DuRant, S. | bioRxiv Science

bioRxiv2024

A high lipid diet leads to greater pathology and lower tolerance during infection

Despite the clear effect of food resources on wildlife disease dynamics, few studies have investigated how shifts in diet, specifically macronutrient content, shape vertebrate host responses to infection. While each individual macronutrient plays a vital role in physiological processes necessary for pathogen defense, it is often difficult to disentangle the role of an individual macronutrient on disease pathology. We explored the effects of dietary macronutrient composition on disease pathology and feeding behavior of canaries (Serinus canaria domestica) infected with Mycoplasma gallisepticum (MG). First, we provided canaries with isocaloric diets comprised of identical ingredients that varied in macronutrient content (high-protein or high-lipid) then MG- or sham-inoculated birds. We then offered both diets to canaries before and after MG- and sham-inoculation. In experiment one, high protein diet birds consumed more food than high lipid diet birds and experienced a more pronounced decrease in food intake after infection. High protein diet birds were more tolerant to MG infection, exhibiting reduced pathology when compared to high lipid diet birds, despite the two treatments having similar levels of MG-specific antibodies and MG loads. When birds had access to both diets, they consumed more of the high protein diet and experienced pathology for less time than lipid or protein restricted birds. These results highlight that macronutrient makeup of the diet can shape host tolerance and pathology and thus affect host-pathogen transmission dynamics. Summary StatementMacronutrient composition of the diet shapes tolerance in an avian host pathogen system. Birds that had greater access to protein exhibited reduced pathology despite similar pathogen loads when compared with birds with greater access to lipids.

ecology↗

bioRxiv2023

Critical reproductive behaviors in Scaled Quail and Northern Bobwhite are affected by thermal variability and mean temperature

Animals can respond differently to shifting thermal variability versus thermal averages, both of which are changing due to climate warming. How these thermal variables affect parental care behaviors can reveal the ability of parents to modify their behaviors to meet the competing demands of their offsprings thermal needs and self-maintenance, which becomes critical in suboptimal thermal conditions. Further, the time frame used to examine the interplay between temperature and behavioral shifts (e.g., seasonal patterns in care vs. drivers of individual care decisions) can provide different information about the plasticity of parental care behavior. We investigated the relationship between thermal means, thermal variability, and incubation behaviors across multiple timescales in Scaled Quail and Northern Bobwhite. Both species decreased off-bout length during periods of high thermal variability, a novel finding among studies of avian parental behavior. Further relationships between thermal endpoints (mean vs. variation) and behavior differed depending on the temporal scale. For instance, total daily time spent off the nest was not influenced by daily average temperature, yet individual off-bout duration increased with increasing average temperature in the two hours prior to the off-bout. These results provide evidence that thermal-behavioral relationships differ across scales and likely represent a birds ability to modify their incubation strategy to rapidly respond to the immediate thermal environment (altering individual off-bout length based on temperature) to meet self-maintenance needs while resulting in a similar outcome for their nest (total daily off-bout time). However, longer off-bout durations during high temperature events can come with reproductive costs, sometimes resulting in acute offspring mortality when eggs or chicks experience lethal temperatures.

animal behavior and cognition↗