that wild populations in this region are genetically distinct even at small spatial scales, lack strong hydrologically associated population structure, rarely exchange gene flow, and have small effective population sizes. Furthermore, wild populations are substantially diverged from known hatchery strains and show minimal evidence of introgression in clustering analyses. However, we demonstrate through empirically informed simulations that distinct wild populations may potentially be hatchery-founded and have since diverged through rapid genetic drift. Collectively, the apparent lack of hydrological population structure and potential for rapid drift in the Driftless Area suggest that many native populations may have been historically extirpated and refounded by stocking events. If this is the case, then commonly used genomic clustering methods and their associated model selection criteria may result in underestimation of hatchery introgression in the face of rapid drift. 

Abstract Large grazers modify vegetated ecosystems and are increasingly viewed as keystone species in trophic rewilding schemes. Yet, as their ecosystem influences are context‐dependent, a crucial challenge is identifying where grazers sustain, versus undermine, important ecosystem properties and their resilience.Previous work in diverse European saltmarshes found that, despite changing plant and invertebrate community structure, grazers do not suppress below‐ground properties, including soil organic carbon (SOC). We hypothesised that, in contrast, eastern US saltmarshes would be sensitive to large grazers as extensive areas are dominated by a single grass,Spartina alterniflora. We predicted that grazers would reduce above‐ and below‐groundSpartinabiomass, suppress invertebrate densities, shift soil texture and ultimately reduce SOC concentration.We tested our hypotheses using a replicated 51‐month large grazer (horse) exclusion experiment in Georgia, coupled with observations of 14 long‐term grazed sites, spanning ~1000 km of the eastern US coast.Grazer exclusion quickly led to increasedSpartinaheight, cover and flowering, and increased snail density. Changes in vegetation structure were reflected in modified soil texture (reduced sand, increased clay) and elevated root biomass, yet we found no response of SOC. Large grazer exclusion also reduced drought‐associated vegetation die‐off.We also observed vegetation shifts in sites along the eastern US seaboard where grazing has occurred for hundreds of years. Unlike in the exclusion experiment, long‐term grazing was associated with reduced SOC. A structural equation model implicated grazing by revealing reduced stem height as a key driver of reduced soil organic carbon.Synthesis: These results illustrate the context dependency of large grazer impacts on ecosystem properties in coastal wetlands. In contrast to well‐studied European marshes, eastern US marshes are dominated and structured by a single foundational grass species resulting in vegetation and soil properties being more sensitive to grazing. Coastal systems characterised by a single foundation species might be inherently vulnerable to large grazers and lack resilience in the face of other disturbances, underlining that frameworks to explain and predict large grazer impacts must account for geographic variation in ecosystem structure. 

While undergraduate Computer Science (CS) degree programs typically prepare students for well-established roles (e.g. software developer, professor, and designer), several emergent CS career roles have gained prominence during the 21st century. CS majors (and students considering CS as a major) are often unaware of the wide range of careers available to job candidates with a CS background. This experience report describes seven innovative courses that broaden awareness of CS career roles and prepare students for technical interviews. Five courses prepared students for these career roles: Full-Stack Developer, Product Manager, ML or NLU Scientist, Technical Entrepreneur, and User Experience Designer/Developer/Researcher. The other two courses had traditional content but explicitly prepared students for technical interviews. These courses were co-developed by industry professionals and CS professors, and co-taught during a semester-long academic program. This paper highlights the replicable aspects of the program: the courses, teaching practices, and evaluation instruments (a teaching practices inventory and a data structures inventory).