Cheating on Unproctored Online Exams: Prevalence, Mitigation Measures, and Effects on Exam Performance

As online courses become increasingly common at the college level, an ongoing concern is how to ensure academic integrity in the online environment. One area that has received particular attention is that of preventing cheating during unproctored online exams. In this study, we examine students’ behavior during unproctored exams taken in an online introductory biology course. A feature of the learning management platform used for the course gave us the ability to detect cheating behavior involving students leaving the test page and viewing other material on their computers. This allowed us to determine what proportion of students cheated and examine the efficacy of various measures to mitigate cheating. We also explored the relationship between cheating behavior and exam performance. We found that 70% of students were observed cheating, and most of those who cheated did so on the majority of test questions. Appealing to students’ honesty or requiring them to pledge their honesty were found to be ineffective at curbing cheating. However, when students received a warning that we had technology that could detect cheating, coupled with threats of harsh penalties, cheating behavior dropped to 15% of students. Unexpectedly, we did not find evidence that students’ exam performance changed when their cheating behavior changed, indicating that this common form of cheating might not be as effective as students, or their instructors believe it to be

Influence of native roadside plants on biological control of Iowa crop pests

Boundaries between cropland and natural plant communities provide food, water, and cover for wildlife. Similarly, field borders com­ posed of natural plant communities, especially those that include flowering plants, may have a marked effect on natural enemies of crop pests within crop fields. Monoculture crops typical of much of the Midwest do not provide adequate sources of food (nectar, pollen) or shelter and breeding sites for these natural enemies. Nectar and pollen are produced by a variety of native Midwestern plants; as these plants flower in succession throughout the growing season, they provide a continuous food source for the natural enemies (parasites) of pests attacking adjacent crops

Monarch Butterflies and Bt Corn: Replacing Hoopla with Science

A correspondence to Nature three years ago reported a preliminary laboratory study that suggested pollen from from Bacillus thuringiensis (Bt) com could be hazardous to the larvae of the monarch butterfly, Danaus plexippus. Losey et al. (1999) showed that young monarch larvae given no choice but to feed on milkweed, Asclepias curassavica, leaves dusted with pollen from Bt corn hybrid ate less, grew more slowly, and had a significantly higher mortality rate than larvae feeding on leaves dusted with nontransgenic pollen. Based on this study, the authors questioned the environmental safety of Bt com and called for scientific investigations

Quasi-extinction risk and population targets for the Eastern, migratory population of monarch butterflies (Danaus plexippus)

The Eastern, migratory population of monarch butterflies (Danaus plexippus), an iconic North American insect, has declined by ~80% over the last decade. The monarch’s multi-generational migration between overwintering grounds in central Mexico and the summer breeding grounds in the northern U.S. and southern Canada is celebrated in all three countries and creates shared management responsibilities across North America. Here we present a novel Bayesian multivariate auto-regressive state-space model to assess quasi-extinction risk and aid in the establishment of a target population size for monarch conservation planning. We find that, given a range of plausible quasi-extinction thresholds, the population has a substantial probability of quasi-extinction, from 11–57% over 20 years, although uncertainty in these estimates is large. Exceptionally high population stochasticity, declining numbers, and a small current population size act in concert to drive this risk. An approximately 5-fold increase of the monarch population size (relative to the winter of 2014–15) is necessary to halve the current risk of quasi-extinction across all thresholds considered. Conserving the monarch migration thus requires active management to reverse population declines, and the establishment of an ambitious target population size goal to buffer against future environmentally driven variability

Reproductive and Pollination Biology of the Endemic Hawaiian Cotton, Gossypium tomentosum (Malvaceae).

v. ill. 23 cm.QuarterlyGossypium tomentosum is a cotton species endemic to the Hawaiian Islands. We studied several aspects of its reproductive biology, including potential pollinators, floral biology, and diurnal and seasonal flowering phenology. Flower visitors were observed in G. tomentosum populations on O‘ahu, Kaho‘olawe, and Maui. Primary visitors were introduced species, honeybees and carpenter bees, both of which were pollinating the flowers. No native bee species were seen visiting flowers. In examining floral biology we found that in some cases 10% of flowers had styles that were as short as the anthers or were recurved toward the anthers. In the greenhouse, in the absence of pollinators, these flowers were the only ones that set fruit. Flowering of G. tomentosum commences in January and February, following the rainy season, peaks in May, and may continue into August and September. In one year, after higher than average precipitation during the rainy season, there was a greater abundance of flowering, and flowering persisted later into the year. Transgenic varieties of commercial cotton, G. hirsutum, are grown in Hawai‘i and are interfertile with G. tomentosum. Honeybees and carpenter bees are also known pollinators of commercial cotton. Because these pollinators are long-distance foragers, we estimate that transgenic cotton fields would have to be greater than 10 km from a G. tomentosum population to prevent gene flow

L'efecte de la mida de la inflorescència sobre les visites de pol-linitzadors de Delphinium nelsonii i Aconitum columbianum

Two factors have been suggested to play a role in determin ing the limit to inflorescence size within a species: energy limitation and diminishing pollination returns for larger inflorescence sizes. In an effort to assess the significance or pollination limitation we examined the effect or inflorescence size on pol1inator visitation patterns for 2 species, Aconitum columbianum and Delphinium nelsonii. These species are similar in their pollination biology, and both have a racemose inflorescence, but they differ markedly in inflorescence size (A. columbianum has from 1-26 open flowers while D. nelsonii has 1-6 open flowers). For each species the following parameters were examined as a function of inflorescence size: visits per inflorescence, flowers visited per visit, and visits per flower. For D. nelsonii all 3 parameters increased with increasing inflorescence size although for large inflorescences the rate of increase slowed slightly for flowers per visit and visits per flower. For A. columbianum all 3 parameters also generally increased with increasing inflorescence size but for the largest sizes there was no further increase in visits per inflorescence or flowers per visit and there was a decrease in visits per flower. The pattern of a smaller increase in attractiveness with progressively larger inflorescences corresponds to what would be expected if inflorescence attractiveness were based on the concept of just noticeable difference. The observed pattern of a smaller increase in flowers per visit with increasing inflorescence size can be described accurately by a model in which there is, on average, a fixed probability of moving from one flower to another on an inflorescence. The number of visits per flower is simply the consequence of the other 2 parameters. The lack of any significant decrease in pollinator visitation with increasing inflorescence size for D. nelsonii suggests that energy is probably the factor limiting inflorescence size. For A. columbianum, the largest Inflorescences have a reduced number of visits per flower and the total number of visits per inflorescence for the very largest inflorescences is reduced. This, in conjunction with a possible reduction in visit quality for large inflorescences, raises the possibility that inflorescence size in A. columbianum may be pollination limited.[ca] S'han suggerit do s factors que juguen un paper en la determinació de la mida de la inflorescència a l'interior d'una espècie: la limitació d'energia i la disminució de la recompensa de la pol-linització per a inflorescències llargues. En un esforç per avalua r la significació de la limitació de la pol-linització, hem examinat l'efecte de la mida de la inflorescència sobre els models de visita dels pol-linitzadors per a dues espècies, Aconitum columbiamun i Delphinium nelsonii. Aquestes espècies tenen una biologia de la pol-linització similar i amb dues presenten una inflorescència racemosa, però difereixen notablement en la mida de llurs inflorescències (A. columbianum té 1-26 flors obertes, mentre que D. Nelsonii només en té 1-6). Per a cada espècie, s'han examinat els paràmetres següents, com a funció de la mida de la inflorescència: visites pe r inflorescència, flors visitades per visita i visites per flor. Per a D. nelsonii, tots tres paràmetres augmenten quan augmenta la mida de la inflorescència, tot i que per a inflorescències llargues, la taxa d'increment se suavitza un xic pel que fa a flors pe r visita i visites per flor. Per a A. columbianum. tots tres paràmetres també augmenten generalment quan augmenta la mida de la inflorescència. però, per a les mides més grans, ja no hi ha més increment en visites per inflorescència o flors per visita. i s'observa una disminució en visites per flor. El model d'un menor increment en l’atractivitat amb inflorescències progressivament més grans correspon al que hom esperaria si l'atractivitat de la inflorescència fos basada en el concepte de diferència exactament perceptible . El model observat, d'un menor increment en flors per visita a mesura que augmenta la mida de la inflorescència, pot ser descrit adequadament per mitjà d'un model en el que hi ha, per regla general, una probabilitat fixada d'abandonar una flor per anar a una altra de la mateixa inflorescència. El nombre de visites per flor és simplement la conseqüència dels altres dos paràmetres. L'absència de cap disminució significativa en les visites de pol-linitzadors a mesura que augmenta la mida de la inflorescència de D. nelsonii suggereix que l'energia és probablement el factor limitant de la mida de la inflorescència. Per a A. columbianum. les inflorescències més llargues tenen un nombre reduït de visites per flor i el nombre total de visites per inflorescència, per a les inflorescències més extremadament llargues, es veu reduït. Això, conjuntament amb la possible reducció de la qualitat de les visites a les inflorescències més llargues, fa més gran la possibilitat que la mida de la inflorescència en Aconitum columbianum pugui ser limitada per la pol-linització

Milkweed loss in agricultural fields because of herbicide use: effect on the monarch butterfly population: Herbicide use and monarch butterflies

1. The size of the Mexican overwintering population of monarch butterflies has decreased over the last decade. Approximately half of these butterflies come from the U.S. Midwest where larvae feed on common milkweed. There has been a large decline in milkweed in agricultural fields in the Midwest over the last decade. This loss is coincident with the increased use of glyphosate herbicide in conjunction with increased planting of genetically modified (GM) glyphosate-tolerant corn (maize) and soybeans (soya). 2. We investigate whether the decline in the size of the overwintering population can be attributed to a decline in monarch production owing to a loss of milkweeds in agricultural fields in the Midwest. We estimate Midwest annual monarch production using data on the number of monarch eggs per milkweed plant for milkweeds in different habitats, the density of milkweeds in different habitats, and the area occupied by those habitats on the landscape. 3. We estimate that there has been a 58% decline in milkweeds on the Midwest landscape and an 81% decline in monarch production in the Midwest from 1999 to 2010. Monarch production in the Midwest each year was positively correlated with the size of the subsequent overwintering population in Mexico. Taken together, these results strongly suggest that a loss of agricultural milkweeds is a major contributor to the decline in the monarch population. 4. The smaller monarch population size that has become the norm will make the species more vulnerable to other conservation threats