Coevolutionary events in the history of association between jerboas (Rodentia: Dipodidae) and their flea parasites

We studied historical patterns of the association between fleas and jerboas using Brooks parsimony analysis (BPA), tree reconciliation analysis, general parsimony analysis (TreeFitter), and the ParaFit method. A phylogenetic host tree reconstructed by BPA was incongruent with the known host phylogeny and most characters were homoplasious. The optimization of the recoded flea tree on the jerboa tree suggested that the common evolutionary history of fleas and jerboas was characterized mainly by inertia, host switching, and sorting events. There was a geographic pattern in parasite-based jerboa trees. Species with common geographic distribution and/or habitat preferences or common geographic origin tended to cluster together. The fit of the phylogenetic trees of jerboas and their fleas by reconciliation did not need cospeciation, but mainly suggested sorting events. Optimal reconstruction by TreeFitter revealed a significant phylogenetic effect only when the costs of host switching and linear sorting were assumed to be low. The global test performed by ParaFit indicated no global relationship between jerboa and flea phylogenies on either species-species or genus-genus levels. Results of the study suggested that evolutionary history of the jerboa-flea associations involved association by colonization with frequent host switching and linear sorting events, whereas widespread cospeciation was absent. Distribution of fleas on jerboas is, therefore, affected mainly by ecological and geographic factors.