Effect of Population Density on Timing of Oviposition and Brood Size Reduction in the Burying Beetle Nicrophorus pustulatus

Burying beetles (Nicrophorus spp.) bury small carcasses to feed their larvae. Carcasses are a limited, high-quality resource and contests over carcasses become more frequent with increasing population density. Successful beetles kill eggs and larvae present on carcass. In response, females should accelerate oviposition, while offspring development should increase to minimize mortality. Both value of a carcass and frequency of contests decrease as larvae develop. If overproduction of offspring is an insurance against high mortality, females should reduce brood size as carcass value declines. Testing our predictions, we reared female burying beetles, Nicrophorus pustulatus, at high and low densities and compared oviposition and brood reduction. High-density females delayed oviposition, suggesting that high population density imposes nutritional and/or physiological stress. Females responded to the physiological constraints and the potentially high mortality rates of eggs and newly hatched larvae by lengthening oviposition period and changing brood reduction rate

Life Science Undergraduate Mentors in NE STEM 4U Significantly Outperform Their Peers in Critical Thinking Skills

The development of critical thinking skills in recent college graduates is keenly requested by employers year after year. Moreover, improving these skills can help students to better question and analyze data. Consequently, we aimed to implement a training program that would add to the critical thinking skills of undergraduate students: Nebraska Science, Technology, Engineering, and Math 4U (NE STEM 4U). In this program, undergraduates provide outreach, mentoring, and science, technology, engineering, and mathematics (STEM) education to K–8 students. To determine the impacts of serving as an undergraduate mentor in this program on critical thinking, we compared undergraduate mentors (intervention group) with nonmentor STEM majors (nonintervention, matched group) using the valid and reliable California Critical Thinking Skills Test (CCTST) as a pre/post measurement. Importantly, before the intervention, both NE STEM 4U mentors and nonmentor undergraduates scored similarly overall on the CCTST. However, the posttest, carried out one academic year later, indicated significant gains in critical thinking by the NE STEM 4U mentors compared with the nonmentors. Specifically, the math-related skills of analysis, inference, and numeracy improved significantly in mentors compared with nonmentors

Morphological traits as indicators of sexual dimorphism in Prairie Rattlesnakes (\u3ci\u3eCrotalus viridis\u3c/i\u3e)

As humans encroach into areas inhabited by predators, the potential of human-predator confrontations increases and the predators become regarded as dangerous pests. Predators exert a measure of population control over pest species such as small rodents, as well as limit the quantity and scope of diseases (e.g. spread of Hantavirus by these prey species). Control of these small rodent pest species can be aided by conserving and managing their predators like rattlesnakes (Crotalus spp). Management of any population requires detailed information on population composition and the ability to determine the key information (especially age and sex) for each individual quickly and with high accuracy. To determine the sex of a snake in the field, traditionally, a probe or forceful expulsion of the hemipenes are used. In the hands of a person unskilled in field herpetology, these methods can potentially be painful to the snake, as well as place the observer in unnecessary danger. The goal of this study was to develop a less invasive field method of determining sex for any life stage in Prairie Rattlesnakes (C. viridis) using morphological characteristics that are commonly collected. Snout-vent length (SVL), and absolute and relative measures of tail length (TL, TL/SVL), rattle length (RL, RL/SVL), number of subcaudal scales (SS, SS/SVL), and number of dorsal saddle patterns (DS, DS/SVL) were examined within and across life stages of a C. viridis populationnear Ulysses, Kansas, USA, collected from 2012-2015 to facilitate a safe working environment for a prairie restoration project. SVL, , RL, and DS as well ass RL/SVL and DS/SVL did not differ between sexes within and across life stages. TL,SS,TL/SVL and SS/SVL did not differ between male and female neonates and juveniles, but were, on average, larger in adult males than females. Regression tree analysis, however, indicated that TL and SS as well as TL/SVL and SS/SVL are not very reliable for sex determination of adult snakes. Yet, if used in conjunction with other reliable methods, such as palpation of the ventral area of a snake to determine gravidity, both absolute and relative measures of tail length and number of subcaudal scales are viable alternatives to the more invasive methods currently in use

Light suppression of nitrate reductase activity in seedling and young plant tissues

Light is often reported to enhance plant nitrate reductase (NR) activity; we have identified a context in which light strongly suppresses NR activity. In vitro NR activity measurements of laboratory-grown seedlings showed strong suppression of nitrate-induced NR activity in cotyledon, hypocotyl, and root tissues of Ipomoea hederacea (L.) Jacquin; robust NR activity accumulated in nitrate-induced tissues in the dark, but was absent or significantly reduced in tissues exposed to light during the incubation. The suppressive mechanism appears to act at a point after nitrate perception; tissues pre-incubated with nitrate in the light were potentiated and developed NR activity more rapidly than nitrate-induced tissues not so pre-exposed. Suppression was affected by moderate to low light levels under full-spectrum light sources and by single-wavelength red, green, and blue sources. The suppression phenomenon persisted in early (first through fourth) leaves of glasshouse plants grown in soil, and in artificially rejuvenated cotyledons. Collectively these observations suggest a link between light perception and NR regulation that remains to be fully characterized

De novo Assembly of the Burying Beetle Nicrophorus orbicollis (Coleoptera: Silphidae) Transcriptome Across Developmental Stages with Identification of Key Immune Transcripts

Burying beetles (Nicrophorus spp.) are among the relatively few insects that provide parental care while not belonging to the eusocial insects such as ants or bees. This behavior incurs energy costs as evidenced by immune deficits and shorter life-spans in reproducing beetles. In the absence of an assembled transcriptome, relatively little is known concerning the molecular biology of these beetles. This work details the assembly and analysis of the Nicrophorus orbicollis transcriptome at multiple developmental stages. RNA-Seq reads were obtained by next-generation sequencing and the transcriptome was assembled using the Trinity assembler. Validation of the assembly was performed by functional characterization using Gene Ontology (GO), Eukaryotic Orthologous Groups (KOG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Differential expression analysis highlights developmental stage-specific expression patterns, and immunity-related transcripts are discussed. The data presented provides a valuable molecular resource to aid further investigation into immunocompetence throughout this organism’s sexual development

Morphological traits as indicators of sexual dimorphism in Prairie Rattlesnakes (\u3ci\u3eCrotalus viridis\u3c/i\u3e)

As humans encroach into areas inhabited by predators, the potential of human-predator confrontations increases and the predators become regarded as dangerous pests. Predators exert a measure of population control over pest species such as small rodents, as well as limit the quantity and scope of diseases (e.g. spread of Hantavirus by these prey species). Control of these small rodent pest species can be aided by conserving and managing their predators like rattlesnakes (Crotalus spp). Management of any population requires detailed information on population composition and the ability to determine the key information (especially age and sex) for each individual quickly and with high accuracy. To determine the sex of a snake in the field, traditionally, a probe or forceful expulsion of the hemipenes are used. In the hands of a person unskilled in field herpetology, these methods can potentially be painful to the snake, as well as place the observer in unnecessary danger. The goal of this study was to develop a less invasive field method of determining sex for any life stage in Prairie Rattlesnakes (C. viridis) using morphological characteristics that are commonly collected. Snout-vent length (SVL), and absolute and relative measures of tail length (TL, TL/SVL), rattle length (RL, RL/SVL), number of subcaudal scales (SS, SS/SVL), and number of dorsal saddle patterns (DS, DS/SVL) were examined within and across life stages of a C. viridis populationnear Ulysses, Kansas, USA, collected from 2012-2015 to facilitate a safe working environment for a prairie restoration project. SVL, , RL, and DS as well ass RL/SVL and DS/SVL did not differ between sexes within and across life stages. TL,SS,TL/SVL and SS/SVL did not differ between male and female neonates and juveniles, but were, on average, larger in adult males than females. Regression tree analysis, however, indicated that TL and SS as well as TL/SVL and SS/SVL are not very reliable for sex determination of adult snakes. Yet, if used in conjunction with other reliable methods, such as palpation of the ventral area of a snake to determine gravidity, both absolute and relative measures of tail length and number of subcaudal scales are viable alternatives to the more invasive methods currently in use