Emily Bruns

University of Virginia | UVa

Genetic variation for disease resistance within host populations can strongly impact the spread of endemic pathogens. In plants, recent work has shown that within-population variation in resistance can also affect the transmission of foreign spillover pathogens if that resistance is general. However, most hosts also possess specific resistance mech...

Pathogen transmission mode is a key determinant of epidemiological outcomes. Theory shows that host density can influence the spread of pathogens differentially depending on their mode of transmission. Host density could therefore play an important role in selecting for pathogen transmission mode. We test theoretical expectations using floral array...

Reciprocal selection promotes the specificity of host-pathogen associations and resistance polymorphisms in response to disease. However, plants and animals also vary in response to pathogen species not previously encountered in nature, with potential effects on new disease emergence. Using anther smut disease, we show that resistance (measured as...

Infection prior to reproduction usually carries greater fitness costs for hosts than infection later in life, suggesting selection should tend to favour juvenile resistance. Yet, juveniles are generally more susceptible than adults across a wide spectrum of host taxa. While physiological constraints and a lack of prior exposure can explain some of...

The evolution of separate males and females is an important evolutionary transition that has occurred multiple times in flowering plants. While empirical studies have stressed the potential importance of natural enemies and organismal interactions in the evolution of separate sexes, there has been no treatment of natural enemies in the theoretical...

Recent theoretical work has shown that long-lived hosts are expected to evolve higher equilibrium levels of disease resistance than shorter-lived hosts, but questions of how longevity affects the rate of resistance evolution and the maintenance of polymorphism remain unanswered. Conventional wisdom suggests that adaptive evolution should occur more...

A trade-off between a pathogen's ability to infect many hosts and its reproductive capacity on each host genotype is predicted to limit the evolution of an expanded host range, yet few empirical results provide evidence for the magnitude of such trade-offs. Here, we test the hypothesis for a trade-off between the number of host genotypes that a fun...

Background Adaptation of pathogens to their hosts depends critically on factors affecting pathogen reproductive rate. While pathogen reproduction is the end result of an intricate interaction between host and pathogen, the relative contributions of host and pathogen genotype to variation in pathogen life history within the host are not well underst...

Summary of ANCOVA results for sporulation capacity for datasets with either of the Pendek or Pendek38 host genotypes excluded.

Virulence profile of five pathogen genotypes against 32 differential host lines.

Summary of ANCOVA results for total spore production for datasets with either of the Pendek or Pc38 host genotypes excluded.

Summary of ANCOVA results for latent period for datasets with either of the Pendek or Pendek38 host genotypes excluded.

Pairwise comparison of slopes due to host genotype for the regression of spore production on pustule density.

The concept of a trade-off has long played a prominent role in understanding the evolution of organismal interactions such as mutualism, parasitism, and competition. Given the complexity inherent to interactions between different evolutionary entities, ecological factors may especially limit the power of trade-off models to predict evolutionary cha...