Amaya Juan Pablo, Areta Juan Ignacio
Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR-CONICET), Anillaco, La Rioja, Argentina.
Universidad Nacional de La Rioja (UNLAR), La Rioja, Argentina.
PeerJ. 2018 Feb 14;6:e4334. doi: 10.7717/peerj.4334. eCollection 2018.
Tuco-tucos ( spp.) are subterranean rodents that produce territorial, high intensity long-range vocalizations (LRVs) of broadband and low frequency that are essential for long-distance communication between individuals in different tunnel systems. Despite their importance, the development of LRVs remains poorly understood. In adult Anillaco Tuco-Tucos ( sp.) the LRV is composed by two types of syllables (series and individual notes) that are repeated a variable number of times. We studied the development of the LRVs in eight juveniles of the Anillaco Tuco-Tuco ranging from 14-28 to 104-118 days after birth. We (1) tested whether the syllables followed any of three alternative developmental modes (retention of juvenile vocalizations, modification of juvenile precursors or appearance in adults), (2) evaluated the development of structural and acoustic features of syllables, and (3) tested the prediction that juveniles should produce a greater proportion of atypical series in precursors of the LRV than adults, due to lack maturation and/or precise coupling of neuromuscular and anatomical structures. The LRV of the Anillaco Tuco-Tuco exhibited a mixed developmental mode: while series developed from juvenile precursors whose acoustic features gradually approached those of adults, individual notes appeared later in the ontogeny and with acoustic features indistinguishable from those of adults. The number of series per vocalization increased through development and varied from one to 25 in juvenile males and from one to six in juvenile females. The structure of the most common series type (triad) did not exhibit ontogenetic changes and was present as such at the onset of the emission of vocalizations. On the contrary, acoustic features of juvenile triad notes changed with age in both sexes (duration 90% increased through development, while bandwidth 90% and peak frequency decreased). Furthermore, juveniles emitted a higher proportion of atypical series than adults (7.4% vs. 0.3%), as expected in the development of any complex behavior that requires practice to be mastered. The maturation of the LRV occurred well before the sexual maturation, presumably due to the protracted time needed to acquire or build a burrow system long before mating is possible. We propose that protracted vocal development is another component in the slow developmental strategy of and subterranean rodents in general.
土豚鼠（spp.）是地下啮齿动物，它们会发出具有领地性的、高强度的长距离叫声（LRVs），这种叫声宽带且低频，对于不同隧道系统中的个体之间的长距离通讯至关重要。尽管其很重要，但LRVs的发育仍知之甚少。在成年阿尼拉科土豚鼠（sp.）中，LRV由两种音节（系列音和单音）组成，这些音节会重复不同的次数。我们研究了8只阿尼拉科土豚鼠幼崽从出生后14 - 28天到104 - 118天期间LRVs的发育情况。我们（1）测试音节是否遵循三种发育模式中的任何一种（保留幼年叫声、修改幼年前体或在成年期出现），（2）评估音节的结构和声学特征的发育，（3）测试这样一个预测，即由于神经肌肉和解剖结构缺乏成熟和/或精确耦合，幼崽在LRV前体中应比成年个体产生更高比例的非典型系列。阿尼拉科土豚鼠的LRV表现出一种混合发育模式：系列音从幼年前体发育而来，其声学特征逐渐接近成年个体，而单音在个体发育后期出现，且声学特征与成年个体无法区分。每次叫声中系列音的数量随着发育而增加，幼年雄性从1个到25个不等，幼年雌性从1个到6个不等。最常见系列类型（三元组）的结构没有表现出个体发育变化，在发声开始时就已存在。相反，幼年三元组音符的声学特征在两性中都随年龄变化（持续时间在发育过程中增加了90%，而带宽90%和峰值频率降低）。此外，幼崽发出的非典型系列比例高于成年个体（7.4%对0.3%），这在任何需要通过练习才能掌握的复杂行为的发育过程中是预期的。LRV的成熟发生在性成熟之前很久，大概是因为在交配可能之前很久就需要很长时间来获取或建造洞穴系统。我们提出，长期的发声发育是土豚鼠以及一般地下啮齿动物缓慢发育策略的另一个组成部分。
