Student projects at UVA
I've been lucky to advise some outstanding undergraduates at the University of Virginia. Here's a sample of some of their independent research projects.
Liz is studying the effects of physiological stage on disease resistance in Silene latifolia. She is using extended photo period and gibberellic acid to manipulate flowering stage.
Jenny is studying the phylogentic signal in mating behavior of Microbotryum. She has extended the work from a former student, Mevish Siddiq, to look at conjugation rates of Microbotyrum from Dianthus pavonius and S. latfiolia on a range of phylogentically divergent hosts.
Indigo Ballister (2019)
Indigo studied age-specific resistance to anther-smut in Silene latifolia. She carried out a large inoculation study to measure the resistance level of 15 maternal families of S. latifolia at different ages. She will be starting dental school at the University of Pennsylvania in the fall.
Samantha Stratton (2019)
Samantha studied the effect of temperature and precipitation on the distribution of Dianthus pavonius and its Microbotryum pathogen. She used GIS and species distribution modeling to investigate climatic variables driving host and pathogen distributions, and to predict how these interactions might vary under future climate scenarios. Sam is now working for an environmental consulting company in DC.
Julia Treubert (2019)
Julia studied the effect of Microbotryum infection on host competition. Anther-smut disease sterilizes, but does not kill its host. Thus, infected plants are maintained in populations, where they not only serve as a source of new infections, but also compete with healthy plants for resources. Understanding the impact of disease on host competitive ability is therefore critical to predicting the impact of disease on the host population dynamics. Julia carried out two large greenhouse experiments with S. latifolia to determine the effect of infection status on host biomass under different competition treatments. She is currently in Taiwan, studying Mandarin, on a fellowship.
Laura Pierce (2018)
Laura spent two summers in the field studying the behavioral ecology of insect pollinators in the Dianthus system, and their contribution to anther-smut transmission. She teamed up with Amherst College students to investigate whether different pollinator species express preferences for diseased vs. healthy plants. Laura is starting a master's program in public health at McGill University this fall.
Zoe Addis (2016)
Zoe studied co-infection dynamics of three different Microbotryum lineages on Dianthus seguieri. She inoculated plants with an endemic strain of Microbotryum known to cause disease on D. seguieri either alone or with one of two strains two different strains collected from other Dianthus species known to have low infection rates on D. seguieri. She found that infection rates were actually higher for the co-infection treatments, then in the single infections. Even more surprising, sequence analysis showed that the non-endemic pathogens out-competed the endemic pathogen in co-infection treatments, indicating facilitation.
Ian Miller (2015)
Ian’s senior honors thesis focused on the role of disease in the evolution of separate sexes. As part of his thesis he developed a theoretical model that examine the effect of disease on the evolution of females when sex is determined by the interaction of cytoplasmic male-sterility (CMS) genes and nuclear restorer genes (Miller and Bruns, 2015). His model showed that not only can disease drive the evolution of higher female frequency, but it can also lead to the evolution of nuclear sex-determination (a necessity for the evolution of sex chromosomes). Ian also came out to Italy where he used floral tube arrays to investigate frequency-dependent selection for females by anther-smut disease. Ian is currently a Ph.D. student in Jess Metcalfe's lab at Princeton.
Audrey Batzel (2015)
Audrey studied the effect of Microbotryum spores on floral closing behavior in Dianthus in the field and greenhouse. She found that the application of spores to the stigmas of healthy females strongly reduced closing behavior and seed set. Her results are important because they show that anther-smut can have strong negative effects on host reproduction even if it is unsuccessful at infecting the host. Audrey is now a data analyst at the Institute for Health Metrics and Evaluation.
Mevish Siddiq (2015)
Mevish studied host preference of the Microbotryum fungus. She found that conjugation rates of haploid spores (an essential precursor to infection) were much higher when the fungus was inoculated on it’s own endemic host species (D. pavonius), than when it was inoculated onto a closely related host species (D. seguieri), a more distantly related host species (Silene vulgaris), or agar media. Her results therefore demonstrate that patterns of host specialization among Microbotryum lineages on Dianthus may be driven in part by fungal mating behavior. Mevish is currently attending Medical School at Georgia Medical College.
Prima Vithoontien (2014)
Prima studied the mating behavior of haploid Microbotryum lineages specialized on D. pavonius. Previous studies of Microbotryum infecting the model species S. latifolia have shown that the mating system of Microbotryum close to 100% selfing. However, hybrid strains of Microbotryum have been found on D. pavonius at relatively high frequency (Petit et al. 2017), indicating that outcrossing must occur. Prima set up in vitro mating tests between the haploid spore stage of 8 strains of Microbotryum, and compared conjugation rates. She found that while most lineages showed strong preferences for selfing, one lineage had higher conjugation rates under outcrossing. These results suggest there may be genetic variation for selfing preference and could help explain the abundance of hybrid lineages. After graduating Prima went to Columbia University to study Physical Therapy.
David Tyson (2014)
David studied the anther-smut disease on Silene baccifera in Europe. He compared ITS sequences of Microbotryum from herbarium collections on S. baccifera to other known Microbotryum species. He also carried out greenhouse inoculation experiments to determine the susceptibility of S. baccifera to three species of Microbotryum endemic to other Silene species. David also ran a field experiment in Italy to determine the potential for pollinators to transmit spores from diseased Silene latifolia to S. baccifera. His work was recently published in the journal Plant Pathology. David is now in Medical School at the University of Florida.