Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA.
J Anat. 2021 Feb;238(2):308-320. doi: 10.1111/joa.13315. Epub 2020 Sep 29.
Sexual displays are some of the most dramatic and varied behaviors that have been documented. The elaboration of such behaviors often relies on the modification of existing morphology. To understand how display elaboration arises, we analyzed the laryngeal anatomy of three species of mice that vary in the presence and complexity of their vocal displays. Mice and rats have a specialized larynx that enables them to produce both low-frequency "audible" sounds, perhaps using vocal fold vibration, as well as distinct mechanisms that are thought to enable higher frequency sounds, such as vocal membrane vibration and intralaryngeal whistles. These mechanisms rely on different structures within the larynx. Using histology, we characterized laryngeal anatomy in Alston's singing mouse (Scotinomys teguina), the northern pygmy mouse (Baiomys taylori), and the laboratory mouse (Mus musculus), which produce different types of vocalizations. We found evidence of a vocal membrane in all species, as well as species differences in vocal fold and ventral pouch size. Presence of a vocal membrane in these three species, which are not known to use vocal membrane vibration, suggests that this structure may be widespread among muroid rodents. An expanded ventral pouch in singing and pygmy mice suggests that these mice may use an intralaryngeal whistle to produce their advertisement songs, and that an expanded ventral pouch may enable lower frequencies than laboratory mouse whistle-produced sounds. Variation in the laryngeal anatomy of rodents fits into a larger pattern across terrestrial vertebrates, where the development and modification of vocal membranes and pouches, or air sacs, are common mechanisms by which vocalizations diversify. Understanding variation in the functional anatomy of relevant organs is the first step in understanding how morphological changes enable novel displays.
性展示是最具戏剧性和多样性的行为之一，已经有文献记载。这些行为的精细化通常依赖于对现有形态的修饰。为了了解展示的精细化是如何产生的，我们分析了三种在发声表现的存在和复杂性上存在差异的小鼠的喉部解剖结构。老鼠和大鼠的喉部有专门的结构，使它们能够发出低频的“可听见”声音，可能是通过声带振动，以及被认为能产生更高频率声音的不同机制，如声膜振动和喉内哨音。这些机制依赖于喉部内的不同结构。通过组织学，我们描述了在歌唱鼠（Scotinomys teguina）、北方小偃鼠（Baiomys taylori）和实验鼠（Mus musculus）的喉部解剖结构，它们发出不同类型的叫声。我们发现所有物种都有声膜的证据，以及声带和腹囊大小的物种差异。这三种物种都有声膜，而它们并不被认为使用声膜振动，这表明这种结构可能在鼠科动物中广泛存在。歌唱鼠和小偃鼠的腹囊扩张表明，这些老鼠可能使用喉内哨音来发出它们的求爱歌曲，而且扩张的腹囊可能使声音的频率低于实验鼠哨音产生的声音。啮齿动物的喉部解剖结构的变异符合陆地脊椎动物更大的模式，其中声膜和气囊的发育和修饰是声音多样化的常见机制。了解相关器官的功能解剖结构的变异是理解形态变化如何使新的展示成为可能的第一步。
