Sexually dimorphic laryngeal morphology in Rana pipiens

Abstract

The sexually dimorphic vocal characteristics of Rana pipiens release calls suggest that there may be differences in the anatomical components of the larynx. The volumes of the arytenoid cartilage, surrounding muscle masses, vocal cords, supporting bronchial process, and the release-call amplitudes of six males and five females were measured in same-sized animals and sexual differences assessed. No qualitative differences in laryngeal morphology were observed, but all features measured except vocal cords were significantly larger in males. The implications of an increased laryngeal size are discussed in relation to differences previously observed in the vocalizations of this and other species and in relation to prior suggestions regarding the developmental basis of anuran sexual dimorphisms.

Current research in amphibians: Studies integrating endocrinology, behavior, and neurobiology

“…The influence of androgens on male courtship signaling begins postmetamorphically with their effect on the development of the muscular systems responsible for the behavior, leading to larynges that are larger in males (Sassoon and Kelley, 1986;McClelland and Wilczynski, 1989;Ryan and Drewes, 1990;McClelland et al, 1997) with sexually dimorphic muscle fibers (Sassoon and Kelley, 1986;Sassoon et al, 1987), innervation (Robertson et al, 1994), and androgen binding characteristics (Segil et al, 1987;Boyd et al, 1999). Similar androgendependent sex differences are found in the oblique muscles of the body wall (Tiagen et al, 1985;Girgenrath and Marsh, 2003), and in the flexor carpi radialis, the forelimb flexor muscle used by males to clasp females while they oviposit (Herrera and Regnier, 1991;Regnier and Herrera, 1993;Dorlöchter et al, 1994;Sidor and Blackburn, 1998).…”

Mating Vocalizations of Female Frogs: Control and Evolutionary Mechanisms

“…Sexual differences in the release calls of R. pipiens and X. laevis are simply a result of such differences [Hannigan and Kelley, 1986;McClelland and Wilczynski, 1989]. Some interspecific and intraspecific differences in advertisement calls of males can also be accounted for by variation in the peripheral morphology [Drewry et al, 1982;Wilczynski et al, 1993;Das Munshi and Marsh, 1996;McClelland et al, 1996McClelland et al, , 1998].…”

“…Sexual dimorphisms are present in all these structures. Males have oblique and laryngeal muscles and laryngeal structures that are more than twice the size as those of females of the same body weight [Trewavas, 1933;Taigen et al, 1985;McClelland and Wilczynski, 1989;Kelley, 1996;McClelland et al, 1997]. Besides being larger, the oblique and laryngeal muscles of males are composed of different fiber types [e.g., Marsh and Taigen, 1987] and myosin heavy chain isoforms [Catz et al, 1992].…”

Fiber Type Composition of the Muscle Responsible for Throat Fan Extension in Green Anole Lizards

“…Perhaps the most extreme dimorphisms exist in mammals and lizards in which the motor neurons and/or muscles associated with penile movements are present in males and virtually absent in females [Hayes, 1965;Breedlove and Arnold, 1980;Ruiz and Wade, 2002]. In certain species of teleost fish, frogs, and birds, males produce courtship sounds unique to that sex and, accordingly, the neural and muscular structures associated with sound production are larger or more numerous in the males of these species [sonic fish : Fine et al, 1984;Bass and Marchaterre, 1989;Bass, 1990;Bass and Baker, 1990; frogs: Sassoon and Kelley, 1986;Kelley et al, 1988;McClelland and Wilczynski, 1989;Boyd et al, 1999;birds: Nottebohm and Arnold, 1976;Wade and Buhlman, 2000;Schultz et al, 2001]. Physiological properties of the muscles, such as fiber type composition, enzymatic activity and/or contractile characteristics, are also sexually dimorphic in patterns consistent with the behavior [Rubinstein et al, 1983;Sassoon et al, 1987;Walsh et al, 1987;Boyd et al, 1999;Peters and Aulner, 2000;Schultz et al, 2001;Girgenrath and Marsh, 2003].…”