Biology subjects

Snell-Rood, E.

Publications and source records attributed to Snell-Rood, E..

5 recordsLinked to original sources

bioRxiv2026

Moving to the city changed you! Rapid photobiont turnover enables acclimation of lichen symbioses to urban environments

Symbioses are widespread and highly successful but vulnerable to the stress sensitivity of either symbiont. In some symbioses, turnover of symbionts has been shown to confer resilience to stressors. While similar mechanisms have been proposed for lichen symbioses, direct evidence for rapid adaptive symbiont turnover has not been shown. We tested the photobiont community composition and physiological responses of the foliose lichen symbiosis Flavoparmelia caperata-Trebouxia to urbanization-induced stress in a transplant experiment. We found evidence for significant compositional change in the photobiont community along an urbanization gradient (measured as vegetation cover), reflecting a turnover in dominance of Trebouxia OTUs from A46 to I05 in more urbanized transplant sites. This change in symbiont composition is associated with a greater physiological tolerance for urbanization, consistent with the hypothesized adaptive role of photobiont turnover. These findings support rapid photobiont turnover as a potential adaptive response to environmental change in lichen symbioses.

ecology↗

bioRxiv2025

Predicting lead hotspots in urban stormwater ponds across the Twin Cities Metro

Stormwater ponds play an important role in urban food webs. Critically these same ponds could also serve as pollution hotspots since stormwater ponds can act as local concentrators of urban runoff. One such contaminant of concern is lead, which remains a significant issue for human and ecosystem health in the United States despite regulatory bans on its use in paint and gasoline imposed in the 1970s. Despite high levels of lead in some urban stormwater, little is known about the distribution of lead in urban aquatic ecosystems. Therefore, we characterized lead within the sediment, water column, and surrounding soil of stormwater ponds across the Minneapolis-Saint Paul Metro Area. We hypothesized that lead would be highest in ponds that receive runoff from landscapes with older construction (i.e., legacy leaded paint and gasoline), have high traffic volume (i.e., legacy leaded gasoline), and areas with low impervious surface cover (i.e., increased mobilization of contaminated soil). Moreover, we hypothesized that stormwater ponds capture lead within sediments, with more dissolved lead at the bottom of the water column, where it would interact with lead containing sediments. Across ponds, we found that age of parcel development where the pond was located was the strongest predictor of surface sediment lead content. Within pond sediments, we found that lead concentrations increased with depth below the sediment surface, which is unsurprising since depth is likely correlated with time. The strongest predictor of surface water lead concentration was the strength of pond stratification, while the strongest predictor of bottom water lead concentration was pond duckweed cover and water conductivity. Water column oxygen concentrations varied across ponds yet were not important in determining dissolved lead within the water column. Importantly, lead within pond water remained quite low despite elevated sediment lead levels. These findings confirm that stormwater ponds can act as one source of environmental lead remediation by capturing lead within sediments under a wide range of environmental conditions. Our results suggest relatively low lead release from ponds to downstream areas, indicating that ponds generally serve as sinks, not sources within the urban lead cycle.

ecology↗

bioRxiv2023

Dietary road salt and monarch butterflies: minimal effects on larval growth, immunity, wing coloration, and migration to Mexico

The spectacular migration of the monarch butterfly is under threat from the loss of habitat and the decline of their milkweed host plants. In the northern part of their range, roadsides could potentially produce millions of monarchs annually due to high densities of milkweed, however roadside milkweed can accumulate chemicals from roads, such as sodium from road salt. Controlled lab studies have shown mixed effects of sodium on monarch development: small increases can be beneficial as sodium is an important micronutrient in brain and muscle development, but large increases can sometimes decrease survival. It is unclear how dietary sodium affects performance in ecologically relevant conditions, and the migration itself. In this experiment, we raised monarchs outdoors, in migration-inducing conditions, on milkweed sprayed with three levels of sodium chloride. We released 2500 tagged monarchs and held an additional 250 for further lab assays. While our recovery rates to the wintering grounds were low (N = 7 individuals), individuals from all three sodium chloride treatments made it to Mexico. Butterflies reared on control milkweed and low salt concentrated sodium in their tissues, while those on high salt diets excreted sodium, suggesting levels were above a physiological optimum. There were no effects of treatment on wing coloration, survival, body size, immunity, or parasite prevalence. Taken together, our results suggest that monarchs are robust to levels of sodium in milkweeds found along roadsides, which is promising with respect to monarch conservation efforts that promote roadside habitat. Significance StatementMonarch butterflies are a flagship species for pollinator conservation, and were recently being listed as endangered by the IUCN. Roadside habitat is a target for monarch breeding habitat as they often have high densities of milkweed, the monarch hostplant. However, roadsides can also have high levels of pollutants, such as salt from deicing treatments. We reared monarch caterpillars on sodium treated milkweeds, measuring a suite of performance measures, and releasing nearly 2500 tagged monarchs for migration. We found little effect of salt on migration to Mexico, survival, body size, development time, parasite prevalence, immunity, or coloration. Monarchs appear robust to levels of sodium found in milkweed along roadsides, supporting the possibility of roadsides as habitat.

ecology↗

bioRxiv2021

Convergent evolution of a novel blood-red nectar pigment in vertebrate-pollinated flowers

Nesocodon mauritianus (Campanulaceae) produces a blood-red nectar that has been proposed to serve as a visual attractant for pollinator visitation. Here we show that the nectars red color is derived from a novel alkaloid termed nesocodin. The first nectar produced is acidic and pale yellow in color, but slowly becomes alkaline before taking on its characteristic red color. Three enzymes secreted into the nectar are either necessary or sufficient for pigment production, including (1) a carbonic anhydrase that creates an alkaline environment, (2) an aryl alcohol oxidase that generates sinapaldehyde, a pigment precursor, and (3) a ferritin-like catalase that protects nesocodin from degradation by hydrogen peroxide. Our findings demonstrate how these three enzymatic activities allow for the condensation of sinapaldehyde and proline to form a novel pigment with a stable imine bond, which in turn is attractive to Phelsuma geckos, the presumed pollinators of Nesocodon. We also identify nesocodin in the red nectar of the distantly related Jaltomata herrerae and provide evidence for convergent evolution of this trait. While the overall enzymatic activities required for red pigment formation in both Nesocodon and J. herrerae nectars are identical, the associated genes encoding the enzymes are not orthologous and, in the case of the aryl alcohol oxidase, even belong to different protein families. This work cumulatively identifies a novel, convergently evolved trait in two vertebrate-pollinated species, suggesting the red pigment is selectively favored and that only a limited number of compounds are likely to underlie this adaptation. SignificanceNearly 90% of flowering plants produce nectar to attract pollinators. Beyond sugars, many types of nectar solutes play important ecological roles; however, the molecular basis for the diversity of nectar composition across species is less explored. One rare trait among flowering plants is the production of colored nectar, which may function to attract and guide prospective pollinators. Our findings indicate convergent evolution of a red-colored nectar across two distantly related plant species. Behavioral data show that the red pigment attracts diurnal geckos, a presumed pollinator of one of these plants. These findings join a growing list of examples of distinct biochemical and molecular mechanisms underlying evolutionary convergence, and provide a fascinating system for testing how interactions across species drive the evolution of novel pigments in an understudied context.

evolutionary biology↗

bioRxiv2017

The Molecular Genetic Basis of Herbivory between Butterflies and their Host-Plants

Interactions between herbivorous insects and their host-plants are a central component of terrestrial food webs and a critical topic in agriculture, where a substantial fraction of potential crop yield is lost annually to pests. Important insights into plant-insect interactions have come from research on specific plant defenses and insect detoxification mechanisms. Yet, much remains unknown about the molecular mechanisms that mediate plant-insect interactions. Here we use multiple genome-wide approaches to map the molecular basis of herbivory from both plant and insect perspectives, focusing on butterflies and their larval host-plants. Parallel genome-wide association studies in the Cabbage White butterfly, Pieris rapae, and its host-plant, Arabidopsis thaliana, pinpointed a small number of butterfly and plant genes that influenced herbivory. These genes, along with much of the genome, were regulated in a dynamic way over the time course of the feeding interaction. Comparative analyses, including diverse butterfly/plant systems, showed a variety of genome-wide responses to herbivory, yet a core set of highly conserved genes in butterflies as well as their host-plants. These results greatly expand our understanding of the genomic causes and evolutionary consequences of ecological interactions across two of Natures most diverse taxa, butterflies and flowering plants.

genomics↗