Abstracts (first author)
Capturing the population structure of microparasites: using ITS-sequence data and a pooled DNA approach
The internal transcribed spacer (ITS) region of nuclear ribosomal DNA is a central target not only for molecular identification of different taxa and strains but also for analyses of population structure of wild microparasite communities. Importantly, the multi-copy nature of this region allows for successful amplification of low quantity samples of the target DNA, a common problem in studies on unicellular, unculturable microparasites. We analysed ITS-sequences from the protozoan parasite Caullerya mesnili (class Ichthyosporea) infecting waterflea (Daphnia) hosts, across several host population samples. We showed that analysing representative ITS-types (as identified by statistical parsimony networks) is a suitable method to address relevant polymorphism. The spatial patterns were consistent regardless of whether parasite DNA was extracted from individual hosts or pooled host samples. Remarkably, the efficiency to detect different sequence types was even higher after sample pooling. As shown by simulations, an easily manageable number of sequences from pooled DNA samples was already sufficient to resolve the spatial population structure in this system. In summary, the ITS-region analysed from pooled DNA samples can provide valuable insights into the spatial and temporal dynamics of microparasites. Moreover, for the analysis of sequence variation in multi-copy gene regions, the application of statistical parsimony network analysis is clearly advantageous.