Evolutionary Trade-Off between Vocal Tract and Testes Dimensions in Howler Monkeys
Evolutionary Trade-Off between Vocal Tract and Testes Dimensions in Howler Monkeys
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DOI：
10.1016/j.cub.2015.09.029
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发表时间：
2015-11-02
期刊：
影响因子：
9.2
通讯作者：
Knapp, Leslie A.
中科院分区：
文献类型：
--
作者：
Dunn, Jacob C.;Halenar, Lauren B.;Knapp, Leslie A.
男性经常面临着在交配前和交配后特征投资之间的权衡[1]，特别是当男性之间的竞争决定了获得配偶的机会[2]。到目前为止，对前刺激策略的研究主要集中在视觉装饰上（例如，颜色）或武器形态（例如，鹿角、角和犬齿）。然而，发声也可以在男性竞争和女性选择中发挥重要作用[3-5]。我们调查了雄性吼猴（Alouatta spp.）声道尺寸的变化，它使用高度专业化和大大扩大的舌骨和喉产生响亮的咆哮[6]。我们研究了雄猴舌骨和睾丸的相对投资与雄猴竞争水平的关系，并分析了舌骨形态变化的声学后果。物种的特点是单男性群体有大的舌骨和小睾丸，这表明高水平的声音介导的竞争。较大的舌骨降低共振峰频率，可能会增加男性身体大小的声学印象，并发挥类似于大型身体尺寸或武器的投资的作用。在不同物种中，随着每组雄性数量的增加，睾丸体积也会增加，表明交配后精子竞争水平较高，而舌骨体积则会减少。这些结果提供了第一个证据的进化之间的权衡投资precopulatory声乐特征和postcopulatory精子生产。
Males often face a trade-off between investments in precopulatory and postcopulatory traits [1], particularly when male-male contest competition determines access to mates [2]. To date, studies of precopulatory strategies have largely focused on visual ornaments (e.g., coloration) or weapon morphology (e.g., antlers, horns, and canines). However, vocalizations can also play an important role in both male competition and female choice [3-5]. We investigated variation in vocal tract dimensions among male howler monkeys (Alouatta spp.), which produce loud roars using a highly specialized and greatly enlarged hyoid bone and larynx [6]. We examined the relative male investment in hyoids and testes among howler monkey species in relation to the level of male-male competition and analyzed the acoustic consequences of variation in hyoid morphology. Species characterized by single-male groups have large hyoids and small testes, suggesting high levels of vocally mediated competition. Larger hyoids lower formant frequencies, probably increasing the acoustic impression of male body size and playing a role analogous to investment in large body size or weaponry. Across species, as the number of males per group increases, testes volume also increases, indicating higher levels of postcopulatory sperm competition, while hyoid volume decreases. These results provide the first evidence of an evolutionary trade-off between investment in precopulatory vocal characteristics and postcopulatory sperm production.