Signalling of information that is neither cryptic nor private

Abstract

It is commonly assumed that in order for animal signals to be advantageous, the information being signalled could not have been obtained otherwise, and is therefore 'cryptic' or 'private'. Here, we suggest a scenario in which individuals can gain an advantage by signalling 'public' information that is neither cryptic nor private. In that scenario, signalling increases the efficiency with which that 'public' information is transmitted. We formalize our idea with a game in which offspring can signal their condition to their parents. Specifically, we consider a resource-strapped parent who can only invest in one of its two offspring, and we allow offspring the chance to influence parental investment through a signal. A parent in the game seeks to invest in the higher-quality offspring, which it could identify either through a publicly available cue, such as body size, or by relying on a signal provided by the offspring. We find that if the signal can convey information about offspring quality more efficiently than cues, then signalling of condition between offspring and parents can be favoured by selection, even though parents could potentially have acquired the same information from the cue. Our results suggest that the biological function of signals may be broader than currently considered, and provide a scenario where low cost signalling can be favoured. More generally, efficiency benefits could explain signalling across a range of biological and economic scenarios.

A general model of biological signals, from cues to handicaps

“…Cues are typically classified as non‐signalling traits because, by definition, they have not evolved for the purpose of conveying information to receivers (Maynard Smith and Harper ; Wild et al. ). However, cues of quality do experience signalling selection: they vary with signaller quality, receivers respond to that variation, and receiver responses affect signaller fitness.…”

“…More generally, the model will apply to analogous contexts, including offspring signalling their need to parents (Godfray ; Wild et al. ) and plants signalling their quality to pollinators or herbivores (Archetti and Brown ; Knauer and Schiestl ). In our approach, males have a signalling strategy that matches their quality to a particular signal size, and females have a strategy that infers signaler quality from signal size.…”

Tadpole plasticity shapes the potential benefits of egg feeding to poison frog parents

“…In nature, R. imitator may depend on parents because parents are selected to deposit them in nutrient‐poor nurseries (Brown et al, 2010; Brown, Morales, & Summers, 2008a; Brown, Twomey, et al, 2008), but offspring traits do not contribute to this dependence. While co‐evolution of parents and offspring is often driven by conflict (Mock & Parker, 1997; Trivers, 1974), cooperative traits can also evolve if their costs are low (Wild et al, 2017); plasticity that enables offspring to efficiently convert parental investment into fitness may be one such example of cooperation within families.…”

Reimagining pheromone signalling in the model nematode Caenorhabditis elegans

“…While these pheromone signals are publically broadcast into the environment, correct interpretation of them could be specific to an ecological community or kin group. In support of this idea, game theory studies have shown that public signals can evolve [ 40 ].…”