Co-Evolution of Invasive Parasites with Old and New Host Species along a Gradient of Ancient to Recent Sympatry

• Applicant: Dr. Mathias Wegner
• Subject Area: Evolution, Anthropology
• Term: from 2012 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 224741041

With the exception of microbial systems where evolutionary change can be observed in real time, it is inherently difficult to determine the time frame in which host-parasite coevolution and local adaptation occurred. As a consequence it is hard to say whether coevolution relies on rapid adaptive changes in wild populations of higher animals. Biological invasions offer the exceptional opportunity not only to set an exact date from which on coevolution occurred, but also to differentiate between invasive parasites infecting new hosts (i.e. emerging disease) and invasive hosts being infected by already present parasites. The invasion of two parasitic copepods of the genus Mytilicola (M. intestinalis and M. orientalis) into the North Sea via aquaculture activities represents a unique system where coevolution can be observed during different time spans in “old” host species already present in the native range as well as in “new” hosts included into the life cycle only after invasion. Therefore the two closely related congeners offer a unique species pair to investigate host-parasite co-evolution along a gradient of ancient to recent sympatry. M. orientalis invaded only recently along with the invasion of Pacific oysters into the North Sea. It follows a more generalist strategy infecting many different bivalve species encountered with only few generations of coevolution. M. intestinalis spread through the Wadden Sea in the early 20th century and is rather specialized on mussels, with which it shares a longer coevolutionary history. By following a transcriptomic approach of both hosts and parasites from native and invaded ranges in a crossed experimental infection scheme, this system can be used to identify physiological responses on the transcriptional level when encountering old or new host parasite combinations as well as evolutionary responses selecting for certain genetic variants favored during the invasion process. This will not only shed light on the role of invasion for coevolution of this parasite genus in particular but also on the evolution and the consequences of generalist vs. specialist strategies during rapid local adaptation and counter-adaptation in emerging diseases.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1399: Host-Parasite Coevolution - Rapid Reciprocal Adaptation and its Genetic Basis
• International Connection: Netherlands, Portugal
• Participating Persons: Dr. Federico Batista; Dr. Christian Buschbaum; Dr. David William Thieltges