Campbell Polly, Pasch Bret, Warren Ashley L, Phelps Steven M
Department of Zoology, Oklahoma State University, Stillwater, Oklahoma, United States of America.
Bioacoustics Research Program and Macaulay Library, Cornell Lab of Ornithology, Ithaca, New York, United States of America.
PLoS One. 2014 Dec 3;9(12):e113628. doi: 10.1371/journal.pone.0113628. eCollection 2014.
Isolation calls produced by dependent young are a fundamental form of communication. For species in which vocal signals remain important to adult communication, the function and social context of vocal behavior changes dramatically with the onset of sexual maturity. The ontogenetic relationship between these distinct forms of acoustic communication is surprisingly under-studied. We conducted a detailed analysis of vocal development in sister species of Neotropical singing mice, Scotinomys teguina and S. xerampelinus. Adult singing mice are remarkable for their advertisement songs, rapidly articulated trills used in long-distance communication; the vocal behavior of pups was previously undescribed. We recorded 30 S. teguina and 15 S. xerampelinus pups daily, from birth to weaning; 23 S. teguina and 11 S. xerampelinus were recorded until sexual maturity. Like other rodent species with poikilothermic young, singing mice were highly vocal during the first weeks of life and stopped vocalizing before weaning. Production of first advertisement songs coincided with the onset of sexual maturity after a silent period of ≧2 weeks. Species differences in vocal behavior emerged early in ontogeny and notes that comprise adult song were produced from birth. However, the organization and relative abundance of distinct note types was very different between pups and adults. Notably, the structure, note repetition rate, and intra-individual repeatability of pup vocalizations did not become more adult-like with age; the highly stereotyped structure of adult song appeared de novo in the first songs of young adults. We conclude that, while the basic elements of adult song are available from birth, distinct selection pressures during maternal dependency, dispersal, and territorial establishment favor major shifts in the structure and prevalence of acoustic signals. This study provides insight into how an evolutionarily conserved form of acoustic signaling provides the raw material for adult vocalizations that are highly species specific.
依赖期幼崽发出的隔离叫声是一种基本的交流形式。对于那些声音信号在成年个体交流中仍很重要的物种而言，随着性成熟的开始，发声行为的功能和社会背景会发生巨大变化。令人惊讶的是，这些不同形式的声学交流之间的个体发生关系却鲜有研究。我们对新热带歌鼠的姐妹物种——特古伊纳歌鼠（Scotinomys teguina）和黄喉歌鼠（S. xerampelinus）的发声发育进行了详细分析。成年歌鼠以其求偶歌曲而闻名，这些歌曲是用于远距离交流的快速清晰的颤音；幼崽的发声行为此前未被描述过。我们每天记录30只特古伊纳歌鼠和15只黄喉歌鼠幼崽从出生到断奶的情况；记录了23只特古伊纳歌鼠和11只黄喉歌鼠直至其性成熟。与其他幼崽体温随环境变化的啮齿动物物种一样，歌鼠在出生后的头几周内非常爱叫，在断奶前就停止发声了。第一首求偶歌曲的产生与至少两周的沉默期后的性成熟开始时间一致。发声行为的物种差异在个体发育早期就出现了，构成成年歌曲的音符从出生就开始产生。然而，幼崽和成年个体之间不同音符类型的组织和相对丰度有很大差异。值得注意的是，幼崽发声的结构、音符重复率和个体内重复性并不会随着年龄增长而变得更像成年个体；成年歌曲高度刻板的结构在年轻成年个体的第一首歌曲中是全新出现的。我们得出结论，虽然成年歌曲的基本元素从出生就存在，但在母性依赖、扩散和领地建立过程中不同的选择压力有利于声学信号的结构和流行程度发生重大变化。这项研究深入了解了一种进化上保守的声学信号形式如何为高度物种特异性的成年发声提供原材料。
