title: Sexual dimorphism and bilateral asymmetry of syrinx and vocal tract in the European starling (Sturnus vulgaris).
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.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Ben
authors.initials: B
authors.lastname: Prince
authors.forename: Tobias
authors.initials: T
authors.lastname: Riede
authors.forename: Franz
authors.initials: F
authors.lastname: Goller
mesh_terms: D000818:Animals; D005260:Female; D008297:Male; D009929:Organ Size; D012737:Sex Factors; D046749:Starlings / Q000033:anatomy & histology* / Q000502:physiology; D014132:Trachea / Q000033:anatomy & histology* / Q000502:physiology; D014828:Vocalization, Animal / Q000502:physiology*
references.citation: Anim Behav. 2000 Feb;59(2):443-458
references.pmid: 10675267
references.citation: J Neurobiol. 2004 Jun;59(3):289-303
references.pmid: 15146546
references.citation: Proc Biol Sci. 2010 Feb 7;277(1680):469-73
references.pmid: 19846451
references.citation: J Neurobiol. 2004 Jun;59(3):319-30
references.pmid: 15146548
references.citation: Proc Biol Sci. 2007 Nov 7;274(1626):2703-10
references.pmid: 17725979
references.citation: J Anat. 2010 Jan;216(1):23-36
references.pmid: 19900184
references.citation: PLoS One. 2010 Jul 30;5(7):e11923
references.pmid: 20689831
references.citation: J Anat. 2007 Dec;211(6):717-36
references.pmid: 17971116
references.citation: Ann N Y Acad Sci. 2004 Jun;1016:109-29
references.pmid: 15313772
references.citation: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2005 Feb;191(2):97-104
references.pmid: 15711965
references.citation: Eur J Appl Physiol Occup Physiol. 1980 Feb;43(1):25-34
references.pmid: 7371625
references.citation: Biol Lett. 2011 Feb 23;7(1):36-8
references.pmid: 20610421
references.citation: J Neurophysiol. 1996 Jul;76(1):287-300
references.pmid: 8836225
references.citation: Proc Natl Acad Sci U S A. 2006 Apr 4;103(14):5543-8
references.pmid: 16567614
references.citation: Dev Neurobiol. 2009 Jun;69(7):462-75
references.pmid: 19373862
references.citation: J Comp Neurol. 2000 Oct 9;426(1):154-64
references.pmid: 10980490
references.citation: J Exp Biol. 2010 Apr;213(Pt 7):1069-78
references.pmid: 20228343
references.citation: Gen Comp Endocrinol. 2004 Apr;136(2):192-9
references.pmid: 15028522
references.citation: Behav Processes. 2009 Nov;82(3):312-8
references.pmid: 19665530
references.citation: Philos Trans R Soc Lond B Biol Sci. 1999 May 29;354(1385):927-39
references.pmid: 10382225
references.citation: Ann Otol Rhinol Laryngol. 2000 Jan;109(1):77-85
references.pmid: 10651418
references.citation: Front Neuroendocrinol. 1998 Oct;19(4):323-62
references.pmid: 9799588
references.citation: Ann N Y Acad Sci. 2004 Jun;1016:130-52
references.pmid: 15313773
references.citation: J Acoust Soc Am. 2008 Jul;124(1):634-47
references.pmid: 18647005
references.citation: J Acoust Soc Am. 2006 Feb;119(2):1005-11
references.pmid: 16521762
references.citation: PLoS One. 2010 Jun 29;5(6):e11368
references.pmid: 20614010
references.citation: J Exp Biol. 2008 Jun;211(Pt 12):1978-91
references.pmid: 18515729
references.citation: Brain Res. 1980 Jun 16;192(1):89-107
references.pmid: 7378793
references.citation: Brain Res. 2003 Jul 18;978(1-2):91-8
references.pmid: 12834902
references.citation: J Neurophysiol. 1996 Feb;75(2):867-76
references.pmid: 8714659
references.citation: Proc Natl Acad Sci U S A. 1997 Dec 23;94(26):14787-91
references.pmid: 9405691
references.citation: Brain Lang. 2010 Oct;115(1):69-80
references.pmid: 20153887
references.citation: J Exp Biol. 1993 Sep;182:147-71
references.pmid: 8228778
references.citation: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2011 Jan;197(1):45-59
references.pmid: 20852867
references.citation: Proc Biol Sci. 2004 Mar 7;271(1538):483-91
references.pmid: 15129958
references.citation: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2009 Feb;195(2):183-92
references.pmid: 19082607
references.citation: J Comp Neurol. 1993 Aug 22;334(4):559-70
references.pmid: 7691901
references.citation: Science. 1976 Oct 8;194(4261):211-3
references.pmid: 959852
references.citation: Brain Res. 2002 Mar 8;929(2):191-201
references.pmid: 11864624
references.citation: J Neurobiol. 1999 Aug;40(2):202-13
references.pmid: 10413450
references.citation: J Neurobiol. 1999 Dec;41(4):513-23
references.pmid: 10590175
references.citation: J Exp Biol. 2004 Feb;207(Pt 4):607-19
references.pmid: 14718504
references.citation: J Exp Biol. 2000 Jun;203(Pt 12):1845-55
references.pmid: 10821742