Biology subjects

Steffen, J. G.

Publications and source records attributed to Steffen, J. G..

3 recordsLinked to original sources

bioRxiv2025

Effect of formic acid treatment on Apis mellifera foraging behavior as assayed using nanopore metabarcoding technologies

The Western honeybee (Apis mellifera) is a crucial contributor to worldwide agriculture and ecological health but is experiencing wide population declines linked to Varroa mite infection. Formic Acid (FA) has been increasingly used to control for Varroa, yet its effects on A. mellifera hives, particularly the impact it might have on their foraging preferences, remain unclear. In this study, we used a combination of pollen DNA metabarcoding with real-time nanopore sequencing to assess how FA treatment influences A. mellifera foraging preferences. DNA sequencing was performed on pollen samples from six University of Utah campus honeybee hives separated into FA and control treatments. Samples were collected before, during, and after FA application. We amplified trnL, a chloroplast DNA region useful for plant identification using portable sequencers from Oxford Nanopore Technologies (ONT). We detected a significant difference in foraging composition between FA-treated and control hives at the end of the experiment. Control hives foraged from a more diverse array of plant genera. We also found individual hives have unique foraging preferences independent of treatment. These findings suggest that FA treatment can have an impact on A. mellifera foraging behavior. The magnitude of FA impact, however, on hive foraging repertoire remains unclear. Pollen DNA metabarcoding with nanopore technology is an effective method for analyzing bee foraging patterns and holds significant potential for advancing ecological research on pollination health.

ecology↗

bioRxiv2024

Investigating Honey Bee Pollen Foraging Patterns Across a Season Using DNA Metabarcoding

The western honey bee, or Apis mellifera, is a vital pollinator, essential for both ecosystems and agriculture worldwide. As human influences on these bees become more pronounced, understanding their pollen foraging behavior is increasingly important. Pollen provides crucial nutrients for A. mellifera such as protein and lipids that are necessary for hive health and prosperity. Pollen DNA metabarcoding allows for the longitudinal analysis of the floral sources of corbicular (bee-collected) pollen. In this study we employ the use of metabarcoding and Oxford Nanopore Sequencing technology to analyze the floral composition of pollen samples collected on a weekly basis from two closely related hives. In total, we identified 74 distinct plant taxa (at the genus level) between the two hives. Although both hives had equivalent values of taxonomic richness and diversity, the majority of taxa identified were unique to the individual hives. This indicates a large degree of variation in pollen foraging despite the hives relative proximity. In addition to this interhive analysis, we also analyzed changes in pollen origin of a single hive across the course of five months. We identified 59 distinct plant taxa within samples from this hive whose presence and relative abundance differ drastically on a weekly basis with no taxa being present in all samples across the observed time period. In addition, even though there was a median of 8 to 9 taxa detected in each sample, each sample was composed primarily of 1 to 2 taxa indicating a degree of foraging preference that changes on a regular basis. Further quantitative and qualitative comparisons completed in this study demonstrate the degree of variation in pollen foraging patterns both throughout the season and between hives.

ecology↗

bioRxiv2017

Plant organ evolution revealed by phylotranscriptomics in Arabidopsis

The evolution of species phenotypes occurs through changes both in protein sequence and gene expression levels. Though much of plant morphological evolution can be explained by changes in gene expression, examining its evolution has challenges. To gain a new perspective on organ evolution in plants, we applied a phylotranscriptomics approach. We combined a phylostratigraphic approach with gene expression based on the strand-specific RNA-seq data from seedling, floral bud, and root of 19 Arabidopsis thaliana accessions to examine the age and sequence divergence of transcriptomes from these organs and how they adapted over time. Our results indicate that, among the sense and antisense transcriptomes of these organs, the sense transcriptomes of seedlings are the evolutionarily oldest across all accessions and are the most conserved in amino acid sequence for most accessions. In contrast, among the sense transcriptomes from these same organs, those from floral bud are evolutionarily youngest and least conserved in sequence for most accessions. Different organs have adaptive peaks at different stages in their evolutionary history, however, from the Magnoliophyta stage to the Brassicale stage, all three organs show a common adaptive signal. Our research is significant because it offers novel evolutionary insight on plant organs revealed by phylotranscriptomics.

evolutionary biology↗