Sazonal relationship between reproduction, energetics and immunocompetence in toads (Rhinella jimi)from Caatinga

Abstract

Trade-offs between two or more phenotypic characteristics have been described in the literature as the relative fitness costs that occur when a benefic change in one characteristic is linked to a disadvantageous change in another one. In reproductive males, the expression of secondary sexual characters, including sexual behavior and territorial defense, would be associated with decresead imunocompetence and resistance to parasite infection, representing a pattern of trade-off between fitness components. This trade-off would be functionally mediated by high plasmatic levels of androgens, such as testosterone (T), and glicocorticoids, such as corticosterone (CORT). It is important to note that the intensity of steroid mediated imunossupression can be dependent of the ecological context, and recent data from our research group pointed to the existence of a seazsnal immunomolation in anuran amphibians from the brazilian semi-arid. In this way, we propose a study that explores the seasonal covariation of caracteristics associated with reproduction (T plasmatic levels and testicular maturation), energetics (CORT plasmatic levels, basal metabolic rate and fat stores) and immunocompetence [plasmatic bacterial capacity, subcutaneal inflamatory response to phytohaemagglutinin (PHA), and energetic cost of response to PHA] in male toads (Rhinella jimi) from Caatinga.