often highly stereotyped, with minimal variation among individuals. On the
other hand, signals used to convey aggressive or sexual motivation are often
more variable or graded, so that the acoustic variation in the signal could
provide to the receiver an indication of the motivational level of the sender.
Marler’s (1955) analysis inspired a great deal of research on quantitative
analysis of acoustic signals and on the formulation of “motivationalstructural rules” for predicting signal form and function (Morton 1975;
Marten and Marler 1977; see Ryan and Kime, Chapter 5).
Since these early studies, evidence has accumulated that the structure of
long-distance communication signals reflects the acoustic habitat of the
species. This “acoustic adaptation hypothesis” is discussed by Ryan and
Kime (Chapter 5) for transmission of sounds in air. As they point out, the
structure of signals is also influenced by morphological constraints (such as
body and larynx size; see also Fitch and Hauser, Chapter 3) and the evolutionary history of the species under consideration. In contrast, the physical
acoustics of signal production cannot predict the structure of vocal signals
used by teleost fishes living in shallow water (Bass and Clark, Chapter 2).
This means that animals cannot always fully exploit the acoustic features
that would theoretically provide maximal transmission in a given environment. Sensory and motor adaptations used by species to circumvent or
exploit these constraints are discussed by Bass and Clark (Chapter 2) and
by Fitch and Hauser (Chapter 3) for underwater and in-air communication,
respectively.
Finally, deciphering the message depends on detecting individual acoustic
features in the signals. However, even in animals, such as frogs, with a
restricted number of relatively well-defined and stereotyped signals, the
receiver’s responses are often guided by a combination of individual
acoustic features rather than by a particular feature alone (Gerhardt 1992).
Careful quantitative analysis of acoustic parameters, both in isolation and
in combination with one another, are needed to determine the relative biological importance of particular signals (Boughman and Moss, Chapter 4).
2.2. Ontogeny and Learning
Debates on the relative roles of genetics and learning in mediating behavior have had a long history in both psychology and biology. In the neuroethological literature, these issues have been discussed primarily in two
contexts: the perception and production of mating songs by orthopteran
insects, where genetic factors are primary (Bentley and Hoy 1972), and the
perception and production of song in oscine birds, where learning is the
predominant mechanism (Marler 1970; Hauser 1997). Detailed analysis of
these issues in other animals is relatively less complete. In social animals
with parental care or overlap of generations, experiments to tease out the
relative roles of genetic mechanisms and learning in the development of
call comprehension and call production can be difficult to design and diffi1. Acoustic Communication
7
other hand, signals used to convey aggressive or sexual motivation are often
more variable or graded, so that the acoustic variation in the signal could
provide to the receiver an indication of the motivational level of the sender.
Marler’s (1955) analysis inspired a great deal of research on quantitative
analysis of acoustic signals and on the formulation of “motivationalstructural rules” for predicting signal form and function (Morton 1975;
Marten and Marler 1977; see Ryan and Kime, Chapter 5).
Since these early studies, evidence has accumulated that the structure of
long-distance communication signals reflects the acoustic habitat of the
species. This “acoustic adaptation hypothesis” is discussed by Ryan and
Kime (Chapter 5) for transmission of sounds in air. As they point out, the
structure of signals is also influenced by morphological constraints (such as
body and larynx size; see also Fitch and Hauser, Chapter 3) and the evolutionary history of the species under consideration. In contrast, the physical
acoustics of signal production cannot predict the structure of vocal signals
used by teleost fishes living in shallow water (Bass and Clark, Chapter 2).
This means that animals cannot always fully exploit the acoustic features
that would theoretically provide maximal transmission in a given environment. Sensory and motor adaptations used by species to circumvent or
exploit these constraints are discussed by Bass and Clark (Chapter 2) and
by Fitch and Hauser (Chapter 3) for underwater and in-air communication,
respectively.
Finally, deciphering the message depends on detecting individual acoustic
features in the signals. However, even in animals, such as frogs, with a
restricted number of relatively well-defined and stereotyped signals, the
receiver’s responses are often guided by a combination of individual
acoustic features rather than by a particular feature alone (Gerhardt 1992).
Careful quantitative analysis of acoustic parameters, both in isolation and
in combination with one another, are needed to determine the relative biological importance of particular signals (Boughman and Moss, Chapter 4).
2.2. Ontogeny and Learning
Debates on the relative roles of genetics and learning in mediating behavior have had a long history in both psychology and biology. In the neuroethological literature, these issues have been discussed primarily in two
contexts: the perception and production of mating songs by orthopteran
insects, where genetic factors are primary (Bentley and Hoy 1972), and the
perception and production of song in oscine birds, where learning is the
predominant mechanism (Marler 1970; Hauser 1997). Detailed analysis of
these issues in other animals is relatively less complete. In social animals
with parental care or overlap of generations, experiments to tease out the
relative roles of genetic mechanisms and learning in the development of
call comprehension and call production can be difficult to design and diffi1. Acoustic Communication
7