The eyes have it: the neuroethology, function and evolution of social gaze

The power of sexual selection to drive changes in mate recognition traits gives it the potential to be a potent force in speciation. Much of the evidence to support this possibility comes from comparative studies that examine differences in the number of species between clades that apparently differ in the intensity of sexual selection. We argue that more detailed studies are needed, examining extinction rates and other sources of variation in species richness. Typically, investigations of extant natural populations have been too indirect to convincingly conclude speciation by sexual selection. Recent empirical work, however, is beginning to take a more direct approach and rule out confounding variables.

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Sexual selection and speciation.

Publisher Summary Environmental noise can affect acoustic communication through limiting the broadcast area, or active space, of a signal by decreasing signal-to-noise ratios at the position of the receiver. At the same time, noise is ubiquitous in all habitats and is, therefore, likely to disturb animals, as well as humans, under many circumstances. However, both animals and humans have evolved diverse solutions to the background noise problem, and this chapter reviews recent advancements in studies of vocal adaptations to interference by background noise and relate these to fundamental issues in sound perception. The chapter starts with the discussion of sender's side by considering potential evolutionary shaping of species-specific signal characteristics and individual short‐term adjustments of signal features. Subsequently, it focuses on the receivers of signals and reviews their sensory capacities for signal detection, recognition, and discrimination and relates these issues to auditory scene analysis and the ecological concept of signal space. The data from studies on insects, anurans, birds, and mammals, including humans, and to a lesser extent available work on fish and reptiles is also discussed in the chapter.

Acoustic Communication in Noise

The basic building blocks of communication are signals, assembled in various sequences and combinations, and used in virtually all inter- and intra-specific interactions. While signal evolution has long been a focus of study, there has been a recent resurgence of interest and research in the complexity of animal displays. Much past research on signal evolution has focused on sensory specialists, or on single signals in isolation, but many animal displays involve complex signaling, or the combination of more than one signal or related component, often serially and overlapping, frequently across multiple sensory modalities. Here, we build a framework of functional hypotheses of complex signal evolution based on content-driven (ultimate) and efficacy-driven (proximate) selection pressures (sensu Guilford and Dawkins 1991). We point out key predictions for various hypotheses and discuss different approaches to uncovering complex signal function. We also differentiate a category of hypotheses based on inter-signal interactions. Throughout our review, we hope to make three points: (1) a complex signal is a functional unit upon which selection can act, (2) both content and efficacy-driven selection pressures must be considered when studying the evolution of complex signaling, and (3) individual signals or components do not necessarily contribute to complex signal function independently, but may interact in a functional way.

/pdf/complex-signal-function-developing-a-framework-of-testable-1thds4dbke.pdf

Complex signal function: developing a framework of testable hypotheses

The Evolution of Language

Part 1 Production, transmission, and reception of signals: the properties of sound fourier analysis sound production sound propogation sound reception properties of light production and transmission of light signals light signal reception chemical signals electroreception. Part 2 Optimizing information transfer: optimizing communication the amount of information the value of information coding signal evolution costs and constraints on signal evolution signal design rules. Part 3 Game theory and signalling strategies: evolutionary game theory signal honesty conflict resolution territorial signalling games mating games and signalling social integration environmental signals autocommunication.

Principles of Animal Communication

Principles of animal communication, 2nd ed.

Economic models of animal communication.

We explore the effectiveness of spectrographs cross-correlation (SPCC) combined with principal coordinates (PCO) analysis as a method for sound comparison. We do this using synthetic sounds modeled after the individually-distinctive, harmonically-rich contact calls of wild orange-fronted conures Aratinga canicularis. Calls with acoustic properties similar to Aratinga contact calls are common in other taxa including non-oscine birds, primates and cetaceans. We generated signals with known variations in time-frequency pattern, duration, noise level, harmonic content and harmonic weighting, and applied SPCC-PCO analysis to obtain an ordering of sounds in n-dimensional space. We find that shared time-frequency patterns dominate the positioning of sounds in PCO space. This was true despite high variability in signal-to-noise ratio (from −60 to +40 dB) and duration (150–275 ms). Furthermore, inclusion of naturally-weighted harmonics (versus fundamentals only) enhances, rather than obscures, the separat...

Jack W. Bradbury

Papers

Principles of Animal Communication

Principles of animal communication, 2nd ed.

Economic models of animal communication.

The comparison of harmonically rich sounds using spectrographic cross-correlation and principal coordinates analysis

Contact call diversity in wild orange-fronted parakeet pairs, Aratinga canicularis