Considering the addition of intermediate transmission steps during life cycle evolution, developmental
plasticity, canalization forces and inherited parental effect must be invoked to explain new host colonization.
Unfortunately, there is a lack of experimental procedures and relevant models to explore the
adaptive value of alternative developmental phenotypes during life cycle evolution. However, within
the monogeneans that are characterized by a direct life cycle, an extension of the transmission strategy
of amphibian parasites has been reported within species of Polystoma and Metapolystoma (Polyopisthocotylea;
Polystomatidae). In this study, we tested whether the infection success of Polystoma gallieni
within tadpoles of its specific host, the Stripeless Tree Frog Hyla meridionalis, differs depending on the
parental origin of the oncomiracidium. An increase in the infection success of the parasitic larvae when
exposed to the same experimental conditions as their parents was expected as an adaptive pattern of
non-genetic inherited information. Twice as many parasites were actually recorded from tadpoles
infected with oncomiracidia hatching from eggs of the bladder parental phenotype (1.63 ± 0.82 parasites
per host) than from tadpoles infected with oncomiracidia hatching from eggs of the branchial parental
phenotype (0.83 ± 0.64 parasites per host). Because in natural environments the alternation of the two
phenotypes is likely to occur due to the ecology of its host, the differential infection success within young
tadpoles could have an adaptive value that favors the parasite transmission over time.http://www.journals.elsevier.com/experimental-parasitology
