The Evolutionary Ecology of Flash Displays and Other Transiently Visible Anti-predation Signals

Hidden signals is an umbrella term used to describe anti-predation signals that are not consistently visible but only exposed transiently. These signals have evolved independently numerous times in taxa ranging from insects to mammals. In spite of the fact that hidden signals are both conspicuous and abundant, we know relatively little about their evolution and function. The aims of this study are to answer two fundamental questions, 1. how do hidden signals generate a fitness benefit, and 2. what ecological circumstances precipitate their evolution? In order to address these questions, I have combined custom-built computer games and phylogenetic character analysis. The computer games use humans as model predators, and allowed us to simulate the deployment of hidden signals while manipulating specific parameters. The phylogenetic character analysis has allowed us to test whether certain morphological and behavioural traits are correlated with the evolution of hidden signals. By combining these two independent approaches we have been able to comprehensively evaluate a variety of hypotheses regarding the evolution of hidden signals. Chapter 1 summarizes the current knowledge of hidden signals. Chapter 2 describes an experimental "proof of concept", to determine if flash displays can generate a survival benefit through one specific proposed mechanism, namely a "decoy" effect. Chapter 3 describes a phylogenetic analysis used to test whether body size (a well-known predictor of predation risk), is correlated with the evolution of hidden signals across a range of insect taxa. Chapter 4 describes an experimental test of the efficacy of startle signals in deterring an insect predator. Chapter 5 combines an experimental and phylogenetic evaluation of the implications of flight initiation distance on the anti-predation benefit of flash displays. Finally, in Chapter 6 I summarize my thoughts on the collective implications of my thesis work. Overall, I argue that hidden signals are an ecologically important adaptation that can prevent attacks through multiple mechanisms and may be selected for by a variety of predator taxa.