Fenología de la reproducción y exposición a ácaros hematófagos en dos lacértidos mediterráneos

Description

The theory of vital strategies postulates that the energy available to individuals is finite and that it is adaptive to prioritize those vital processes that allow maximizing biological efficiency. Reproduction is the fundamental piece of this theory, since through its direct action individuals leave offspring and therefore reproducing is a priority over any other vital process. However, it is energetically very demanding and can produce costs in other important processes that are also energetically demanding; for example, the maintenance of the immune system and other antiparasitic mechanisms. We have tested this hypothesis by analyzing the correlation between the phenological patterns of investment in reproduction of two lizard species with different ecological habits and the seasonal variation in the number of mites that parasitize them. Some interspecific discrepancies were found in the phenological patterns of parasitization, where the species that prefers wetter microhabitats had a higher prevalence and number of mites and these increased from April to July. Additionally, gravid females of the species that prefers drier environments had as many mites as the first species, suggesting that they might select wetter locations during egg formation. However, there was no significant relationship between seasonal variation in the number of mites and reproductive phenology in males. Therefore, it is unlikely that investment in reproduction increases susceptibility to mites in these two lizard species.

Steps to reproduce

We performed the statistical analyzes in Statistica 12.0 (StatSoft, Hamburg, Germany). To compare mite prevalence between species, we used a Chi-square test. For mite counts, the four models carried out fit best with a Gaussian distribution of the residuals after transforming the mite data using decimal logarithm. In the first model, which analyzed the total data (N = 220), the factors month, species and sex of the lizards were included as predictors. And interactions between month and sex, month and species, and sex and species were included. Three more models were carried out to analyze the variation in infestation intensity in relation to the reproductive investment indicators used. In the case of females, the data from both species could be analyzed together (n = 117) since the pregnancy status was the indicator used. The model was controlled by the factors month, species and pregnancy status. The interaction between pregnancy status and species was included to check whether the number of mites is influenced differently, depending on the species, by pregnancy status. Body length was included as a possible confounding variable. In the case of A. erythrurus males (n = 28) the mites were modeled including month as a factor and testicular width as a linear predictor. In the case of P. algirus males (n = 75), the mites were modeled also including the month as a factor and the extent of nuptial coloration group in which they were assigned as a categorical predictor.

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