Salamander Fungus Batrachochytrium salamandrivorans, Europe

Although size-assortative mating (SAM) is a frequently studied phenomenon in anurans, its effect on fitness rarely has been evaluated. Using a controlled experiment, we assessed the presence of SAM in the common toad, Bufo bufo , and evaluated the effect on fertilization success of male-female size (snout-vent length, SVL) difference and ratio in mated pairs. Even though the toads paired non-randomly with respect to size, the difference and ratio of female and male SVL in pairs had no significant effect on fertilization success. Our findings and the majority of other studies suggest that the commonly accepted idea that SAM serves to maximize fitness may not be completely accurate. The statistical power and effect size in these studies are often poor, however, and the methods used are inconsistent. We conclude that more manipulative experiments with appropriate sample sizes are needed to fully understand this phenomenon.

Size-assortative mating (SAM) is a widespread phenomenon related to individual fitness. In our study, we examined: (i) the appearance of SAM, and (ii) the effect of sex ratio on intensity of SAM in wild populations of two explosively breeding anurans, common frogs, Rana temporaria , and common toads, Bufo bufo . Despite a higher male-biased operational sex ratio (OSR) in toads, the body lengths of the paired males and females were significantly correlated only in frogs. Increasing male-male competition, assessed via the OSR, resulted in a stronger correlation also in frogs only. Thus, great variability in the presence and intensity of SAM has been observed within both studied species.

Environmental DNA (eDNA) is becoming an indispensable tool in biodiversity monitoring, including the monitoring of invasive species and pathogens. Aquatic chytrid fungi Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) are major threats to amphibians. However, the use of eDNA for detecting these pathogens has not yet become widespread, due to technological and economic obstacles. Using the enhanced eDNA approach (a simple and cheap sampling protocol) and the universally accepted qPCR assay, we confirmed the presence of Bsal and Bd in previously identified sites in Spain, including four sites that were new for Bsal. The new approach was successfully tested in laboratory conditions using manufactured gene fragments (gBlocks) of the targeted DNA sequence. A comparison of storage methods showed that samples kept in ethanol had the best DNA yield. Our results showed that the number of DNA copies in the Internal Transcribed Spacer region was 120 copies per Bsal cell. Eradication of emerging diseases requires quick and cost-effective solutions. We therefore performed cost-efficiency analyses of standard animal swabbing, a previous eDNA approach, and our own approach. The procedure presented here was evaluated as the most cost-efficient. Our findings will help to disseminate information about efforts to prevent the spread of chytrid fungi.