Woodpeckers' drumming: Conserved meaning despite different structure
over the years

Date:
October 2, 2020
Source:
University of Zurich
Summary:
How do animals produce and perceive biological information
in sounds? To what extent does the acoustic structure and its
associated meaning change during evolution? An international
team has reconstructed the evolutionary history of an animal
communication system, focusing on drumming signals of woodpeckers.



FULL STORY ========================================================================== Animal acoustic signals are amazingly diverse. Researchers from the
University of Zurich and the University of Saint-Etienne, together with
French, American and Dutch collaborators, explored the function and diversification of animal acoustic signals and the mechanisms underlying
the evolution of animal communication systems.


==========================================================================
To this end, they used Shannon & Weaver's 'Mathematical Theory of Communication' originally applied to telecommunications in 1949, which
has transformed the scientific understanding of animal communication. This theory allows the amount of information in a signal to be quantified. The researchers were the first to use this framework within an evolutionary perspective to explore the biological information encoded in an animal
signal.

How drumming structure evolves over time In deciding which biological
model to choose, the researchers selected the woodpeckers' drumming as
their ideal candidate. This bird family is known for rapidly striking
their beaks on tree trunks to communicate. The team combined acoustic
analyses of drumming from 92 species of woodpeckers, together with
theoretic calculations, evolutionary reconstructions, investigations at
the level of ecological communities as well as playback experiments in
the field.

"We wanted to test whether drumming has evolved to enhance
species-specific biological information, thereby promoting species recognition," says lead author Maxime Garcia of the UZH Department of Evolutionary Biology and Environmental Studies.

Constant amount of information for 22 million years Results demonstrate
the emergence of new drumming types during woodpeckers evolution. Yet,
despite these changes in drumming structure, the amount of biological information about species identity has remained relatively constant for
22 million years. Selection towards increased biological information thus
does not seem to represent a major evolutionary driver in this animal communication system. How then can biological information be concretely maintained in nature? Analyses of existing communities around the globe
show that ecological arrangements facilitate the efficiency of drumming signals: Communities are composed of only a few species, which distribute
their drumming strategies to avoid acoustic overlap. "The responses to different drumming structures seen in our experimental approach show
the ability of individuals to recognize their own species based on
acoustic cues about species identity found in drumming signals," says
Garcia. This way, biological information about species identity can be maintained without necessarily inducing a strong evolutionary pressure
on drumming signals.

The present study shows that random and unpredictable changes in the
structure of communication signals over time can occur while maintaining
the signals overall informative potential within and across species. This
work leads the way to further investigate the evolution of meaning
associated with communicating through multiple communication channels.


========================================================================== Story Source: Materials provided by University_of_Zurich. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Maxime Garcia, Fre'de'ric Theunissen, Fre'de'ric Se`be, Julien
Clavel,
Andrea Ravignani, Thibaut Marin-Cudraz, Je'ro^me Fuchs, Nicolas
Mathevon.

Evolution of communication signals and information during
species radiation. Nature Communications, 2020; 11 (1) DOI:
10.1038/s41467-020- 18772-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201002091037.htm

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