Meeting Abstract
Condition dependence of sexual traits has been proposed as an important mechanism that maintains trait honesty. In this context, condition is defined as the pool of resources allocable to traits. However, the operational definition of condition has varied widely. Often, studies have manipulated the supply of total energy or a few molecular resources, implicitly assuming shifts in the amount of allocable resources to condition-dependent traits. Ecological supply of energy carrying molecules, or specific molecular resources is heterogeneous, and covaries with other important energy sources and molecules. It is difficult to quantify all the energetic and molecular resources while maintaining ecological relevance. Nonetheless, such obstacles hinder robust testing of the condition-dependence hypothesis. Examining condition dependence at the elemental level has the potential to overcome these obstacles. Complexity in environmental supply of resources and an individual’s composition can be reduced to about 25 biologically active elements, or the ionome. We posit that measuring ionomic profiles of resources in the environment, the individual, and traits of individuals will reveal the elemental signatures of condition dependence. Specifically, we predict that the expression of a condition-dependent trait is more sensitive than non-sexual traits to the element that has the greatest physiological demand and in least ecological supply. It follows that higher condition is a function of not only the genomic capacity of a genotype to acquire, assimilate, and allocate this element, but also the ecological supply of the limiting element. Understanding the elemental signatures of condition dependence has the potential to reveal fundamental rules underlying the evolution of condition dependent traits in all taxa with unrivaled ecological rigor.
