Sexual dimorphism and bilateral asymmetry of syrinx and vocal tract in the European starling (Sturnus vulgaris) - PubMed (original) (raw)

. 2011 Dec;272(12):1527-36.

doi: 10.1002/jmor.11007. Epub 2011 Aug 25.

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Sexual dimorphism and bilateral asymmetry of syrinx and vocal tract in the European starling (Sturnus vulgaris)

Ben Prince et al. J Morphol. 2011 Dec.

Abstract

Sexually dimorphic vocal behavior in zebra finches (Taeniopygia guttata) is associated with a 100% larger syrinx in males and other morphological adaptations of the sound source. The songbird syrinx consists of two independent sound sources, whose specialization for different spectral ranges may be reflected in morphological properties, but the morphology of labia and syringeal skeleton have not been investigated for lateralized specializations. Similarly, little is known whether the morphology of the songbird vocal tract reflects differences in vocal behavior. Here, we tested the hypothesis that different vocal behavior and specialization is reflected in the morphology. We investigated syringeal and upper vocal tract morphology of male and female European starlings (Sturnus vulgaris). Female starlings exhibit smaller vocal repertoires and sing at lower rates than males. In males, the left syrinx produces mostly low frequencies, while the right one is used for higher notes. Macroscopic and histological techniques were used to record nineteen measurements from the syrinx and the vocal tract which were tested for sexual differences in syrinx and vocal tract and for lateral asymmetry within the syrinx. Sexually dimorphic vocal behavior is reflected in the morphology of the starling syrinx. Males have a larger syrinx with the size difference attributable to increased muscle mass and three enlarged elements of the syringeal skeleton. The upper vocal tract, however, does not differ between males and females. Distinct lateralization was found in two elements of the syringeal skeleton of females, and the labia in the left syrinx are larger than those on the right in both sexes. The sexual dimorphism of the syringeal size is smaller in starlings (35%) than in zebra finches (100%), which is consistent with the different vocal behavior of females in both species. The morphological differences between the two sound sources are discussed in relation to their vocal performance.

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Figures

Fig. 1

Fig. 1

A: Schematic ventral view of a syrinx. The grey plane indicates the section level of the other images (B–D). B: Schematic of a mid-organ section through syrinx indicating all elements measured. C: Mid-organ section of three male syringes (HandE stain). D: Mid-organ section of three female syringes (HandE stain). Note the smaller muscle mass in females. The bar in D indicates a 1 mm distance and applies to C and D. M, intrinsic syringeal muscles; B, primary bronchi; T, trachea; LL, lateral labia; ML, medial labia; MTM, medial tympaniform membrane; Ty, tympanum; P, pessulus; A1, A2, A3, first, second and third bronchial half ring.

Fig. 2

Fig. 2

Syrinx measurements from dorsal (level 1) to ventral (level 10) in male and female starlings. Data from the left syrinx are shown in the left column and data from the right in the right column. Circles (females) and triangles (males) indicate means and error bars indicate standard deviation. LL, lateral labia; ML, medial labia; MTM, medial tympaniform membrane; Ty, tympanum; P, pessulus; A1, A2, A3, first, second and third bronchial half ring.

Fig. 2

Fig. 2

Syrinx measurements from dorsal (level 1) to ventral (level 10) in male and female starlings. Data from the left syrinx are shown in the left column and data from the right in the right column. Circles (females) and triangles (males) indicate means and error bars indicate standard deviation. LL, lateral labia; ML, medial labia; MTM, medial tympaniform membrane; Ty, tympanum; P, pessulus; A1, A2, A3, first, second and third bronchial half ring.

Fig. 3

Fig. 3

Partial mid-organ sections of two male (A,B) and two female syringes (C,D). The dotted square in the schematic on top indicates the location of the images in A–D. The cranio-caudal length of the medial tympaniform membrane (MTM) was measured between the transition between labium and MTM and the point where the interbronchial desmus (IBD), a band of connective tissue and muscle, connects to the bronchus (indicated by arrows). Bar in C: 100 lm, applies to all images. LL, lateral labia; Ty, tympanum; P, pessulus; A1, A2, A3, first, second and third bronchial half ring.

Fig. 4

Fig. 4

Left-right ratio of syringeal measurements. Circles are females and triangles are males. Levels 1 to 10 represent dorsal to ventral. LL, lateral labia; ML, medial labia; MTM, medial tympaniform membrane; Ty, tympanum; P, pessulus; A1, A2, A3, first, second and third bronchial half ring.

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References

    1. Bermúdez-Cuamatzin E, Ríos-Chelén AA, Gil D, Macías Garcia C. Experimental evidence for real-time song frequency shift in response to urban noise in a passerine bird. Biol Lett. 2011;7:36–38. - PMC - PubMed
    1. Bernard DJ, Castro JM, Ball GF. Sexual dimorphism in the volume of song control nuclei in European Starlings: Assessment by a Nissl stain and autoradiography for musca-rinic cholinergic receptors. J Comp Neurol. 1993;334:559–570. - PubMed
    1. Cooke B, Hegstrom CD, Villeneuve LS, Breedlove SM. Sexual differentiation of the vertebrate brain: Principles and mechanisms. Front Neuroendocrin. 1998;19:323–362. - PubMed
    1. Daley M, Goller F. Tracheal length changes during zebra finch song and their possible role in upper vocal tract filtering. J Neurobiol. 2004;59:319–330. - PubMed
    1. Eens M. Understanding the complex song of the European starling: An integrated ethological approach. Adv Study Beh. 1997;26:355–434.

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