Research

My lab is currently investigating two broad avenues of research.  The first involves elucidating the environmental variables underlying species invasions and disease outbreaks in the Upper Mississippi River.  The second revolves around understanding the roles that host genetics and nutrition play in the transmission of the human parasite Schistosoma mansoni. 

INVASIVE SNAILS AND PARASITES ARE ALTERING NATIVE COMMUNITIES IN THE UPPER MISSISSIPPI RIVER

 Aquatic invasive species are rapidly altering the structure of native communities across North America, which has important consequences for species diversity, conservation policy, and ultimately, national economics.  One of the key hotspots for aquatic invasions has been the Great Lakes system where over 50 species have been introduced over the last 30 years.  Bithynia tentaculata is an invasive aquatic snail that has recently spread from the Great Lakes into the Upper Mississippi River.  Range expansion has generated 2 disconcerting patterns in the river: First, the snails appear to dominate the mollusk community, and second, the snail transmits exotic parasites that kill waterfowl by the thousands.  Unfortunately, even though B. tentaculata and its parasites are directly disrupting general ecosystem stability and economics in the Upper Midwest, little is actually known about the factors responsible for snail colonization and parasite transmission.  Using a series of field surveys, semi-natural experiments and laboratory manipulations we are attempting to 1) elucidate the abiotic factors correlating with invasive snails and parasites, 2) determine how competition and infection influence B. tentaculata establishment, and 3) understand the role that other aquatic species play in transmitting these exotic parasites to birds.  Preliminary data suggest that native aquatic species may be extremely important in exotic parasite persistence and transmission to waterfowl.  Results from this research will instrumental in the development of management models aimed at curbing the spread of this invasive host-parasite association.  This work is conducted in collaboration with a number of agencies including the United States Geological Survey and US Fish and Wildlife.

THE PARASITE, SCHISTOSOMA MANSONI, IS RESPONSIBLE FOR HUMAN SUFFERING AROUND THE GLOBE

Recent research  using microsatellite markers suggests that relative migration rates of Schistosoma mansoni and its host, Biomphalaria glabrata in Brazil may allow parasites to become locally adapted to their hosts, particularly if snail populations are genetically similar and/or inbred.  Although B. glabrata migration rates appear to be low, movement among populations does occur which could impact host-parasite interactions through the introduction of novel host alleles.  In order to investigate this scenario, we conduct experiments aimed at assessing the effects of increased genetic variability on the interaction between B. glabrata and S. mansoni.   Inbred and outcrossed B. glabrata lines have been established and  progeny from these lines are exposed to different strains of Schistosoma mansoni.  Results were somewhat unexpected, as both inbred and outcrossed snails exhibited very high levels of parasitic infection.  However, outcrossed snails appeared to better accommodate these infections surviving significantly longer, generating far more eggs and producing greater numbers of viable offspring compared to inbred snails.  In addition, S. mansoni cercariae tended to be released in lower numbers from outcrossed snails relative to their inbred counterparts.  This work demonstrates that host outcrossing can provide a fitness advantage in the face of parasitism which may have consequences for the transmission of S. mansoni in different Brazilian populations of B. glabrata.

Click here to see a list of recent presentations or here for a list of publications

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