A century of morphological variation in Cyprinidae fishes

Background Aquatic habitats have been altered over the past century due to a variety of anthropogenic influences. Ecomorphology is an area of aquatic ecology that can both directly and indirectly assess the effects of habitat alterations on organisms. However, few studies have explored long term trends in morphological variation. Long term changes in morphology can potentially impact niche and ultimately contribute to organismal success and the ecosystem. Therefore, in this study we assessed long term morphological variation with body size, sex, time, and hydrology using museum collections of five species of Cyprinidae (Minnows) from lentic and lotic systems over the past 100 years to gain insight into long term patterns in morphology. Results Variation in Cyprinidae morphology tended to relate to: body size—indicating strong allometric growth patterns with robustness of larger individuals; sex—indicating a level of fecundity selection for deeper bodies in females compared with males; and year—indirectly suggesting responses to habitat changes over the past century. In lotic ecosystems, Cyprinidae morphology tended to be more fusiform in conjunction with lower mean annual discharge or higher variation in discharge. In lentic ecosystems, change in morphology was observed but no historic habitat variables were available to discern potential mechanisms. Interestingly, not all species responded in the same magnitude or directionality. Conclusions Long term changes in morphological variation provide a link to exploring functional relationships between taxa and their environment and have implications for understanding ecosystem attributes, community assembly patterns, and conservation

A Large Sample Comparison of Grade Based Student Learning Outcomes in Online vs. Face-to-Face Courses

Comparisons of grade based learning outcomes between online and face-to-face course formats have become essential because the number of online courses, online programs and institutional student enrollments have seen rapid growth in recent years. Overall, online education is largely viewed by education professionals as being equivalent to instruction conducted face-to-face. However, the research investigating student performance in online versus face-to-face courses has been mixed and is often hampered by small samples or a lack of demographic and academic controls. This study utilizes a dataset that includes over 5,000 courses taught by over 100 faculty members over a period of ten academic terms at a large, public, four-year university. The unique scale of the dataset facilitates macro level understanding of course formats at an institutional level. Multiple regression was used to account for student demographic and academic corollaries--factors known to bias course format selection and grade based outcomes--to generate a robust test for differences in grade based learning outcomes that could be attributed to course format. The final model identified a statistical difference between course formats that translated into a negligible difference of less than 0.07 GPA points on a 4 point scale. The primary influence on individual course grades was student GPA. Interestingly, a model based interaction between course type and student GPA indicated a cumulative effect whereby students with higher GPAs will perform even better in online courses (or alternatively, struggling students perform worse when taking courses in an online format compared to a face-to-face format). These results indicate that, given the large scale university level, multi course, and student framework of the current study, there is little to no difference in grade based student performance between instructional modes for courses where both modes are applicable

Evidence of Morphological and Functional Variation among Bluegill Lepomis macrochirus Populations across Grand Lake St Mary\u27s Watershed Area

A myriad of factors have been shown to influence the morphology offreshwaterfish. However, studies that parse out where variation is comingfrom (e.g. body size, sex, and habitat) as well as what potential thesechanges have to influence function (e.g. swimming performance) areunderstudied. Therefore, the objectives of this study were to describemorphological variation of BluegillLepomis macrochirusacross the GrandLake St Mary’s watershed area (northwest OH, USA) and test forcovariation of morphology with size, sex, and habitat as well as to assessswimming performance to discern whether any differences in habitat (andmorphology) correspond with functional aspects related to criticalswimming velocity. Geometric morphometric methods were used toassess shape variation among individuals and general linear models wereused to test for covariation of morphology with size, sex, and habitat.Analyses indicated that body size was the strongest driver ofmorphological variation followed by sex, habitat, and interactions–indicating the presence of allometry, sexual dimorphism, and the potentialfor habitat induced plasticity. In general, more robust morphologiestended to correspond with larger individuals, males, and/or individualsfrom lentic habitats. Swimming performance trials supported functionaldifferences as individuals from lotic habitats demonstrated significantlyhigherUcritswimming performance values (»+20%) than lenticindividuals. Broader applications of thesefindings can link to evolutionaryecology, management, and conservation

Macroecology of North American Suckers (Catostomidae): Tests of Bergmann\u27s and Rapoport\u27s Rules

Discerning spatial macroecological patterns in freshwater fishes has broad implications for community assembly, ecosystem dynamics, management, and conservation. This study explores the potential interspecific covariation of geographic range (Rapoport\u27s rule) and body size (Bergmann\u27s rule) with latitude in North American sucker fishes (Cypriniformes: Catostomidae). While numerous tests of Rapoport\u27s and Bergmann\u27s rules are documented in the literature, comparatively few of these studies have specifically tested for these patterns, and none have incorporated information reflecting shared ancestry into analyses of North American freshwater fish through a hierarchical model. This study utilized a hierarchical modeling approach with Bayesian inference to evaluate the role that evolution has played in shaping these distributional corollaries. Rapoport\u27s rule was supported at the tribe level but not across family and subfamily groupings. Particularly within the Catostominae subfamily, two tribes reflected strong support for Rapoport\u27s rule while two suggested a pattern was present. Conversely, Bergmann\u27s rule was not supported in Catostomidae. This study provides additional information regarding the pervasiveness of these \u27rules\u27 by expanding inferences in freshwater fishes and specifically addressing the potential for these macroecological patterns to play a role in the distribution of the understudied group Catostomidae. [ABSTRACT FROM AUTHOR

Incorporation of Feeding Functional Group Information Informs Explanatory Patterns of Long-term Population Changes in Fish Assemblages

The objective of this study was to evaluate long term trends of fish taxa in southern Lake Michigan while incorporating their functional roles to improve our understanding of ecosystem level changes that have occurred in the system over time. The approach used here highlighted the ease of incorporating ecological mechanisms into population models so researchers can take full advantage of available long-term ecosystem information. Long term studies of fish assemblages can be used to inform changes in community structure resulting from perturbations to aquatic systems and understanding these changes in fish assemblages can be better contextualized by grouping species according to functional groups that are grounded in niche theory. We hypothesized that describing the biological process based on partial pooling of information across functional groups would identify shifts in fish assemblages that coincide with major changes in the ecosystem (e.g., for this study, shifts in zooplankton abundance over time). Herein, we analyzed a long-term Lake Michigan fisheries dataset using a multi-species state space modeling approach within a Bayesian framework. Our results suggested the population growth rates of planktivores and benthic invertivores have been more variable than general invertivores over time and that trends in planktivores can be partially explained by ecosystem changes in zooplankton abundance. Additional work incorporating more ecosystem parameters (e.g., primary production, etc.) should be incorporated into future iterations of this novel modeling concept

Variation in Student Perceptions of Higher Education Course Quality and Difficulty as a Result of Widespread Implementation of Online Education During the COVID-19 Pandemic

The onset of the COVID-19 global pandemic affected higher education in a myriad of ways. One of the most notable effects however was the rapid and sudden transition of nearly all courses at most institutions to an online environment. And while there are a growing number of courses offered online already, this transition to nearly 100% remote education presented numerous challenges for instructors and students of face-to-face and hybrid style courses. Since student perceptions are closely tied to recruitment and retention, it is important to know if there are differences in student perceptions present in the way different courses are taught. This study extends the work of other authors that have investigated student perceptions by looking specifically at how the COVID-19 pandemic may have changed student views of course difficulty and quality both overall and across discipline or institution categories. Course evaluations from 837 courses from 191 different schools archived on RateMyProfessors.com were used in a general linear model where a statistically significant overall decline of 6% in perceived course difficulty and 4% decline in perceived quality was detected. In addition to calculating this mean decrease, courses were also categorized on the basis of academic discipline (Business, Engineering and Mathematics, Humanities, Natural Sciences, Social Sciences), institution type (2-Year, 4-Year), and whether instructors had previous experience teaching online courses (No, Yes) to determine any variation in differences that may have appeared as a result of more nuanced details in course type or delivery. Most notably, declines in course difficulty were slightly more apparent with instructors that had no previous online teaching experience. No other discipline, institution type, or teaching experience interactions were detected with either difficulty or quality variation. These data suggest that there were very real changes in perceived quality and difficulty but that these changes were largely universal irrespective of discipline, institution type, or prior experience teaching online (with exception of course difficulty)

Evaluating Winter Malting Barley Grain Yield with Fractional Green Canopy Cover

Because of growth in the craft brewing industry, farmers in the eastern United States are planting winter malting barley (Hordeum vulgare L.) to meet demands for locally sourced grain. However, given that barley is a relatively new crop in this region, basic agronomic information relating to stand assessment is needed. This is particularly relevant in this region, as climatic variability from extreme temperature fluctuations during the winter and spring can reduce a barley stand, creating the need for farmers to estimate grain yield potential. The objective of the research was to evaluate the relationship between spring stem counts, fractional green canopy cover (FGCC), and normalized difference vegetation index (NDVI) and barley grain yield. Trials were established at five site-years in Ohio, where seeding rate treatments of 0.75, 1.0, 1.5, 2.0 and 2.5 million seeds acre−1 were used to simulate a range of poor to excellent plant stands. All barley stand assessment methods were conducted in the spring at the Feekes 5 growth stage. Stem counts were correlated with FGCC and NDVI measurements (r = .76 and .74, respectively). Stem counts (R2 = .67) and FGCC (R2 = .65) measurements accounted for the greatest variability in barley grain yield. Specifically, FGCC ≤5% corresponded to yield between 27 and 39 bu acre−1, whereas 5 to 10% corresponded to yield between 60 and 89 bu acre−1. Fractional green canopy cover should be considered as a stand and yield assessment tool, as it reduces labor compared with stem counting techniques

On the Potential for Saturated Buffers in Northwest Ohio to Remediate Nutrients from Agricultural Runoff

Nutrient loading from nonpoint source runoff in the Midwest has emerged as one of the largest threats to water quality as the frequency of harmful algal blooms, hypoxic zones, and issues associated with human-resource interactions have risen abruptly over the past several decades. In this study, a saturated buffer ~500 m in length located in the western basin of the Lake Erie watershed was evaluated for its potential to reduce edge of field runoff and nutrient loading. Saturated buffers reduce runoff by routing subsurface tile drainage water into the riparian zone, providing an opportunity for drainage volume as well as nutrient reduction of runoff waters. Over a 12-month study period, controlled drainage was used to redirect nearly 25% of the total tile flow into the riparian zone from a subwatershed in corn/soybean rotation with near complete reductions of dissolved nitrogen and phosphorus from tile inflows averaging 4.7 and 0.08 mg/L, respectively, as well as total reduction of suspended sediments (average 10.4 mg/L). This study provides additional evidence that riparian areas are an important part of nutrient reduction strategies as they can act as both controlled drainage points by raising water tables in fields as well as nutrient sinks which couple to help mitigate nutrient runoff in the region