Do ectoparasites affect survival of three species of lizards of the genus Sceloporus?

The short-term effects that ectoparasites cause to their hosts, such as local wounds and secondary infections that occur within a few hours or days after infection, are well documented in a wide variety of taxa, whereas long-term negative effects on the fitness of hosts, which result from chronic infections and are evident after several months, are less understood. Lizards are hosts of distinct species of mites and ticks that cause short-term negative effects such as ulcers, sores and local inflammation. However, the negative effects that these ectoparasites may have on the long-term survival of lizards have not been evaluated. In this study, we collected two years of capture-mark-recapture data and implemented a multi-model inference framework to examine if high ectoparasite loads have negative effects on the long-term survival probability of three lizard species of the genus Sceloporus (S. grammicus, S. megalepidurus, and S. torquatus). In addition, we considered that the potential negative effect of ectoparasites on survival may vary depending on sex, body condition, reproductive season, or climatic season. Contrary to our expectations, our results did not support the hypothesis that high ectoparasite loads reduce the survival probability of these lizards. In S. grammicus and S. megalepidurus we found no evidence of an effect of ectoparasite load on host survival. In S. torquatus ectoparasites influenced survival probability, but the effect was opposite to what we predicted: survival increased substantially as ectoparasite load increased. This unexpected result might be explained by mites discriminating between hosts and attaching more frequently to lizards in better health status, or by high-quality lizards having greater chances of contracting ectoparasites, because these individuals move around large areas and frequently engage in social interactions.