Biology subjects

Pfenning-Butterworth, A. C.

Publications and source records attributed to Pfenning-Butterworth, A. C..

3 recordsLinked to original sources

bioRxiv2022

Natural variation in host defense strategies impacts both host and pathogen fitness

O_LIAnimals ranging from mosquitoes to humans often vary their feeding behavior when infected or merely exposed to pathogens. For example, some individuals drastically reduce their food intake ( illness-mediated anorexia) while others increase food intake ( hyperphagia). While these so-called sickness behaviors are well documented, their functional consequences remain poorly resolved. C_LIO_LIHere, we examine links between natural genetic variation in susceptibility to infection, feeding behaviors, multiple traits of the host, and within-host pathogen production. Using a zooplankton host (Daphnia dentifera) and a fungal pathogen (Metschnikowia bicuspidata) as a case study, we show that genotypic and dose-dependent variation in feeding behaviors are associated with both resistance and tolerance mechanisms. C_LIO_LIIn one genotype, immune-mediated anorexia was associated with increased tolerance to infection; unlike other genotypes, these individuals did not upregulate phenoloxidase activity, but lived longer, had the highest overall fecundity, and produced higher pathogen loads, despite their reduced growth rates and resultant smaller body sizes. In these hosts, peak parasite load remained unchanged, suggesting a tolerance mechanism that offset fecundity costs. C_LIO_LIIn other genotypes, feeding behaviors followed either a flat or hump-shaped pattern with pathogen dose, exhibiting hyperphagia at intermediate doses and anorexia at higher doses. In these cases, anorexia functioned primarily in resistance. C_LIO_LIOur results suggest that infection-mediated changes in host feeding behavior -- which are traditionally interpreted as immunopathology -- may in fact serve as crucial components of host defense strategies. Moreover, these phenomena vary across host genotypes, and were associated with apparent trade-offs with another melanization component of immune defense. Together, these results underscore that while resistance and tolerance are typically viewed as alternative and fixed defense strategies, the immense genetic diversity for immune defense may result in more of a plastic spectrum spanning a gradient from resistance to tolerance. C_LI

ecology↗

bioRxiv2021

Daily feeding rhythm linked to microbiome composition in two zooplankton species

Host-associated microbial communities are impacted by external and within-host factors, i.e., diet and feeding behavior. For organisms known to have a circadian rhythm in feeding behavior, microbiome composition is likely impacted by the different rates of microbe introduction and removal across a daily cycle, in addition to any diet-induced changes in microbial interactions. Here, we measured feeding behavior and used 16S rRNA sequencing to compare the microbial community across a diel cycle in two distantly related species of Daphnia, that differ in their life history traits, to assess how daily feeding patterns impact microbiome composition. We find that Daphnia species reared under similar laboratory conditions have significantly different microbial communities. Additionally, we reveal that Daphnia have daily differences in their microbial composition that correspond with feeding behavior, such that there is greater microbiome diversity at night during the host's active feeding phase. These results highlight that zooplankton microbiomes are relatively distinct and are likely influenced by host phylogeny.

microbiology↗

bioRxiv2021

On the evolution of host specificity: a case study of helminths

The significant variation in host specificity exhibited by parasites has been separately linked to evolutionary history and ecological factors in specific host-parasite associations. Yet, whether there are any general patterns in the factors that shape host specificity across parasites more broadly is unknown. Here we constructed a molecular phylogeny for 249 helminth species infecting free-range mammals and find that the influence of ecological factors and evolutionary history varies across different measures of host specificity. Whereas the phylogenetic range of hosts a parasite can infect shows a strong signal of evolutionary constraint, the number of hosts a parasite infects does not. Our results shed new light on the evolution of host specificity in parasites, suggesting that phylogenetic breadth may capture the evolutionary potential of a parasite to jump between hosts, whereas the number of hosts may reflect ecological opportunity. Finally, we show parasite phylogenies can also provide an alternative perspective on zoonosis by identifying which hosts are infected by a broad phylogenetic range of parasites.

evolutionary biology↗