Signalling and phosphorus: correlations between mate signalling effort and body elemental composition in crickets

Recent findings in the field of ecological stoichiometry indicate that the relationships among key macronutrient elements (e.g. carbon, nitrogen and phosphorus) of organisms and their resources may underlie variation in fitness-conferring behaviours. The amount of phosphorus in an individual's body is often correlated with its rate of growth and reproduction, and low-phosphorus diets are known to reduce growth in a number of insect and crustacean herbivores. These findings suggest that the stoichiometric imbalance between organismal biomass requirements and the relative scarcity of nutrients in nature may underlie variation in condition-dependent behaviours. Here we investigate relationships between body elemental composition and long-distance mate attraction signals produced by male Texas field crickets, Gryllus texensis. Signalling was strongly and positively correlated with the percentage of phosphorus present in the body, but was not correlated with the percentage of carbon or nitrogen present. We also found evidence suggesting that callers and noncalling satellites differ in their elemental composition. To our knowledge, our data are the first to indicate that there may be a relationship between total body phosphorus content and a sexually selected trait. We present a preliminary evaluation of proximate hypotheses to account for the observed patterns. Our results indicate that a stoichiometric perspective may help us to understand the causes of variation in behaviour.