Data from: Does vocal learning accelerate acoustic diversification? Evolution of contact calls in neotropical parrots

Learning has been traditionally though to accelerate the evolutionary change of behavioral traits. We evaluated the evolutionary rate of learned vocalizations and the interplay of morphology and ecology in the evolution of these signals. We examined contact calls of 51 species of Neotropical parrots from the tribe Arini. Parrots are ideal subjects due to their wide range of body sizes and habitats, and their open-ended vocal learning that allows them to modify their calls throughout life. We estimated the evolutionary rate of acoustic parameters of parrot contact calls and directly compared them to those of morphological traits and habitat. We also evaluated the effect of body mass, bill length, vegetation density, and species interactions on acoustic parameters of contact calls while controlling for phylogeny. Evolutionary rates of acoustic parameters did not differ from those of our predictor variables except for spectral entropy, which had a significantly slower rate of evolution. We found support for correlated evolution of call duration, and fundamental and peak frequencies with body mass, and of fundamental frequency with bill length. The degree of sympatry between species did not have a significant effect on acoustic parameters. Our results suggest that parrot contact calls, which are learned acoustic signals, show evolutionary rates similar to those of morphological traits. This is the first study to our knowledge to provide evidence that change through cultural evolution does not necessarily accelerate the evolutionary rate of traits acquired through life-long vocal learning.

长期以来，学界普遍认为学习可加速行为性状的演化变迁。本研究针对习得发声的演化速率，以及形态学与生态学因素在这类信号演化过程中的相互作用展开评估。研究对象为来自金刚鹦鹉族（Arini）的51种新热带区鹦鹉的联络鸣叫。鹦鹉是理想的研究模型，原因在于其体型与栖息环境跨度极广，且具备开放式发声学习能力——可在终生中持续调整自身鸣唱。本研究估算了鹦鹉联络鸣叫的声学参数演化速率，并将其直接与形态性状及栖息生境的演化速率进行对比。同时，本研究在控制系统发育（phylogeny）关系的前提下，评估了体重、喙长、植被密度以及物种间相互作用对联络鸣叫声学参数的影响。除频谱熵（spectral entropy）的演化速率显著更慢外，声学参数的演化速率与本研究的预测变量并无显著差异。研究结果证实，鸣叫时长、基频与峰值频率的演化与体重存在协同演化关系，基频的演化亦与喙长存在协同演化关系。物种间的同域分布程度对声学参数无显著影响。本研究结果表明，作为习得性声学信号的鹦鹉联络鸣叫，其演化速率与形态性状的演化速率相近。据我们所知，本研究首次提供证据表明，通过文化演化实现的性状改变，未必会加速终身发声学习所获得的性状的演化速率。