Related Experiment Video
Updated: Jul 14, 2026
06:34
Infant Auditory Processing and Event-related Brain Oscillations
Published on: July 1, 2015
Temporal order and the evolution of complex acoustic signals
H Carl Gerhardt1, Sarah C Humfeld, Vincent T Marshall
1Division of Biological Sciences, 215 Tucker Hall, University of Missouri, Columbia, MO 65211, USA. gerhardth@missouri.edu
Proceedings. Biological Sciences
|May 18, 2007
Summary
Complex signals evolve due to hidden preferences. In grey treefrogs, adding sounds after the main call made it more attractive, but not when added before, suggesting order matters in signal evolution.
Area of Science:
- Animal behavior
- Bioacoustics
- Evolutionary biology
Background:
- Complex animal signals may evolve due to pre-existing sensory biases or hidden preferences.
- The structure and attractiveness of signals can be influenced by various factors, including the order of signal components.
Purpose of the Study:
- To investigate how acoustic appendages affect the attractiveness of conspecific advertisement calls in grey treefrogs (Hyla chrysoscelis and Hyla versicolor).
- To determine if the order of signal components (call followed by appendage vs. appendage followed by call) influences female preference.
Main Methods:
- Female grey treefrogs were presented with synthesized compound acoustic signals.
- These signals combined a conspecific advertisement call with various acoustic appendages (other calls, noise).
- The order of the advertisement call and appendages was manipulated (call-appendage vs. appendage-call).
Main Results:
- Compound signals with appendages *following* the advertisement call were often more attractive than the advertisement call alone.
- Compound signals with appendages *preceding* the advertisement call were never more attractive and sometimes less attractive.
- An order effect was particularly pronounced in Hyla versicolor, especially when advertisement call duration was reduced.
Conclusions:
- Signal attractiveness is sensitive to the order of components, not just the presence of additional stimulation.
- These findings suggest that signal component order and other contextual effects can constrain the evolution of complex and extravagant signals in nature.
- The results challenge simple models of signal evolution based solely on pre-existing biases and highlight the importance of temporal dynamics.
Related Concept Videos
01:54Convergent Evolution
Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.The structures that arise from convergent evolution are called analogous structures. They are similar in function even if they are dissimilar in structure. Further, structures can be analogous while also...
01:30Classification of Signals
In signal processing, signals are classified based on various characteristics: continuous-time versus discrete-time, periodic versus aperiodic, analog versus digital, and causal versus noncausal. Each category highlights distinct properties crucial for understanding and manipulating signals.
A continuous-time signal holds a value at every instant in time, representing information seamlessly. In contrast, a discrete-time signal holds values only at specific moments, often denoted as x(n), where...
A continuous-time signal holds a value at every instant in time, representing information seamlessly. In contrast, a discrete-time signal holds values only at specific moments, often denoted as x(n), where...
01:31Hearing
When we hear a sound, our nervous system is detecting sound waves—pressure waves of mechanical energy traveling through a medium. The frequency of the wave is perceived as pitch, while the amplitude is perceived as loudness.
01:41Signal Sequences and Sorting Receptors
Signal sequences are short amino acid sequences that guide newly synthesized proteins to their proper location within the cell. Classical signal sequences are fifteen to sixty amino acids long and present at the N-terminus of a polypeptide chain. Each signal sequence has a conserved segment of basic residues towards their N terminus, a hydrophobic core, and a C-terminus rich in polar residues. The C-terminus also contains a signal cleavage site and features a -3 -1 sequence motif. The -3-1...
01:21Perceiving Loudness, Pitch, and Location
The human brain perceives pitch through two primary mechanisms reflected in place theory and frequency theory. Each mechanism describes how sound waves are interpreted as specific pitches by the brain, offering insights into the intricate processes of auditory perception.
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by identifying...
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by identifying...
01:13The Cochlea
The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.