Biology subjects

Green, E. T.

Publications and source records attributed to Green, E. T..

3 recordsLinked to original sources

bioRxiv2024

Amplification of disease by nutrient addition: Testing mechanisms from individual to community levels

Nutrient supply can amplify disease epidemics through mechanisms from individual to community levels. Within host individuals, nutrient addition can drive pathogen replication or growth. Across a host population, nutrient addition can drive disease transmission by increasing host growth and abundance relative to defense. Furthermore, such effects may be influenced by pathogen species interactions. Understanding how nutrients impact disease epidemics requires a framework that integrates these mechanisms across biological levels. To build such a framework, we conducted a field experiment in an old field on tall fescue, Lolium arundinaceum, and used structural equation models to integrate multiple hypothesized mechanisms. Nutrient addition (NPK fertilizer) increased brown patch disease but was best modeled as a direct path and not mediated by host abundance. To expand our framework, we also re-analyzed a previous experiment. That experiment reproduced the direct path from nutrients to disease, and added an indirect path mediated by host population abundance. Nutrient addition also increased foliar nitrogen, consistent with individual-level mechanism, but this did not increase disease. Brown patch decreased with burden of another disease, anthracnose, independently of nutrients. These results partially support both individual- and population-level hypotheses, emphasizing the importance of considering multiple biological levels underlying impacts of abiotic change.

ecology↗

bioRxiv2023

Order of arrival and nutrient supply alter outcomes of coinfection with two fungal pathogens

A pathogen arriving on a host typically encounters a diverse community of microbes that can shape priority effects, other within-host interactions, and infection outcomes. In plants, environmental nutrients can drive tradeoffs between host growth and defense and can mediate interactions between coinfecting pathogens. Nutrients may thus alter the outcome of pathogen priority effects for the host, but this possibility has received little experimental investigation. To disentangle the relationship between nutrient availability and coinfection dynamics, we factorially manipulated nutrient availability and order of arrival of two foliar fungal pathogens (Rhizoctonia solani and Colletotrichum cereale) on the host grass tall fescue (Festuca arundinacea) and tracked disease outcomes. Overall, C. cereale infection facilitated infection by R. solani, increasing its infection rate regardless of their order of inoculation. Additionally, simultaneous and C. cereale-first inoculations decreased plant growth and - in plants that did not receive nutrient addition - increased leaf nitrogen concentrations compared to uninoculated plants. Nutrient addition did not influence infection rates, severity of infection, or plant biomass. These findings highlight the importance of understanding the intricate associations between the order of pathogen arrival, host nutrient availability, and host defense to better predict infection outcomes.

ecology↗

bioRxiv2020

Habitat patchiness drives spatial structure in morphological trait variation and co-variation in spotted salamanders (Ambystoma maculatum)

The influence of intraspecific trait variation on species interactions makes trait-based approaches critical to understanding eco-evolutionary processes. Because species occupy habitats that are patchily distributed in space, advancement in trait-based ecology hinges on understanding how trait variation is distributed within and between habitat patches. We sampled larval spotted salamanders (Ambystoma maculatum) across spatially discrete ponds to quantify within- and between-pond variation in mass, length, and their allometric relationship. Between-pond variation explained 7-35% of total observed variation in the length and shape of salamander larvae, depending on the body segment measured (i.e., head, body, or tail). Salamander tail morphology was more variable and exhibited more between-pond variation than head or body morphology. Salamander mass was highly variable and strongly correlated with total length. Allometric analysis revealed that the slopes of mass-length relationships were similar across ponds, but that intercepts differed across ponds. Preliminary evidence hinted that newly constructed ponds were a driver of the observed differences in mass-length relationships. Pond construction may therefore bolster trait diversity across the broader landscape, and in so doing instil more adaptive potential of salamander populations under current and future environmental change.

ecology↗