Who's chasing who? Host-parasite interactions, cryptic diversity and behavioral manipulation

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My research addresses fundamental questions in ecology and evolution using parasites and their hosts as study models, with particular interest in host manipulation by parasites and cryptic diversity (i.e. morphologically identical but genetically divergent lineages). Many examples of parasites altering host phenotype have been documented, some truly spectacular! However, the actual fitness benefits of host manipulation for the parasite are virtually never assessed; I have published one of only three studies that actually demonstrated the adaptive value of host manipulation. Studies of the complexity, adaptive value and mechanisms of host manipulation are extremely rare and at the cutting edge of research. Cryptic diversity is simply never considered in such studies. The proposed program will employ innovative, multidisciplinary approaches to test key hypotheses around host manipulation and cryptic diversity. The 5-year program includes four main objectives: 1. How common are host manipulation and cryptic diversity in host-parasite systems? Focusing on freshwater host-parasite associations of Alberta as study models, we will use DNA barcoding to estimate cryptic diversity in multiple host-parasite combinations. We will then assess host manipulation intensity in a range of host-parasite associations with varying levels of cryptic diversity to test for potential links between host manipulation and such hidden diversity. 2. Are cryptic hosts also cryptic to parasites? Using controlled, experimental cross-infections among host and parasite lineages, we will test the effects of genetic distance on host-parasite compatibility and host manipulation intensity. 3. Is parasite-induced manipulation adaptive? One of the most important, yet least tested aspects of host manipulation. Using field and mesocosm experiments, we will test for adaptive value, complexity (array of host traits targeted), and repeatability (temporal consistency on daily, seasonal and ontogenic scales) of host manipulation. 4. What are the underlying mechanisms of host manipulation? We will combine genomic and proteomic approaches to assess the mechanisms through which these parasitic puppeteers take control of their hosts and induce behavioral traits apparently tailored to their own interests. Significance This program combines multidisciplinary projects using various study models to test universal hypotheses at the cutting edge of research in parasitology, ecology and evolution. It will shed new light on host manipulation complexity, fitness value and underlying mechanisms by treating it not as an isolated phenomenon but as part of the complex interaction of multiple selection pressures on hosts and parasites. We will use innovative approaches at the crossroads of parasitology, molecular ecology (DNA barcoding) and proteomic/genomic that will significantly advance our knowledge of host manipulation complexity, adaptive value and mechanisms by combining pioneering methodologies.