Abstract

Character displacement, or a shift in traits where species co-occur, is one of the most common ecological patterns to result from interactions between closely related species. Usually, character displacement is associated to divergence in traits, though, they might be convergent, especially when used for aggressive interference between species. In the context of animal communication, territorial calls are predicted to converge in order to increase context recognition and decrease the costs of ecological interference competition. However, such signals might also be adapted to characteristics of the shared environment. In this study, we used data from 15 groups of two parapatric tamarins, Saguinus midas and S. bicolor, to test for similarities in long calls among sympatric and allopatric groups. We hypothesized that calls would converge in sympatric areas, as it would be mutually beneficial if both species recognize territorial contexts, but that convergence would depend on forest type due to acoustic adaptation. As predicted, long calls converged in sympatry, with S. midas shifting its calls towards S. bicolor’s acoustic pattern. However, this shift only occurred in primary forest. In sympatric areas, S. midas produced sounds with narrower bandwidths in primary than in secondary forest, consistent with optimization of sound propagation while both species produced longer calls in primary forests independently of geographic location (i.e. sympatry and allopatry). Our results suggest that both social and environmental pressures are important in shaping tamarin sounds. As their effects can interact, analyses, which assume that these ecological pressures act independently, are likely to miss important patterns.

Significance statement

Territorial signals between closely related sympatric species are expected to be convergent to increase context recognition and decrease the costs of interference competition. However, such signals might also be adapted to characteristics of the shared environment, such as forest structure characteristics. We analysed vocalisations from two parapatric tamarins and found that, though their long calls asymmetrically converged in sympatry, only red-handed tamarins shifted towards pied tamarin call type, and this only occurred in primary forest. Our results suggest that both social and environmental pressures are important in shaping primate calls. Because their effects can interact, analyses which assume that these pressures act independently, are likely to miss important patterns.

中文翻译：

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同胞绢毛猴呼叫中的收敛性字符置换（Saguinus spp。）

摘要

字符位移或物种同时发生的性状转变是密切相关物种之间相互作用的最常见生态模式之一。通常，字符位移与性状的差异相关，但是，它们可能会趋于一致，尤其是当用于物种之间的积极干扰时。在动物交流的背景下，预计领土呼声会聚，以增加背景识别并降低生态干扰竞争的成本。但是，此类信号也可能适用于共享环境的特征。在这项研究中，我们使用了来自15个小组的数据，这两个小组有两个副祖母绢毛猴Saguinus midas和S. bicolor，以测试同族和同种异体群体在长途通话中的相似性。我们假设通话会在同伴区域内汇聚，因为如果两个物种都认识到领土环境，这将是互惠互利的，但是由于声音的适应性，汇合将取决于森林类型。正如预测的那样，长话费会聚在同域，与S. MIDAS改变其呼叫朝S.双色”小号声学模式。但是，这种转变仅发生在原始林中。在同胞区，麦达斯链球菌在原始森林中产生的声音带宽比在次生森林中窄，这与声音传播的优化一致，而两种物种在原始森林中产生的呼声都更长，与地理位置无关（即共生和异变）。我们的研究结果表明，社交和环境压力在塑造绢毛猴声音方面都非常重要。由于它们的影响可以相互作用，因此假设这些生态压力独立起作用的分析可能会遗漏重要的模式。

重要性声明

密切相伴的同胞物种之间的领土信号有望会聚，以提高背景识别能力并降低干扰竞争的成本。但是，此类信号也可能适用于共享环境的特征，例如森林结构特征。我们分析了两个副para猴的发声，发现尽管它们的长鸣不对称地交汇在交响乐中，但只有红手猴向着斑状的marin猴鸣叫转变，并且仅发生在原始森林中。我们的结果表明，社会和环境压力对塑造灵长类动物的呼唤都非常重要。由于它们的影响可以相互作用，因此假设这些压力独立起作用的分析可能会遗漏重要的模式。