Sex But Not Altitude, Modulates Phenotypic Coyariations Between Growth and Physiological Traits in Adult Asiatic Toads

The pace-of-life syndrome (POLS) hypothesis predicts that most variation in life history, physiology, and behavior among individuals, populations, and species falls along a continuum from slow to fast pace of life. While there is evidence for climatic gradient-mediated POI'S patterns among species, this approach has rarely been explicitly used to study POLS patterns among- and within- populations. In addition, the roles of sex in POLS evolution among- or within- populations are largely unknown. In this study. we investigated the effects of attitudinal gradient and sex on the covariations between growth rate and several physiological traits closely associated with POLS (blood glucose, baseline-and stress-induced glucocorticoids (GCs), hemolysis and hemagglutination) in the Asiatic toad Bufo gargarizans. Contrary to our expectation, altitudinal gradient had no influence on the covariations between growth rate and physiological traits, neither at the among- nor within-population level, indicating that these trait integrations have similar fitness payoffs across hierarchical levels. In contrast, we found evidence for sex-specific POLS composition: there was a negative covariance structure between growth rate and baseline GCs- but only in females, and a positive covariance structure between growth rate and baseline GCs- but only in females, and a positive covariance structure between growth rate and hemagglutination-but only in males. This observation indicates that these trait associations differ dramatically in advancing fitness for each sex, and supports the idea that sex-specific POTS composition could evolve in species in which the reproductive roles largely differ between the sexes.