Figure 1

Graphical representation of the 4-week reciprocal translocation experiment carried out in this study using Pelophylax perezi and Bufo spinosus tadpoles. The experiment design consisted in four experimental groups (2 source waters × 2 host species) and one control group for each source water (aquaria without tadpoles). The figure displays the number of replicas per experimental group (× 1, × 2), the sampling events (Days) and the four types of samples collected at each day – skin (open circle), gut (closed circle), newly collected water from the waterbody (white drop), and water collected from the aquarium (black drop). Different colours represent different water sources: Gafanha (yellow), Lousada (green). Three tadpoles were sampled weekly from each group replicate, where skin swabs and gut were collected. At the sampling days 7, 14 and 21, we partially replaced the water of the aquaria (wave arrow), by mixing freshly-collected water from the waterbody (70%) with the 1-week old water of the respective aquarium (30%), to which tadpoles were exposed in the previous seven days (see Methods for details).