Complex signals alter recognition accuracy and conspecific acceptance thresholds

Abstract

Many aspects of behaviour depend on recognition, but accurate recognition is difficult because the traits used for recognition often overlap. For example, brood parasitic birds mimic host eggs, so it is challenging for hosts to discriminate between their own eggs and parasitic eggs. Complex signals that occur in multiple sensory modalities or involve multiple signal components are thought to facilitate accurate recognition. However, we lack models that explore the effect of complex signals on the evolution of recognition systems. Here, we use individual-based models with a genetic algorithm to test how complex signals influence recognition thresholds, signaller phenotypes and receiver responses. The model has three main results. First, complex signals lead to more accurate recognition than simple signals. Second, when two signals provide different amounts of information, receivers will rely on the more informative signal to make recognition decisions and may ignore the less informative signal. As a result, the particular traits used for recognition change over evolutionary time as sender and receiver phenotypes evolve. Third, complex signals are more likely to evolve when recognition errors are high cost than when errors are low cost. Overall, redundant, complex signals are an evolutionarily stable mechanism to reduce recognition errors. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.

The evolution of manipulative cheating

“…Such effects of linkage (interactions) are not discovered in game-theoretical analysis because inclusive fitness effects are estimated as independent factor (i.e., no linkage between traits). Similar complication in coevolving traits have also been observed in other studies involving individual-based simulations (Tibbetts et al . 2020; Liu et al .…”

Long-distance vocalizations of spotted hyenas contain individual, but not group, signatures

“…Signal redundancy has been shown to improve recognition accuracy in evolutionary agent-based models of recognition [85], so redundancy within whoop bouts probably increases both the probability of detection and the receiver's ability to identify the caller. This notion was supported by our calculations of increasing classification accuracies over the course of whoop bouts, although this increase did not reach the classification accuracies expected if each whoop was equally informative and accuracy with each additional whoop followed a Bayesian updating rule.…”

Visual and chemical signals provide different information in Polistes fuscatus wasps

“…Further, this study was done near the end of the nesting season, when there is no usurpation risk. Theory suggests backup signals may only evolve when recognition errors are very costly (Tibbetts et al., 2020).…”

“…Many animals communicate using complex signals that convey information in multiple sensory modalities. Complex signals are typically divided into two main categories based on information content of the signals: redundant signals convey similar information, while non‐redundant signals (or “multiple messages”) convey different information (Hebets & Papaj, 2005; Tibbetts et al., 2020). For example, Schizocosa wolf spiders have redundant sexual signals, as female wolf spiders assess the quality of potential male mates via both visual signals (male leg bristle size) and vibratory signals (amplitude and peak frequency of leg strikes) (Stoffer & Uetz, 2017).…”