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We study how pathogens influence plant populations and communities.
Our most recent work focuses on understanding and predicting how pathogens spread among hosts of different species, and therefore how the diversity and makeup of plant communities influences disease pressure. We are using phylogenetic ecology to predict the structure of plant-fungal networks, analyzing these networks across ecosystems using next-generation sequencing, and testing their predictions with agro-ecological experiments at an operational scale.
Ingrid and Greg are having fun writing a graduate-level textbook for Oxford University Press, The Evolutionary Ecology of Plant Disease. We are looking forward to wrapping up that project, years in the making!
PATHOGENS AS A MECHANISM FOR COEXISTENCE
We used our system of 17 co-occurring species of clovers (Trifolium and Medicago) to test hypotheses about how host-pathogen interactions might act as either stabilizing or equalizing mechanisms in Chesson's coexistence theory. As shown in this graphical abstract, we found some evidence for both--but life history tradeoffs and tolerance to infection also plays a role.
From Parker and Gilbert 2018, Journal of Ecology
PHYLOGENETIC ECOLOGY, PATHOGEN SPILLOVER, AND RARE SPECIES ADVANTAGE
From Parker et al. 2015, Nature
Read a news article on this work.
Locally rare species are expected to have a survival advantage over more abundant species, because rarity reduces their risk of damage from pathogens. This “rare-species advantage” may help maintain plant diversity in natural systems and explain how introduced plant species become invasive weeds.
However, most pathogens are able to infect a variety of different hosts. Which hosts are susceptible is not a random assortment of species, because closely related species are more likely to share a pathogen than are more distantly related species. This means that rarity is not simply a function of species density (numerical rarity), but of the combined density of all species with which it shares a pathogen. A species with no closely related neighbors has the added benefit of “phylogenetic rarity”.
INTRODUCED SPECIES & BIODIVERSITY-DISEASE RELATIONSHIPS
A common assertion is that invasions occur because species “leave their natural enemies behind” and are released from pest pressure to become aggressive competitors in their introduced range. We have been studying the ecological as well as evolutionary aspects of this theory for over two decades.
Together with Hillary Young and colleagues, we have also explored how biological invasions of both animals and plants change the predictions of biodiversity-disease relationships, with important implications for the "dilution effect," a core theory in disease ecology.
From Young et al. 2016, TREE
You can find publications from these projects and more at Ingrid's Google Scholar page.
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