Local adaptation and host specificity to copepod intermediate hosts by the tapeworm

Area of Science:

• Evolutionary biology
• Parasitology
• Ecology

Background:

• Host-parasite coevolution can drive local adaptation in either species.
• Parasites with complex life cycles face challenges adapting to multiple hosts.
• Schistocephalus solidus tapeworm shows local adaptation to its second intermediate host, the threespine stickleback.

Purpose of the Study:

• To investigate local adaptation and host specificity of Schistocephalus solidus to its first intermediate copepod hosts.
• To determine if tapeworm populations adapt to geographically distinct copepod populations.

Main Methods:

• Reciprocal exposure experiment using copepods and tapeworms from five lakes in Vancouver Island.
• Assessed infection rates of tapeworms in local and foreign copepod populations.
• Examined host specificity across different copepod species and cestode populations.

Main Results:

• Schistocephalus solidus did not exhibit local adaptation to its first intermediate copepod hosts.
• Moderate host specificity was observed, with higher infection rates in certain copepod species.
• Infection rates varied significantly among different tapeworm (cestode) populations.
• Copepod species were not equally competent hosts for the tapeworm.

Conclusions:

• Local adaptation to first intermediate hosts is not a primary driver of Schistocephalus solidus epidemiology.
• Partial specialization on specific copepod species significantly influences tapeworm distribution and infection dynamics across lakes.
• Understanding host-parasite interactions in complex life cycles is crucial for predicting parasite epidemiology.