a more narrow message, such as information about the identity of a specific
individual within a group. Sounds might be used in such contexts as mate
selection, predator avoidance, parental behavior, foraging, and coordinating group activities. Within these different behavioral contexts, sounds may
communicate the sender’s motivational or cognitive state. Transmission of
the message of species identity in the form of mating or advertisement
signals has been a major topic of study both in the ethological and in the
neuroethological literature (Ryan and Kime, Chapter 5). Fitch and Hauser
(Chapter 3), Boughman and Moss (Chapter 4), and Yamaguchi and Kelley
(Chapter 6) all add to this literature by their neuroethological analyses of
the evolution, function and/or hormonal mechanisms underlying other
types of communication sounds, such as courtship calls, alarm calls, contact
calls, and isolation calls. In particular, Boughman and Moss ask whether
certain kinds of acoustic signals used by animals can be understood as individual signatures, much like names.
The transfer of information in animal communication systems is sometimes presumed to be intentional and of mutual benefit both to the sender
and the receiver.An example of this mutual benefit is the male túngara frog,
Physalaemus pustulosus, vocalizing to attract females to him for mating.
However, sound by its very nature moves in all directions from its source
and, because it is broadcast, can be detected by any receiver within range.
Thus, information transfer either to conspecific animals (competitors) or to
heterospecific animals (predators) can be an unwanted by-product of the
communicative process. Ryan and Kime (Chapter 5) discuss, among other
examples, how the fringe-lipped bat, Trachops cirrhosus, exploits the male
túngara frog’s calling behavior to locate him as prey. These unintended consequences of acoustic communication play an important role in the evolution of signal structure.
The issues of intent and mutual benefit in communicative interactions are
further analyzed by Fitch and Hauser (Chapter 3) in the context of the role
of honesty in communication. Dawkins and Krebs (1978) first proposed
that, from an evolutionary point of view, communication signals are
designed to manipulate the behavior of receivers to the advantage of signalers and thus do not necessarily convey an accurate (honest) picture of
the signaler. Fitch and Hauser analyze this proposition in terms of the mechanisms of signal production, arguing that morphological features of the
signaler (such as body size and length of the vocal tract) constrain the form
and the variability of communication sounds and thus their ability to
deceive a receiver. These physiological constraints may maintain signal
honesty in the absence of any particular selective pressure for honesty.
Communication is also described as a process by which one individual’s
(the sender) behavior effects some change in a second individual (the
receiver). These changes can be behavioral, hormonal, or morphological.
Most often, we focus on behavioral changes because these are readily
observable. A good example is mate calling by male anurans. Here, we say
1. Acoustic Communication
5
individual within a group. Sounds might be used in such contexts as mate
selection, predator avoidance, parental behavior, foraging, and coordinating group activities. Within these different behavioral contexts, sounds may
communicate the sender’s motivational or cognitive state. Transmission of
the message of species identity in the form of mating or advertisement
signals has been a major topic of study both in the ethological and in the
neuroethological literature (Ryan and Kime, Chapter 5). Fitch and Hauser
(Chapter 3), Boughman and Moss (Chapter 4), and Yamaguchi and Kelley
(Chapter 6) all add to this literature by their neuroethological analyses of
the evolution, function and/or hormonal mechanisms underlying other
types of communication sounds, such as courtship calls, alarm calls, contact
calls, and isolation calls. In particular, Boughman and Moss ask whether
certain kinds of acoustic signals used by animals can be understood as individual signatures, much like names.
The transfer of information in animal communication systems is sometimes presumed to be intentional and of mutual benefit both to the sender
and the receiver.An example of this mutual benefit is the male túngara frog,
Physalaemus pustulosus, vocalizing to attract females to him for mating.
However, sound by its very nature moves in all directions from its source
and, because it is broadcast, can be detected by any receiver within range.
Thus, information transfer either to conspecific animals (competitors) or to
heterospecific animals (predators) can be an unwanted by-product of the
communicative process. Ryan and Kime (Chapter 5) discuss, among other
examples, how the fringe-lipped bat, Trachops cirrhosus, exploits the male
túngara frog’s calling behavior to locate him as prey. These unintended consequences of acoustic communication play an important role in the evolution of signal structure.
The issues of intent and mutual benefit in communicative interactions are
further analyzed by Fitch and Hauser (Chapter 3) in the context of the role
of honesty in communication. Dawkins and Krebs (1978) first proposed
that, from an evolutionary point of view, communication signals are
designed to manipulate the behavior of receivers to the advantage of signalers and thus do not necessarily convey an accurate (honest) picture of
the signaler. Fitch and Hauser analyze this proposition in terms of the mechanisms of signal production, arguing that morphological features of the
signaler (such as body size and length of the vocal tract) constrain the form
and the variability of communication sounds and thus their ability to
deceive a receiver. These physiological constraints may maintain signal
honesty in the absence of any particular selective pressure for honesty.
Communication is also described as a process by which one individual’s
(the sender) behavior effects some change in a second individual (the
receiver). These changes can be behavioral, hormonal, or morphological.
Most often, we focus on behavioral changes because these are readily
observable. A good example is mate calling by male anurans. Here, we say
1. Acoustic Communication
5