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 Asynchrony between solitary bee emergence and flower availability reduces flower visitation rate and may affect offspring size(Elsevier, 2021-08) Slominski, Anthony H.; Burkle, Laura A.Climate change can disrupt plant-pollinator interactions when shifts in the timing of pollinator activity and flowering occur unequally (i.e., phenological asynchrony). Phenological asynchrony between spring-emerging solitary bees and spring-flowering plants may cause bees to experience food deprivation that can affect their reproductive success. However, the mechanisms underlying the effects of food deprivation on solitary bee reproduction remain unknown. We investigated 1) whether food deprivation caused by phenological asynchrony affects solitary bee reproduction by influencing female lifespan and/or visitation to flowers, and 2) the relationship between the magnitude of asynchrony and bee responses. We simulated phenological asynchrony by depriving emerged female Osmia cornifrons (a spring-active solitary bee species) of nectar and pollen for 0 to 16 days. Following asynchrony treatments, we used flight cages to monitor 1) post-treatment female lifespan, 2) flower visitation, and 3) reproduction (i.e., total offspring, offspring weight, sex ratio). We found that post-treatment female lifespan was not affected by phenological asynchrony treatments, but that flower visitation rate and offspring weight decreased as the magnitude of asynchrony increased. Due to low offspring production and a lack of female offspring across treatments, we were unable to assess the effects of phenological asynchrony on total offspring produced or sex ratio. Findings suggest that post-emergence food deprivation caused by phenological asynchrony may affect offspring size by influencing nest-provisioning rates. In solitary bees, body size influences wintering survival, fecundity, and mating success. Thus, phenological asynchrony may have consequences for solitary bee populations that stem from reduced flower visitation rates, and these consequences may increase as the magnitude of asynchrony increases. Because many wild flowering plants and crops rely on pollination services provided by bees for reproductive success, bee responses to phenological asynchrony may also affect wild plant biodiversity and crop yields.Item Ichthyoplankton density and Shovelnose sturgeon spawning in relation to varying discharge treatments(Montana State University - Bozeman, College of Letters & Science, 2009) Goodman, Benjamin Joseph; Chairperson, Graduate Committee: Christopher S. GuyMany lotic fish species use natural patterns of variation in discharge and water temperature as spawning cues and these natural patterns are often altered by river regulation. The effects of spring discharge and water temperature variation on the spawning of shovelnose sturgeon Scaphirhynchus platorynchus and other fishes in the upper Missouri River have not been well documented. In 2006, 2007, and 2008, I had the unique opportunity to study the effects of experimental discharge levels on ichthyoplankton density in the lower Marias River, a regulated tributary to the upper Missouri River. The objective of this study was to evaluate the effects of contrasting discharge treatments and water temperature variation on spatial and temporal variation in spawning of shovelnose sturgeon (and other species sampled as bycatch) as measured by embryonic and larval fish density in the lower Marias River. Ichthyoplankton was sampled about every four days in June and July of 2006, 2007, and 2008. Overall larval fish density was greater in 2006 than in 2007, and increased density was associated with increased discharge in 2006. In 2006, shovelnose sturgeon spawning occurred in the Marias River in conjunction with the ascending, peak (134 m³/s), and descending portions of the spring hydrograph and water temperatures from 16°C to 19°C. No evidence of sturgeon spawning was documented in the lower Marias River in 2007 when peak discharge remained low (9 m³/s to 14 m³/s) despite the occurrence of water temperatures suitable for shovelnose sturgeon embryo development. In 2008, shovelnose sturgeon spawning occurred in conjunction with the peak (118 m³/s) and descending portions of the spring hydrograph, and during a prolonged period of increased discharge (28 m³/s to 39 m³/s), coupled with water temperatures from 11°C to 23°C in the lower Marias River. These data suggest that discharge must reach a threshold level (28 m³/s), and should be coupled with water temperatures suitable (12°C to 24°C) or optimal (16°C to 20°C) for shovelnose sturgeon embryo development, to provide a spawning cue to shovelnose sturgeon in the lower Marias River.