No abstract

In a flipped classroom model, learning of basic content is shifted before class while in-class time is used for concept application. Empirical and controlled research studies are lacking on the best strategies to provide the necessary pre-class content instruction.In this study, we tested three methods of pre-class content learning-interactive online tutorials, video lectures, and textbookstyle readings-while holding the content and the in-class application activities constant. Identical introductory, non-majors biology classes were manipulated at both a public, open-enrollment institution and a private, highly selective institution. We found that video lectures offer a small advantage to overall student learning over interactive tutorials or textbook-style readings. Although our two populations differed in their ability to effectively learn from pre-class activities, through a student-centered flipped classroom approach, students at both institutions demonstrated equal learning gains by the final assessment. Potential reasons for some observed differences are suggested.

Graduate teaching assistants (GTAs) are often the primary instructors for undergraduate biology laboratories and serve as research mentors in course-based undergraduate research experiences (CUREs). While several studies have explored undergraduate perceptions of CUREs, no previous study has qualitatively described GTAs’ perceptions about teaching CUREs, despite the essential instructional role GTAs play. The purpose of this phenomenological study was to describe and ascribe meaning to the perceptions that GTAs have regarding benefits and challenges with instructional experiences in introductory biology CUREs. We conducted semistructured interviews with 11 GTAs instructing an introductory biology CURE at a 4-year public university. We found that, while GTAs perceived professional benefits such as experience in research mentoring and postsecondary teaching, they also described challenges, including the time required to instruct a CURE, motivating students to take ownership, and a lack of expertise in mentoring undergraduates about a copepod-based CURE. Feelings of inadequacy in serving as a research mentor and high levels of critical thinking were also cited as perceived issues. We recommend that the greater responsibility and increased time commitment perceived by GTAs in the current study warrants reconsideration by lab coordinators and administrators as to what content and practices should be included in pedagogical training specifically designed for CURE GTAs and how departmental and institutional policies may need to be adapted to better implement CUREs.

No abstract

Regrettably, the sciences are not untouched by the plagiarism affliction that threatens the integrity of budding professionals in classrooms around the world. My research, however, suggests that plagiarism training can improve students' recognition of plagiarism. I found that 148 undergraduate ecology students successfully identified plagiarized or unplagiarized paragraphs three-quarters of the time. The students' ability to identify plagiarism was not significantly different when the quoted or paraphrased text included complex sentence structure and scientific jargon and when it included only simple sentences that mostly lacked jargon. The students who received plagiarism training performed significantly better at plagiarism detection than did those who did not receive the training. Most of the students, independent of training, identified properly paraphrased, quoted, and attributed material but had much greater difficulty identifying paraphrases that included long strings of copied text-up to 15 words-or proper paraphrases that lacked citations. The misunderstanding of paraphrasing and citation conventions found here could manifest as unintentional plagiarism in these students' later work.

We describe lichen community structure and its relation to environment in the Bering Land Bridge National Preserve in northwestern Alaska. We used a stratified random sample to estimate macrolichen abundance and several environmental variables from 78 0.38-ha plots within lichendominated areas of the Preserve. We found a total of 140 macrolichen taxa. Two primary gradients in lichen species composition were related to habitat rockiness and a substrate-topographic gradient. The strongest gradient, rockiness, correlates with lichen succession. Rocky habitats have less competition from vascular plants and may be more resistant to soil disturbance. The substrate-topography gradient is largely driven by the presence of Sphagnum moss contrasting with calcareous parent rock material. To uncover additional underlying patterns in lichen community composition, we deleted rocky and calcareous plots and strictly saxicolous species from the analyses. Although we found similar patterns from the original analysis in this subset, diversity and community composition also varied with differing microtopography. These gradients of lichen community composition can also be divided into three major groups; rocky non-calcareous sites, calcareous areas, and the remaining plots form the alluvial lowland communities. We used two-way cluster analysis which combines independent clustering of sample units and species into a single diagram. This technique linked individual species and species assemblages with these major trends.

No abstract

Atranorin is a secondary metabolite found in many lichens. This compound can act as a photo-buffer, supporting its use as a marker of metabolic response to changes in light. In preliminary trials, atranorin was found to be unstable over time when in solution, potentially precluding its usefulness in this capacity. The present study tests the stability of atranorin in different extraction solvents and at different pH values over time using HPLC analysis. We found that atranorin is most stable in acetonitrile, among six tested solvents, and that the presence of strong acid or a strong base destabilizes the compound. We propose that atranorin breaks down through transesterification in methanol and ethanol until an equilibrium is reached, while a strong base breaks down atranorin through saponification and under acidic conditions, atranorin concentration significantly increases with time. Although atranorin levels were found to be stable in whole thallus extracts from fresh lichens using a leaching method, chemicals isolated using chromatographic separation showed similar breakdown to an atranorin standard. In future work on lichens atranorin should be extracted in acetonitrile or acetone without an added base or acid to yield the greatest stability and thus provide more accurate concentration values of atranorin with time using HPLC. The interactions of atranorin with acid and with chloroform need further study.