“Ecology and Epidemiology of the Sudden Oak Death Epidemic: Interspecific Competition, Disease Incidence and the Population Genetics of Phytophthora ramorum within a CA Watershed”
Introduction by Matteo Garbelotto
Phytophthora ramorum is causing landscape-level alterations in forest composition throughout California. While the likely origin and geographic pathways of spread have been reconstructed, little is known about local-scale processes contributing to disease maintenance and progression. Since 2008, a network of plots in the San Francisco region have been surveyed 3 times per year in order to determine seasonal patterns in the incidence and population genetics of P. ramorum and to examine the relationship between infection on dead-end (Oak) and amplifying (Bay Laurel) hosts. A diagnostic qPCR assay was used to score nearly 4500 samples and over 1500 isolates have been genotyped. Underlying processes of pathogen expansion, contraction and spread have been inferred and genetic structure examined both spatially and temporally. A period of drought from 2007-2009 followed by a period of normal precipitation in 2010-2011 provided an opportunity to examine the effects of abiotic disturbance on disease progression as well. Here, I will present research focused on assessing seasonal patterns in genotypic diversity of viable infections that act as reservoirs of new infectious propagules, fluctuations in isolation success throughout the year and microclimate factors which support perennial sources of inoculum. Additionally I will discuss the effect of drought as a potential selection agent on the pathogen and the role of competitive interactions with two sympatric Phytophthora species.
I would like to thank my advisor Matteo Garbelotto for all his support and enthusiasm, as well as my lab mates, particularly Todd Osmundson, Katy Hayden, Catherine Eyre and Dora Barbosa for their friendship, advice, and humorous anecdotes over the years. I would also like to thank my friends and family, for their patience, unwavering confidence and support.
My favorite ESPM memories go back to the days of Brad Balukjian as social coordinator. Never have emails on a mailing list made me laugh so genuinely. From the camping trip to sunny happy hours on the lawn playing flip cup, the comradery and spirit of this department will always stand out in my mind.