College of Letters & Science
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The College of Letters and Science, the largest center for learning, teaching and research at Montana State University, offers students an excellent liberal arts and sciences education in nearly 50 majors, 25 minors and over 25 graduate degrees within the four areas of the humanities, natural sciences, mathematics and social sciences.
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Item Yellowstone Cutthroat Trout Recovery in Yellowstone Lake: Complex Interactions Among Invasive Species Suppression, Disease, and Climate Change(Wiley, 2023-10) Glassic, Hayley C.; Chagaris, David D.; Guy, Christopher S.; Tronstad, Lusha M.; Lujan, Dominque R.; Briggs, Michelle A.; Albertson, Lindsey K.; Brenden, Travis O.; Walsworth, Timothy E.; Koel, Todd M.n Yellowstone Lake, Wyoming, the largest inland population of nonhybridized Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri, hereafter Cutthroat Trout, declined throughout the 2000s because of predation from invasive Lake Trout Salvelinus namaycush, drought, and whirling disease Myxobolus cerebralis. To maintain ecosystem function and conserve Cutthroat Trout, a Lake Trout gill netting suppression program was established in 1995, decreasing Lake Trout abundance and biomass. Yet, the response of Cutthroat Trout to varying Lake Trout suppression levels, collectively with the influence of disease and climate, is unknown. We developed an ecosystem model (calibrated to historical data) to forecast (2020–2050) whether Cutthroat Trout would achieve recovery benchmarks given disease, varying suppression effort, and climate change. Lake Trout suppression influenced Cutthroat Trout recovery; current suppression effort levels resulted in Cutthroat Trout recovering from historical lows in the early 2000s. However, Cutthroat Trout did not achieve conservation benchmarks when incorporating the influence of disease and climate. Therefore, the National Park Service intends to incorporate age‐specific abundance, spawner biomass, or both in conservation benchmarks to provide better indication of how management actions and environmental conditions influence Cutthroat Trout. Our results illustrate how complex interactions within an ecosystem must be simultaneously considered to establish and achieve realistic benchmarks for species of conservation concern.Item Declines in body size of sockeye salmon associated with increased competition in the ocean(The Royal Society, 2023-02) Ohlberger, Jan; Cline, Timothy J.; Schindler, Daniel E.; Lewis, BertDeclining body sizes have been documented for several species of Pacific salmon; however, whether size declines are caused mainly by ocean warming or other ecological factors, and whether they result primarily from trends in age at maturation or changing growth rates remain poorly understood. We quantified changes in mean body size and contributions from shifting size-at-age and age structure of mature sockeye salmon returning to Bristol Bay, Alaska, over the past 60 years. Mean length declined by 3%, corresponding to a 10% decline in mean body mass, since the early 1960s, though much of this decline occurred since the early 2000s. Changes in size-at-age were the dominant cause of body size declines and were more consistent than trends in age structure among the major rivers that flow into Bristol Bay. Annual variation in size-at-age was largely explained by competition among Bristol Bay sockeye salmon and interspecific competition with other salmon in the North Pacific Ocean. Warm winters were associated with better growth of sockeye salmon, whereas warm summers were associated with reduced growth. Our findings point to competition at sea as the main driver of sockeye salmon size declines, and emphasize the trade-off between fish abundance and body size.Item Understanding Local Adaptation to Prepare Populations for Climate Change(Oxford University Press, 2022-11) Meek, Mariah H; Beever, Erik A; Barbosa, Soraia; Fitzpatrick, Sarah W; Fletcher, Nicholas K; Mittan-Moreau, Cinnamon S; Reid, Brendan N; Campbell-Staton, Shane C; Green, Nancy F; Hellmann, Jessica JAdaptation within species to local environments is widespread in nature. Better understanding this local adaptation is critical to conserving biodiversity. However, conservation practices can rely on species’ trait averages or can broadly assume homogeneity across the range to inform management. Recent methodological advances for studying local adaptation provide the opportunity to fine-tune efforts for managing and conserving species. The implementation of these advances will allow us to better identify populations at greatest risk of decline because of climate change, as well as highlighting possible strategies for improving the likelihood of population persistence amid climate change. In the present article, we review recent advances in the study of local adaptation and highlight ways these tools can be applied in conservation efforts. Cutting-edge tools are available to help better identify and characterize local adaptation. Indeed, increased incorporation of local adaptation in management decisions may help meet the imminent demands of managing species amid a rapidly changing world.Item Warming temperatures affect meadow‐wide nectar resources, with implications for plant–pollinator communities(Wiley, 2022-07) McCombs, Audrey L.; Debinski, Diane M.; Reinhardt, Keith; Germino, Matthew J.; Caragea, PetrutzaNectar production may be a point of sensitivity that can help link primary and secondary trophic responses to climate shifts, and is therefore important to our understanding of ecosystem responses. We evaluated the nectar response of two widespread native forbs, Balsamorhiza sagittata and Eriogonum umbellatum, to experimental warming in a high-elevation sagebrush meadow in the Teton Range, WY, USA, over two years, 2015 and 2016. Warming treatments reduced the occurrence of nighttime freezing and nectar volume but increased sugar concentration in nectar in both species in both years. Warming effects were also evident in a consistent increase in the number of flowers produced by B. sagittata. Our research suggests that warming associated with climate change has the potential to induce shifts in the nectar-feeding community by changing nectar characteristics such as volume and sugar concentration to which nectar feeders are adapted.Item Earlier spring snowmelt drives arrowleaf balsamroot phenology in montane meadow(Wiley, 2022-08) Durney, J. Simone; Engel, Arden; Debinski, Diane M.; Burkle, Laura A.Climate change is shifting phenology globally, altering when and how species respond to environmental cues such as temperature and the timing of snowmelt. These shifts may result in phenological mismatches among interacting species, creating cascading effects on community and ecosystem dynamics. Using passive warming structures and snow removal, we examined how experimentally increased temperatures, earlier spring snowmelt, and the poorly understood interaction between warming and earlier spring snowmelt affected flower onset, flowering duration, and maximum floral display of the spring-flowering montane species, arrowleaf balsamroot (Balsamorhiza sagittata), over a 7-year period. Additionally, potential cumulative effects of treatments were evaluated over the study duration. The combination of heating with snow removal led to earlier flower onset, extended flowering duration, and increased maximum floral display. While there was year-to-year variation in floral phenology, the effect of heating with snow removal on earlier onset and maximum floral display strengthened over time. This suggests that short-term studies likely underestimate the potential for climate change to influence phenological plant traits. Overall, this research indicates that B. sagittata's flowering onset responded more strongly to snow removal than to heating, but the combination of heating with snow removal allowed plants to bloom earlier, longer, and more profusely, providing more pollinator resources in spring. If warming and early snowmelt cause similar responses in other plant species, these patterns could mitigate phenological mismatches with pollinators by providing a wider window of time for interaction and resiliency in the face of change. This example demonstrates that a detailed understanding of how spring-flowering plants respond to specific aspects of predicted climatic scenarios will improve our understanding of the effects of climate change on native plant–pollinator interactions in montane ecosystems. Studies like this help elucidate the long-term physiological effects of climate-induced stressors on plant phenology in long-lived forbs.Item Warming temperatures affect meadow‐wide nectar resources, with implications for plant–pollinator communities(Wiley, 2022-07) McCombs, Audrey L.; Debinski, Diane M.; Reinhardt, Keith; Germino, Matthew J.; Caragea, PetrutzaNectar production may be a point of sensitivity that can help link primary and secondary trophic responses to climate shifts, and is therefore important to our understanding of ecosystem responses. We evaluated the nectar response of two widespread native forbs, Balsamorhiza sagittata and Eriogonum umbellatum, to experimental warming in a high-elevation sagebrush meadow in the Teton Range, WY, USA, over two years, 2015 and 2016. Warming treatments reduced the occurrence of nighttime freezing and nectar volume but increased sugar concentration in nectar in both species in both years. Warming effects were also evident in a consistent increase in the number of flowers produced by B. sagittata. Our research suggests that warming associated with climate change has the potential to induce shifts in the nectar-feeding community by changing nectar characteristics such as volume and sugar concentration to which nectar feeders are adapted.Item Earlier spring snowmelt drives arrowleaf balsamroot phenology in montane meadows(Wiley, 2022-08) Durney, J. Simone; Engel, Arden; Debinski, Diane M.; Burkle, Laura A.Climate change is shifting phenology globally, altering when and how species respond to environmental cues such as temperature and the timing of snowmelt. These shifts may result in phenological mismatches among interacting species, creating cascading effects on community and ecosystem dynamics. Using passive warming structures and snow removal, we examined how experimentally increased temperatures, earlier spring snowmelt, and the poorly understood interaction between warming and earlier spring snowmelt affected flower onset, flowering duration, and maximum floral display of the spring-flowering montane species, arrowleaf balsamroot (Balsamorhiza sagittata), over a 7-year period. Additionally, potential cumulative effects of treatments were evaluated over the study duration. The combination of heating with snow removal led to earlier flower onset, extended flowering duration, and increased maximum floral display. While there was year-to-year variation in floral phenology, the effect of heating with snow removal on earlier onset and maximum floral display strengthened over time. This suggests that short-term studies likely underestimate the potential for climate change to influence phenological plant traits. Overall, this research indicates that B. sagittata's flowering onset responded more strongly to snow removal than to heating, but the combination of heating with snow removal allowed plants to bloom earlier, longer, and more profusely, providing more pollinator resources in spring. If warming and early snowmelt cause similar responses in other plant species, these patterns could mitigate phenological mismatches with pollinators by providing a wider window of time for interaction and resiliency in the face of change. This example demonstrates that a detailed understanding of how spring-flowering plants respond to specific aspects of predicted climatic scenarios will improve our understanding of the effects of climate change on native plant–pollinator interactions in montane ecosystems. Studies like this help elucidate the long-term physiological effects of climate-induced stressors on plant phenology in long-lived forbs.Item Shifts in the wintering distribution and abundance of emperor geese in Alaska(Elsevier BV, 2021-01) Uher-Koch, Brian D.; Buchheit, Raymond M.; Eldermire, Charles R.; Wilson, Heather M.; Schmutz, Joel A.For wildlife species that winter at northern latitudes, harsh overwinter conditions can play an important role in population dynamics. Recent changes in global temperatures have resulted in distributional shifts of wildlife species, as well as amelioration of winter climates in northern landscapes. The emperor goose (Anser canagicus), an endemic migratory bird of the Bering Sea region, winters across a large area of the subarctic, with potential differences in migration strategies and costs among individuals. As a long-standing species of conservation concern due to decreased population size, understanding the response of emperor geese to changing conditions has become critical to on-going management. We sought to evaluate changes in wintering distribution and arrival/departure dates over time, by comparing spatial and temporal patterns of wintering emperor geese from 2015 to 2017 (using geolocator data) to satellite telemetry data collected from 1999 to 2004. Further, we quantified changes in spatial patterns of winter abundance by comparing historical and contemporary aerial and ground surveys at three island complexes encompassing most of their winter distribution. Our results indicate that emperor geese are arriving at wintering areas earlier and spending more time at these areas than in the past. Our comparisons among historical aerial and ground surveys suggests that increasing numbers of emperor geese are wintering closer to breeding areas in western Alaska; a change likely related to increasing habitat availability due to shifting environmental conditions. Our results also showed that fewer emperor geese are using an area in the core of their wintering range, suggesting either decreased habitat quality or a reduction in migration distance via alternative wintering locations. Overall, our study highlights a rapid response to apparent habitat change likely due to warming temperatures and a reduction in ice cover and emphasizes the importance of understanding complex interactions among migration distance, the environment, and habitat in interpreting site selection.Item Warming alters coupled carbon and nutrient cycles in experimental streams.(2016-06) Williamson, Tanner J; Cross, Wyatt F.; Benstead, Jonathan P; Gislason, Gisli M; Hood, James M.; Huryn, Alexander D.; Johnson, Philip W; Welter, Jill RAlthough much effort has been devoted to quantifying how warming alters carbon cycling across diverse ecosystems, less is known about how these changes are linked to the cycling of bioavailable nitrogen and phosphorus. In freshwater ecosystems, benthic biofilms (i.e. thin films of algae, bacteria, fungi, and detrital matter) act as biogeochemical hotspots by controlling important fluxes of energy and material. Understanding how biofilms respond to warming is thus critical for predicting responses of coupled elemental cycles in freshwater systems. We developed biofilm communities in experimental streamside channels along a gradient of mean water temperatures (7.5–23.6 °C), while closely maintaining natural diel and seasonal temperature variation with a common water and propagule source. Both structural (i.e. biomass, stoichiometry, assemblage structure) and functional (i.e. metabolism, N2-fixation, nutrient uptake) attributes of biofilms were measured on multiple dates to link changes in carbon flow explicitly to the dynamics of nitrogen and phosphorus. Temperature had strong positive effects on biofilm biomass (2.8- to 24-fold variation) and net ecosystem productivity (44- to 317-fold variation), despite extremely low concentrations of limiting dissolved nitrogen. Temperature had surprisingly minimal effects on biofilm stoichiometry: carbon:nitrogen (C:N) ratios were temperature-invariant, while carbon:phosphorus (C:P) ratios declined slightly with increasing temperature. Biofilm communities were dominated by cyanobacteria at all temperatures (>91% of total biovolume) and N2-fixation rates increased up to 120-fold between the coldest and warmest treatments. Although ammonium-N uptake increased with temperature (2.8- to 6.8-fold variation), the much higher N2-fixation rates supplied the majority of N to the ecosystem at higher temperatures. Our results demonstrate that temperature can alter how carbon is cycled and coupled to nitrogen and phosphorus. The uncoupling of C fixation from dissolved inorganic nitrogen supply produced large unexpected changes in biofilm development, elemental cycling, and likely downstream exports of nutrients and organic matter.