Host diversity and disease risk

Research questions

1) Does the effect of host species diversity on pathogen prevalence depend on the level of host specificity?

2) What are the associations between host and bacterial species diversity and their consequences for disease risk?

3) Is the effect of host species diversity on pathogen prevalence mediated by the vector fitness?

4) What are the underlying mechanisms of the negative relationships between host species diversity and disease risk?

Description

Host species diversity is expected to have dramatic effects on disease risk via multiple, sometime contrasting mechanisms. We employed the natural gradient of rodent species diversity in the Negev sand dunes to explore the bacterial community in the rodent’s blood and fleas. By looking at the entire bacterial community and by exploring simultaneously the effects of various correlates of host species diversity, we have shown that diversity effects are more complex in reality that those previously assumed, but are still predictable.

To disentangle the mechanisms that mediate the relationships between host species diversity and disease, we conducted broad physiological and behavioral assessments of interacting hosts and pathogens in the laboratory. We focused on the interactions of Mycoplasma pathogens, which are diluted in the field by increased host species diversity, with each of the host species and found that one host species plays the role of disease amplifier and the other two of diluters. This project illustrates that field and laboratory approaches complement each other and jointly provide a comprehensive mechanistic understanding of complex natural patterns.