Genome size influences adaptive plasticity of water loss, but not metabolic rates in lungless salamanders

Many expressions of phenotype, such as physiological performance, integrate multiple underlying traits to function. Linking component traits to adaptive physiology thus gives insight into mechanisms of selection acting on performance. Genome size (C-value) is a trait that influences physiology in multiple taxa by exerting a nucleotypic effect, constraining cell size and cellular physiology such that whole-organism mass-specific metabolism is reduced with increasing C-value. We tested for this mechanism of C-value function acting in lungless salamanders, plus an unexplored potential mechanism of C-value effects constraining water transport across the body surface to influence cutaneous water loss rates. We found no evidence for a nucleotypic effect on metabolic rates, but we demonstrate a relationship between C-value and water loss physiology. Under warmer experimental conditions, C-value was inversely correlated with water loss and positively correlated with resistance to water loss, wh...