Honest signalling was termed “ubiquitous” in a recent game theory paper modeling signal evolution [1]. Biological signals are considered honest when they provide useful information to the receiver [2]. More specifically, sexual signals are considered honest when they indicate the potential benefits that a female could receive by mating with an advertising male [3]–[10]. Sexual signals may indicate mating benefits because (1) preferred signals are often costly to produce; (2) only males good at acquiring nutrients or using them efficiently may be able to support the costs of signal production; and (3) males with more nutrients may be of higher fitness or may be able to invest more in providing benefits to females. Males that are able to obtain more nutrients may have greater energy stores, and several studies have found a positive relationship between dietary nutrient availability and sexual signalling [11]–[16]. Given these points, females may benefit from selecting mates that exhibit condition-dependent signals. Here condition is defined as variation in resource acquisition ability [17], which may result from differences in resource availability in the environment and/or individual physiological differences in the ability to assimilate and utilize resources.

The cost of producing sexual signals is often dependent on available nutrients, which in turn is subject to life-history trade-offs. Allocating nutrients to sexual signalling must, therefore, be balanced against the nutrients required for growth and survival [8], [18], [19]. High condition males with an abundance of nutrients may be better able to afford the costs of allocating resources to sexual signalling than poor condition males (i.e. honest signalling [20]). Alternatively, poor condition males with reduced future reproductive potential may allocate more nutrients towards sexual signalling, thereby